File 5d779811-x86-fix-CPUID7-0-eax-levelling-MSR.patch of Package xen.15892

# Commit b50d78d0eaffb43d5f5ceeda55fa22c11f47d01b
# Date 2019-09-10 13:33:21 +0100
# Author Andrew Cooper <andrew.cooper3@citrix.com>
# Committer Andrew Cooper <andrew.cooper3@citrix.com>
x86/cpuid: Fix handling of the CPUID.7[0].eax levelling MSR

7a0 is an integer field, not a mask - taking the logical and of the hardware
and policy values results in nonsense.  Instead, take the policy value
directly.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Roger Pau Monné <roger.pau@cirtrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>

--- a/xen/arch/x86/domctl.c
+++ b/xen/arch/x86/domctl.c
@@ -211,11 +211,15 @@ static int update_domain_cpuid_info(stru
         if ( is_pv_domain(d) && ((levelling_caps & LCAP_7ab0) == LCAP_7ab0) )
         {
             uint64_t mask = cpuidmask_defaults._7ab0;
-            uint32_t eax = ctl->eax;
-            uint32_t ebx = p->feat._7b0;
 
+            /*
+             * Leaf 7[0].eax is max_subleaf, not a feature mask.  Take it
+             * wholesale from the policy, but clamp the features in 7[0].ebx
+             * per usual.
+             */
             if ( boot_cpu_data.x86_vendor == X86_VENDOR_AMD )
-                mask &= ((uint64_t)eax << 32) | ebx;
+                mask = (((uint64_t)p->feat.max_subleaf << 32) |
+                        ((uint32_t)mask & p->feat._7b0));
 
             d->arch.pv_domain.cpuidmasks->_7ab0 = mask;
         }