KVM: x86: emulator: em_sysexit should update ctxt->mode

stable inclusion
from stable-v5.10.154
commit c8a2fd7a715d9882eed5ddb4105bce2f6a8163c2
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I64YCB

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=c8a2fd7a715d9882eed5ddb4105bce2f6a8163c2

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

commit 5015bb89 upstream.

SYSEXIT is one of the instructions that can change the
processor mode, thus ctxt->mode should be updated after it.

Note that this is likely a benign bug, because the only problematic
mode change is from 32 bit to 64 bit which can lead to truncation of RIP,
and it is not possible to do with sysexit,
since sysexit running in 32 bit mode will be limited to 32 bit version.
Signed-off-by: NMaxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20221025124741.228045-11-mlevitsk@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NLipeng Sang <sanglipeng1@jd.com>
(cherry picked from commit 78979ae9)

arch/x86/kvm/emulate.c

@@ -2957,6 +2957,7 @@ static int em_sysexit(struct x86_emulate_ctxt *ctxt)
 	ops->set_segment(ctxt, ss_sel, &ss, 0, VCPU_SREG_SS);
 
 	ctxt->_eip = rdx;
+	ctxt->mode = usermode;
 	*reg_write(ctxt, VCPU_REGS_RSP) = rcx;
 
 	return X86EMUL_CONTINUE;