Re: [PATCH 0/2] KVM: SVM: Set pCPU during IRTE update if vCPU is running

[Sean Christopherson]

On Tue, 08 Aug 2023 16:31:30 -0700, Sean Christopherson wrote:
> Fix a bug where KVM doesn't set the pCPU affinity for running vCPUs when
> updating IRTE routing.  Not setting the pCPU means the IOMMU will signal
> the wrong pCPU's doorbell until the vCPU goes through a put+load cycle.
> 
> I waffled for far too long between making this one patch or two.  Moving
> the lock doesn't make all that much sense as a standalone patch, but in the
> end, I decided that isolating the locking change would be useful in the
> unlikely event that it breaks something.  If anyone feels strongly about
> making this a single patch, I have no objection to squashing these together.
> 
> [...]

Applied to kvm-x86 svm, with a massaged changelog in patch 2 to state that the
bug "only" delays IRQs.

[1/2] KVM: SVM: Take and hold ir_list_lock when updating vCPU's Physical ID entry
      https://github.com/kvm-x86/linux/commit/4c08e737f056
[2/2] KVM: SVM: Set target pCPU during IRTE update if target vCPU is running
      https://github.com/kvm-x86/linux/commit/f3cebc75e742

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https://github.com/kvm-x86/linux/tree/next
https://github.com/kvm-x86/linux/tree/fixes