clang warns on this because it has an unannotated fall-through between
cases:
arch/x86/kvm/x86.c:4819:2: error: unannotated fall-through between switch labels [-Werror,-Wimplicit-fallthrough]
and while we could annotate it as a fallthrough, the proper fix is to
just add the break for this case, instead of falling through to the
default case and the break there.
gcc also has that warning, but it looks like gcc only warns for the
cases where they fall through to "real code", rather than to just a
break. Odd.
Fixes: d30d9ee94c ("KVM: x86: Only advertise KVM_CAP_READONLY_MEM when supported by VM")
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Tom Dohrmann <erbse.13@gmx.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
- Fixup missed comments from the REMOVED_SPTE=>FROZEN_SPTE rename.
- Ensure a root is successfully loaded when pre-faulting SPTEs.
- Grab kvm->srcu when handling KVM_SET_VCPU_EVENTS to guard against accessing
memslots if toggling SMM happens to force a VM-Exit.
- Emulate MSR_{FS,GS}_BASE on SVM even though interception is always disabled,
so that KVM does the right thing if KVM's emulator encounters {RD,WR}MSR.
- Explicitly clear BUS_LOCK_DETECT from KVM's caps on AMD, as KVM doesn't yet
virtualize BUS_LOCK_DETECT on AMD.
- Cleanup the help message for CONFIG_KVM_AMD_SEV, and call out that KVM now
supports SEV-SNP too.
- Specialize return value of KVM_CHECK_EXTENSION(KVM_CAP_READONLY_MEM),
based on VM type
- Remove unnecessary dependency on CONFIG_HIGH_RES_TIMERS
- Note an RCU quiescent state on guest exit. This avoids a call to rcu_core()
if there was a grace period request while guest was running.
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm
Pull x86 kvm fixes from Paolo Bonzini:
"Many small fixes that accumulated while I was on vacation...
- Fixup missed comments from the REMOVED_SPTE => FROZEN_SPTE rename
- Ensure a root is successfully loaded when pre-faulting SPTEs
- Grab kvm->srcu when handling KVM_SET_VCPU_EVENTS to guard against
accessing memslots if toggling SMM happens to force a VM-Exit
- Emulate MSR_{FS,GS}_BASE on SVM even though interception is always
disabled, so that KVM does the right thing if KVM's emulator
encounters {RD,WR}MSR
- Explicitly clear BUS_LOCK_DETECT from KVM's caps on AMD, as KVM
doesn't yet virtualize BUS_LOCK_DETECT on AMD
- Cleanup the help message for CONFIG_KVM_AMD_SEV, and call out that
KVM now supports SEV-SNP too
- Specialize return value of
KVM_CHECK_EXTENSION(KVM_CAP_READONLY_MEM), based on VM type
- Remove unnecessary dependency on CONFIG_HIGH_RES_TIMERS
- Note an RCU quiescent state on guest exit. This avoids a call to
rcu_core() if there was a grace period request while guest was
running"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
KVM: Remove HIGH_RES_TIMERS dependency
kvm: Note an RCU quiescent state on guest exit
KVM: x86: Only advertise KVM_CAP_READONLY_MEM when supported by VM
KVM: SEV: Update KVM_AMD_SEV Kconfig entry and mention SEV-SNP
KVM: SVM: Don't advertise Bus Lock Detect to guest if SVM support is missing
KVM: SVM: fix emulation of msr reads/writes of MSR_FS_BASE and MSR_GS_BASE
KVM: x86: Acquire kvm->srcu when handling KVM_SET_VCPU_EVENTS
KVM: x86/mmu: Check that root is valid/loaded when pre-faulting SPTEs
KVM: x86/mmu: Fixup comments missed by the REMOVED_SPTE=>FROZEN_SPTE rename
Commit 92b5265d38 ("KVM: Depend on HIGH_RES_TIMERS") added a dependency
to high resolution timers with the comment:
KVM lapic timer and tsc deadline timer based on hrtimer,
setting a leftmost node to rb tree and then do hrtimer reprogram.
If hrtimer not configured as high resolution, hrtimer_enqueue_reprogram
do nothing and then make kvm lapic timer and tsc deadline timer fail.
That was back in 2012, where hrtimer_start_range_ns() would do the
reprogramming with hrtimer_enqueue_reprogram(). But as that was a nop with
high resolution timers disabled, this did not work. But a lot has changed
in the last 12 years.
For example, commit 49a2a07514 ("hrtimer: Kick lowres dynticks targets on
timer enqueue") modifies __hrtimer_start_range_ns() to work with low res
timers. There's been lots of other changes that make low res work.
ChromeOS has tested this before as well, and it hasn't seen any issues
with running KVM with high res timers disabled. There could be problems,
especially at low HZ, for guests that do not support kvmclock and rely
on precise delivery of periodic timers to keep their clock running.
This can be the APIC timer (provided by the kernel), the RTC (provided
by userspace), or the i8254 (choice of kernel/userspace). These guests
are few and far between these days, and in the case of the APIC timer +
Intel hosts we can use the preemption timer (which is TSC-based and has
better latency _and_ accuracy).
In KVM, only x86 is requiring CONFIG_HIGH_RES_TIMERS; perhaps a "depends
on HIGH_RES_TIMERS || EXPERT" could be added to virt/kvm, or a pr_warn
could be added to kvm_init if HIGH_RES_TIMERS are not enabled. But in
general, it seems that there must be other code in the kernel (maybe
sound/?) that is relying on having high-enough HZ or hrtimers but that's
not documented anywhere. Whenever you disable it you probably need to
know what you're doing and what your workload is; so the dependency is
not particularly interesting, and we can just remove it.
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Message-ID: <20240821095127.45d17b19@gandalf.local.home>
[Added the last two paragraphs to the commit message. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Until recently, KVM_CAP_READONLY_MEM was unconditionally supported on
x86, but this is no longer the case for SEV-ES and SEV-SNP VMs.
When KVM_CHECK_EXTENSION is invoked on a VM, only advertise
KVM_CAP_READONLY_MEM when it's actually supported.
Fixes: 66155de93b ("KVM: x86: Disallow read-only memslots for SEV-ES and SEV-SNP (and TDX)")
Cc: Sean Christopherson <seanjc@google.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Michael Roth <michael.roth@amd.com>
Signed-off-by: Tom Dohrmann <erbse.13@gmx.de>
Message-ID: <20240902144219.3716974-1-erbse.13@gmx.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
- x2apic_disable() clears x2apic_state and x2apic_mode unconditionally,
even when the state is X2APIC_ON_LOCKED, which prevents the kernel to
disable it thereby creating inconsistent state.
Reorder the logic so it actually works correctly
- The XSTATE logic for handling LBR is incorrect as it assumes that
XSAVES supports LBR when the CPU supports LBR. In fact both conditions
need to be true. Otherwise the enablement of LBR in the IA32_XSS MSR
fails and subsequently the machine crashes on the next XRSTORS
operation because IA32_XSS is not initialized.
Cache the XSTATE support bit during init and make the related functions
use this cached information and the LBR CPU feature bit to cure this.
