Right now, PGD caching requires a complicated dance of first computing
the MMU role and passing it to __kvm_mmu_new_pgd(), and then separately calling
kvm_init_mmu().
Part of this is due to kvm_mmu_free_roots using mmu->root_level and
mmu->shadow_root_level to distinguish whether the page table uses a single
root or 4 PAE roots. Because kvm_init_mmu() can overwrite mmu->root_level,
kvm_mmu_free_roots() must be called before kvm_init_mmu().
However, even after kvm_init_mmu() there is a way to detect whether the
page table may hold PAE roots, as root.hpa isn't backed by a shadow when
it points at PAE roots. Using this method results in simpler code, and
is one less obstacle in moving all calls to __kvm_mmu_new_pgd() after the
MMU has been initialized.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The root_hpa and root_pgd fields form essentially a struct kvm_mmu_root_info.
Use the struct to have more consistency between mmu->root and
mmu->prev_roots.
The patch is entirely search and replace except for cached_root_available,
which does not need a temporary struct kvm_mmu_root_info anymore.
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
WARN and bail if KVM attempts to free a root that isn't backed by a shadow
page. KVM allocates a bare page for "special" roots, e.g. when using PAE
paging or shadowing 2/3/4-level page tables with 4/5-level, and so root_hpa
will be valid but won't be backed by a shadow page. It's all too easy to
blindly call mmu_free_root_page() on root_hpa, be nice and WARN instead of
crashing KVM and possibly the kernel.
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
In current async pagefault logic, when a page is ready, KVM relies on
kvm_arch_can_dequeue_async_page_present() to determine whether to deliver
a READY event to the Guest. This function test token value of struct
kvm_vcpu_pv_apf_data, which must be reset to zero by Guest kernel when a
READY event is finished by Guest. If value is zero meaning that a READY
event is done, so the KVM can deliver another.
But the kvm_arch_setup_async_pf() may produce a valid token with zero
value, which is confused with previous mention and may lead the loss of
this READY event.
This bug may cause task blocked forever in Guest:
INFO: task stress:7532 blocked for more than 1254 seconds.
Not tainted 5.10.0 #16
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:stress state:D stack: 0 pid: 7532 ppid: 1409
flags:0x00000080
Call Trace:
__schedule+0x1e7/0x650
schedule+0x46/0xb0
kvm_async_pf_task_wait_schedule+0xad/0xe0
? exit_to_user_mode_prepare+0x60/0x70
__kvm_handle_async_pf+0x4f/0xb0
? asm_exc_page_fault+0x8/0x30
exc_page_fault+0x6f/0x110
? asm_exc_page_fault+0x8/0x30
asm_exc_page_fault+0x1e/0x30
RIP: 0033:0x402d00
RSP: 002b:00007ffd31912500 EFLAGS: 00010206
RAX: 0000000000071000 RBX: ffffffffffffffff RCX: 00000000021a32b0
RDX: 000000000007d011 RSI: 000000000007d000 RDI: 00000000021262b0
RBP: 00000000021262b0 R08: 0000000000000003 R09: 0000000000000086
R10: 00000000000000eb R11: 00007fefbdf2baa0 R12: 0000000000000000
R13: 0000000000000002 R14: 000000000007d000 R15: 0000000000001000
Signed-off-by: Liang Zhang <zhangliang5@huawei.com>
Message-Id: <20220222031239.1076682-1-zhangliang5@huawei.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Remove mmu_audit.c and all its collateral, the auditing code has suffered
severe bitrot, ironically partly due to shadow paging being more stable
and thus not benefiting as much from auditing, but mostly due to TDP
supplanting shadow paging for non-nested guests and shadowing of nested
TDP not heavily stressing the logic that is being audited.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
When using KVM_DIRTY_LOG_INITIALLY_SET, huge pages are not
write-protected when dirty logging is enabled on the memslot. Instead
they are write-protected once userspace invokes KVM_CLEAR_DIRTY_LOG for
the first time and only for the specific sub-region being cleared.
