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

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Message-ID: <9835d255-dd9a-222b-f4a2-93611175b326@redhat.com>
Date:   Thu, 20 Sep 2018 18:30:17 +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 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?

> ---
>  arch/x86/kvm/emulate.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
> index 106482d..aecf9a72 100644
> --- a/arch/x86/kvm/emulate.c
> +++ b/arch/x86/kvm/emulate.c
> @@ -5105,8 +5105,11 @@ int x86_decode_insn(struct x86_emulate_ctxt *ctxt, void *insn, int insn_len)
>  		memcpy(ctxt->fetch.data, insn, insn_len);
>  	else {
>  		rc = __do_insn_fetch_bytes(ctxt, 1);
> -		if (rc != X86EMUL_CONTINUE)
> +		if (rc != X86EMUL_CONTINUE) {
> +			if (rc == X86EMUL_PROPAGATE_FAULT)
> +				ctxt->have_exception = true;
>  			return rc;
> +		}
>  	}
>  
>  	switch (mode) {
>