Re: [RFC PATCH v12 07/33] KVM: Add KVM_EXIT_MEMORY_FAULT exit to report faults to userspace

[Sean Christopherson]

On Fri, Sep 22, 2023, Sean Christopherson wrote:
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 7c0e38752526..d13b646188e5 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -4184,6 +4184,16 @@ static long kvm_vcpu_ioctl(struct file *filp,
>  				synchronize_rcu();
>  			put_pid(oldpid);
>  		}
> +
> +		/*
> +		 * Reset the exit reason if the previous userspace exit was due
> +		 * to a memory fault.  Not all -EFAULT exits are annotated, and
> +		 * so leaving exit_reason set to KVM_EXIT_MEMORY_FAULT could
> +		 * result in feeding userspace stale information.
> +		 */
> +		if (vcpu->run->exit_reason == KVM_EXIT_MEMORY_FAULT)
> +			vcpu->run->exit_reason = KVM_EXIT_UNKNOWN

Darn semicolons.  Doesn't look like I botched anything else though.

> +
>  		r = kvm_arch_vcpu_ioctl_run(vcpu);
>  		trace_kvm_userspace_exit(vcpu->run->exit_reason, r);
>  		break;
> 
> base-commit: 2358793cd9062b068ac25ac9c965c00d685eea92
> -- 
> 2.42.0.515.g380fc7ccd1-goog
>