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

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

[Avi Kivity]

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

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

[Marcelo Tosatti]

On Thu, Aug 26, 2010 at 02:31:30PM +0300, Avi Kivity wrote:
> 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(-)

Applied, thanks.