[Xen-changelog] [xen master] x86emul: correct EVEX decoding

[patchbot@xxxxxxx]

commit eb4e638a474792137414f03409e78477810c3436
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Tue Sep 5 17:32:43 2017 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Tue Sep 5 17:32:43 2017 +0200

    x86emul: correct EVEX decoding
    
    While these are latent issues only for now, correct them right away:
    - unnamed (in the SDM) EVEX bits need to be set/clear respectively
    - EVEX.V' (called RX in our code) needs to uniformly be 1 in non-64-bit
      modes,
    - EXEX.R' (called R in our code) is uniformly being ignored in
      non-64-bit modes.
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
 xen/arch/x86/x86_emulate/x86_emulate.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/x86_emulate/x86_emulate.c 
b/xen/arch/x86/x86_emulate/x86_emulate.c
index d977e37..c1e2300 100644
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -495,13 +495,13 @@ union evex {
     uint8_t raw[3];
     struct {
         uint8_t opcx:2;
-        uint8_t :2;
+        uint8_t mbz:2;
         uint8_t R:1;
         uint8_t b:1;
         uint8_t x:1;
         uint8_t r:1;
         uint8_t pfx:2;
-        uint8_t evex:1;
+        uint8_t mbs:1;
         uint8_t reg:4;
         uint8_t w:1;
         uint8_t opmsk:3;
@@ -2544,6 +2544,14 @@ x86_decode(
                         evex.raw[1] = vex.raw[1];
                         evex.raw[2] = insn_fetch_type(uint8_t);
 
+                        generate_exception_if(evex.mbs || !evex.mbz, EXC_UD);
+
+                        if ( !mode_64bit() )
+                        {
+                            generate_exception_if(!evex.RX, EXC_UD);
+                            evex.R = 1;
+                        }
+
                         vex.opcx = evex.opcx;
                         break;
                     case 0xc4:
--
generated by git-patchbot for /home/xen/git/xen.git#master

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