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 0c4a866813b31263730a36d23435d96153d3597c..695a5d159de879074f1d165e374f601af1e9503b 100644 (file)
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -1955,7 +1955,7 @@ 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);