[PATCH 1/3] selftest: kvm: Reorder vcpu_load_state steps for AMX

Yang Zhong
2021-12-21T14:20:15Z

From: Paolo Bonzini <pbonzini@redhat.com>

For AMX support it is recommended to load XCR0 after XFD, so
that KVM does not see XFD=0, XCR=1 for a save state that will
eventually be disabled (which would lead to premature allocation
of the space required for that save state).

It is also required to load XSAVE data after XCR0 and XFD, so
that KVM can trigger allocation of the extra space required to
store AMX state.

Adjust vcpu_load_state to obey these new requirements.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Yang Zhong <yang.zhong@intel.com>
---
.../selftests/kvm/lib/x86_64/processor.c | 29 ++++++++++---------
1 file changed, 15 insertions(+), 14 deletions(-)

diff --git a/tools/testing/selftests/kvm/lib/x86_64/processor.c b/tools/testing/selftests/kvm/lib/x86_64/processor.c
index 00324d73c687..9b5abf488211 100644
--- a/tools/testing/selftests/kvm/lib/x86_64/processor.c
+++ b/tools/testing/selftests/kvm/lib/x86_64/processor.c
@@ -1192,9 +1192,14 @@ void vcpu_load_state(struct kvm_vm *vm, uint32_t vcpuid, struct kvm_x86_state *s
struct vcpu *vcpu = vcpu_find(vm, vcpuid);
int r;

- r = ioctl(vcpu->fd, KVM_SET_XSAVE, &state->xsave);
- TEST_ASSERT(r == 0, "Unexpected result from KVM_SET_XSAVE, r: %i",
- r);
+ r = ioctl(vcpu->fd, KVM_SET_SREGS, &state->sregs);
+ TEST_ASSERT(r == 0, "Unexpected result from KVM_SET_SREGS, r: %i",
+ r);
+
+ r = ioctl(vcpu->fd, KVM_SET_MSRS, &state->msrs);
+ TEST_ASSERT(r == state->msrs.nmsrs,
+ "Unexpected result from KVM_SET_MSRS,r: %i (failed at %x)",
+ r, r == state->msrs.nmsrs ? -1 : state->msrs.entries[r].index);

if (kvm_check_cap(KVM_CAP_XCRS)) {
r = ioctl(vcpu->fd, KVM_SET_XCRS, &state->xcrs);
@@ -1202,17 +1207,13 @@ void vcpu_load_state(struct kvm_vm *vm, uint32_t vcpuid, struct kvm_x86_state *s
r);
}

- r = ioctl(vcpu->fd, KVM_SET_SREGS, &state->sregs);
- TEST_ASSERT(r == 0, "Unexpected result from KVM_SET_SREGS, r: %i",
- r);
-
- r = ioctl(vcpu->fd, KVM_SET_MSRS, &state->msrs);
- TEST_ASSERT(r == state->msrs.nmsrs, "Unexpected result from KVM_SET_MSRS, r: %i (failed at %x)",
- r, r == state->msrs.nmsrs ? -1 : state->msrs.entries[r].index);
+ r = ioctl(vcpu->fd, KVM_SET_XSAVE, &state->xsave);
+ TEST_ASSERT(r == 0, "Unexpected result from KVM_SET_XSAVE, r: %i",
+ r);

r = ioctl(vcpu->fd, KVM_SET_VCPU_EVENTS, &state->events);
- TEST_ASSERT(r == 0, "Unexpected result from KVM_SET_VCPU_EVENTS, r: %i",
- r);
+ TEST_ASSERT(r == 0, "Unexpected result from KVM_SET_VCPU_EVENTS, r: %i",
+ r);

r = ioctl(vcpu->fd, KVM_SET_MP_STATE, &state->mp_state);
TEST_ASSERT(r == 0, "Unexpected result from KVM_SET_MP_STATE, r: %i",
@@ -1223,8 +1224,8 @@ void vcpu_load_state(struct kvm_vm *vm, uint32_t vcpuid, struct kvm_x86_state *s
r);

r = ioctl(vcpu->fd, KVM_SET_REGS, &state->regs);
- TEST_ASSERT(r == 0, "Unexpected result from KVM_SET_REGS, r: %i",
- r);
+ TEST_ASSERT(r == 0, "Unexpected result from KVM_SET_REGS, r: %i",
+ r);

if (state->nested.size) {
r = ioctl(vcpu->fd, KVM_SET_NESTED_STATE, &state->nested);