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From: Marc Zyngier <maz@kernel.org>
To: Andrew Jones <drjones@redhat.com>,
	kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org
Cc: mark.rutland@arm.com
Subject: Re: [PATCH v2] arm64: KVM: Only skip MMIO insn once
Date: Thu, 22 Aug 2019 13:21:23 +0100
Message-ID: <af0737b1-ffe8-1ace-5aab-f08331b6d940@kernel.org> (raw)
In-Reply-To: <20190822110305.18035-1-drjones@redhat.com>

On 22/08/2019 12:03, Andrew Jones wrote:
> If after an MMIO exit to userspace a VCPU is immediately run with an
> immediate_exit request, such as when a signal is delivered or an MMIO
> emulation completion is needed, then the VCPU completes the MMIO
> emulation and immediately returns to userspace. As the exit_reason
> does not get changed from KVM_EXIT_MMIO in these cases we have to
> be careful not to complete the MMIO emulation again, when the VCPU is
> eventually run again, because the emulation does an instruction skip
> (and doing too many skips would be a waste of guest code :-) We need
> to use additional VCPU state to track if the emulation is complete.
> As luck would have it, we already have 'mmio_needed', which even
> appears to be used in this way by other architectures already.
> 
> Fixes: 0d640732dbeb ("arm64: KVM: Skip MMIO insn after emulation")
> Signed-off-by: Andrew Jones <drjones@redhat.com>
> ---
> v2: move mmio_needed use closer to other mmio state use [maz]
> 
>  virt/kvm/arm/mmio.c | 7 +++++++
>  1 file changed, 7 insertions(+)

Applied with Mark's Ack.

Thanks,

	M.
-- 
Jazz is not dead, it just smells funny...

      parent reply index

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-22 11:03 Andrew Jones
2019-08-22 11:59 ` Mark Rutland
2019-08-22 12:21 ` Marc Zyngier [this message]

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