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

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: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20221025124741.228045-11-mlevitsk@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 3b27622d46425b58c7285f11f60b346a550c8f84..261732957431b8381ec0d527b1737a02df4ae94e 100644 (file)
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -2876,6 +2876,7 @@ 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;