diff mbox series

[v3,07/13] KVM: selftests: x86: Fix the checks to XFD_ERR using and operation

Message ID 20230221163655.920289-8-mizhang@google.com
State New
Headers
Series Overhauling amx_test |

Commit Message

Mingwei Zhang Feb. 21, 2023, 4:36 p.m. UTC 
  Fix the checks to XFD_ERR using logical AND operation because XFD_ERR might
contain more information in the future. According Intel SDM Vol 1. 13.14:

"Specifically, the MSR is loaded with the logical AND of the IA32_XFD MSR
and the bitmap corresponding to the state component(s) required by the
faulting instruction."

So fix the check by using AND instead of '=='.

Signed-off-by: Mingwei Zhang <mizhang@google.com>
---
 tools/testing/selftests/kvm/x86_64/amx_test.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

Sean Christopherson March 24, 2023, 8:41 p.m. UTC | #1 
On Tue, Feb 21, 2023, Mingwei Zhang wrote:
> Fix the checks to XFD_ERR using logical AND operation because XFD_ERR might
> contain more information in the future. According Intel SDM Vol 1. 13.14:

If that happens, then the future change is responsible for updating the check.
The test very clearly does a straight write of MSR_IA32_XFD.  If there are extra
bits set then something is broken.

	wrmsr(MSR_IA32_XFD, XFEATURE_MASK_XTILEDATA);
diff mbox series

Patch

diff --git a/tools/testing/selftests/kvm/x86_64/amx_test.c b/tools/testing/selftests/kvm/x86_64/amx_test.c
index 296c954dfd6d..62fff3363b3b 100644
--- a/tools/testing/selftests/kvm/x86_64/amx_test.c
+++ b/tools/testing/selftests/kvm/x86_64/amx_test.c
@@ -217,10 +217,10 @@  void guest_nm_handler(struct ex_regs *regs)
 	/* Check if #NM is triggered by XFEATURE_MASK_XTILEDATA */
 	GUEST_SYNC(7);
 	GUEST_ASSERT((get_cr0() & X86_CR0_TS) == 0);
-	GUEST_ASSERT(rdmsr(MSR_IA32_XFD_ERR) == XFEATURE_MASK_XTILEDATA);
+	GUEST_ASSERT(rdmsr(MSR_IA32_XFD_ERR) & XFEATURE_MASK_XTILEDATA);
 	GUEST_ASSERT(rdmsr(MSR_IA32_XFD) & XFEATURE_MASK_XTILEDATA);
 	GUEST_SYNC(8);
-	GUEST_ASSERT(rdmsr(MSR_IA32_XFD_ERR) == XFEATURE_MASK_XTILEDATA);
+	GUEST_ASSERT(rdmsr(MSR_IA32_XFD_ERR) & XFEATURE_MASK_XTILEDATA);
 	GUEST_ASSERT(rdmsr(MSR_IA32_XFD) & XFEATURE_MASK_XTILEDATA);
 	/* Clear xfd_err */
 	wrmsr(MSR_IA32_XFD_ERR, 0);