[Xen-devel] [PATCH 2 of 2] vpmu: Add a vpmu cpuid function

[Dietmar Hahn <dietmar.hahn@xxxxxxxxxxxxxx>]

 tools/libxc/xc_cpuid_x86.c        |   1 +
 xen/arch/x86/hvm/vmx/vmx.c        |   2 ++
 xen/arch/x86/hvm/vmx/vpmu_core2.c |  38 ++++++++++++++++++++++++++++++++++++--
 xen/arch/x86/hvm/vpmu.c           |  25 ++++++++++++++++++-------
 xen/include/asm-x86/hvm/vpmu.h    |   6 ++++++
 5 files changed, 63 insertions(+), 9 deletions(-)


The  "Debug Store" cpuid flag in the Intel processors gets enabled in the libxc.
A new function call arch_vpmu_cpuid is added to the struct arch_vpmu_ops and for
Intel processors the function core2_vpmu_cpuid() is added.
The aim is that always a "struct arch_vpmu_ops" is accessible at least with
a cpuid function to switch off special PMU cpuid flags dynamically depending on
the boot variable opt_vpmu_enabled.

Signed-off-by: Dietmar Hahn <dietmar.hahn@xxxxxxxxxxxxxx>

diff -r 7a82c2e2eb33 tools/libxc/xc_cpuid_x86.c
--- a/tools/libxc/xc_cpuid_x86.c        Thu Jan 19 13:14:02 2012 +0100
+++ b/tools/libxc/xc_cpuid_x86.c        Thu Jan 19 14:37:17 2012 +0100
@@ -343,6 +343,7 @@ static void xc_cpuid_hvm_policy(
                     bitmaskof(X86_FEATURE_CMOV) |
                     bitmaskof(X86_FEATURE_PAT) |
                     bitmaskof(X86_FEATURE_CLFLSH) |
+                    bitmaskof(X86_FEATURE_DS) |
                     bitmaskof(X86_FEATURE_PSE36) |
                     bitmaskof(X86_FEATURE_MMX) |
                     bitmaskof(X86_FEATURE_FXSR) |
diff -r 7a82c2e2eb33 xen/arch/x86/hvm/vmx/vmx.c
--- a/xen/arch/x86/hvm/vmx/vmx.c        Thu Jan 19 13:14:02 2012 +0100
+++ b/xen/arch/x86/hvm/vmx/vmx.c        Thu Jan 19 14:37:17 2012 +0100
@@ -1603,6 +1603,8 @@ static void vmx_cpuid_intercept(
             break;
     }
 
+    vpmu_do_cpuid(input, eax, ebx, ecx, edx);
+
     HVMTRACE_5D (CPUID, input, *eax, *ebx, *ecx, *edx);
 }
 
diff -r 7a82c2e2eb33 xen/arch/x86/hvm/vmx/vpmu_core2.c
--- a/xen/arch/x86/hvm/vmx/vpmu_core2.c Thu Jan 19 13:14:02 2012 +0100
+++ b/xen/arch/x86/hvm/vmx/vpmu_core2.c Thu Jan 19 14:37:17 2012 +0100
@@ -598,6 +598,29 @@ static void core2_vpmu_destroy(struct vc
     vpmu->flags &= ~VPMU_CONTEXT_ALLOCATED;
 }
 
+/**
+ * core2_vpmu_cpuid - prepare special vpmu cpuid bits
+ * If emulation of vpmu is switched off, some bits are swtiched off, currently:
+ * - EAX[0x1].EAX[Bits 0-7]: PMC revision id.
+ * - EAX[0xa].EDX[Bit 21]:   Debug Store
+ */
+#define bitmaskof(idx)  (1U << ((idx) & 31))
+static void core2_vpmu_cpuid(unsigned int input,
+                             unsigned int *eax, unsigned int *ebx,
+                             unsigned int *ecx, unsigned int *edx)
+{
+    switch ( input )
+    {
+    case 0x1:
+        *edx &= ~bitmaskof(X86_FEATURE_DS);    /* Debug Store not supported */
+        break;
+    case 0xa:
+        if ( !opt_vpmu_enabled )
+            *eax &= ~(unsigned int)0xff;       /* Clear pmc version id. */
+        break;
+    }
+}
+
 struct arch_vpmu_ops core2_vpmu_ops = {
     .do_wrmsr = core2_vpmu_do_wrmsr,
     .do_rdmsr = core2_vpmu_do_rdmsr,
@@ -605,7 +628,13 @@ struct arch_vpmu_ops core2_vpmu_ops = {
     .arch_vpmu_initialise = core2_vpmu_initialise,
     .arch_vpmu_destroy = core2_vpmu_destroy,
     .arch_vpmu_save = core2_vpmu_save,
-    .arch_vpmu_load = core2_vpmu_load
+    .arch_vpmu_load = core2_vpmu_load,
+    .arch_vpmu_cpuid = core2_vpmu_cpuid
+};
+
+/* Used if vpmu is disabled. */
+struct arch_vpmu_ops core2_vpmu_dis_ops = {
+    .arch_vpmu_cpuid = core2_vpmu_cpuid
 };
 
 int vmx_vpmu_initialize(struct vcpu *v)
@@ -615,7 +644,7 @@ int vmx_vpmu_initialize(struct vcpu *v)
     __u8 cpu_model = current_cpu_data.x86_model;
 
     if ( !opt_vpmu_enabled )
-        return -EINVAL;
+        goto func_out;
 
     if ( family == 6 )
     {
@@ -635,6 +664,11 @@ int vmx_vpmu_initialize(struct vcpu *v)
     printk("VPMU: Initialization failed. "
            "Intel processor family %d model %d has not "
            "been supported\n", family, cpu_model);
+
+func_out:
+
+    vpmu->arch_vpmu_ops = &core2_vpmu_dis_ops;
+
     return -EINVAL;
 }
 
diff -r 7a82c2e2eb33 xen/arch/x86/hvm/vpmu.c
--- a/xen/arch/x86/hvm/vpmu.c   Thu Jan 19 13:14:02 2012 +0100
+++ b/xen/arch/x86/hvm/vpmu.c   Thu Jan 19 14:37:17 2012 +0100
@@ -39,7 +39,7 @@ int vpmu_do_wrmsr(unsigned int msr, uint
 {
     struct vpmu_struct *vpmu = vcpu_vpmu(current);
 
