From 6550e1f165f384f3a46b60a1be9aba4bc3c2adad Mon Sep 17 00:00:00 2001 From: Gleb Natapov Date: Sun, 21 Mar 2010 13:08:21 +0200 Subject: [PATCH] KVM: x86 emulator: add decoding of CMPXCHG8B dst operand Decode CMPXCHG8B destination operand in decoding stage. Fixes regression introduced by "If LOCK prefix is used dest arg should be memory" commit. This commit relies on dst operand be decoded at the beginning of an instruction emulation. Signed-off-by: Gleb Natapov Signed-off-by: Avi Kivity --- arch/x86/kvm/emulate.c | 24 ++++++++++-------------- 1 file changed, 10 insertions(+), 14 deletions(-) diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index 48de4b890055..b8ce53861f68 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -52,6 +52,7 @@ #define DstMem (3<<1) /* Memory operand. */ #define DstAcc (4<<1) /* Destination Accumulator */ #define DstDI (5<<1) /* Destination is in ES:(E)DI */ +#define DstMem64 (6<<1) /* 64bit memory operand */ #define DstMask (7<<1) /* Source operand type. */ #define SrcNone (0<<4) /* No source operand. */ @@ -360,7 +361,7 @@ static u32 group_table[] = { DstMem | SrcImmByte | ModRM, DstMem | SrcImmByte | ModRM | Lock, DstMem | SrcImmByte | ModRM | Lock, DstMem | SrcImmByte | ModRM | Lock, [Group9*8] = - 0, ImplicitOps | ModRM | Lock, 0, 0, 0, 0, 0, 0, + 0, DstMem64 | ModRM | Lock, 0, 0, 0, 0, 0, 0, }; static u32 group2_table[] = { @@ -1205,6 +1206,7 @@ done_prefixes: c->twobyte && (c->b == 0xb6 || c->b == 0xb7)); break; case DstMem: + case DstMem64: if ((c->d & ModRM) && c->modrm_mod == 3) { c->dst.bytes = (c->d & ByteOp) ? 1 : c->op_bytes; c->dst.type = OP_REG; @@ -1214,7 +1216,10 @@ done_prefixes: } c->dst.type = OP_MEM; c->dst.ptr = (unsigned long *)c->modrm_ea; - c->dst.bytes = (c->d & ByteOp) ? 1 : c->op_bytes; + if ((c->d & DstMask) == DstMem64) + c->dst.bytes = 8; + else + c->dst.bytes = (c->d & ByteOp) ? 1 : c->op_bytes; c->dst.val = 0; if (c->d & BitOp) { unsigned long mask = ~(c->dst.bytes * 8 - 1); @@ -1706,12 +1711,7 @@ static inline int emulate_grp9(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops) { struct decode_cache *c = &ctxt->decode; - u64 old, new; - int rc; - - rc = ops->read_emulated(c->modrm_ea, &old, 8, ctxt->vcpu); - if (rc != X86EMUL_CONTINUE) - return rc; + u64 old = c->dst.orig_val; if (((u32) (old >> 0) != (u32) c->regs[VCPU_REGS_RAX]) || ((u32) (old >> 32) != (u32) c->regs[VCPU_REGS_RDX])) { @@ -1719,15 +1719,12 @@ static inline int emulate_grp9(struct x86_emulate_ctxt *ctxt, c->regs[VCPU_REGS_RAX] = (u32) (old >> 0); c->regs[VCPU_REGS_RDX] = (u32) (old >> 32); ctxt->eflags &= ~EFLG_ZF; - } else { - new = ((u64)c->regs[VCPU_REGS_RCX] << 32) | + c->dst.val = ((u64)c->regs[VCPU_REGS_RCX] << 32) | (u32) c->regs[VCPU_REGS_RBX]; - rc = ops->cmpxchg_emulated(c->modrm_ea, &old, &new, 8, ctxt->vcpu); - if (rc != X86EMUL_CONTINUE) - return rc; ctxt->eflags |= EFLG_ZF; + c->lock_prefix = 1; } return X86EMUL_CONTINUE; } @@ -3245,7 +3242,6 @@ twobyte_insn: rc = emulate_grp9(ctxt, ops); if (rc != X86EMUL_CONTINUE) goto done; - c->dst.type = OP_NONE; break; } goto writeback; -- 2.20.1