linux-kernel - Re: [PATCH v2 3/6] KVM: arm64: Allow userspace to inject external instruction aborts

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Message-ID: <aHFpIpIfqVCQZVgG@linux.dev>
Date: Fri, 11 Jul 2025 12:42:26 -0700
From: Oliver Upton <oliver.upton@...ux.dev>
To: Jiaqi Yan <jiaqiyan@...gle.com>
Cc: maz@...nel.org, joey.gouly@....com, suzuki.poulose@....com,
	yuzenghui@...wei.com, catalin.marinas@....com, will@...nel.org,
	pbonzini@...hat.com, corbet@....net, shuah@...nel.org,
	kvm@...r.kernel.org, kvmarm@...ts.linux.dev,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	linux-doc@...r.kernel.org, linux-kselftest@...r.kernel.org,
	duenwen@...gle.com, rananta@...gle.com, jthoughton@...gle.com
Subject: Re: [PATCH v2 3/6] KVM: arm64: Allow userspace to inject external
 instruction aborts

On Wed, Jun 04, 2025 at 05:08:58AM +0000, Jiaqi Yan wrote:
> From: Raghavendra Rao Ananta <rananta@...gle.com>
> 
> When KVM returns to userspace for KVM_EXIT_ARM_SEA, the userspace is
> encouraged to inject the abort into the guest via KVM_SET_VCPU_EVENTS.
> 
> KVM_SET_VCPU_EVENTS currently only allows injecting external data aborts.
> However, the synchronous external abort that caused KVM_EXIT_ARM_SEA
> is possible to be an instruction abort. Userspace is already able to
> tell if an abort is due to data or instruction via kvm_run.arm_sea.esr,
> by checking its Exception Class value.
> 
> Extend the KVM_SET_VCPU_EVENTS ioctl to allow injecting instruction
> abort into the guest.
> 
> Signed-off-by: Raghavendra Rao Ananta <rananta@...gle.com>
> Signed-off-by: Jiaqi Yan <jiaqiyan@...gle.com>

Hmm. Since we expose an ESR value to userspace I get the feeling that we
should allow the user to supply an ISS for the external abort, similar
to what we already do for SErrors.

Thanks,
Oliver