- Cure a long standing bug in KASLR
KASLR uses the full address space between PAGE_OFFSET and vaddr_end to
randomize the starting points of the direct map, vmalloc and vmemmap
regions. It thereby limits the size of the direct map by using the
installed memory size plus an extra configurable margin for hot-plug
memory. This limitation is done to gain more randomization space
because otherwise only the holes between the direct map, vmalloc,
vmemmap and vaddr_end would be usable for randomizing.
The limited direct map size is not exposed to the rest of the kernel, so
the memory hot-plug and resource management related code paths still
operate under the assumption that the available address space can be
determined with MAX_PHYSMEM_BITS.
request_free_mem_region() allocates from (1 << MAX_PHYSMEM_BITS) - 1
downwards. That means the first allocation happens past the end of the
direct map and if unlucky this address is in the vmalloc space, which
causes high_memory to become greater than VMALLOC_START and consequently
causes iounmap() to fail for valid ioremap addresses.
Cure this by exposing the end of the direct map via PHYSMEM_END and use
that for the memory hot-plug and resource management related places
instead of relying on MAX_PHYSMEM_BITS. In the KASLR case PHYSMEM_END
maps to a variable which is initialized by the KASLR initialization and
otherwise it is based on MAX_PHYSMEM_BITS as before.
- Prevent a data leak in mmio_read(). The TDVMCALL exposes the value of
an initialized variabled on the stack to the VMM. The variable is only
required as output value, so it does not have to exposed to the VMM in
the first place.
- Prevent an array overrun in the resource control code on systems with
Sub-NUMA Clustering enabled because the code failed to adjust the index
by the number of SNC nodes per L3 cache.
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Merge tag 'x86-urgent-2024-09-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 fixes from Thomas Gleixner:
- x2apic_disable() clears x2apic_state and x2apic_mode unconditionally,
even when the state is X2APIC_ON_LOCKED, which prevents the kernel to
disable it thereby creating inconsistent state.
Reorder the logic so it actually works correctly
- The XSTATE logic for handling LBR is incorrect as it assumes that
XSAVES supports LBR when the CPU supports LBR. In fact both
conditions need to be true. Otherwise the enablement of LBR in the
IA32_XSS MSR fails and subsequently the machine crashes on the next
XRSTORS operation because IA32_XSS is not initialized.
Cache the XSTATE support bit during init and make the related
functions use this cached information and the LBR CPU feature bit to
cure this.
- Cure a long standing bug in KASLR
KASLR uses the full address space between PAGE_OFFSET and vaddr_end
to randomize the starting points of the direct map, vmalloc and
vmemmap regions. It thereby limits the size of the direct map by
using the installed memory size plus an extra configurable margin for
hot-plug memory. This limitation is done to gain more randomization
space because otherwise only the holes between the direct map,
vmalloc, vmemmap and vaddr_end would be usable for randomizing.
The limited direct map size is not exposed to the rest of the kernel,
so the memory hot-plug and resource management related code paths
still operate under the assumption that the available address space
can be determined with MAX_PHYSMEM_BITS.
request_free_mem_region() allocates from (1 << MAX_PHYSMEM_BITS) - 1
downwards. That means the first allocation happens past the end of
the direct map and if unlucky this address is in the vmalloc space,
which causes high_memory to become greater than VMALLOC_START and
consequently causes iounmap() to fail for valid ioremap addresses.
Cure this by exposing the end of the direct map via PHYSMEM_END and
use that for the memory hot-plug and resource management related
places instead of relying on MAX_PHYSMEM_BITS. In the KASLR case
PHYSMEM_END maps to a variable which is initialized by the KASLR
initialization and otherwise it is based on MAX_PHYSMEM_BITS as
before.
- Prevent a data leak in mmio_read(). The TDVMCALL exposes the value of
an initialized variabled on the stack to the VMM. The variable is
only required as output value, so it does not have to exposed to the
VMM in the first place.
- Prevent an array overrun in the resource control code on systems with
Sub-NUMA Clustering enabled because the code failed to adjust the
index by the number of SNC nodes per L3 cache.
* tag 'x86-urgent-2024-09-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/resctrl: Fix arch_mbm_* array overrun on SNC
x86/tdx: Fix data leak in mmio_read()
x86/kaslr: Expose and use the end of the physical memory address space
x86/fpu: Avoid writing LBR bit to IA32_XSS unless supported
x86/apic: Make x2apic_disable() work correctly
SEV-SNP support is present since commit 1dfe571c12 ("KVM: SEV: Add
initial SEV-SNP support") but Kconfig entry wasn't updated and still
mentions SEV and SEV-ES only. Add SEV-SNP there and, while on it, expand
'SEV' in the description as 'Encrypted VMs' is not what 'SEV' stands for.
No functional change.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Link: https://lore.kernel.org/r/20240828122111.160273-1-vkuznets@redhat.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
When using resctrl on systems with Sub-NUMA Clustering enabled, monitoring
groups may be allocated RMID values which would overrun the
arch_mbm_{local,total} arrays.
This is due to inconsistencies in whether the SNC-adjusted num_rmid value or
the unadjusted value in resctrl_arch_system_num_rmid_idx() is used. The
num_rmid value for the L3 resource is currently:
resctrl_arch_system_num_rmid_idx() / snc_nodes_per_l3_cache
As a simple fix, make resctrl_arch_system_num_rmid_idx() return the
SNC-adjusted, L3 num_rmid value on x86.
Fixes: e13db55b5a ("x86/resctrl: Introduce snc_nodes_per_l3_cache")
Signed-off-by: Peter Newman <peternewman@google.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://lore.kernel.org/r/20240822190212.1848788-1-peternewman@google.com
The mmio_read() function makes a TDVMCALL to retrieve MMIO data for an
address from the VMM.
Sean noticed that mmio_read() unintentionally exposes the value of an
initialized variable (val) on the stack to the VMM.
This variable is only needed as an output value. It did not need to be
passed to the VMM in the first place.
Do not send the original value of *val to the VMM.
[ dhansen: clarify what 'val' is used for. ]
Fixes: 31d58c4e55 ("x86/tdx: Handle in-kernel MMIO")
Reported-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc:stable@vger.kernel.org
Link: https://lore.kernel.org/all/20240826125304.1566719-1-kirill.shutemov%40linux.intel.com
Running the ltp test cve-2015-3290 concurrently reports the following
warnings.
perfevents: irq loop stuck!
WARNING: CPU: 31 PID: 32438 at arch/x86/events/intel/core.c:3174
intel_pmu_handle_irq+0x285/0x370
Call Trace:
<NMI>
? __warn+0xa4/0x220
? intel_pmu_handle_irq+0x285/0x370
? __report_bug+0x123/0x130
? intel_pmu_handle_irq+0x285/0x370
? __report_bug+0x123/0x130
? intel_pmu_handle_irq+0x285/0x370
? report_bug+0x3e/0xa0
? handle_bug+0x3c/0x70
? exc_invalid_op+0x18/0x50
? asm_exc_invalid_op+0x1a/0x20
? irq_work_claim+0x1e/0x40
? intel_pmu_handle_irq+0x285/0x370
perf_event_nmi_handler+0x3d/0x60
nmi_handle+0x104/0x330
Thanks to Thomas Gleixner's analysis, the issue is caused by the low
initial period (1) of the frequency estimation algorithm, which triggers
the defects of the HW, specifically erratum HSW11 and HSW143. (For the
details, please refer https://lore.kernel.org/lkml/87plq9l5d2.ffs@tglx/)
The HSW11 requires a period larger than 100 for the INST_RETIRED.ALL
event, but the initial period in the freq mode is 1. The erratum is the
same as the BDM11, which has been supported in the kernel. A minimum
period of 128 is enforced as well on HSW.
