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Code Issues Releases Wiki Activity

KVM: selftests: Disallow "get supported CPUID" before REQ_XCOMP_GUEST_PERM

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Disallow using kvm_get_supported_cpuid() and thus caching KVM's supported
CPUID info before enabling XSAVE-managed features that are off-by-default
and must be enabled by ARCH_REQ_XCOMP_GUEST_PERM.  Caching the supported
CPUID before all XSAVE features are enabled can result in false negatives
due to testing features that were cached before they were enabled.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20221128225735.3291648-4-seanjc@google.com
This commit is contained in:
Sean Christopherson 2022-11-28 22:57:34 +00:00
parent 2ceade1d36
commit cd5f3d2100
1 changed files with 12 additions and 6 deletions
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18
tools/testing/selftests/kvm/lib/x86_64/processor.c
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@ -601,21 +601,24 @@ void vcpu_arch_free(struct kvm_vcpu *vcpu)
free(vcpu->cpuid);
}
/* Do not use kvm_supported_cpuid directly except for validity checks. */
static void *kvm_supported_cpuid;
const struct kvm_cpuid2 *kvm_get_supported_cpuid(void)
{
static struct kvm_cpuid2 *cpuid;
int kvm_fd;
if (cpuid)
return cpuid;
if (kvm_supported_cpuid)
return kvm_supported_cpuid;
cpuid = allocate_kvm_cpuid2(MAX_NR_CPUID_ENTRIES);
kvm_supported_cpuid = allocate_kvm_cpuid2(MAX_NR_CPUID_ENTRIES);
kvm_fd = open_kvm_dev_path_or_exit();
kvm_ioctl(kvm_fd, KVM_GET_SUPPORTED_CPUID, cpuid);
kvm_ioctl(kvm_fd, KVM_GET_SUPPORTED_CPUID,
(struct kvm_cpuid2 *)kvm_supported_cpuid);
close(kvm_fd);
return cpuid;
return kvm_supported_cpuid;
}
static uint32_t __kvm_cpu_has(const struct kvm_cpuid2 *cpuid,
@ -684,6 +687,9 @@ void __vm_xsave_require_permission(int bit, const char *name)
.addr = (unsigned long) &bitmask
};
TEST_ASSERT(!kvm_supported_cpuid,
"kvm_get_supported_cpuid() cannot be used before ARCH_REQ_XCOMP_GUEST_PERM");
kvm_fd = open_kvm_dev_path_or_exit();
rc = __kvm_ioctl(kvm_fd, KVM_GET_DEVICE_ATTR, &attr);
close(kvm_fd);