linux-kernel - Re: [PATCH v1 1/2] KVM: arm64: handle single-stepping trapped instructions

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Message-ID: <ec903fcc-6e73-40c6-69b0-b37d7d53d431@arm.com>
Date:   Fri, 6 Oct 2017 14:15:21 +0100
From:   Julien Thierry <julien.thierry@....com>
To:     Alex Bennée <alex.bennee@...aro.org>,
        kvm@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        kvmarm@...ts.cs.columbia.edu, christoffer.dall@...aro.org,
        marc.zyngier@....com
Cc:     Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1 1/2] KVM: arm64: handle single-stepping trapped
 instructions



On 06/10/17 12:39, Alex Bennée wrote:
> If we are using guest debug to single-step the guest we need to ensure
> we exit after emulating the instruction. This only affects
> instructions completely emulated by the kernel. For userspace emulated
> instructions we need to exit and return to complete the emulation.
> 
> We fake debug.arch.hsr to contain ESR_ELx_EC_SOFTSTP_LOW so QEMU knows
> it was a single-step event (and without altering the userspace ABI).
> 
> Signed-off-by: Alex Bennée <alex.bennee@...aro.org>

Reviewed-by: Julien Thierry <julien.thierry@....com>

Thanks,

-- 
Julien Thierry