Signed-off-by: Andrew Cooper <andrew.coop...@citrix.com>
---
CC: Jan Beulich <jbeul...@suse.com>
---
xen/tools/gen-cpuid.py | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/xen/tools/gen-cpuid.py b/xen/tools/gen-cpuid.py
index 5cab6db..6531ca8 100755
--- a/xen/tools/gen-cpuid.py
+++ b/xen/tools/gen-cpuid.py
@@ -225,9 +225,13 @@ def crunch_numbers(state):
XSAVE: [XSAVEOPT, XSAVEC, XGETBV1, XSAVES,
AVX, MPX, PKU, LWP],
- # AVX is taken to mean hardware support for VEX encoded instructions,
- # 256bit registers, and the instructions themselves. Each of these
- # subsequent instruction groups may only be VEX encoded.
+ # AVX is taken to mean hardware support for 256bit registers (which in
+ # practice depends on the VEX prefix to encode), and the instructions
+ # themselves.
+ #
+ # AVX is not taken to mean support for the VEX prefix itself.
+ # VEX-encoded GPR instructions, such as those from the BMI{1,2} sets
+ # function fine in the absence of any enabled xstate.
AVX: [FMA, FMA4, F16C, AVX2, XOP],
# CX16 is only encodable in Long Mode. LAHF_LM indicates that the
--
2.1.4
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