On Thu, 27 Feb 2025 14:24:05 -0800, Sean Christopherson wrote:
> Fix a long-lurking bug in SVM where KVM runs the guest with the host's
> DEBUGCTL if LBR virtualization is disabled. AMD CPUs rather stupidly
> context switch DEBUGCTL if and only if LBR virtualization is enabled (not
> just supported, but fully enabled).
>
> The bug has gone unnoticed because until recently, the only bits that
> KVM would leave set were things like BTF, which are guest visible but
> won't cause functional problems unless guest software is being especially
> particular about #DBs.
>
> [...]
Applied patch 6 to kvm-x86 svm (1-5 already went into 6.15).
[6/6] KVM: SVM: Treat DEBUGCTL[5:2] as reserved
https://github.com/kvm-x86/linux/commit/5ecdb48dd918
--
https://github.com/kvm-x86/linux/tree/next