HSW143 is regarding that the fixed counter 1 may overcount 32 with the
Hyper-Threading is enabled. However, based on the test, the hardware
has more issues than it tells. Besides the fixed counter 1, the message
'interrupt took too long' can be observed on any counter which was armed
with a period < 32 and two events expired in the same NMI. A minimum
period of 32 is enforced for the rest of the events.
The recommended workaround code of the HSW143 is not implemented.
Because it only addresses the issue for the fixed counter. It brings
extra overhead through extra MSR writing. No related overcounting issue
has been reported so far.
Fixes: 3a632cb229 ("perf/x86/intel: Add simple Haswell PMU support")
Reported-by: Li Huafei <lihuafei1@huawei.com>
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/20240819183004.3132920-1-kan.liang@linux.intel.com
Closes: https://lore.kernel.org/lkml/20240729223328.327835-1-lihuafei1@huawei.com/
If host supports Bus Lock Detect, KVM advertises it to guests even if
SVM support is absent. Additionally, guest wouldn't be able to use it
despite guest CPUID bit being set. Fix it by unconditionally clearing
the feature bit in KVM cpu capability.
Reported-by: Jim Mattson <jmattson@google.com>
Closes: https://lore.kernel.org/r/CALMp9eRet6+v8Y1Q-i6mqPm4hUow_kJNhmVHfOV8tMfuSS=tVg@mail.gmail.com
Fixes: 76ea438b4a ("KVM: X86: Expose bus lock debug exception to guest")
Cc: stable@vger.kernel.org
Signed-off-by: Ravi Bangoria <ravi.bangoria@amd.com>
Reviewed-by: Jim Mattson <jmattson@google.com>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Link: https://lore.kernel.org/r/20240808062937.1149-4-ravi.bangoria@amd.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
If these msrs are read by the emulator (e.g due to 'force emulation' prefix),
SVM code currently fails to extract the corresponding segment bases,
and return them to the emulator.
Fix that.
Cc: stable@vger.kernel.org
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Link: https://lore.kernel.org/r/20240802151608.72896-3-mlevitsk@redhat.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Grab kvm->srcu when processing KVM_SET_VCPU_EVENTS, as KVM will forcibly
leave nested VMX/SVM if SMM mode is being toggled, and leaving nested VMX
reads guest memory.
Note, kvm_vcpu_ioctl_x86_set_vcpu_events() can also be called from KVM_RUN
via sync_regs(), which already holds SRCU. I.e. trying to precisely use
kvm_vcpu_srcu_read_lock() around the problematic SMM code would cause
problems. Acquiring SRCU isn't all that expensive, so for simplicity,
grab it unconditionally for KVM_SET_VCPU_EVENTS.
=============================
WARNING: suspicious RCU usage
6.10.0-rc7-332d2c1d713e-next-vm #552 Not tainted
-----------------------------
include/linux/kvm_host.h:1027 suspicious rcu_dereference_check() usage!
other info that might help us debug this:
rcu_scheduler_active = 2, debug_locks = 1
1 lock held by repro/1071:
#0: ffff88811e424430 (&vcpu->mutex){+.+.}-{3:3}, at: kvm_vcpu_ioctl+0x7d/0x970 [kvm]
stack backtrace:
CPU: 15 PID: 1071 Comm: repro Not tainted 6.10.0-rc7-332d2c1d713e-next-vm #552
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
Call Trace:
<TASK>
dump_stack_lvl+0x7f/0x90
lockdep_rcu_suspicious+0x13f/0x1a0
kvm_vcpu_gfn_to_memslot+0x168/0x190 [kvm]
kvm_vcpu_read_guest+0x3e/0x90 [kvm]
nested_vmx_load_msr+0x6b/0x1d0 [kvm_intel]
load_vmcs12_host_state+0x432/0xb40 [kvm_intel]
vmx_leave_nested+0x30/0x40 [kvm_intel]
kvm_vcpu_ioctl_x86_set_vcpu_events+0x15d/0x2b0 [kvm]
kvm_arch_vcpu_ioctl+0x1107/0x1750 [kvm]
? mark_held_locks+0x49/0x70
? kvm_vcpu_ioctl+0x7d/0x970 [kvm]
? kvm_vcpu_ioctl+0x497/0x970 [kvm]
kvm_vcpu_ioctl+0x497/0x970 [kvm]
? lock_acquire+0xba/0x2d0
? find_held_lock+0x2b/0x80
? do_user_addr_fault+0x40c/0x6f0
? lock_release+0xb7/0x270
__x64_sys_ioctl+0x82/0xb0
do_syscall_64+0x6c/0x170
entry_SYSCALL_64_after_hwframe+0x4b/0x53
RIP: 0033:0x7ff11eb1b539
</TASK>
Fixes: f7e570780e ("KVM: x86: Forcibly leave nested virt when SMM state is toggled")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20240723232055.3643811-1-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Replace "removed" with "frozen" in comments as appropriate to complete the
rename of REMOVED_SPTE to FROZEN_SPTE.
Fixes: 964cea8171 ("KVM: x86/tdp_mmu: Rename REMOVED_SPTE to FROZEN_SPTE")
Signed-off-by: Yan Zhao <yan.y.zhao@intel.com>
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Link: https://lore.kernel.org/r/20240712233438.518591-1-rick.p.edgecombe@intel.com
[sean: write changelog]
Signed-off-by: Sean Christopherson <seanjc@google.com>
iounmap() on x86 occasionally fails to unmap because the provided valid
ioremap address is not below high_memory. It turned out that this
happens due to KASLR.
KASLR uses the full address space between PAGE_OFFSET and vaddr_end to
randomize the starting points of the direct map, vmalloc and vmemmap
regions. It thereby limits the size of the direct map by using the
installed memory size plus an extra configurable margin for hot-plug
memory. This limitation is done to gain more randomization space
because otherwise only the holes between the direct map, vmalloc,
vmemmap and vaddr_end would be usable for randomizing.
The limited direct map size is not exposed to the rest of the kernel, so
the memory hot-plug and resource management related code paths still
operate under the assumption that the available address space can be
determined with MAX_PHYSMEM_BITS.
request_free_mem_region() allocates from (1 << MAX_PHYSMEM_BITS) - 1
downwards. That means the first allocation happens past the end of the
direct map and if unlucky this address is in the vmalloc space, which
causes high_memory to become greater than VMALLOC_START and consequently
causes iounmap() to fail for valid ioremap addresses.
MAX_PHYSMEM_BITS cannot be changed for that because the randomization
does not align with address bit boundaries and there are other places
which actually require to know the maximum number of address bits. All
remaining usage sites of MAX_PHYSMEM_BITS have been analyzed and found
to be correct.
Cure this by exposing the end of the direct map via PHYSMEM_END and use
that for the memory hot-plug and resource management related places
instead of relying on MAX_PHYSMEM_BITS. In the KASLR case PHYSMEM_END
maps to a variable which is initialized by the KASLR initialization and
otherwise it is based on MAX_PHYSMEM_BITS as before.
