KVM: x86/emulator: Fix handing of POP SS to correctly set interruptibility

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@rbox.co>
Fixes: a5457e7bcf9a ("KVM: emulate: POP SS triggers a MOV SS shadow too")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/20220821215900.1419215-1-mhal@rbox.co
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 5b9ec38b7202c92c0d63cf553fc1d6a7f63bc1e8..21480a6b1adcca9b4753920bd37d927b48f63663 100644 (file)
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -1988,7 +1988,7 @@ static int em_pop_sreg(struct x86_emulate_ctxt *ctxt)
        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);