Enhance KVM_CLEAR_DIRTY_LOG to also try to split huge pages prior to
write-protecting to avoid causing write-protection faults on vCPU
threads. This also allows userspace to smear the cost of huge page
splitting across multiple ioctls, rather than splitting the entire
memslot as is the case when initially-all-set is not used.
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220119230739.2234394-17-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
When dirty logging is enabled without initially-all-set, try to split
all huge pages in the memslot down to 4KB pages so that vCPUs do not
have to take expensive write-protection faults to split huge pages.
Eager page splitting is best-effort only. This commit only adds the
support for the TDP MMU, and even there splitting may fail due to out
of memory conditions. Failures to split a huge page is fine from a
correctness standpoint because KVM will always follow up splitting by
write-protecting any remaining huge pages.
Eager page splitting moves the cost of splitting huge pages off of the
vCPU threads and onto the thread enabling dirty logging on the memslot.
This is useful because:
1. Splitting on the vCPU thread interrupts vCPUs execution and is
disruptive to customers whereas splitting on VM ioctl threads can
run in parallel with vCPU execution.
2. Splitting all huge pages at once is more efficient because it does
not require performing VM-exit handling or walking the page table for
every 4KiB page in the memslot, and greatly reduces the amount of
contention on the mmu_lock.
For example, when running dirty_log_perf_test with 96 virtual CPUs, 1GiB
per vCPU, and 1GiB HugeTLB memory, the time it takes vCPUs to write to
all of their memory after dirty logging is enabled decreased by 95% from
2.94s to 0.14s.
Eager Page Splitting is over 100x more efficient than the current
implementation of splitting on fault under the read lock. For example,
taking the same workload as above, Eager Page Splitting reduced the CPU
required to split all huge pages from ~270 CPU-seconds ((2.94s - 0.14s)
* 96 vCPU threads) to only 1.55 CPU-seconds.
Eager page splitting does increase the amount of time it takes to enable
dirty logging since it has split all huge pages. For example, the time
it took to enable dirty logging in the 96GiB region of the
aforementioned test increased from 0.001s to 1.55s.
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220119230739.2234394-16-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
restore_acc_track_spte() is pure SPTE bit manipulation, making it a good
fit for spte.h. And now that the WARN_ON_ONCE() calls have been removed,
there isn't any good reason to not inline it.
This move also prepares for a follow-up commit that will need to call
restore_acc_track_spte() from spte.c
No functional change intended.
Reviewed-by: Ben Gardon <bgardon@google.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220119230739.2234394-11-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The new_spte local variable is unnecessary. Deleting it can save a line
of code and simplify the remaining lines a bit.
No functional change intended.
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220119230739.2234394-10-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The warnings in restore_acc_track_spte() can be removed because the only
caller checks is_access_track_spte(), and is_access_track_spte() checks
!spte_ad_enabled(). In other words, the warning can never be triggered.
No functional change intended.
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220119230739.2234394-9-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The function formerly known as rmap_write_protect() has been renamed to
kvm_vcpu_write_protect_gfn(), so we can get rid of the double
underscores in front of __rmap_write_protect().
No functional change intended.
Reviewed-by: Ben Gardon <bgardon@google.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220119230739.2234394-3-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
rmap_write_protect() is a poor name because it also write-protects SPTEs
in the TDP MMU, not just SPTEs in the rmap. It is also confusing that
rmap_write_protect() is not a simple wrapper around
__rmap_write_protect(), since that is the common pattern for functions
with double-underscore names.
Rename rmap_write_protect() to kvm_vcpu_write_protect_gfn() to convey
that KVM is write-protecting a specific gfn in the context of a vCPU.
No functional change intended.
Reviewed-by: Ben Gardon <bgardon@google.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220119230739.2234394-2-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Consolidate the large comment above DEFAULT_SPTE_HOST_WRITABLE with the
large comment above is_writable_pte() into one comment. This comment
explains the different reasons why an SPTE may be non-writable and KVM
keeps track of that with the {Host,MMU}-writable bits.
