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@xxxxxxxxxx>
---
arch/x86/kvm/emulate.c | 30 +++++++++++++++++++++++++++++-
1 file changed, 29 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 8375622..6302e5c 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -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 int check_perm_out(struct x86_emulate_ctxt *ctxt)
};
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] = {
--
1.7.10
--
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