[Devel] [PATCH RHEL7 COMMIT] ms/KVM: x86: add Align16 instruction flag

[Konstantin Khorenko]

The commit is pushed to "branch-rh7-3.10.0-514.26.1.vz7.35.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-514.26.1.vz7.33.22
------>
commit 79cf059f7fbbdb12900628a7c8c31918b69ac37b
Author: Radim Krčmář <rkrcmar at redhat.com>
Date:   Mon Aug 7 14:41:09 2017 +0400

    ms/KVM: x86: add Align16 instruction flag
    
    Patchset description:
    FXSR emulation backport
    
    Upstream backport of FXSR (FXSAVE, FXRSTOR) emulation + bugfixes on it
    Fixes PSBM-69206
    
    Radim Krčmář (4):
      KVM: x86: add Align16 instruction flag
      KVM: x86: save one bit in ctxt->d
      KVM: x86: add asm_safe wrapper
      KVM: x86: emulate FXSAVE and FXRSTOR
    
    ===============================================================
    This patch description:
    
    Needed for FXSAVE and FXRSTOR.
    
    Signed-off-by: Radim Krčmář <rkrcmar at redhat.com>
    Signed-off-by: Paolo Bonzini <pbonzini at redhat.com>
    
    https://jira.sw.ru/browse/PSBM-69206
    ms commit: d3fe959f81024072068e9ed86b39c2acfd7462a9
    
    Signed-off-by: Evgeny Yakovlev <eyakovlev at virtuozzo.com>
---
 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 7b19846..aeb96c4 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -172,6 +172,7 @@
 #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)
 
@@ -652,21 +653,24 @@ 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,
@@ -723,7 +727,7 @@ static __always_inline int __linearize(struct x86_emulate_ctxt *ctxt,
 		la &= (u32)-1;
 		break;
 	}
-	if (insn_aligned(ctxt, size) && ((la & (size - 1)) != 0))
+	if (la & (insn_alignment(ctxt, size) - 1))
 		return emulate_gp(ctxt, 0);
 	*linear = la;
 	return X86EMUL_CONTINUE;