No functional change intended.
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220125230723.1701061-1-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Both "writeable" and "writable" are valid, but we should be consistent
about which we use. DEFAULT_SPTE_MMU_WRITEABLE was the odd one out in
the SPTE code, so rename it to DEFAULT_SPTE_MMU_WRITABLE.
No functional change intended.
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220125230713.1700406-1-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Check SPTE writable invariants when setting SPTEs rather than in
spte_can_locklessly_be_made_writable(). By the time KVM checks
spte_can_locklessly_be_made_writable(), the SPTE has long been since
corrupted.
Note that these invariants only apply to shadow-present leaf SPTEs (i.e.
not to MMIO SPTEs, non-leaf SPTEs, etc.). Add a comment explaining the
restriction and only instrument the code paths that set shadow-present
leaf SPTEs.
To account for access tracking, also check the SPTE writable invariants
when marking an SPTE as an access track SPTE. This also lets us remove
a redundant WARN from mark_spte_for_access_track().
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220125230518.1697048-3-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Rename a variety of kvm_x86_op function pointers so that preferred name
for vendor implementations follows the pattern <vendor>_<function>, e.g.
rename .run() to .vcpu_run() to match {svm,vmx}_vcpu_run(). This will
allow vendor implementations to be wired up via the KVM_X86_OP macro.
In many cases, VMX and SVM "disagree" on the preferred name, though in
reality it's VMX and x86 that disagree as SVM blindly prepended _svm to
the kvm_x86_ops name. Justification for using the VMX nomenclature:
- set_{irq,nmi} => inject_{irq,nmi} because the helper is injecting an
event that has already been "set" in e.g. the vIRR. SVM's relevant
VMCB field is even named event_inj, and KVM's stat is irq_injections.
- prepare_guest_switch => prepare_switch_to_guest because the former is
ambiguous, e.g. it could mean switching between multiple guests,
switching from the guest to host, etc...
- update_pi_irte => pi_update_irte to allow for matching match the rest
of VMX's posted interrupt naming scheme, which is vmx_pi_<blah>().
- start_assignment => pi_start_assignment to again follow VMX's posted
interrupt naming scheme, and to provide context for what bit of code
might care about an otherwise undescribed "assignment".
The "tlb_flush" => "flush_tlb" creates an inconsistency with respect to
Hyper-V's "tlb_remote_flush" hooks, but Hyper-V really is the one that's
wrong. x86, VMX, and SVM all use flush_tlb, and even common KVM is on a
variant of the bandwagon with "kvm_flush_remote_tlbs", e.g. a more
appropriate name for the Hyper-V hooks would be flush_remote_tlbs. Leave
that change for another time as the Hyper-V hooks always start as NULL,
i.e. the name doesn't matter for using kvm-x86-ops.h, and changing all
names requires an astounding amount of churn.
VMX and SVM function names are intentionally left as is to minimize the
diff. Both VMX and SVM will need to rename even more functions in order
to fully utilize KVM_X86_OPS, i.e. an additional patch for each is
inevitable.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220128005208.4008533-5-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The "struct kvm_vcpu *vcpu" parameter of reset_ept_shadow_zero_bits_mask()
and reset_tdp_shadow_zero_bits_mask() is not used, so remove it.
No functional change intended.
Signed-off-by: Jinrong Liang <cloudliang@tencent.com>
Message-Id: <20220125095909.38122-4-cloudliang@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The "struct kvm *kvm" parameter of __rmap_write_protect()
is not used, so remove it. No functional change intended.
Signed-off-by: Jinrong Liang <cloudliang@tencent.com>
Message-Id: <20220125095909.38122-3-cloudliang@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The "struct kvm *kvm" parameter of kvm_mmu_unlink_parents()
is not used, so remove it. No functional change intended.
