From: Andrew Cooper <andrew.cooper3@citrix.com>
Date: Mon, 23 Sep 2019 12:41:37 +0000 (+0200)
Subject: x86/cpuid: Fix handling of the CPUID.7[0].eax levelling MSR
X-Git-Tag: archive/raspbian/4.11.3+24-g14b62ab3e5-1+rpi1^2~55^2~103
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=37ccdfd545b3441d6a0e2e522dbad5954e474f15;p=xen.git

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>
master commit: b50d78d0eaffb43d5f5ceeda55fa22c11f47d01b
master date: 2019-09-10 13:33:21 +0100
---

diff --git a/xen/arch/x86/domctl.c b/xen/arch/x86/domctl.c
index dd91038a67..d6fcb3db23 100644
--- a/xen/arch/x86/domctl.c
+++ b/xen/arch/x86/domctl.c
@@ -210,11 +210,15 @@ static int update_domain_cpuid_info(struct domain *d,
         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;
         }