Re: [PATCH v4 0/5] KVM: SVM: Add Bus Lock Detect support and refactor LBRV

[Shivansh Dhiman <shivansh.dhiman@amd.com>]

On 25-09-26 23:15, Sean Christopherson wrote:
> On Tue, Jul 21, 2026, Shivansh Dhiman wrote:
>> Shivansh Dhiman (5):
>>   KVM: SVM: Refactor svm_update_lbrv()
>>   KVM: nSVM: Disable LBRV in nested control cache when unsupported
>>   KVM: nSVM: Sanitize nested DR6 using kvm_dr6_fixed()
>>   KVM: SVM: Turn DEBUGCTL_RESERVED_BITS into a helper
>>   KVM: SVM: Add Bus Lock Detect support
> 
> I'll send a v5 as I have variety of changes (I already responded to each patch),
> and I'm not in the mood to deal with another version as I'm quite grumpy that no
> one bothered to follow up on Sashiko's bug report, or to write tests.

Thanks for taking this over, and sorry for missing Sashiko's report. Ravi had
posted a KUT fix for the default DR6 value [1]. I just hadn't rebased and
resent it yet and your KUT tests cover that as well.

I ran them with v5 on AMD hardware and they all pass. I also reproduced
Sashiko's issue and confirmed that v5 fixes it.

[1] https://lore.kernel.org/all/20250224112601.6504-1-ravi.bangoria@amd.com

Regards,
Shivansh

> 
> I'll also post a KUT testcase, which I created to verify the bug Sashiko pointed
> out as well as the fix. 
> 
>>  arch/x86/kvm/regs.c       |  3 ++-
>>  arch/x86/kvm/regs.h       |  1 +
>>  arch/x86/kvm/svm/nested.c | 26 ++++++++++++++------------
>>  arch/x86/kvm/svm/svm.c    | 28 ++++++++++++++++++++--------
>>  arch/x86/kvm/svm/svm.h    | 13 +++++++++++--
>>  5 files changed, 48 insertions(+), 23 deletions(-)