Signed-off-by: Jinrong Liang <cloudliang@tencent.com>
Message-Id: <20220125095909.38122-2-cloudliang@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Rewrite the comment in kvm_mmu_slot_remove_write_access() that explains
why it is safe to flush TLBs outside of the MMU lock after
write-protecting SPTEs for dirty logging. The current comment is a long
run-on sentence that was difficult to understand. In addition it was
specific to the shadow MMU (mentioning mmu_spte_update()) when the TDP
MMU has to handle this as well.
The new comment explains:
- Why the TLB flush is necessary at all.
- Why it is desirable to do the TLB flush outside of the MMU lock.
- Why it is safe to do the TLB flush outside of the MMU lock.
No functional change intended.
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220113233020.3986005-5-dmatlack@google.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Pick commit fdba608f15 ("KVM: VMX: Wake vCPU when delivering posted
IRQ even if vCPU == this vCPU"). In addition to fixing a bug, it
also aligns the non-nested and nested usage of triggering posted
interrupts, allowing for additional cleanups.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Play nice with a NULL shadow page when checking for an obsolete root in
the page fault handler by flagging the page fault as stale if there's no
shadow page associated with the root and KVM_REQ_MMU_RELOAD is pending.
Invalidating memslots, which is the only case where _all_ roots need to
be reloaded, requests all vCPUs to reload their MMUs while holding
mmu_lock for lock.
The "special" roots, e.g. pae_root when KVM uses PAE paging, are not
backed by a shadow page. Running with TDP disabled or with nested NPT
explodes spectaculary due to dereferencing a NULL shadow page pointer.
Skip the KVM_REQ_MMU_RELOAD check if there is a valid shadow page for the
root. Zapping shadow pages in response to guest activity, e.g. when the
guest frees a PGD, can trigger KVM_REQ_MMU_RELOAD even if the current
vCPU isn't using the affected root. I.e. KVM_REQ_MMU_RELOAD can be seen
with a completely valid root shadow page. This is a bit of a moot point
as KVM currently unloads all roots on KVM_REQ_MMU_RELOAD, but that will
be cleaned up in the future.
Fixes: a955cad84c ("KVM: x86/mmu: Retry page fault if root is invalidated by memslot update")
Cc: stable@vger.kernel.org
Cc: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211209060552.2956723-2-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This bit is very close to mean "role.quadrant is not in use", except that
it is false also when the MMU is mapping guest physical addresses
directly. In that case, role.quadrant is indeed not in use, but there
are no guest PTEs at all.
Changing the name and direction of the bit removes the special case,
since a guest with paging disabled, or not considering guest paging
structures as is the case for two-dimensional paging, does not have
to deal with 4-byte guest PTEs.
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Message-Id: <20211124122055.64424-10-jiangshanlai@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The level of supported large page on nEPT affects the rsvds_bits_mask.
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Message-Id: <20211124122055.64424-8-jiangshanlai@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Bit 7 on pte depends on the level of supported large page.
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Message-Id: <20211124122055.64424-7-jiangshanlai@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reduce an indirect function call (retpoline) and some intialization
code.
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Message-Id: <20211124122055.64424-4-jiangshanlai@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The mmu->gva_to_gpa() has no "struct kvm_mmu *mmu", so an extra
FNAME(gva_to_gpa_nested) is needed.
Add the parameter can simplify the code. And it makes it explicit that
the walk is upon vcpu->arch.walk_mmu for gva and vcpu->arch.mmu for L2
gpa in translate_nested_gpa() via the new parameter.
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Message-Id: <20211124122055.64424-3-jiangshanlai@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
role.quadrant is only valid when gpte size is 4 bytes and only be
calculated when gpte size is 4 bytes.
Although "vcpu->arch.mmu->root_level <= PT32_ROOT_LEVEL" also means
gpte size is 4 bytes, but using "!role.gpte_is_8_bytes" is clearer
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Message-Id: <20211118110814.2568-15-jiangshanlai@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
role.gpte_is_8_bytes is unused when role.direct; there is no
point in changing a bit in the role, the value that was set
when the MMU is initialized is just fine.
