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 3b4e1d8d239a2427ab5cbb08845f7b7a1008bbae..45d82a9501328c015719f10017cc123f31a38182 100644 (file)
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -1936,7 +1936,7 @@ 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);