[Xen-devel] [PATCH v2 2/3] x86/vpmu: Disable VPMU if guest's CPUID indicates no PMU support

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

When toolstack overrides CPUID leaf 0xa values (on Intel processors)
VPMU should not be available to the guest.

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
---
* New in v2

 xen/arch/x86/cpu/vpmu_intel.c |  4 ++++
 xen/arch/x86/domctl.c         | 14 ++++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/xen/arch/x86/cpu/vpmu_intel.c b/xen/arch/x86/cpu/vpmu_intel.c
index 16e5afb..051bf85 100644
--- a/xen/arch/x86/cpu/vpmu_intel.c
+++ b/xen/arch/x86/cpu/vpmu_intel.c
@@ -884,6 +884,10 @@ int vmx_vpmu_initialise(struct vcpu *v)
     if ( vpmu_mode == XENPMU_MODE_OFF )
         return 0;
 
+    if ( MASK_EXTR(v->domain->arch.cpuid->basic.raw[0xa].a, 
+                   PMU_VERSION_MASK) == 0 )
+        return -EINVAL;
+
     if ( (arch_pmc_cnt + fixed_pmc_cnt) == 0 )
         return -EINVAL;
 
diff --git a/xen/arch/x86/domctl.c b/xen/arch/x86/domctl.c
index 8e5259f..cbcc207 100644
--- a/xen/arch/x86/domctl.c
+++ b/xen/arch/x86/domctl.c
@@ -253,6 +253,20 @@ static int update_domain_cpuid_info(struct domain *d,
         }
         break;
 
+    case 0xa:
+        if ( boot_cpu_data.x86_vendor != X86_VENDOR_INTEL )
+            break;
+
+        /* If PMU version is invalid then the guest doesn't have VPMU */
+        if ( MASK_EXTR(leaf.a, 0xff) == 0 )
+        {
+            struct vcpu *v;
+
+            for_each_vcpu( d, v )
+                vpmu_destroy(v);
+        }
+        break;
+
     case 0xd:
         if ( ctl->input[1] != 1 )
             break;
-- 
1.8.3.1


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