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Message-Id: <20211118110814.2568-14-jiangshanlai@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The allocation of special roots is moved to mmu_alloc_special_roots().
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Message-Id: <20211118110814.2568-12-jiangshanlai@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
It is never used.
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Message-Id: <20211118110814.2568-11-jiangshanlai@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
change 0 to false and 1 to true to fix following cocci warnings:
arch/x86/kvm/mmu/mmu.c:1485:9-10: WARNING: return of 0/1 in function 'kvm_set_pte_rmapp' with return type bool
arch/x86/kvm/mmu/mmu.c:1636:10-11: WARNING: return of 0/1 in function 'kvm_test_age_rmapp' with return type bool
Signed-off-by: Vihas Mak <makvihas@gmail.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Wanpeng Li <wanpengli@tencent.com>
Cc: Jim Mattson <jmattson@google.com>
Cc: Joerg Roedel <joro@8bytes.org>
Message-Id: <20211114164312.GA28736@makvihas>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
In preparation for implementing in-place hugepage promotion, various
functions will need to be called from zap_collapsible_spte_range, which
has the const qualifier on its memslot argument. Propagate the const
qualifier to the various functions which will be needed. This just serves
to simplify the following patch.
No functional change intended.
Signed-off-by: Ben Gardon <bgardon@google.com>
Message-Id: <20211115234603.2908381-11-bgardon@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The vCPU argument to mmu_try_to_unsync_pages is now only used to get a
pointer to the associated struct kvm, so pass in the kvm pointer from
the beginning to remove the need for a vCPU when calling the function.
Signed-off-by: Ben Gardon <bgardon@google.com>
Message-Id: <20211115234603.2908381-7-bgardon@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
kvm_slot_page_track_is_active only uses its vCPU argument to get a
pointer to the assoicated struct kvm, so just pass in the struct KVM to
remove the need for a vCPU pointer.
No functional change intended.
Signed-off-by: Ben Gardon <bgardon@google.com>
Message-Id: <20211115234603.2908381-6-bgardon@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Introduce a memslots gfn upper bound operation and use it to optimize
kvm_zap_gfn_range().
This way this handler can do a quick lookup for intersecting gfns and won't
have to do a linear scan of the whole memslot set.
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Message-Id: <ef242146a87a335ee93b441dcf01665cb847c902.1638817641.git.maciej.szmigiero@oracle.com>
The current memslot code uses a (reverse gfn-ordered) memslot array for
keeping track of them.
Because the memslot array that is currently in use cannot be modified
every memslot management operation (create, delete, move, change flags)
has to make a copy of the whole array so it has a scratch copy to work on.
Strictly speaking, however, it is only necessary to make copy of the
memslot that is being modified, copying all the memslots currently present
is just a limitation of the array-based memslot implementation.
Two memslot sets, however, are still needed so the VM continues to run
on the currently active set while the requested operation is being
performed on the second, currently inactive one.
In order to have two memslot sets, but only one copy of actual memslots
it is necessary to split out the memslot data from the memslot sets.
The memslots themselves should be also kept independent of each other
so they can be individually added or deleted.
These two memslot sets should normally point to the same set of
memslots. They can, however, be desynchronized when performing a
memslot management operation by replacing the memslot to be modified
by its copy. After the operation is complete, both memslot sets once
again point to the same, common set of memslot data.
This commit implements the aforementioned idea.
For tracking of gfns an ordinary rbtree is used since memslots cannot
overlap in the guest address space and so this data structure is
sufficient for ensuring that lookups are done quickly.
The "last used slot" mini-caches (both per-slot set one and per-vCPU one),
that keep track of the last found-by-gfn memslot, are still present in the
new code.
Co-developed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Message-Id: <17c0cf3663b760a0d3753d4ac08c0753e941b811.1638817641.git.maciej.szmigiero@oracle.com>
There is no point in recalculating from scratch the total number of pages
in all memslots each time a memslot is created or deleted. Use KVM's
cached nr_memslot_pages to compute the default max number of MMU pages.
