linux-kernel - Re: [PATCH] KVM: x86: fix failure of injecting exceptions in x86_emulate

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Message-ID: <a9a47c9b-c8b9-74f4-78ef-fb54c7fe806d@redhat.com>
Date:   Thu, 20 Sep 2018 18:53:55 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Yi Wang <wang.yi59@....com.cn>
Cc:     rkrcmar@...hat.com, tglx@...utronix.de, mingo@...hat.com,
        hpa@...or.com, x86@...nel.org, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, zhong.weidong@....com.cn,
        xu.xi8@....com.cn
Subject: Re: [PATCH] KVM: x86: fix failure of injecting exceptions in
 x86_emulate_instruction

On 20/09/2018 18:30, Paolo Bonzini wrote:
> On 06/09/2018 10:02, Yi Wang wrote:
>> In order to fix a page table walk issue, commit 6ea6e84309ca
>> ("KVM: x86: inject exceptions produced by x86_decode_insn") check
>> if variable ctxt->have_exception true and inject the exception.
>> Unfortunately, ctxt->have_exception is set to true only in function
>> x86_emulate_insn(), which won't be called before invoking
>> inject_emulated_exception() in the 6ea6e84309ca.
>> This patch fix this issue.
>>
>> Signed-off-by: Yi Wang <wang.yi59@....com.cn>
>> Reviewed-by: Xi Xu <xu.xi8@....com.cn>
> 
> Queued, thanks.  Do you have a testcase for this?

Unqueued, sorry.  The hypercall test from kvm-unit-tests fails.  A
VMCALL on the "edge" of canonical address space, i.e. at 0x7ffffffffffd,
raises a general protection fault before this patch and a double fault
afterwards.

Paolo