To prevent future hickups add a check into add_pages() to catch callers
trying to add memory above PHYSMEM_END.
Fixes: 0483e1fa6e ("x86/mm: Implement ASLR for kernel memory regions")
Reported-by: Max Ramanouski <max8rr8@gmail.com>
Reported-by: Alistair Popple <apopple@nvidia.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-By: Max Ramanouski <max8rr8@gmail.com>
Tested-by: Alistair Popple <apopple@nvidia.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Alistair Popple <apopple@nvidia.com>
Reviewed-by: Kees Cook <kees@kernel.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/87ed6soy3z.ffs@tglx
There are two distinct CPU features related to the use of XSAVES and LBR:
whether LBR is itself supported and whether XSAVES supports LBR. The LBR
subsystem correctly checks both in intel_pmu_arch_lbr_init(), but the
XSTATE subsystem does not.
The LBR bit is only removed from xfeatures_mask_independent when LBR is not
supported by the CPU, but there is no validation of XSTATE support.
If XSAVES does not support LBR the write to IA32_XSS causes a #GP fault,
leaving the state of IA32_XSS unchanged, i.e. zero. The fault is handled
with a warning and the boot continues.
Consequently the next XRSTORS which tries to restore supervisor state fails
with #GP because the RFBM has zero for all supervisor features, which does
not match the XCOMP_BV field.
As XFEATURE_MASK_FPSTATE includes supervisor features setting up the FPU
causes a #GP, which ends up in fpu_reset_from_exception_fixup(). That fails
due to the same problem resulting in recursive #GPs until the kernel runs
out of stack space and double faults.
Prevent this by storing the supported independent features in
fpu_kernel_cfg during XSTATE initialization and use that cached value for
retrieving the independent feature bits to be written into IA32_XSS.
[ tglx: Massaged change log ]
Fixes: f0dccc9da4 ("x86/fpu/xstate: Support dynamic supervisor feature for LBR")
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Mitchell Levy <levymitchell0@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/20240812-xsave-lbr-fix-v3-1-95bac1bf62f4@gmail.com
Disallow read-only memslots for SEV-{ES,SNP} VM types, as KVM can't
directly emulate instructions for ES/SNP, and instead the guest must
explicitly request emulation. Unless the guest explicitly requests
emulation without accessing memory, ES/SNP relies on KVM creating an MMIO
SPTE, with the subsequent #NPF being reflected into the guest as a #VC.
But for read-only memslots, KVM deliberately doesn't create MMIO SPTEs,
because except for ES/SNP, doing so requires setting reserved bits in the
SPTE, i.e. the SPTE can't be readable while also generating a #VC on
writes. Because KVM never creates MMIO SPTEs and jumps directly to
emulation, the guest never gets a #VC. And since KVM simply resumes the
guest if ES/SNP guests trigger emulation, KVM effectively puts the vCPU
into an infinite #NPF loop if the vCPU attempts to write read-only memory.
Disallow read-only memory for all VMs with protected state, i.e. for
upcoming TDX VMs as well as ES/SNP VMs. For TDX, it's actually possible
to support read-only memory, as TDX uses EPT Violation #VE to reflect the
fault into the guest, e.g. KVM could configure read-only SPTEs with RX
protections and SUPPRESS_VE=0. But there is no strong use case for
supporting read-only memslots on TDX, e.g. the main historical usage is
to emulate option ROMs, but TDX disallows executing from shared memory.
And if someone comes along with a legitimate, strong use case, the
restriction can always be lifted for TDX.
Don't bother trying to retroactively apply the restriction to SEV-ES
VMs that are created as type KVM_X86_DEFAULT_VM. Read-only memslots can't
possibly work for SEV-ES, i.e. disallowing such memslots is really just
means reporting an error to userspace instead of silently hanging vCPUs.
Trying to deal with the ordering between KVM_SEV_INIT and memslot creation
isn't worth the marginal benefit it would provide userspace.
Fixes: 26c44aa9e0 ("KVM: SEV: define VM types for SEV and SEV-ES")
Fixes: 1dfe571c12 ("KVM: SEV: Add initial SEV-SNP support")
Cc: Peter Gonda <pgonda@google.com>
Cc: Michael Roth <michael.roth@amd.com>
Cc: Vishal Annapurve <vannapurve@google.com>
Cc: Ackerly Tng <ackerleytng@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-ID: <20240809190319.1710470-2-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Ignore the userspace provided x2APIC ID when fixing up APIC state for
KVM_SET_LAPIC, i.e. make the x2APIC fully readonly in KVM. Commit
a92e2543d6 ("KVM: x86: use hardware-compatible format for APIC ID
register"), which added the fixup, didn't intend to allow userspace to
modify the x2APIC ID. In fact, that commit is when KVM first started
treating the x2APIC ID as readonly, apparently to fix some race:
static inline u32 kvm_apic_id(struct kvm_lapic *apic)
{
- return (kvm_lapic_get_reg(apic, APIC_ID) >> 24) & 0xff;
+ /* To avoid a race between apic_base and following APIC_ID update when
+ * switching to x2apic_mode, the x2apic mode returns initial x2apic id.
+ */
+ if (apic_x2apic_mode(apic))
+ return apic->vcpu->vcpu_id;
+
+ return kvm_lapic_get_reg(apic, APIC_ID) >> 24;
}
Furthermore, KVM doesn't support delivering interrupts to vCPUs with a
modified x2APIC ID, but KVM *does* return the modified value on a guest
RDMSR and for KVM_GET_LAPIC. I.e. no remotely sane setup can actually
work with a modified x2APIC ID.
Making the x2APIC ID fully readonly fixes a WARN in KVM's optimized map
calculation, which expects the LDR to align with the x2APIC ID.
WARNING: CPU: 2 PID: 958 at arch/x86/kvm/lapic.c:331 kvm_recalculate_apic_map+0x609/0xa00 [kvm]
CPU: 2 PID: 958 Comm: recalc_apic_map Not tainted 6.4.0-rc3-vanilla+ #35
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Arch Linux 1.16.2-1-1 04/01/2014
RIP: 0010:kvm_recalculate_apic_map+0x609/0xa00 [kvm]
Call Trace:
<TASK>
kvm_apic_set_state+0x1cf/0x5b0 [kvm]
kvm_arch_vcpu_ioctl+0x1806/0x2100 [kvm]
kvm_vcpu_ioctl+0x663/0x8a0 [kvm]
__x64_sys_ioctl+0xb8/0xf0
do_syscall_64+0x56/0x80
entry_SYSCALL_64_after_hwframe+0x46/0xb0
RIP: 0033:0x7fade8b9dd6f
Unfortunately, the WARN can still trigger for other CPUs than the current
one by racing against KVM_SET_LAPIC, so remove it completely.
Reported-by: Michal Luczaj <mhal@rbox.co>
Closes: https://lore.kernel.org/all/814baa0c-1eaa-4503-129f-059917365e80@rbox.co
Reported-by: Haoyu Wu <haoyuwu254@gmail.com>
Closes: https://lore.kernel.org/all/20240126161633.62529-1-haoyuwu254@gmail.com
Reported-by: syzbot+545f1326f405db4e1c3e@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/000000000000c2a6b9061cbca3c3@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-ID: <20240802202941.344889-2-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Use this_cpu_ptr() instead of open coding the equivalent in various
user return MSR helpers.
Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
Reviewed-by: Chao Gao <chao.gao@intel.com>
Reviewed-by: Yuan Yao <yuan.yao@intel.com>
[sean: massage changelog]
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Pankaj Gupta <pankaj.gupta@amd.com>
Message-ID: <20240802201630.339306-1-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
There is no caller in tree since introduction in commit b4f69df0f6 ("KVM:
x86: Make Hyper-V emulation optional")
Signed-off-by: Yue Haibing <yuehaibing@huawei.com>
Message-ID: <20240803113233.128185-1-yuehaibing@huawei.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
x2apic_disable() clears x2apic_state and x2apic_mode unconditionally, even
when the state is X2APIC_ON_LOCKED, which prevents the kernel to disable
it thereby creating inconsistent state.
Due to the early state check for X2APIC_ON, the code path which warns about
a locked X2APIC cannot be reached.
Test for state < X2APIC_ON instead and move the clearing of the state and
mode variables to the place which actually disables X2APIC.
[ tglx: Massaged change log. Added Fixes tag. Moved clearing so it's at the
right place for back ports ]
Fixes: a57e456a7b ("x86/apic: Fix fallout from x2apic cleanup")
Signed-off-by: Yuntao Wang <yuntao.wang@linux.dev>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/20240813014827.895381-1-yuntao.wang@linux.dev
The copy_from_user() function returns the number of bytes which it
was not able to copy. Return -EFAULT instead.
Fixes: dee5a47cc7 ("KVM: SEV: Add KVM_SEV_SNP_LAUNCH_UPDATE command")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Message-ID: <20240612115040.2423290-4-dan.carpenter@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
If snp_lookup_rmpentry() fails then "assigned" is printed in the error
message but it was never initialized. Initialize it to false.
Fixes: dee5a47cc7 ("KVM: SEV: Add KVM_SEV_SNP_LAUNCH_UPDATE command")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Message-ID: <20240612115040.2423290-3-dan.carpenter@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
MTRRs have an obsolete fixed variant for fine grained caching control
of the 640K-1MB region that uses separate MSRs. This fixed variant has
a separate capability bit in the MTRR capability MSR.
So far all x86 CPUs which support MTRR have this separate bit set, so it
went unnoticed that mtrr_save_state() does not check the capability bit
before accessing the fixed MTRR MSRs.
Though on a CPU that does not support the fixed MTRR capability this
results in a #GP. The #GP itself is harmless because the RDMSR fault is
handled gracefully, but results in a WARN_ON().
Add the missing capability check to prevent this.
Fixes: 2b1f6278d7 ("[PATCH] x86: Save the MTRRs of the BSP before booting an AP")
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/20240808000244.946864-1-ak@linux.intel.com
The kernel can change spinlock behavior when running as a guest. But this
guest-friendly behavior causes performance problems on bare metal.
The kernel uses a static key to switch between the two modes.
In theory, the static key is enabled by default (run in guest mode) and
should be disabled for bare metal (and in some guests that want native
behavior or paravirt spinlock).
A performance drop is reported when running encode/decode workload and
BenchSEE cache sub-workload.
Bisect points to commit ce0a1b608b ("x86/paravirt: Silence unused
native_pv_lock_init() function warning"). When CONFIG_PARAVIRT_SPINLOCKS is
disabled the virt_spin_lock_key is incorrectly set to true on bare
metal. The qspinlock degenerates to test-and-set spinlock, which decreases
the performance on bare metal.
Set the default value of virt_spin_lock_key to false. If booting in a VM,
enable this key. Later during the VM initialization, if other
high-efficient spinlock is preferred (e.g. paravirt-spinlock), or the user
wants the native qspinlock (via nopvspin boot commandline), the
virt_spin_lock_key is disabled accordingly.
This results in the following decision matrix:
X86_FEATURE_HYPERVISOR Y Y Y N
CONFIG_PARAVIRT_SPINLOCKS Y Y N Y/N
PV spinlock Y N N Y/N
virt_spin_lock_key N Y/N Y N
Fixes: ce0a1b608b ("x86/paravirt: Silence unused native_pv_lock_init() function warning")
Reported-by: Prem Nath Dey <prem.nath.dey@intel.com>
Reported-by: Xiaoping Zhou <xiaoping.zhou@intel.com>
Suggested-by: Dave Hansen <dave.hansen@linux.intel.com>
Suggested-by: Qiuxu Zhuo <qiuxu.zhuo@intel.com>
Suggested-by: Nikolay Borisov <nik.borisov@suse.com>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Nikolay Borisov <nik.borisov@suse.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/20240806112207.29792-1-yu.c.chen@intel.com
On a platform using the "Multiprocessor Wakeup Structure"[1] to startup
secondary CPUs the control processor needs to memremap() the physical
address of the MP Wakeup Structure mailbox to the variable
acpi_mp_wake_mailbox, which holds the virtual address of mailbox.
To wake up the AP the control processor writes the APIC ID of AP, the
wakeup vector and the ACPI_MP_WAKE_COMMAND_WAKEUP command into the mailbox.
Current implementation doesn't consider the case which restricts boot time
CPU bringup to 1 with the kernel parameter "maxcpus=1" and brings other
CPUs online later from user space as it sets acpi_mp_wake_mailbox to
read-only after init. So when the first AP is tried to brought online
after init, the attempt to update the variable results in a kernel panic.
The memremap() call that initializes the variable cannot be moved into
acpi_parse_mp_wake() because memremap() is not functional at that point in
the boot process. Also as the APs might never be brought up, keep the
memremap() call in acpi_wakeup_cpu() so that the operation only takes place
when needed.
Fixes: 24dd05da8c ("x86/apic: Mark acpi_mp_wake_* variables as __ro_after_init")
Signed-off-by: Zhiquan Li <zhiquan1.li@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Link: https://lore.kernel.org/all/20240805103531.1230635-1-zhiquan1.li@intel.com
So it turns out that we have to do two passes of
pti_clone_entry_text(), once before initcalls, such that device and
late initcalls can use user-mode-helper / modprobe and once after
free_initmem() / mark_readonly().
Now obviously mark_readonly() can cause PMD splits, and
pti_clone_pgtable() doesn't like that much.
Allow the late clone to split PMDs so that pagetables stay in sync.
[peterz: Changelog and comments]
Reported-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lkml.kernel.org/r/20240806184843.GX37996@noisy.programming.kicks-ass.net
- Prevent a deadlock on cpu_hotplug_lock in the aperf/mperf driver.
A recent change in the ACPI code which consolidated code pathes moved
the invocation of init_freq_invariance_cppc() to be moved to a CPU
hotplug handler. The first invocation on AMD CPUs ends up enabling a
static branch which dead locks because the static branch enable tries to
acquire cpu_hotplug_lock but that lock is already held write by the
hotplug machinery.
Use static_branch_enable_cpuslocked() instead and take the hotplug
lock read for the Intel code path which is invoked from the
architecture code outside of the CPU hotplug operations.
- Fix the number of reserved bits in the sev_config structure bit field
so that the bitfield does not exceed 64 bit.