Note that even with nr_memslot_pages capped at ULONG_MAX we can't safely
multiply it by KVM_PERMILLE_MMU_PAGES (20) since this operation can
possibly overflow an unsigned long variable.
Write this "* 20 / 1000" operation as "/ 50" instead to avoid such
overflow.
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
[sean: use common KVM field and rework changelog accordingly]
Reviewed-by: Sean Christopherson <seanjc@google.com>
Message-Id: <d14c5a24535269606675437d5602b7dac4ad8c0e.1638817640.git.maciej.szmigiero@oracle.com>
Bail from the page fault handler if the root shadow page was obsoleted by
a memslot update. Do the check _after_ acuiring mmu_lock, as the TDP MMU
doesn't rely on the memslot/MMU generation, and instead relies on the
root being explicit marked invalid by kvm_mmu_zap_all_fast(), which takes
mmu_lock for write.
For the TDP MMU, inserting a SPTE into an obsolete root can leak a SP if
kvm_tdp_mmu_zap_invalidated_roots() has already zapped the SP, i.e. has
moved past the gfn associated with the SP.
For other MMUs, the resulting behavior is far more convoluted, though
unlikely to be truly problematic. Installing SPs/SPTEs into the obsolete
root isn't directly problematic, as the obsolete root will be unloaded
and dropped before the vCPU re-enters the guest. But because the legacy
MMU tracks shadow pages by their role, any SP created by the fault can
can be reused in the new post-reload root. Again, that _shouldn't_ be
problematic as any leaf child SPTEs will be created for the current/valid
memslot generation, and kvm_mmu_get_page() will not reuse child SPs from
the old generation as they will be flagged as obsolete. But, given that
continuing with the fault is pointess (the root will be unloaded), apply
the check to all MMUs.
Fixes: b7cccd397f ("KVM: x86/mmu: Fast invalidation for TDP MMU")
Cc: stable@vger.kernel.org
Cc: Ben Gardon <bgardon@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211120045046.3940942-5-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Account for the '0' being a default, "let KVM choose" period, when
determining whether or not the recovery worker needs to be awakened in
response to userspace reducing the period. Failure to do so results in
the worker not being awakened properly, e.g. when changing the period
from '0' to any small-ish value.
Fixes: 4dfe4f40d8 ("kvm: x86: mmu: Make NX huge page recovery period configurable")
Cc: stable@vger.kernel.org
Cc: Junaid Shahid <junaids@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211120015706.3830341-1-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Initialize the mask for PKU permissions as if CR4.PKE=0, avoiding
incorrect interpretations of the nested hypervisor's page tables.
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Drop the "flush" param and return values to/from the TDP MMU's helper for
zapping collapsible SPTEs. Because the helper runs with mmu_lock held
for read, not write, it uses tdp_mmu_zap_spte_atomic(), and the atomic
zap handles the necessary remote TLB flush.
Similarly, because mmu_lock is dropped and re-acquired between zapping
legacy MMUs and zapping TDP MMUs, kvm_mmu_zap_collapsible_sptes() must
handle remote TLB flushes from the legacy MMU before calling into the TDP
MMU.
Fixes: e2209710cc ("KVM: x86/mmu: Skip rmap operations if rmaps not allocated")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211120045046.3940942-4-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
INVLPG operates on guest virtual address, which are represented by
vcpu->arch.walk_mmu. In nested virtualization scenarios,
kvm_mmu_invlpg() was using the wrong MMU structure; if L2's invlpg were
emulated by L0 (in practice, it hardly happen) when nested two-dimensional
paging is enabled, the call to ->tlb_flush_gva() would be skipped and
the hardware TLB entry would not be invalidated.
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Message-Id: <20211124122055.64424-5-jiangshanlai@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
If the is an L1 with nNPT in 32bit, the shadow walk starts with
pae_root.