-    if ( vpmu->arch_vpmu_ops )
+    if ( vpmu->arch_vpmu_ops && vpmu->arch_vpmu_ops->do_wrmsr )
         return vpmu->arch_vpmu_ops->do_wrmsr(msr, msr_content);
     return 0;
 }
@@ -48,7 +48,7 @@ int vpmu_do_rdmsr(unsigned int msr, uint
 {
     struct vpmu_struct *vpmu = vcpu_vpmu(current);
 
-    if ( vpmu->arch_vpmu_ops )
+    if ( vpmu->arch_vpmu_ops && vpmu->arch_vpmu_ops->do_rdmsr )
         return vpmu->arch_vpmu_ops->do_rdmsr(msr, msr_content);
     return 0;
 }
@@ -57,7 +57,7 @@ int vpmu_do_interrupt(struct cpu_user_re
 {
     struct vpmu_struct *vpmu = vcpu_vpmu(current);
 
-    if ( vpmu->arch_vpmu_ops )
+    if ( vpmu->arch_vpmu_ops && vpmu->arch_vpmu_ops->do_interrupt )
         return vpmu->arch_vpmu_ops->do_interrupt(regs);
     return 0;
 }
@@ -66,7 +66,7 @@ void vpmu_save(struct vcpu *v)
 {
     struct vpmu_struct *vpmu = vcpu_vpmu(v);
 
-    if ( vpmu->arch_vpmu_ops )
+    if ( vpmu->arch_vpmu_ops && vpmu->arch_vpmu_ops->arch_vpmu_save )
         vpmu->arch_vpmu_ops->arch_vpmu_save(v);
 }
 
@@ -74,7 +74,7 @@ void vpmu_load(struct vcpu *v)
 {
     struct vpmu_struct *vpmu = vcpu_vpmu(v);
 
-    if ( vpmu->arch_vpmu_ops )
+    if ( vpmu->arch_vpmu_ops && vpmu->arch_vpmu_ops->arch_vpmu_load )
         vpmu->arch_vpmu_ops->arch_vpmu_load(v);
 }
 
@@ -109,7 +109,8 @@ void vpmu_initialise(struct vcpu *v)
     {
         vpmu->flags = 0;
         vpmu->context = NULL;
-        vpmu->arch_vpmu_ops->arch_vpmu_initialise(v);
+        if ( vpmu->arch_vpmu_ops->arch_vpmu_initialise )
+            vpmu->arch_vpmu_ops->arch_vpmu_initialise(v);
     }
 }
 
@@ -117,7 +118,17 @@ void vpmu_destroy(struct vcpu *v)
 {
     struct vpmu_struct *vpmu = vcpu_vpmu(v);
 
-    if ( vpmu->arch_vpmu_ops )
+    if ( vpmu->arch_vpmu_ops && vpmu->arch_vpmu_ops->arch_vpmu_destroy )
         vpmu->arch_vpmu_ops->arch_vpmu_destroy(v);
 }
 
+void vpmu_do_cpuid(unsigned int input,
+                   unsigned int *eax, unsigned int *ebx,
+                   unsigned int *ecx, unsigned int *edx)
+{
+    struct vpmu_struct *vpmu = vcpu_vpmu(current);
+
+    if ( vpmu->arch_vpmu_ops && vpmu->arch_vpmu_ops->arch_vpmu_cpuid)
+        vpmu->arch_vpmu_ops->arch_vpmu_cpuid(input, eax, ebx, ecx, edx);
+}
+
diff -r 7a82c2e2eb33 xen/include/asm-x86/hvm/vpmu.h
--- a/xen/include/asm-x86/hvm/vpmu.h    Thu Jan 19 13:14:02 2012 +0100
+++ b/xen/include/asm-x86/hvm/vpmu.h    Thu Jan 19 14:37:17 2012 +0100
@@ -56,6 +56,9 @@ struct arch_vpmu_ops {
     void (*arch_vpmu_destroy)(struct vcpu *v);
     void (*arch_vpmu_save)(struct vcpu *v);
     void (*arch_vpmu_load)(struct vcpu *v);
+    void (*arch_vpmu_cpuid)(unsigned int input,
+                            unsigned int *eax, unsigned int *ebx,
+                            unsigned int *ecx, unsigned int *edx);
 };
 
 int vmx_vpmu_initialize(struct vcpu *v);
@@ -78,6 +81,9 @@ void vpmu_initialise(struct vcpu *v);
 void vpmu_destroy(struct vcpu *v);
 void vpmu_save(struct vcpu *v);
 void vpmu_load(struct vcpu *v);
+void vpmu_do_cpuid(unsigned int input,
+                   unsigned int *eax, unsigned int *ebx,
+                   unsigned int *ecx, unsigned int *edx);
 
 extern int acquire_pmu_ownership(int pmu_ownership);
 extern void release_pmu_ownership(int pmu_ownership);

-- 
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