- Add missing Zen5 model numbers
- Fix the alignment assumptions of pti_clone_pgtable() and
clone_entry_text() on 32-bit:
The code assumes PMD aligned code sections, but on 32-bit the kernel
entry text is not PMD aligned. So depending on the code size and
location, which is configuration and compiler dependent, entry text
can cross a PMD boundary. As the start is not PMD aligned adding PMD
size to the start address is larger than the end address which
results in partially mapped entry code for user space. That causes
endless recursion on the first entry from userspace (usually #PF).
Cure this by aligning the start address in the addition so it ends up
at the next PMD start address.
clone_entry_text() enforces PMD mapping, but on 32-bit the tail might
eventually be PTE mapped, which causes a map fail because the PMD for
the tail is not a large page mapping. Use PTI_LEVEL_KERNEL_IMAGE for
the clone() invocation which resolves to PTE on 32-bit and PMD on
64-bit.
- Zero the 8-byte case for get_user() on range check failure on 32-bit
The recend consolidation of the 8-byte get_user() case broke the
zeroing in the failure case again. Establish it by clearing ECX
before the range check and not afterwards as that obvioulsy can't be
reached when the range check fails
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Merge tag 'x86-urgent-2024-08-04' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 fixes from Thomas Gleixner:
- Prevent a deadlock on cpu_hotplug_lock in the aperf/mperf driver.
A recent change in the ACPI code which consolidated code pathes moved
the invocation of init_freq_invariance_cppc() to be moved to a CPU
hotplug handler. The first invocation on AMD CPUs ends up enabling a
static branch which dead locks because the static branch enable tries
to acquire cpu_hotplug_lock but that lock is already held write by
the hotplug machinery.
Use static_branch_enable_cpuslocked() instead and take the hotplug
lock read for the Intel code path which is invoked from the
architecture code outside of the CPU hotplug operations.
- Fix the number of reserved bits in the sev_config structure bit field
so that the bitfield does not exceed 64 bit.
- Add missing Zen5 model numbers
- Fix the alignment assumptions of pti_clone_pgtable() and
clone_entry_text() on 32-bit:
The code assumes PMD aligned code sections, but on 32-bit the kernel
entry text is not PMD aligned. So depending on the code size and
location, which is configuration and compiler dependent, entry text
can cross a PMD boundary. As the start is not PMD aligned adding PMD
size to the start address is larger than the end address which
results in partially mapped entry code for user space. That causes
endless recursion on the first entry from userspace (usually #PF).
Cure this by aligning the start address in the addition so it ends up
at the next PMD start address.
clone_entry_text() enforces PMD mapping, but on 32-bit the tail might
eventually be PTE mapped, which causes a map fail because the PMD for
the tail is not a large page mapping. Use PTI_LEVEL_KERNEL_IMAGE for
the clone() invocation which resolves to PTE on 32-bit and PMD on
64-bit.
- Zero the 8-byte case for get_user() on range check failure on 32-bit
The recend consolidation of the 8-byte get_user() case broke the
zeroing in the failure case again. Establish it by clearing ECX
before the range check and not afterwards as that obvioulsy can't be
reached when the range check fails
* tag 'x86-urgent-2024-08-04' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/uaccess: Zero the 8-byte get_range case on failure on 32-bit
x86/mm: Fix pti_clone_entry_text() for i386
x86/mm: Fix pti_clone_pgtable() alignment assumption
x86/setup: Parse the builtin command line before merging
x86/CPU/AMD: Add models 0x60-0x6f to the Zen5 range
x86/sev: Fix __reserved field in sev_config
x86/aperfmperf: Fix deadlock on cpu_hotplug_lock
- Move the smp_processor_id() invocation back into the non-preemtible
region, so that the result is valid to use.
- Add the missing package C2 residency counters for Sierra Forest CPUs
to make the newly added support actually useful
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Merge tag 'perf-urgent-2024-08-04' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 perf fixes from Thomas Gleixner:
- Move the smp_processor_id() invocation back into the non-preemtible
region, so that the result is valid to use
- Add the missing package C2 residency counters for Sierra Forest CPUs
to make the newly added support actually useful
* tag 'perf-urgent-2024-08-04' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf/x86: Fix smp_processor_id()-in-preemptible warnings
perf/x86/intel/cstate: Add pkg C2 residency counter for Sierra Forest
confidential VMs
* fix "underline too short" in docs
* eliminate log spam from limited APIC timer periods
* disallow pre-faulting of memory before SEV-SNP VMs are initialized
* delay clearing and encrypting private memory until it is added to
guest page tables
* this change also enables another small cleanup: the checks in
SNP_LAUNCH_UPDATE that limit it to non-populated, private pages
can now be moved in the common kvm_gmem_populate() function
* fix compilation error that the RISC-V merge introduced in selftests
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm
Pull kvm updates from Paolo Bonzini:
"The bulk of the changes here is a largish change to guest_memfd,
delaying the clearing and encryption of guest-private pages until they
are actually added to guest page tables. This started as "let's make
it impossible to misuse the API" for SEV-SNP; but then it ballooned a
bit.
The new logic is generally simpler and more ready for hugepage support
in guest_memfd.
Summary:
- fix latent bug in how usage of large pages is determined for
confidential VMs
- fix "underline too short" in docs
- eliminate log spam from limited APIC timer periods
- disallow pre-faulting of memory before SEV-SNP VMs are initialized
- delay clearing and encrypting private memory until it is added to
guest page tables
- this change also enables another small cleanup: the checks in
SNP_LAUNCH_UPDATE that limit it to non-populated, private pages can
now be moved in the common kvm_gmem_populate() function
- fix compilation error that the RISC-V merge introduced in selftests"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
KVM: x86/mmu: fix determination of max NPT mapping level for private pages
KVM: riscv: selftests: Fix compile error
KVM: guest_memfd: abstract how prepared folios are recorded
KVM: guest_memfd: let kvm_gmem_populate() operate only on private gfns
KVM: extend kvm_range_has_memory_attributes() to check subset of attributes
KVM: cleanup and add shortcuts to kvm_range_has_memory_attributes()
KVM: guest_memfd: move check for already-populated page to common code
KVM: remove kvm_arch_gmem_prepare_needed()
KVM: guest_memfd: make kvm_gmem_prepare_folio() operate on a single struct kvm
KVM: guest_memfd: delay kvm_gmem_prepare_folio() until the memory is passed to the guest
KVM: guest_memfd: return locked folio from __kvm_gmem_get_pfn
KVM: rename CONFIG_HAVE_KVM_GMEM_* to CONFIG_HAVE_KVM_ARCH_GMEM_*
KVM: guest_memfd: do not go through struct page
KVM: guest_memfd: delay folio_mark_uptodate() until after successful preparation
KVM: guest_memfd: return folio from __kvm_gmem_get_pfn()
KVM: x86: disallow pre-fault for SNP VMs before initialization
KVM: Documentation: Fix title underline too short warning
KVM: x86: Eliminate log spam from limited APIC timer periods
confidential VMs
* fix "underline too short" in docs
* eliminate log spam from limited APIC timer periods
* disallow pre-faulting of memory before SEV-SNP VMs are initialized
* delay clearing and encrypting private memory until it is added to
guest page tables
* this change also enables another small cleanup: the checks in
SNP_LAUNCH_UPDATE that limit it to non-populated, private pages
can now be moved in the common kvm_gmem_populate() function
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Merge branch 'kvm-fixes' into HEAD
* fix latent bug in how usage of large pages is determined for
confidential VMs
* fix "underline too short" in docs
* eliminate log spam from limited APIC timer periods
* disallow pre-faulting of memory before SEV-SNP VMs are initialized
* delay clearing and encrypting private memory until it is added to
guest page tables
* this change also enables another small cleanup: the checks in
SNP_LAUNCH_UPDATE that limit it to non-populated, private pages
can now be moved in the common kvm_gmem_populate() function
Despite multiple attempts to get the syscall number assignment right
for the newly added uretprobe syscall, we ended up with a bit of a mess:
- The number is defined as 467 based on the assumption that the
xattrat family of syscalls would use 463 through 466, but those
did not make it into 6.11.
