linux-kernel - Re: [PATCH -v3] KVM, Fix QEMU-KVM is killed by guest SRAO MCE (resend)

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Date:	Mon, 31 May 2010 14:02:34 +0300
From:	Avi Kivity <avi@...hat.com>
To:	Huang Ying <ying.huang@...el.com>
CC:	Marcelo Tosatti <mtosatti@...hat.com>,
	Andi Kleen <andi@...stfloor.org>, linux-kernel@...r.kernel.org,
	kvm@...r.kernel.org, Andrew Morton <akpm@...ux-foundation.org>,
	masbock@...ux.vnet.ibm.com, Wu Fengguang <fengguang.wu@...el.com>
Subject: Re: [PATCH -v3] KVM, Fix QEMU-KVM is killed by guest SRAO MCE (resend)

On 05/31/2010 09:28 AM, Huang Ying wrote:
> In common cases, guest SRAO MCE will cause corresponding poisoned page
> be un-mapped and SIGBUS be sent to QEMU-KVM, then QEMU-KVM will relay
> the MCE to guest OS.
>
> But it is reported that if the poisoned page is accessed in guest
> after un-mapped and before MCE is relayed to guest OS, QEMU-KVM will
> be killed.
>
> The reason is as follow. Because poisoned page has been un-mapped,
> guest access will cause guest exit and kvm_mmu_page_fault will be
> called. kvm_mmu_page_fault can not get the poisoned page for fault
> address, so kernel and user space MMIO processing is tried in turn. In
> user MMIO processing, poisoned page is accessed again, then QEMU-KVM
> is killed by force_sig_info.
>
> To fix the bug, kvm_mmu_page_fault send HWPOISON signal to QEMU-KVM
> and do not try kernel and user space MMIO processing for poisoned
> page.
>    

Applied, thanks.  Sorry about the delay.

-- 
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.

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