linux-kernel - Re: [PATCH v3 3/3] kvm: arm64: handle single-step of userspace mmio instructions

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Date:   Thu, 16 Nov 2017 17:44:02 +0000
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:     open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 3/3] kvm: arm64: handle single-step of userspace mmio
 instructions



On 16/11/17 15:39, Alex Bennée wrote:
> The system state of KVM when using userspace emulation is not complete
> until we return into KVM_RUN. To handle mmio related updates we wait
> until they have been committed and then schedule our KVM_EXIT_DEBUG.
> 
> The kvm_arm_handle_step_debug() helper tells us if we need to return
> and sets up the exit_reason for us.
> 
> Signed-off-by: Alex Bennée <alex.bennee@...aro.org>
> 

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

> ---
> v2
>    - call helper directly from kvm_arch_vcpu_ioctl_run
> v3
>    - return 0 (ioctl success) instead of 1
> ---
>   virt/kvm/arm/arm.c | 3 +++
>   1 file changed, 3 insertions(+)
> 
> diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c
> index 95cba0799828..b40440defca1 100644
> --- a/virt/kvm/arm/arm.c
> +++ b/virt/kvm/arm/arm.c
> @@ -625,6 +625,9 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
>   		ret = kvm_handle_mmio_return(vcpu, vcpu->run);
>   		if (ret)
>   			return ret;
> +		if (kvm_arm_handle_step_debug(vcpu, vcpu->run))
> +			return 0;
> +
>   	}
>   
>   	if (run->immediate_exit)
> 

-- 
Julien Thierry