Commit 5a759117 authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

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: default avatarSean Christopherson <seanjc@google.com>
Message-Id: <20230613203037.1968489-4-seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent c4abd735

tools/testing/selftests/kvm/x86_64/set_sregs_test.c

+39 −31
Original line number Diff line number Diff line
@@ -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. */