[PATCH] KVM: x86 emulator: fix regression with cmpxchg8b on i386 hosts

Avi Kivity
2010-08-26T11:31:32Z

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>
---
arch/x86/include/asm/kvm_emulate.h | 6 +++++-
arch/x86/kvm/emulate.c | 9 ++++-----
2 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/arch/x86/include/asm/kvm_emulate.h b/arch/x86/include/asm/kvm_emulate.h
index f22e5da..1bbf2b6 100644
--- a/arch/x86/include/asm/kvm_emulate.h
+++ b/arch/x86/include/asm/kvm_emulate.h
@@ -153,13 +153,17 @@ struct x86_emulate_ops {
struct operand {
enum { OP_REG, OP_MEM, OP_IMM, OP_NONE } type;
unsigned int bytes;
- unsigned long orig_val;
+ union {
+ unsigned long orig_val;
+ u64 orig_val64;
+ };
union {
unsigned long *reg;
unsigned long mem;
} addr;
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 d613690..1702ea8 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -1479,17 +1479,16 @@ 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;
}
@@ -2978,7 +2977,7 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt)
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) {
--
1.7.1