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

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Date:   Thu, 6 Sep 2018 16:02:44 +0800
From:   Yi Wang <wang.yi59@....com.cn>
To:     pbonzini@...hat.com
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, wang.yi59@....com.cn,
        zhong.weidong@....com.cn, xu.xi8@....com.cn
Subject: [PATCH] KVM: x86: fix failure of injecting exceptions in x86_emulate_instruction

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>
---
 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) {
-- 
1.8.3.1