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KVM: x86 emulator: add support for vector alignment 

x86 defines three classes of vector instructions: explicitly
aligned (#GP(0) if unaligned, explicitly unaligned, and default
(which depends on the encoding: AVX is unaligned, SSE is aligned).

Add support for marking an instruction as explicitly aligned or
unaligned, and mark MOVDQU as unaligned.

Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
This commit is contained in:
Avi Kivity 2012-04-09 18:39:59 +03:00 committed by Marcelo Tosatti
parent ae75954457
commit 1c11b37669
1 changed files with 29 additions and 1 deletions
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30
arch/x86/kvm/emulate.c
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@ -142,6 +142,9 @@
#define Src2FS (OpFS << Src2Shift)
#define Src2GS (OpGS << Src2Shift)
#define Src2Mask (OpMask << Src2Shift)
#define Aligned ((u64)1 << 41) /* Explicitly aligned (e.g. MOVDQA) */
#define Unaligned ((u64)1 << 42) /* Explicitly unaligned (e.g. MOVDQU) */
#define Avx ((u64)1 << 43) /* Advanced Vector Extensions */
#define X2(x...) x, x
#define X3(x...) X2(x), x
@ -557,6 +560,29 @@ static void set_segment_selector(struct x86_emulate_ctxt *ctxt, u16 selector,
ctxt->ops->set_segment(ctxt, selector, &desc, base3, seg);
}
/*
* x86 defines three classes of vector instructions: explicitly
* aligned, explicitly unaligned, and the rest, which change behaviour
* depending on whether they're AVX encoded or not.
*
* Also included is CMPXCHG16B which is not a vector instruction, yet it is
* subject to the same check.
*/
static bool insn_aligned(struct x86_emulate_ctxt *ctxt, unsigned size)
{
if (likely(size < 16))
return false;
if (ctxt->d & Aligned)
return true;
else if (ctxt->d & Unaligned)
return false;
else if (ctxt->d & Avx)
return false;
else
return true;
}
static int __linearize(struct x86_emulate_ctxt *ctxt,
struct segmented_address addr,
unsigned size, bool write, bool fetch,
@ -621,6 +647,8 @@ static int __linearize(struct x86_emulate_ctxt *ctxt,
}
if (fetch ? ctxt->mode != X86EMUL_MODE_PROT64 : ctxt->ad_bytes != 8)
la &= (u32)-1;
if (insn_aligned(ctxt, size) && ((la & (size - 1)) != 0))
return emulate_gp(ctxt, 0);
*linear = la;
return X86EMUL_CONTINUE;
bad:
@ -3415,7 +3443,7 @@ static struct opcode group11[] = {
};
static struct gprefix pfx_0f_6f_0f_7f = {
N, N, N, I(Sse, em_movdqu),
N, N, N, I(Sse | Unaligned, em_movdqu),
};
static struct opcode opcode_table[256] = {