- The include/uapi/asm-generic/unistd.h file still lists the number
463, but the new scripts/syscall.tbl that was supposed to have the
same data lists 467 instead as the number for arc, arm64, csky,
hexagon, loongarch, nios2, openrisc and riscv. None of these
architectures actually provide a uretprobe syscall.
- All the other architectures (powerpc, arm, mips, ...) don't list
this syscall at all.
There are two ways to make it consistent again: either list it with
the same syscall number on all architectures, or only list it on x86
but not in scripts/syscall.tbl and asm-generic/unistd.h.
Based on the most recent discussion, it seems like we won't need it
anywhere else, so just remove the inconsistent assignment and instead
move the x86 number to the next available one in the architecture
specific range, which is 335.
Fixes: 5c28424e9a ("syscalls: Fix to add sys_uretprobe to syscall.tbl")
Fixes: 190fec72df ("uprobe: Wire up uretprobe system call")
Fixes: 63ded11097 ("uprobe: Change uretprobe syscall scope and number")
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
While zeroing the upper 32 bits of an 8-byte getuser on 32-bit x86 was
fixed by commit 8c860ed825 ("x86/uaccess: Fix missed zeroing of ia32 u64
get_user() range checking") it was broken again in commit 8a2462df15
("x86/uaccess: Improve the 8-byte getuser() case").
This is because the register which holds the upper 32 bits (%ecx) is being
cleared _after_ the check_range, so if the range check fails, %ecx is never
cleared.
This can be reproduced with:
./tools/testing/kunit/kunit.py run --arch i386 usercopy
Instead, clear %ecx _before_ check_range in the 8-byte case. This
reintroduces a bit of the ugliness we were trying to avoid by adding
another #ifndef CONFIG_X86_64, but at least keeps check_range from needing
a separate bad_get_user_8 jump.
Fixes: 8a2462df15 ("x86/uaccess: Improve the 8-byte getuser() case")
Signed-off-by: David Gow <davidgow@google.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/all/20240731073031.4045579-1-davidgow@google.com
The `if (req_max_level)` test was meant ignore req_max_level if
PG_LEVEL_NONE was returned. Hence, this function should return
max_level instead of the ignored req_max_level.
This is only a latent issue for now, since guest_memfd does not
support large pages.
Signed-off-by: Ackerley Tng <ackerleytng@google.com>
Message-ID: <20240801173955.1975034-1-ackerleytng@google.com>
Fixes: f32fb32820 ("KVM: x86: Add hook for determining max NPT mapping level")
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
While x86_64 has PMD aligned text sections, i386 does not have this
luxery. Notably ALIGN_ENTRY_TEXT_END is empty and _etext has PAGE
alignment.
This means that text on i386 can be page granular at the tail end,
which in turn means that the PTI text clones should consistently
account for this.
Make pti_clone_entry_text() consistent with pti_clone_kernel_text().
Fixes: 16a3fe634f ("x86/mm/pti: Clone kernel-image on PTE level for 32 bit")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Guenter reported dodgy crashes on an i386-nosmp build using GCC-11
that had the form of endless traps until entry stack exhaust and then
#DF from the stack guard.
It turned out that pti_clone_pgtable() had alignment assumptions on
the start address, notably it hard assumes start is PMD aligned. This
is true on x86_64, but very much not true on i386.
These assumptions can cause the end condition to malfunction, leading
to a 'short' clone. Guess what happens when the user mapping has a
short copy of the entry text?
Use the correct increment form for addr to avoid alignment
assumptions.
Fixes: 16a3fe634f ("x86/mm/pti: Clone kernel-image on PTE level for 32 bit")
Reported-by: Guenter Roeck <linux@roeck-us.net>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20240731163105.GG33588@noisy.programming.kicks-ass.net
Commit in Fixes was added as a catch-all for cases where the cmdline is
parsed before being merged with the builtin one.
And promptly one issue appeared, see Link below. The microcode loader
really needs to parse it that early, but the merging happens later.
Reshuffling the early boot nightmare^W code to handle that properly would
be a painful exercise for another day so do the chicken thing and parse the
builtin cmdline too before it has been merged.
Fixes: 0c40b1c7a8 ("x86/setup: Warn when option parsing is done too early")
Reported-by: Mike Lothian <mike@fireburn.co.uk>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20240730152108.GAZqkE5Dfi9AuKllRw@fat_crate.local
Link: https://lore.kernel.org/r/20240722152330.GCZp55ck8E_FT4kPnC@fat_crate.local
The following bug was triggered on a system built with
CONFIG_DEBUG_PREEMPT=y:
# echo p > /proc/sysrq-trigger
BUG: using smp_processor_id() in preemptible [00000000] code: sh/117
caller is perf_event_print_debug+0x1a/0x4c0
CPU: 3 UID: 0 PID: 117 Comm: sh Not tainted 6.11.0-rc1 #109
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014
Call Trace:
<TASK>
dump_stack_lvl+0x4f/0x60
check_preemption_disabled+0xc8/0xd0
perf_event_print_debug+0x1a/0x4c0
__handle_sysrq+0x140/0x180
write_sysrq_trigger+0x61/0x70
proc_reg_write+0x4e/0x70
vfs_write+0xd0/0x430
? handle_mm_fault+0xc8/0x240
ksys_write+0x9c/0xd0
do_syscall_64+0x96/0x190
entry_SYSCALL_64_after_hwframe+0x4b/0x53
This is because the commit d4b294bf84 ("perf/x86: Hybrid PMU support
for counters") took smp_processor_id() outside the irq critical section.
If a preemption occurs in perf_event_print_debug() and the task is
migrated to another cpu, we may get incorrect pmu debug information.
Move smp_processor_id() back inside the irq critical section to fix this
issue.
Fixes: d4b294bf84 ("perf/x86: Hybrid PMU support for counters")
Signed-off-by: Li Huafei <lihuafei1@huawei.com>
Reviewed-and-tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
Link: https://lore.kernel.org/r/20240729220928.325449-1-lihuafei1@huawei.com
Add some new Zen5 models for the 0x1A family.
[ bp: Merge the 0x60 and 0x70 ranges. ]
Signed-off-by: Perry Yuan <perry.yuan@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20240729064626.24297-1-bp@kernel.org
sev_config currently has debug, ghcbs_initialized, and use_cas fields.
However, __reserved count has not been updated. Fix this.
