Use a magic value to signal a ucall_alloc() failure instead of simply
doing GUEST_ASSERT(). GUEST_ASSERT() relies on ucall_alloc() and so a
failure puts the guest into an infinite loop.
Use -1 as the magic value, as a real ucall struct should never wrap.
Reported-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
x86 Xen-for-KVM:
* Allow the Xen runstate information to cross a page boundary
* Allow XEN_RUNSTATE_UPDATE flag behaviour to be configured
* add support for 32-bit guests in SCHEDOP_poll
x86 fixes:
* One-off fixes for various emulation flows (SGX, VMXON, NRIPS=0).
* Reinstate IBPB on emulated VM-Exit that was incorrectly dropped a few
years back when eliminating unnecessary barriers when switching between
vmcs01 and vmcs02.
* Clean up the MSR filter docs.
* Clean up vmread_error_trampoline() to make it more obvious that params
must be passed on the stack, even for x86-64.
* Let userspace set all supported bits in MSR_IA32_FEAT_CTL irrespective
of the current guest CPUID.
* Fudge around a race with TSC refinement that results in KVM incorrectly
thinking a guest needs TSC scaling when running on a CPU with a
constant TSC, but no hardware-enumerated TSC frequency.
* Advertise (on AMD) that the SMM_CTL MSR is not supported
* Remove unnecessary exports
Selftests:
* Fix an inverted check in the access tracking perf test, and restore
support for asserting that there aren't too many idle pages when
running on bare metal.
* Fix an ordering issue in the AMX test introduced by recent conversions
to use kvm_cpu_has(), and harden the code to guard against similar bugs
in the future. Anything that tiggers caching of KVM's supported CPUID,
kvm_cpu_has() in this case, effectively hides opt-in XSAVE features if
the caching occurs before the test opts in via prctl().
* Fix build errors that occur in certain setups (unsure exactly what is
unique about the problematic setup) due to glibc overriding
static_assert() to a variant that requires a custom message.
* Introduce actual atomics for clear/set_bit() in selftests
Documentation:
* Remove deleted ioctls from documentation
* Various fixes
MEM_REGION_TEST_DATA is meant to hold data explicitly used by a
selftest, not implicit allocations due to the selftests infrastructure.
Allocate the ucall pool from MEM_REGION_DATA much like the rest of the
selftests library allocations.
Fixes: 426729b2cf ("KVM: selftests: Add ucall pool based implementation")
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Message-Id: <20221207214809.489070-5-oliver.upton@linux.dev>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Drop the "atomic_" prefix from tools' atomic_test_and_set_bit() to
match the kernel nomenclature where test_and_set_bit() is atomic,
and __test_and_set_bit() provides the non-atomic variant.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20221119013450.2643007-9-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
To play nice with guests whose stack memory is encrypted, e.g. AMD SEV,
introduce a new "ucall pool" implementation that passes the ucall struct
via dedicated memory (which can be mapped shared, a.k.a. as plain text).
Because not all architectures have access to the vCPU index in the guest,
use a bitmap with atomic accesses to track which entries in the pool are
free/used. A list+lock could also work in theory, but synchronizing the
individual pointers to the guest would be a mess.
Note, there's no need to rewalk the bitmap to ensure success. If all
vCPUs are simply allocating, success is guaranteed because there are
enough entries for all vCPUs. If one or more vCPUs are freeing and then
reallocating, success is guaranteed because vCPUs _always_ walk the
bitmap from 0=>N; if vCPU frees an entry and then wins a race to
re-allocate, then either it will consume the entry it just freed (bit is
the first free bit), or the losing vCPU is guaranteed to see the freed
bit (winner consumes an earlier bit, which the loser hasn't yet visited).
Reviewed-by: Andrew Jones <andrew.jones@linux.dev>
Signed-off-by: Peter Gonda <pgonda@google.com>
Co-developed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20221006003409.649993-8-seanjc@google.com
Consolidate the actual copying of a ucall struct from guest=>host into
the common get_ucall(). Return a host virtual address instead of a guest
virtual address even though the addr_gva2hva() part could be moved to
get_ucall() too. Conceptually, get_ucall() is invoked from the host and
should return a host virtual address (and returning NULL for "nothing to
see here" is far superior to returning 0).
Use pointer shenanigans instead of an unnecessary bounce buffer when the
caller of get_ucall() provides a valid pointer.
Reviewed-by: Andrew Jones <andrew.jones@linux.dev>
Tested-by: Peter Gonda <pgonda@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20221006003409.649993-3-seanjc@google.com
Make ucall() a common helper that populates struct ucall, and only calls
into arch code to make the actually call out to userspace.
Rename all arch-specific helpers to make it clear they're arch-specific,
and to avoid collisions with common helpers (one more on its way...)
Add WRITE_ONCE() to stores in ucall() code (as already done to aarch64
code in commit 9e2f6498ef ("selftests: KVM: Handle compiler
optimizations in ucall")) to prevent clang optimizations breaking ucalls.
Cc: Colton Lewis <coltonlewis@google.com>
Reviewed-by: Andrew Jones <andrew.jones@linux.dev>
Tested-by: Peter Gonda <pgonda@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20221006003409.649993-2-seanjc@google.com
