Re: [PATCH 3/6] Emulator: Inject #PF when page was not found

From: Joerg Roedel <joerg.roedel@amd.com>
To: Alexander Graf <agraf@suse.de>
Cc: kvm@vger.kernel.org
Subject: Re: [PATCH 3/6] Emulator: Inject #PF when page was not found
Date: Fri, 15 May 2009 15:40:00 +0200	[thread overview]
Message-ID: <20090515133959.GW9835@amd.com> (raw)
In-Reply-To: <1242375740-31222-4-git-send-email-agraf@suse.de>

On Fri, May 15, 2009 at 10:22:17AM +0200, Alexander Graf wrote:
> If we couldn't find a page on read_emulated, it might be a good
> idea to tell the guest about that and inject a #PF.
> 
> We do the same already for write faults. I don't know why it was
> not implemented for reads.

Have you checked that the emulator will never ever do speculative reads?
This may be the reason why the fault was not injected here.

> 
> Signed-off-by: Alexander Graf <agraf@suse.de>
> ---
>  arch/x86/kvm/x86.c |    7 +++++--
>  1 files changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 5fcde2c..5aa1219 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -2131,10 +2131,13 @@ static int emulator_read_emulated(unsigned long addr,
>  		goto mmio;
>  
>  	if (kvm_read_guest_virt(addr, val, bytes, vcpu)
> -				== X86EMUL_CONTINUE)
> +				== X86EMUL_CONTINUE) {
>  		return X86EMUL_CONTINUE;
> -	if (gpa == UNMAPPED_GVA)
> +	}
> +	if (gpa == UNMAPPED_GVA) {
> +		kvm_inject_page_fault(vcpu, addr, 0);
>  		return X86EMUL_PROPAGATE_FAULT;
> +	}
>  
>  mmio:
>  	/*
> -- 
> 1.6.0.2
> 
> 

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