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

stable inclusion
from stable-v5.10.150
commit 085ca1d33b198048b26d8c5644809b6cdc89d651
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I6D0XA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=085ca1d33b198048b26d8c5644809b6cdc89d651

--------------------------------

commit 6aa5c47c 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: NMichal Luczaj <mhal@rbox.co>
Fixes: a5457e7b ("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.coSigned-off-by: NSean Christopherson <seanjc@google.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NJialin Zhang <zhangjialin11@huawei.com>

arch/x86/kvm/emulate.c

@@ -2039,7 +2039,7 @@ 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);