KVM: x86: Distinguish between stack operation and near branches

commit 58b7075d059f7d37ca86c76fb1446fa3447b9f4f upstream.

In 64-bit, stack operations default to 64-bits, but can be overriden (to
16-bit) using opsize override prefix. In contrast, near-branches are always
64-bit.  This patch distinguish between the different behaviors.

Signed-off-by: Nadav Amit <namit@cs.technion.ac.il>
Signed-off-by: Bruce Rogers <brogers@suse.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 4cb80f2c6fdbb02e297caf5f9b24693fcaa8f564..987fdb379df64814f2c5779c2f0e366fe73b57b1 100644 (file)
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -161,6 +161,7 @@
 #define Fastop      ((u64)1 << 44)  /* Use opcode::u.fastop */
 #define NoWrite     ((u64)1 << 45)  /* No writeback */
 #define SrcWrite    ((u64)1 << 46)  /* Write back src operand */
+#define NearBranch  ((u64)1 << 52)  /* Near branches */
 
 #define DstXacc     (DstAccLo | SrcAccHi | SrcWrite)
 
@@ -3646,9 +3647,9 @@ static const struct opcode group4[] = {
 static const struct opcode group5[] = {
        F(DstMem | SrcNone | Lock,              em_inc),
        F(DstMem | SrcNone | Lock,              em_dec),
-       I(SrcMem | Stack,                       em_call_near_abs),
+       I(SrcMem | NearBranch,                  em_call_near_abs),
        I(SrcMemFAddr | ImplicitOps | Stack,    em_call_far),
-       I(SrcMem | Stack,                       em_jmp_abs),
+       I(SrcMem | NearBranch,                  em_jmp_abs),
        I(SrcMemFAddr | ImplicitOps,            em_jmp_far),
        I(SrcMem | Stack,                       em_push), D(Undefined),
 };
@@ -3812,7 +3813,7 @@ static const struct opcode opcode_table[256] = {
        I2bvIP(DstDI | SrcDX | Mov | String | Unaligned, em_in, ins, check_perm_in), /* insb, insw/insd */
        I2bvIP(SrcSI | DstDX | String, em_out, outs, check_perm_out), /* outsb, outsw/outsd */
        /* 0x70 - 0x7F */
-       X16(D(SrcImmByte)),
+       X16(D(SrcImmByte | NearBranch)),
        /* 0x80 - 0x87 */
        G(ByteOp | DstMem | SrcImm, group1),
        G(DstMem | SrcImm, group1),
@@ -3850,8 +3851,8 @@ static const struct opcode opcode_table[256] = {
        X8(I(DstReg | SrcImm64 | Mov, em_mov)),
        /* 0xC0 - 0xC7 */
        G(ByteOp | Src2ImmByte, group2), G(Src2ImmByte, group2),
-       I(ImplicitOps | Stack | SrcImmU16, em_ret_near_imm),
-       I(ImplicitOps | Stack, em_ret),
+       I(ImplicitOps | NearBranch | SrcImmU16, em_ret_near_imm),
+       I(ImplicitOps | NearBranch, em_ret),
        I(DstReg | SrcMemFAddr | ModRM | No64 | Src2ES, em_lseg),
        I(DstReg | SrcMemFAddr | ModRM | No64 | Src2DS, em_lseg),
        G(ByteOp, group11), G(0, group11),
@@ -3872,11 +3873,11 @@ static const struct opcode opcode_table[256] = {
        N, E(0, &escape_d9), N, E(0, &escape_db), N, E(0, &escape_dd), N, N,
        /* 0xE0 - 0xE7 */
        X3(I(SrcImmByte, em_loop)),
-       I(SrcImmByte, em_jcxz),
+       I(SrcImmByte | NearBranch, em_jcxz),
        I2bvIP(SrcImmUByte | DstAcc, em_in,  in,  check_perm_in),
        I2bvIP(SrcAcc | DstImmUByte, em_out, out, check_perm_out),
        /* 0xE8 - 0xEF */
-       I(SrcImm | Stack, em_call), D(SrcImm | ImplicitOps),
+       I(SrcImm | NearBranch, em_call), D(SrcImm | ImplicitOps),
        I(SrcImmFAddr | No64, em_jmp_far), D(SrcImmByte | ImplicitOps),
        I2bvIP(SrcDX | DstAcc, em_in,  in,  check_perm_in),
        I2bvIP(SrcAcc | DstDX, em_out, out, check_perm_out),
@@ -4356,8 +4357,12 @@ done_prefixes:
        if (!(ctxt->d & VendorSpecific) && ctxt->only_vendor_specific_insn)
                return EMULATION_FAILED;
 
-       if (mode == X86EMUL_MODE_PROT64 && (ctxt->d & Stack))
-               ctxt->op_bytes = 8;
+       if (mode == X86EMUL_MODE_PROT64) {
+               if (ctxt->op_bytes == 4 && (ctxt->d & Stack))
+                       ctxt->op_bytes = 8;
+               else if (ctxt->d & NearBranch)
+                       ctxt->op_bytes = 8;
+       }
 
        if (ctxt->d & Op3264) {
                if (mode == X86EMUL_MODE_PROT64)