KVM: x86 emulator: fix regression with cmpxchg8b on i386 hosts

operand::val and operand::orig_val are 32-bit on i386, whereas cmpxchg8b
operands are 64-bit.

Fix by adding val64 and orig_val64 union members to struct operand, and
using them where needed.

Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

2 files changed, 10 insertions, 6 deletions

diff --git a/arch/x86/include/asm/kvm_emulate.h b/arch/x86/include/asm/kvm_emulate.h
index 51cfd730ac5d..1f99ecfc48e1 100644
--- a/arch/x86/include/asm/kvm_emulate.h
+++ b/arch/x86/include/asm/kvm_emulate.h
@@ -152,9 +152,14 @@ struct x86_emulate_ops {
 struct operand {
         enum { OP_REG, OP_MEM, OP_IMM, OP_NONE } type;
         unsigned int bytes;
-        unsigned long orig_val, *ptr;
+        union {
+                unsigned long orig_val;
+                u64 orig_val64;
+        };
+        unsigned long *ptr;
         union {
                 unsigned long val;
+                u64 val64;
                 char valptr[sizeof(unsigned long) + 2];
         };
 };
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index b38bd8b92aa6..66ca98aafdd6 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -1870,17 +1870,16 @@ static inline int emulate_grp9(struct x86_emulate_ctxt *ctxt,
                                struct x86_emulate_ops *ops)
 {
         struct decode_cache *c = &ctxt->decode;
-        u64 old = c->dst.orig_val;
+        u64 old = c->dst.orig_val64;
 
         if (((u32) (old >> 0) != (u32) c->regs[VCPU_REGS_RAX]) ||
             ((u32) (old >> 32) != (u32) c->regs[VCPU_REGS_RDX])) {
-
                 c->regs[VCPU_REGS_RAX] = (u32) (old >> 0);
                 c->regs[VCPU_REGS_RDX] = (u32) (old >> 32);
                 ctxt->eflags &= ~EFLG_ZF;
         } else {
-                c->dst.val = ((u64)c->regs[VCPU_REGS_RCX] << 32) |
-                       (u32) c->regs[VCPU_REGS_RBX];
+                c->dst.val64 = ((u64)c->regs[VCPU_REGS_RCX] << 32) |
+                        (u32) c->regs[VCPU_REGS_RBX];
 
                 ctxt->eflags |= EFLG_ZF;
         }
@@ -2616,7 +2615,7 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
                                         c->src.valptr, c->src.bytes);
                 if (rc != X86EMUL_CONTINUE)
                         goto done;
-                c->src.orig_val = c->src.val;
+                c->src.orig_val64 = c->src.val64;
         }
 
         if (c->src2.type == OP_MEM) {