On 12/5/22 4:23 AM, Borislav Petkov wrote:
On Wed, Nov 30, 2022 at 07:49:57PM -0600, Kim Phillips wrote:
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -307,6 +307,7 @@
#define X86_FEATURE_SGX_EDECCSSA (11*32+18) /* "" SGX EDECCSSA user leaf function */
#define X86_FEATURE_CALL_DEPTH (11*32+19) /* "" Call depth tracking for RSB stuffing */
#define X86_FEATURE_MSR_TSX_CTRL (11*32+20) /* "" MSR IA32_TSX_CTRL (Intel) implemented */
+#define X86_FEATURE_NO_NESTED_DATA_BP (11*32+21) /* "" AMD No Nested Data Breakpoints */
Right, what is the use of this bit in a KVM guest? Running perf tool in
a guest would use that bit how?
This is starting to get off-topic. Propagating that bit to
the guest was originally added by:
commit 58b3d12c0a860cda34ed9d2378078ea5134e6812
Author: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Date: Thu Oct 28 13:26:38 2021 -0400
KVM: x86: add support for CPUID leaf 0x80000021
In the future, it will be used by:
https://lore.kernel.org/lkml/20221201021948.9259-1-aik@xxxxxxx/
to allow hardware swapping of debug registers.
If it can't be used in the nested VM case, I can remove the
guest propagation code for it from PATCH 4/7 with a Fixes: for
the above commit, but this 1/7 PATCH will remain.
Thanks,
Kim
