KVM: VMX: Handle #SS faults from real mode

Instructions with address size override prefix opcode 0x67
Cause the #SS fault with 0 error code in VM86 mode.  Forward
them to the emulator.

Signed-Off-By: Nitin A Kamble <nitin.a.kamble@intel.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

1 files changed, 5 insertions, 1 deletions

diff --git a/drivers/kvm/vmx.c b/drivers/kvm/vmx.c
index c4c553588a20..a05bfa085877 100644
--- a/drivers/kvm/vmx.c
+++ b/drivers/kvm/vmx.c
@@ -1488,7 +1488,11 @@ static int handle_rmode_exception(struct kvm_vcpu *vcpu,
         if (!vcpu->rmode.active)
                 return 0;
 
-        if (vec == GP_VECTOR && err_code == 0)
+        /*
+         * Instruction with address size override prefix opcode 0x67
+         * Cause the #SS fault with 0 error code in VM86 mode.
+         */
+        if (((vec == GP_VECTOR) || (vec == SS_VECTOR)) && err_code == 0)
                 if (emulate_instruction(vcpu, NULL, 0, 0) == EMULATE_DONE)
                         return 1;
         return 0;