[PATCH v3 1/4] KVM: x86: add Align16 instruction flag

From: Radim KrÄmÃÅ
Date: Tue Nov 08 2016 - 14:54:39 EST


Needed for FXSAVE and FXRSTOR.

Signed-off-by: Radim KrÄmÃÅ <rkrcmar@xxxxxxxxxx>
---
v2: split into a separate patch
---
arch/x86/kvm/emulate.c | 20 ++++++++++++--------
1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index cbd7b92585bb..eb74d3b56e1c 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -171,6 +171,7 @@
#define NearBranch ((u64)1 << 52) /* Near branches */
#define No16 ((u64)1 << 53) /* No 16 bit operand */
#define IncSP ((u64)1 << 54) /* SP is incremented before ModRM calc */
+#define Aligned16 ((u64)1 << 55) /* Aligned to 16 byte boundary (e.g. FXSAVE) */

#define DstXacc (DstAccLo | SrcAccHi | SrcWrite)

@@ -632,21 +633,24 @@ static void set_segment_selector(struct x86_emulate_ctxt *ctxt, u16 selector,
* 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.
+ * subject to the same check. FXSAVE and FXRSTOR are checked here too as their
+ * 512 bytes of data must be aligned to a 16 byte boundary.
*/
-static bool insn_aligned(struct x86_emulate_ctxt *ctxt, unsigned size)
+static unsigned insn_alignment(struct x86_emulate_ctxt *ctxt, unsigned size)
{
if (likely(size < 16))
- return false;
+ return 1;

if (ctxt->d & Aligned)
- return true;
+ return size;
else if (ctxt->d & Unaligned)
- return false;
+ return 1;
else if (ctxt->d & Avx)
- return false;
+ return 1;
+ else if (ctxt->d & Aligned16)
+ return 16;
else
- return true;
+ return size;
}

static __always_inline int __linearize(struct x86_emulate_ctxt *ctxt,
@@ -704,7 +708,7 @@ static __always_inline int __linearize(struct x86_emulate_ctxt *ctxt,
}
break;
}
- if (insn_aligned(ctxt, size) && ((la & (size - 1)) != 0))
+ if (la & (insn_alignment(ctxt, size) - 1))
return emulate_gp(ctxt, 0);
return X86EMUL_CONTINUE;
bad:
--
2.10.2