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

From: Avi Kivity
Date: Mon May 31 2010 - 07:03:36 EST


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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