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

[p***@xen.org]

commit 5d91b689dde48522a591ad3cac7c0520b4dec30c
Author: Jan Beulich <***@suse.com>
AuthorDate: Fri Oct 26 17:50:01 2018 +0200
Commit: Jan Beulich <***@suse.com>
CommitDate: Fri Oct 26 17:50:01 2018 +0200

x86emul: correct EVEX decoding

Fix an inverted pair of checks, drop an incorrect instance of #UD
raising for non-64-bit mode, and add further generic checks.

Note: Despite what SDM Vol 2 rev 067 states, EVEX.V' is _not_ ignored
outside of 64-bit mode when the field does not encode a register.
Just like EVEX.VVVV is required to be 0b1111 in that case, EVEX.V'
is required to be 1 there.

Also rename the bcst field to br, as #UD generation for individual insns
will need to consider both of its possible meanings.

Signed-off-by: Jan Beulich <***@suse.com>
Acked-by: Andrew Cooper <***@citrix.com>
---
xen/arch/x86/x86_emulate/x86_emulate.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/xen/arch/x86/x86_emulate/x86_emulate.c b/xen/arch/x86/x86_emulate/x86_emulate.c
index 90132f4c7c..d8ebecd49d 100644
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -650,7 +650,7 @@ union evex {
uint8_t w:1;
uint8_t opmsk:3;
uint8_t RX:1;
- uint8_t bcst:1;
+ uint8_t br:1;
uint8_t lr:2;
uint8_t z:1;
};
@@ -2760,13 +2760,11 @@ 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);
+ generate_exception_if(!evex.mbs || evex.mbz, EXC_UD);
+ generate_exception_if(!evex.opmsk && evex.z, EXC_UD);

if ( !mode_64bit() )
- {
- generate_exception_if(!evex.RX, EXC_UD);
evex.R = 1;
- }

vex.opcx = evex.opcx;
break;
@@ -3404,6 +3402,7 @@ x86_emulate(
d = (d & ~DstMask) | DstMem;
/* Becomes a normal DstMem operation from here on. */
case DstMem:
+ generate_exception_if(ea.type == OP_MEM && evex.z, EXC_UD);
if ( state->simd_size )
{
generate_exception_if(lock_prefix, EXC_UD);
--
generated by git-patchbot for /home/xen/git/xen.git#staging