[Xen-devel] [PATCH v7 02/19] VPMU: Mark context LOADED before registers are loaded

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

Because a PMU interrupt may be generated as soon as PMU registers are loaded 
(or,
more precisely, as soon as HW PMU is "armed") we don't want to delay marking
context as LOADED until after registers are loaded. Otherwise during interrupt
handling VPMU_CONTEXT_LOADED may not be set and this could be confusing.

(Technically, only SVM needs this change right now since VMX will "arm" PMU 
later,
during VMRUN when global control register is loaded from VMCS. However, both
AMD and Intel code will require this patch when we introduce PV VPMU).

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Acked-by: Kevin Tian <kevin.tian@xxxxxxxxx>
Reviewed-by: Dietmar Hahn <dietmar.hahn@xxxxxxxxxxxxxx>
Tested-by: Dietmar Hahn <dietmar.hahn@xxxxxxxxxxxxxx>
---
 xen/arch/x86/hvm/svm/vpmu.c       | 2 ++
 xen/arch/x86/hvm/vmx/vpmu_core2.c | 2 ++
 xen/arch/x86/hvm/vpmu.c           | 3 +--
 3 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/hvm/svm/vpmu.c b/xen/arch/x86/hvm/svm/vpmu.c
index 66a3815..3ac7d53 100644
--- a/xen/arch/x86/hvm/svm/vpmu.c
+++ b/xen/arch/x86/hvm/svm/vpmu.c
@@ -203,6 +203,8 @@ static void amd_vpmu_load(struct vcpu *v)
         return;
     }
 
+    vpmu_set(vpmu, VPMU_CONTEXT_LOADED);
+
     context_load(v);
 }
 
diff --git a/xen/arch/x86/hvm/vmx/vpmu_core2.c 
b/xen/arch/x86/hvm/vmx/vpmu_core2.c
index 3129ebd..ccd14d9 100644
--- a/xen/arch/x86/hvm/vmx/vpmu_core2.c
+++ b/xen/arch/x86/hvm/vmx/vpmu_core2.c
@@ -369,6 +369,8 @@ static void core2_vpmu_load(struct vcpu *v)
     if ( vpmu_is_set(vpmu, VPMU_CONTEXT_LOADED) )
         return;
 
+    vpmu_set(vpmu, VPMU_CONTEXT_LOADED);
+
     __core2_vpmu_load(v);
 }
 
diff --git a/xen/arch/x86/hvm/vpmu.c b/xen/arch/x86/hvm/vpmu.c
index 21fbaba..63765fa 100644
--- a/xen/arch/x86/hvm/vpmu.c
+++ b/xen/arch/x86/hvm/vpmu.c
@@ -211,10 +211,9 @@ void vpmu_load(struct vcpu *v)
     if ( vpmu->arch_vpmu_ops && vpmu->arch_vpmu_ops->arch_vpmu_load )
     {
         apic_write_around(APIC_LVTPC, vpmu->hw_lapic_lvtpc);
+        /* Arch code needs to set VPMU_CONTEXT_LOADED */
         vpmu->arch_vpmu_ops->arch_vpmu_load(v);
     }
-
-    vpmu_set(vpmu, VPMU_CONTEXT_LOADED);
 }
 
 void vpmu_initialise(struct vcpu *v)
-- 
1.8.1.4


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