x86/cpuid: Fix HLE and RTM handling (again)

For reasons which are my fault, but I don't recall why, the
FDP_EXCP_ONLY/NO_FPU_SEL adjustment uses the whole special_features[] array
element, not the two relevant bits.

HLE and RTM were recently added to the list of special features, causing them
to be always set in guest view, irrespective of the toolstacks choice on the
matter.

Rewrite the logic to refer to the features specifically, rather than relying
on the contents of the special_features[] array.

Fixes: 8fe24090d9 ("x86/cpuid: Rework HLE and RTM handling")
Reported-by: Edwin Török <edvin.torok@citrix.com>
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>

diff --git a/xen/arch/x86/cpuid.c b/xen/arch/x86/cpuid.c
index f3c8950aa3e53ec82cb24d32f9507bbff197ea99..958caf35da1fd71793ea7843f5bf63178a2834d2 100644 (file)
--- a/xen/arch/x86/cpuid.c
+++ b/xen/arch/x86/cpuid.c
@@ -672,9 +672,11 @@ void recalculate_cpuid_policy(struct domain *d)
     sanitise_featureset(fs);
 
     /* Fold host's FDP_EXCP_ONLY and NO_FPU_SEL into guest's view. */
-    fs[FEATURESET_7b0] &= ~special_features[FEATURESET_7b0];
+    fs[FEATURESET_7b0] &= ~(cpufeat_mask(X86_FEATURE_FDP_EXCP_ONLY) |
+                            cpufeat_mask(X86_FEATURE_NO_FPU_SEL));
     fs[FEATURESET_7b0] |= (host_cpuid_policy.feat._7b0 &
-                           special_features[FEATURESET_7b0]);
+                           (cpufeat_mask(X86_FEATURE_FDP_EXCP_ONLY) |
+                            cpufeat_mask(X86_FEATURE_NO_FPU_SEL)));
 
     cpuid_featureset_to_policy(fs, p);