Re: [PATCH V11 10/10] arm/arm64: KVM: add guest SEA support

From	Marc Zyngier <marc.zyngier@arm.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH V11 10/10] arm/arm64: KVM: add guest SEA support
Date	2017-03-02 10:50 +0100
Message-ID	<tgvwZ-pp-3@gated-at.bofh.it> (permalink)
References	(2 earlier) <teEXL-4kM-1@gated-at.bofh.it> <tfvfJ-7o7-49@gated-at.bofh.it> <tfJC1-DE-7@gated-at.bofh.it> <tfQ0O-4XF-13@gated-at.bofh.it> <tg2lk-4F1-23@gated-at.bofh.it>
Organization	ARM Ltd

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On 01/03/17 02:31, Xiongfeng Wang wrote:

[lot of things]

> If an SEA is injected into guest OS, the guest OS will jump to the SEA
> exception entry when the context switched to guest OS. And the CPSR and
> FAR_EL1 are recovered according to the content of vcpu. Then the guest
> OS can signal a process or panic. If another guest process read the
> error data, another SEA will be generated and it will be single too.
> 
> Without QEMU involved, the drawback is that no APEI table can be mocked
> up in guest OS, and no memory_failure() will be called. So the memory of
> error data will be released into buddy system and assigned to another
> process. If the error was caused by instantaneous radiation or
> electromagnetic, the memory is usable again if it is written with a
> correct data. If the memory has wore out and a correct data is written,
> the ECC error may occurs again with high possibility. Before a 2-bit ECC
> error is reported, much more 1-bit errors will be reported. This is
> report to host os, the host os can determine the memory node has worn
> out and hot-plug out the memory node, and guest os may be terminated if
> its memory data can't be migrated.
> 
> Of course, it is better to get QEMU involved, so the memory_failure can
> be executed in guest OS. But before that implemented, can we add SEA
> injection in kvm_handle_guest_abort()?

No. I will strongly object to that. This is a platform decision to
forward SEAs, not an architectural one. The core KVM code is only
concerned about implementing the ARM architecture, and not something
that is firmware dependent.

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...

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Re: [PATCH V11 10/10] arm/arm64: KVM: add guest SEA support Marc Zyngier <marc.zyngier@arm.com> - 2017-03-02 10:50 +0100
  Re: [PATCH V11 10/10] arm/arm64: KVM: add guest SEA support Xiongfeng Wang <wangxiongfeng2@huawei.com> - 2017-03-06 04:50 +0100

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