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KVM: selftests: Expand x86's sregs test to cover illegal CR0 values 

Add coverage to x86's set_sregs_test to verify KVM rejects vendor-agnostic
illegal CR0 values, i.e. CR0 values whose legality doesn't depend on the
current VMX mode.  KVM historically has neglected to reject bad CR0s from
userspace, i.e. would happily accept a completely bogus CR0 via
KVM_SET_SREGS{2}.

Punt VMX specific subtests to future work, as they would require quite a
bit more effort, and KVM gets coverage for CR0 checks in general through
other means, e.g. KVM-Unit-Tests.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20230613203037.1968489-4-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2023-06-13 13:30:37 -07:00 committed by Paolo Bonzini
parent c4abd73520
commit 5a7591176c
1 changed files with 39 additions and 31 deletions
tools/testing/selftests/kvm/x86_64
set_sregs_test.c

70
tools/testing/selftests/kvm/x86_64/set_sregs_test.c
View File

@ -22,26 +22,25 @@
#include "kvm_util.h"
#include "processor.h"
static void test_cr4_feature_bit(struct kvm_vcpu *vcpu, struct kvm_sregs *orig,
uint64_t feature_bit)
{
struct kvm_sregs sregs;
int rc;
/* Skip the sub-test, the feature is supported. */
if (orig->cr4 & feature_bit)
return;
memcpy(&sregs, orig, sizeof(sregs));
sregs.cr4 |= feature_bit;
rc = _vcpu_sregs_set(vcpu, &sregs);
TEST_ASSERT(rc, "KVM allowed unsupported CR4 bit (0x%lx)", feature_bit);
/* Sanity check that KVM didn't change anything. */
vcpu_sregs_get(vcpu, &sregs);
TEST_ASSERT(!memcmp(&sregs, orig, sizeof(sregs)), "KVM modified sregs");
}
#define TEST_INVALID_CR_BIT(vcpu, cr, orig, bit) \
do { \
struct kvm_sregs new; \
int rc; \
\
/* Skip the sub-test, the feature/bit is supported. */ \
if (orig.cr & bit) \
break; \
\
memcpy(&new, &orig, sizeof(sregs)); \
new.cr |= bit; \
\
rc = _vcpu_sregs_set(vcpu, &new); \
TEST_ASSERT(rc, "KVM allowed invalid " #cr " bit (0x%lx)", bit); \
\
/* Sanity check that KVM didn't change anything. */ \
vcpu_sregs_get(vcpu, &new); \
TEST_ASSERT(!memcmp(&new, &orig, sizeof(new)), "KVM modified sregs"); \
} while (0)
static uint64_t calc_supported_cr4_feature_bits(void)
{
@ -80,7 +79,7 @@ int main(int argc, char *argv[])
struct kvm_vcpu *vcpu;
struct kvm_vm *vm;
uint64_t cr4;
int rc;
int rc, i;
/*
* Create a dummy VM, specifically to avoid doing KVM_SET_CPUID2, and
@ -92,6 +91,7 @@ int main(int argc, char *argv[])
vcpu_sregs_get(vcpu, &sregs);
sregs.cr0 = 0;
sregs.cr4 |= calc_supported_cr4_feature_bits();
cr4 = sregs.cr4;
@ -103,16 +103,24 @@ int main(int argc, char *argv[])
sregs.cr4, cr4);
/* Verify all unsupported features are rejected by KVM. */
test_cr4_feature_bit(vcpu, &sregs, X86_CR4_UMIP);
test_cr4_feature_bit(vcpu, &sregs, X86_CR4_LA57);
test_cr4_feature_bit(vcpu, &sregs, X86_CR4_VMXE);
test_cr4_feature_bit(vcpu, &sregs, X86_CR4_SMXE);
test_cr4_feature_bit(vcpu, &sregs, X86_CR4_FSGSBASE);
test_cr4_feature_bit(vcpu, &sregs, X86_CR4_PCIDE);
test_cr4_feature_bit(vcpu, &sregs, X86_CR4_OSXSAVE);
test_cr4_feature_bit(vcpu, &sregs, X86_CR4_SMEP);
test_cr4_feature_bit(vcpu, &sregs, X86_CR4_SMAP);
test_cr4_feature_bit(vcpu, &sregs, X86_CR4_PKE);
TEST_INVALID_CR_BIT(vcpu, cr4, sregs, X86_CR4_UMIP);
TEST_INVALID_CR_BIT(vcpu, cr4, sregs, X86_CR4_LA57);
TEST_INVALID_CR_BIT(vcpu, cr4, sregs, X86_CR4_VMXE);
TEST_INVALID_CR_BIT(vcpu, cr4, sregs, X86_CR4_SMXE);
TEST_INVALID_CR_BIT(vcpu, cr4, sregs, X86_CR4_FSGSBASE);
TEST_INVALID_CR_BIT(vcpu, cr4, sregs, X86_CR4_PCIDE);
TEST_INVALID_CR_BIT(vcpu, cr4, sregs, X86_CR4_OSXSAVE);
TEST_INVALID_CR_BIT(vcpu, cr4, sregs, X86_CR4_SMEP);
TEST_INVALID_CR_BIT(vcpu, cr4, sregs, X86_CR4_SMAP);
TEST_INVALID_CR_BIT(vcpu, cr4, sregs, X86_CR4_PKE);
for (i = 32; i < 64; i++)
TEST_INVALID_CR_BIT(vcpu, cr0, sregs, BIT(i));
/* NW without CD is illegal, as is PG without PE. */
TEST_INVALID_CR_BIT(vcpu, cr0, sregs, X86_CR0_NW);
TEST_INVALID_CR_BIT(vcpu, cr0, sregs, X86_CR0_PG);
kvm_vm_free(vm);
/* Create a "real" VM and verify APIC_BASE can be set. */