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KVM: x86: Emulator does not decode clflush well

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Currently, all group15 instructions are decoded as clflush (e.g., mfence,
xsave).  In addition, the clflush instruction requires no prefix (66/f2/f3)
would exist. If prefix exists it may encode a different instruction (e.g.,
clflushopt).

Creating a group for clflush, and different group for each prefix.

This has been the case forever, but the next patch needs the cflush group
in order to fix a bug introduced in 3.17.

Fixes: 41061cdb98
Cc: stable@vger.kernel.org
Signed-off-by: Nadav Amit <namit@cs.technion.ac.il>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Nadav Amit 2014-10-13 13:04:13 +03:00 committed by Paolo Bonzini
parent a430c91663
commit 13e457e0ee
1 changed files with 17 additions and 3 deletions
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20
arch/x86/kvm/emulate.c
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@ -3462,6 +3462,12 @@ static int em_bswap(struct x86_emulate_ctxt *ctxt)
return X86EMUL_CONTINUE;
}
static int em_clflush(struct x86_emulate_ctxt *ctxt)
{
/* emulating clflush regardless of cpuid */
return X86EMUL_CONTINUE;
}
static bool valid_cr(int nr)
{
switch (nr) {
@ -3800,6 +3806,16 @@ static const struct opcode group11[] = {
X7(D(Undefined)),
};
static const struct gprefix pfx_0f_ae_7 = {
I(0, em_clflush), N, N, N,
};
static const struct group_dual group15 = { {
N, N, N, N, N, N, N, GP(0, &pfx_0f_ae_7),
}, {
N, N, N, N, N, N, N, N,
} };
static const struct gprefix pfx_0f_6f_0f_7f = {
I(Mmx, em_mov), I(Sse | Aligned, em_mov), N, I(Sse | Unaligned, em_mov),
};
@ -4063,7 +4079,7 @@ static const struct opcode twobyte_table[256] = {
F(DstMem | SrcReg | ModRM | BitOp | Lock | PageTable, em_bts),
F(DstMem | SrcReg | Src2ImmByte | ModRM, em_shrd),
F(DstMem | SrcReg | Src2CL | ModRM, em_shrd),
D(ModRM), F(DstReg | SrcMem | ModRM, em_imul),
GD(0, &group15), F(DstReg | SrcMem | ModRM, em_imul),
/* 0xB0 - 0xB7 */
I2bv(DstMem | SrcReg | ModRM | Lock | PageTable, em_cmpxchg),
I(DstReg | SrcMemFAddr | ModRM | Src2SS, em_lseg),
@ -4993,8 +5009,6 @@ int x86_emulate_insn(struct x86_emulate_ctxt *ctxt)
case 0x90 ... 0x9f: /* setcc r/m8 */
ctxt->dst.val = test_cc(ctxt->b, ctxt->eflags);
break;
case 0xae: /* clflush */
break;
case 0xb6 ... 0xb7: /* movzx */
ctxt->dst.bytes = ctxt->op_bytes;
ctxt->dst.val = (ctxt->src.bytes == 1) ? (u8) ctxt->src.val