Fixes: 34ff659017 ("x86/sev: Use kernel provided SVSM Calling Areas")
Signed-off-by: Pavan Kumar Paluri <papaluri@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20240729180808.366587-1-papaluri@amd.com
The broken patch results in a call to init_freq_invariance_cppc() in a CPU
hotplug handler in both the path for initially present CPUs and those
hotplugged later. That function includes a one time call to
amd_set_max_freq_ratio() which in turn calls freq_invariance_enable() that has
a static_branch_enable() which takes the cpu_hotlug_lock which is already
held.
Avoid the deadlock by using static_branch_enable_cpuslocked() as the lock will
always be already held. The equivalent path on Intel does not already hold
this lock, so take it around the call to freq_invariance_enable(), which
results in it being held over the call to register_syscall_ops, which looks to
be safe to do.
Fixes: c1385c1f0b ("ACPI: processor: Simplify initial onlining to use same path for cold and hotplug")
Closes: https://lore.kernel.org/all/CABXGCsPvqBfL5hQDOARwfqasLRJ_eNPBbCngZ257HOe=xbWDkA@mail.gmail.com/
Reported-by: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
Tested-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20240729105504.2170-1-Jonathan.Cameron@huawei.com
Package C2 residency counter is also available on Sierra Forest.
So add it support in srf_cstates.
Fixes: 3877d55a0d ("perf/x86/intel/cstate: Add Sierra Forest support")
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
Tested-by: Wendy Wang <wendy.wang@intel.com>
Link: https://lore.kernel.org/r/20240717031609.74513-1-zhenyuw@linux.intel.com
Commit 3a7e02c040 ("minmax: avoid overly complicated constant
expressions in VM code") added the simpler MIN_T/MAX_T macros in order
to avoid some excessive expansion from the rather complicated regular
min/max macros.
The complexity of those macros stems from two issues:
(a) trying to use them in situations that require a C constant
expression (in static initializers and for array sizes)
(b) the type sanity checking
and MIN_T/MAX_T avoids both of these issues.
Now, in the whole (long) discussion about all this, it was pointed out
that the whole type sanity checking is entirely unnecessary for
min_t/max_t which get a fixed type that the comparison is done in.
But that still leaves min_t/max_t unnecessarily complicated due to
worries about the C constant expression case.
However, it turns out that there really aren't very many cases that use
min_t/max_t for this, and we can just force-convert those.
This does exactly that.
Which in turn will then allow for much simpler implementations of
min_t()/max_t(). All the usual "macros in all upper case will evaluate
the arguments multiple times" rules apply.
We should do all the same things for the regular min/max() vs MIN/MAX()
cases, but that has the added complexity of various drivers defining
their own local versions of MIN/MAX, so that needs another level of
fixes first.
Link: https://lore.kernel.org/all/b47fad1d0cf8449886ad148f8c013dae@AcuMS.aculab.com/
Cc: David Laight <David.Laight@aculab.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Merge tag 'for-linus-6.11-rc1a-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip
Pull xen fixes from Juergen Gross:
"Two fixes for issues introduced in this merge window:
- fix enhanced debugging in the Xen multicall handling
- two patches fixing a boot failure when running as dom0 in PVH mode"
* tag 'for-linus-6.11-rc1a-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
x86/xen: fix memblock_reserve() usage on PVH
x86/xen: move xen_reserve_extra_memory()
xen: fix multicall debug data referencing
We have some very fancy min/max macros that have tons of sanity checking
to warn about mixed signedness etc.
This is all things that a sane compiler should warn about, but there are
no sane compiler interfaces for this, and '-Wsign-compare' is broken [1]
and not useful.
So then we compensate (some would say over-compensate) by doing the
checks manually with some truly horrid macro games.
And no, we can't just use __builtin_types_compatible_p(), because the
whole question of "does it make sense to compare these two values" is a
lot more complicated than that.
For example, it makes a ton of sense to compare unsigned values with
simple constants like "5", even if that is indeed a signed type. So we
have these very strange macros to try to make sensible type checking
decisions on the arguments to 'min()' and 'max()'.
But that can cause enormous code expansion if the min()/max() macros are
used with complicated expressions, and particularly if you nest these
things so that you get the first big expansion then expanded again.
The xen setup.c file ended up ballooning to over 50MB of preprocessed
noise that takes 15s to compile (obviously depending on the build host),
largely due to one single line.
So let's split that one single line to just be simpler. I think it ends
up being more legible to humans too at the same time. Now that single
file compiles in under a second.
Reported-and-reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Link: https://lore.kernel.org/all/c83c17bb-be75-4c67-979d-54eee38774c6@lucifer.local/
Link: https://staticthinking.wordpress.com/2023/07/25/wsign-compare-is-garbage/ [1]
Cc: David Laight <David.Laight@aculab.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This check is currently performed by sev_gmem_post_populate(), but it
applies to all callers of kvm_gmem_populate(): the point of the function
is that the memory is being encrypted and some work has to be done
on all the gfns in order to encrypt them.
Therefore, check the KVM_MEMORY_ATTRIBUTE_PRIVATE attribute prior
to invoking the callback, and stop the operation if a shared page
is encountered. Because CONFIG_KVM_PRIVATE_MEM in principle does
not require attributes, this makes kvm_gmem_populate() depend on
CONFIG_KVM_GENERIC_PRIVATE_MEM (which does require them).
Reviewed-by: Michael Roth <michael.roth@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
While currently there is no other attribute than KVM_MEMORY_ATTRIBUTE_PRIVATE,
KVM code such as kvm_mem_is_private() is written to expect their existence.
Allow using kvm_range_has_memory_attributes() as a multi-page version of
kvm_mem_is_private(), without it breaking later when more attributes are
introduced.
Reviewed-by: Michael Roth <michael.roth@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Do not allow populating the same page twice with startup data. In the
case of SEV-SNP, for example, the firmware does not allow it anyway,
since the launch-update operation is only possible on pages that are
still shared in the RMP.
Even if it worked, kvm_gmem_populate()'s callback is meant to have side
effects such as updating launch measurements, and updating the same
page twice is unlikely to have the desired results.
Races between calls to the ioctl are not possible because
kvm_gmem_populate() holds slots_lock and the VM should not be running.
But again, even if this worked on other confidential computing technology,
it doesn't matter to guest_memfd.c whether this is something fishy
such as missing synchronization in userspace, or rather something
intentional. One of the racers wins, and the page is initialized by
either kvm_gmem_prepare_folio() or kvm_gmem_populate().
Anyway, out of paranoia, adjust sev_gmem_post_populate() anyway to use
the same errno that kvm_gmem_populate() is using.
Reviewed-by: Michael Roth <michael.roth@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
It is enough to return 0 if a guest need not do any preparation.
This is in fact how sev_gmem_prepare() works for non-SNP guests,
and it extends naturally to Intel hosts: the x86 callback for
gmem_prepare is optional and returns 0 if not defined.
Reviewed-by: Michael Roth <michael.roth@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Add "ARCH" to the symbols; shortly, the "prepare" phase will include both
the arch-independent step to clear out contents left in the page by the
host, and the arch-dependent step enabled by CONFIG_HAVE_KVM_GMEM_PREPARE.
For consistency do the same for CONFIG_HAVE_KVM_GMEM_INVALIDATE as well.
Reviewed-by: Michael Roth <michael.roth@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
