Re: [PATCH stable-5.12.y backport 2/2] KVM: arm64: Resolve all pending PC updates before immediate exit

[Marc Zyngier]

On Tue, 01 Jun 2021 12:12:38 +0100,
Zenghui Yu <yuzenghui@xxxxxxxxxx> wrote:
> 
> commit e3e880bb1518eb10a4b4bb4344ed614d6856f190 upstream.
> 
> Commit 26778aaa134a ("KVM: arm64: Commit pending PC adjustemnts before
> returning to userspace") fixed the PC updating issue by forcing an explicit
> synchronisation of the exception state on vcpu exit to userspace.
> 
> However, we forgot to take into account the case where immediate_exit is
> set by userspace and KVM_RUN will exit immediately. Fix it by resolving all
> pending PC updates before returning to userspace.
> 
> Since __kvm_adjust_pc() relies on a loaded vcpu context, I moved the
> immediate_exit checking right after vcpu_load(). We will get some overhead
> if immediate_exit is true (which should hopefully be rare).
> 
> Fixes: 26778aaa134a ("KVM: arm64: Commit pending PC adjustemnts before returning to userspace")
> Signed-off-by: Zenghui Yu <yuzenghui@xxxxxxxxxx>
> Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
> Link: https://lore.kernel.org/r/20210526141831.1662-1-yuzenghui@xxxxxxxxxx
> Cc: stable@xxxxxxxxxxxxxxx # 5.11

Reviewed-by: Marc Zyngier <maz@xxxxxxxxxx>

	M.

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