Intel/VPMU: Add support for full-width PMC writes

A recent Linux commit (069e0c3c405814778c7475d95b9fff5318f39834) added
support for full-width PMC writes to performance counter registers,
making these registers default for perf. Since current Xen VPMU does
not support these new MSRs perf will fail to initialise in guests.

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: Dietmar Hahn <dietmar.hahn@ts.fujitsu.com>
Acked-by: Keir Faser <keir@xen.org>

2 files changed, 37 insertions, 6 deletions

diff --git a/xen/arch/x86/hvm/vmx/vpmu_core2.c b/xen/arch/x86/hvm/vmx/vpmu_core2.c
index 15b2036c8d..41a326bc11 100644
--- a/xen/arch/x86/hvm/vmx/vpmu_core2.c
+++ b/xen/arch/x86/hvm/vmx/vpmu_core2.c
@@ -64,6 +64,10 @@
 #define PMU_FIXED_WIDTH_BITS     8  /* 8 bits 5..12 */
 #define PMU_FIXED_WIDTH_MASK     (((1 << PMU_FIXED_WIDTH_BITS) -1) << PMU_FIXED_WIDTH_SHIFT)
 
+/* Alias registers (0x4c1) for full-width writes to PMCs */
+#define MSR_PMC_ALIAS_MASK       (~(MSR_IA32_PERFCTR0 ^ MSR_IA32_A_PERFCTR0))
+static bool_t __read_mostly full_width_write;
+
 /*
  * QUIRK to workaround an issue on various family 6 cpus.
  * The issue leads to endless PMC interrupt loops on the processor.
@@ -195,6 +199,7 @@ static int core2_get_bitwidth_fix_count(void)
 static int is_core2_vpmu_msr(u32 msr_index, int *type, int *index)
 {
     int i;
+    u32 msr_index_pmc;
 
     for ( i = 0; i < core2_fix_counters.num; i++ )
     {
@@ -224,11 +229,12 @@ static int is_core2_vpmu_msr(u32 msr_index, int *type, int *index)
         return 1;
     }
 
-    if ( (msr_index >= MSR_IA32_PERFCTR0) &&
-         (msr_index < (MSR_IA32_PERFCTR0 + core2_get_pmc_count())) )
+    msr_index_pmc = msr_index & MSR_PMC_ALIAS_MASK;
+    if ( (msr_index_pmc >= MSR_IA32_PERFCTR0) &&
+         (msr_index_pmc < (MSR_IA32_PERFCTR0 + core2_get_pmc_count())) )
     {
         *type = MSR_TYPE_ARCH_COUNTER;
-        *index = msr_index - MSR_IA32_PERFCTR0;
+        *index = msr_index_pmc - MSR_IA32_PERFCTR0;
         return 1;
     }
 
@@ -259,6 +265,13 @@ static void core2_vpmu_set_msr_bitmap(unsigned long *msr_bitmap)
         clear_bit(msraddr_to_bitpos(MSR_IA32_PERFCTR0+i), msr_bitmap);
         clear_bit(msraddr_to_bitpos(MSR_IA32_PERFCTR0+i),
                   msr_bitmap + 0x800/BYTES_PER_LONG);
+
+        if ( full_width_write )
+        {
+            clear_bit(msraddr_to_bitpos(MSR_IA32_A_PERFCTR0 + i), msr_bitmap);
+            clear_bit(msraddr_to_bitpos(MSR_IA32_A_PERFCTR0 + i),
+                      msr_bitmap + 0x800/BYTES_PER_LONG);
+        }
     }
 
     /* Allow Read PMU Non-global Controls Directly. */
@@ -283,7 +296,15 @@ static void core2_vpmu_unset_msr_bitmap(unsigned long *msr_bitmap)
         set_bit(msraddr_to_bitpos(MSR_IA32_PERFCTR0+i), msr_bitmap);
         set_bit(msraddr_to_bitpos(MSR_IA32_PERFCTR0+i),
                 msr_bitmap + 0x800/BYTES_PER_LONG);
+
+        if ( full_width_write )
+        {
+            set_bit(msraddr_to_bitpos(MSR_IA32_A_PERFCTR0 + i), msr_bitmap);
+            set_bit(msraddr_to_bitpos(MSR_IA32_A_PERFCTR0 + i),
+                      msr_bitmap + 0x800/BYTES_PER_LONG);
+        }
     }
+
     for ( i = 0; i < core2_ctrls.num; i++ )
         set_bit(msraddr_to_bitpos(core2_ctrls.msr[i]), msr_bitmap);
     for ( i = 0; i < core2_get_pmc_count(); i++ )
@@ -322,13 +343,18 @@ static int core2_vpmu_save(struct vcpu *v)
 
 static inline void __core2_vpmu_load(struct vcpu *v)
 {
-    int i;
+    unsigned int i, pmc_start;
     struct core2_vpmu_context *core2_vpmu_cxt = vcpu_vpmu(v)->context;
 
     for ( i = 0; i < core2_fix_counters.num; i++ )
         wrmsrl(core2_fix_counters.msr[i], core2_vpmu_cxt->fix_counters[i]);
+
+    if ( full_width_write )
+        pmc_start = MSR_IA32_A_PERFCTR0;
+    else
+        pmc_start = MSR_IA32_PERFCTR0;
     for ( i = 0; i < core2_get_pmc_count(); i++ )
-        wrmsrl(MSR_IA32_PERFCTR0+i, core2_vpmu_cxt->arch_msr_pair[i].counter);
+        wrmsrl(pmc_start + i, core2_vpmu_cxt->arch_msr_pair[i].counter);
 
     for ( i = 0; i < core2_ctrls.num; i++ )
         wrmsrl(core2_ctrls.msr[i], core2_vpmu_cxt->ctrls[i]);
@@ -855,6 +881,11 @@ int vmx_vpmu_initialise(struct vcpu *v, unsigned int vpmu_flags)
 
     if ( family == 6 )
     {
+        u64 caps;
+
+        rdmsrl(MSR_IA32_PERF_CAPABILITIES, caps);
+        full_width_write = (caps >> 13) & 1;
+
         switch ( cpu_model )
         {
         /* Core2: */
diff --git a/xen/include/asm-x86/msr-index.h b/xen/include/asm-x86/msr-index.h
index f500efdf4f..03cb00ecaf 100644
--- a/xen/include/asm-x86/msr-index.h
+++ b/xen/include/asm-x86/msr-index.h
@@ -33,7 +33,7 @@
 
 /* Intel MSRs. Some also available on other CPUs */
 #define MSR_IA32_PERFCTR0		0x000000c1
-#define MSR_IA32_PERFCTR1		0x000000c2
+#define MSR_IA32_A_PERFCTR0		0x000004c1
 #define MSR_FSB_FREQ			0x000000cd
 
 #define MSR_NHM_SNB_PKG_CST_CFG_CTL	0x000000e2