linux-kernel - [PATCH 5.15 123/530] KVM: x86/emulator: Fix handing of POP SS to correctly set interruptibility

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Message-Id: <20221024113050.624835954@linuxfoundation.org>
Date:   Mon, 24 Oct 2022 13:27:47 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Michal Luczaj <mhal@...x.co>,
        Sean Christopherson <seanjc@...gle.com>
Subject: [PATCH 5.15 123/530] KVM: x86/emulator: Fix handing of POP SS to correctly set interruptibility

From: Michal Luczaj <mhal@...x.co>

commit 6aa5c47c351b22c21205c87977c84809cd015fcf upstream.

The emulator checks the wrong variable while setting the CPU
interruptibility state, the target segment is embedded in the instruction
opcode, not the ModR/M register.  Fix the condition.

Signed-off-by: Michal Luczaj <mhal@...x.co>
Fixes: a5457e7bcf9a ("KVM: emulate: POP SS triggers a MOV SS shadow too")
Cc: stable@...r.kernel.org
Link: https://lore.kernel.org/all/20220821215900.1419215-1-mhal@rbox.co
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 arch/x86/kvm/emulate.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -1936,7 +1936,7 @@ static int em_pop_sreg(struct x86_emulat
 	if (rc != X86EMUL_CONTINUE)
 		return rc;
 
-	if (ctxt->modrm_reg == VCPU_SREG_SS)
+	if (seg == VCPU_SREG_SS)
 		ctxt->interruptibility = KVM_X86_SHADOW_INT_MOV_SS;
 	if (ctxt->op_bytes > 2)
 		rsp_increment(ctxt, ctxt->op_bytes - 2);