Fixes: a717a780fc ("KVM: x86/mmu: Support shadowing NPT when 5-level paging is enabled in host)
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Message-Id: <20211124122055.64424-2-jiangshanlai@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Commit 63f5a1909f ("KVM: x86: Alert userspace that KVM_SET_CPUID{,2}
after KVM_RUN is broken") officially deprecated KVM_SET_CPUID{,2} ioctls
after first successful KVM_RUN and promissed to make this sequence forbiden
in 5.16. It's time to fulfil the promise.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20211122175818.608220-3-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Since tlb flush has been done for legacy MMU before
kvm_tdp_mmu_zap_collapsible_sptes(), so the parameter flush
should be false for kvm_tdp_mmu_zap_collapsible_sptes().
Fixes: e2209710cc ("KVM: x86/mmu: Skip rmap operations if rmaps not allocated")
Signed-off-by: Hou Wenlong <houwenlong93@linux.alibaba.com>
Message-Id: <21453a1d2533afb6e59fb6c729af89e771ff2e76.1637140154.git.houwenlong93@linux.alibaba.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
If the parameter flush is set, zap_gfn_range() would flush remote tlb
when yield, then tlb flush is not needed outside. So use the return
value of zap_gfn_range() directly instead of OR on it in
kvm_unmap_gfn_range() and kvm_tdp_mmu_unmap_gfn_range().
Fixes: 3039bcc744 ("KVM: Move x86's MMU notifier memslot walkers to generic code")
Signed-off-by: Hou Wenlong <houwenlong93@linux.alibaba.com>
Message-Id: <5e16546e228877a4d974f8c0e448a93d52c7a5a9.1637140154.git.houwenlong93@linux.alibaba.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
* Fixes for Xen emulation
* Kill kvm_map_gfn() / kvm_unmap_gfn() and broken gfn_to_pfn_cache
* Fixes for migration of 32-bit nested guests on 64-bit hypervisor
* Compilation fixes
* More SEV cleanups
Incorporate EFER.LMA into kvm_mmu_extended_role, as it used to compute the
guest root level and is not reflected in kvm_mmu_page_role.level when TDP
is in use. When simply running the guest, it is impossible for EFER.LMA
and kvm_mmu.root_level to get out of sync, as the guest cannot transition
from PAE paging to 64-bit paging without toggling CR0.PG, i.e. without
first bouncing through a different MMU context. And stuffing guest state
via KVM_SET_SREGS{,2} also ensures a full MMU context reset.
However, if KVM_SET_SREGS{,2} is followed by KVM_SET_NESTED_STATE, e.g. to
set guest state when migrating the VM while L2 is active, the vCPU state
will reflect L2, not L1. If L1 is using TDP for L2, then root_mmu will
have been configured using L2's state, despite not being used for L2. If
L2.EFER.LMA != L1.EFER.LMA, and L2 is using PAE paging, then root_mmu will
be configured for guest PAE paging, but will match the mmu_role for 64-bit
paging and cause KVM to not reconfigure root_mmu on the next nested VM-Exit.
Alternatively, the root_mmu's role could be invalidated after a successful
KVM_SET_NESTED_STATE that yields vcpu->arch.mmu != vcpu->arch.root_mmu,
i.e. that switches the active mmu to guest_mmu, but doing so is unnecessarily
tricky, and not even needed if L1 and L2 do have the same role (e.g., they
are both 64-bit guests and run with the same CR4).
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20211115131837.195527-3-mlevitsk@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
* Fix misuse of gfn-to-pfn cache when recording guest steal time / preempted status
* Fix selftests on APICv machines
* Fix sparse warnings
* Fix detection of KVM features in CPUID
* Cleanups for bogus writes to MSR_KVM_PV_EOI_EN
* Fixes and cleanups for MSR bitmap handling
* Cleanups for INVPCID
* Make x86 KVM_SOFT_MAX_VCPUS consistent with other architectures
