Commit 77709820 authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

KVM: selftests: Load XSAVE state into untouched vCPU during state test 



Expand x86's state test to load XSAVE state into a "dummy" vCPU prior to
KVM_SET_CPUID2, and again with an empty guest CPUID model.  Except for
off-by-default features, i.e. AMX, KVM's ABI for KVM_SET_XSAVE is that
userspace is allowed to load xfeatures so long as they are supported by
the host.  This is a regression test for a combination of KVM bugs where
the state saved by KVM_GET_XSAVE{2} could not be loaded via KVM_SET_XSAVE
if the saved xstate_bv would load guest-unsupported xfeatures.

Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Message-Id: <20230928001956.924301-5-seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 60d351f1

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

+17 −2
Original line number Diff line number Diff line
@@ -231,9 +231,9 @@ static void __attribute__((__flatten__)) guest_code(void *arg) 
int main(int argc, char *argv[])

{

	vm_vaddr_t nested_gva = 0;



	struct kvm_cpuid2 empty_cpuid = {};

	struct kvm_regs regs1, regs2;

	struct kvm_vcpu *vcpu;

	struct kvm_vcpu *vcpu, *vcpuN;

	struct kvm_vm *vm;

	struct kvm_x86_state *state;

	struct ucall uc;
@@ -286,6 +286,21 @@ int main(int argc, char *argv[]) 
		/* Restore state in a new VM.  */

		vcpu = vm_recreate_with_one_vcpu(vm);

		vcpu_load_state(vcpu, state);



		/*

		 * Restore XSAVE state in a dummy vCPU, first without doing

		 * KVM_SET_CPUID2, and then with an empty guest CPUID.  Except

		 * for off-by-default xfeatures, e.g. AMX, KVM is supposed to

		 * allow KVM_SET_XSAVE regardless of guest CPUID.  Manually

		 * load only XSAVE state, MSRs in particular have a much more

		 * convoluted ABI.

		 */

		vcpuN = __vm_vcpu_add(vm, vcpu->id + 1);

		vcpu_xsave_set(vcpuN, state->xsave);



		vcpu_init_cpuid(vcpuN, &empty_cpuid);

		vcpu_xsave_set(vcpuN, state->xsave);



		kvm_x86_state_cleanup(state);



		memset(&regs2, 0, sizeof(regs2));