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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v3] x86/VPMU: implement ipc and arch filter flags
This introduces a way to have a restricted VPMU, by specifying one of two
predefined groups of PMCs to make available. For secure environments, this
allows the VPMU to be used without needing to enable all PMCs.
Signed-off-by: Brendan Gregg <bgregg@xxxxxxxxxxx>
---
Changes in v3:
* addressing review comments from Boris:
* ensure final flag is validated
* code tidy
Changes in v2:
* feature flags can now be combined (eg, "vpmu=ipc,bts")
* addressing review comments from Boris:
* restrict DS_AREA and PEBS_ENABLE access when filters are in use
* better variable types
* include MSR_IA32_CMT_EVTSEL_UE_MASK flag
---
docs/misc/xen-command-line.markdown | 14 +++++++++-
xen/arch/x86/cpu/vpmu.c | 51 +++++++++++++++++++++++++++++--------
xen/arch/x86/cpu/vpmu_intel.c | 49 +++++++++++++++++++++++++++++++++++
xen/include/asm-x86/msr-index.h | 1 +
xen/include/public/pmu.h | 14 ++++++++--
5 files changed, 115 insertions(+), 14 deletions(-)
diff --git a/docs/misc/xen-command-line.markdown
b/docs/misc/xen-command-line.markdown
index 70daa84..6055a68 100644
--- a/docs/misc/xen-command-line.markdown
+++ b/docs/misc/xen-command-line.markdown
@@ -1452,7 +1452,7 @@ Use Virtual Processor ID support if available. This
prevents the need for TLB
flushes on VM entry and exit, increasing performance.
### vpmu
-> `= ( bts )`
+> `= ( <boolean> | { bts | ipc | arch [, ...] } )`
> Default: `off`
@@ -1468,6 +1468,18 @@ wrong behaviour (see handle\_pmc\_quirk()).
If 'vpmu=bts' is specified the virtualisation of the Branch Trace Store (BTS)
feature is switched on on Intel processors supporting this feature.
+vpmu=ipc enables performance monitoring, but restricts the counters to the
+most minimum set possible: instructions, cycles, and reference cycles. These
+can be used to calculate instructions per cycle (IPC).
+
+vpmu=arch enables performance monitoring, but restricts the counters to the
+pre-defined architectural events only. These are exposed by cpuid, and listed
+in Table 18-1 from the Intel 64 and IA-32 Architectures Software Developer's
+Manual, Volume 3B, System Programming Guide, Part 2.
+
+If a boolean is not used, combinations of flags are allowed, comma separated.
+For example, vpmu=arch,bts.
+
Note that if **watchdog** option is also specified vpmu will be turned off.
*Warning:*
diff --git a/xen/arch/x86/cpu/vpmu.c b/xen/arch/x86/cpu/vpmu.c
index 2f5156a..46b5324 100644
--- a/xen/arch/x86/cpu/vpmu.c
+++ b/xen/arch/x86/cpu/vpmu.c
@@ -43,34 +43,59 @@ CHECK_pmu_data;
CHECK_pmu_params;
/*
- * "vpmu" : vpmu generally enabled
- * "vpmu=off" : vpmu generally disabled
- * "vpmu=bts" : vpmu enabled and Intel BTS feature switched on.
+ * "vpmu" : vpmu generally enabled (all counters)
+ * "vpmu=off" : vpmu generally disabled
+ * "vpmu=bts" : vpmu enabled and Intel BTS feature switched on.
+ * "vpmu=ipc" : vpmu enabled for IPC counters only (most restrictive)
+ * "vpmu=arch" : vpmu enabled for predef arch counters only (restrictive)
+ * flag combinations are allowed, eg, "vpmu=ipc,bts".
*/
static unsigned int __read_mostly opt_vpmu_enabled;
unsigned int __read_mostly vpmu_mode = XENPMU_MODE_OFF;
unsigned int __read_mostly vpmu_features = 0;
-static void parse_vpmu_param(char *s);
-custom_param("vpmu", parse_vpmu_param);
+static void parse_vpmu_params(char *s);
+custom_param("vpmu", parse_vpmu_params);
static DEFINE_SPINLOCK(vpmu_lock);
static unsigned vpmu_count;
static DEFINE_PER_CPU(struct vcpu *, last_vcpu);
-static void __init parse_vpmu_param(char *s)
+static int parse_vpmu_param(char *s, int len)
{
+ if ( ! *s || ! len )
+ return 0;
+ if ( !strncmp(s, "bts", len) )
+ vpmu_features |= XENPMU_FEATURE_INTEL_BTS;
+ else if ( !strncmp(s, "ipc", len) )
+ vpmu_features |= XENPMU_FEATURE_IPC_ONLY;
+ else if ( !strncmp(s, "arch", len) )
+ vpmu_features |= XENPMU_FEATURE_ARCH_ONLY;
+ else
+ return 1;
+ return 0;
+}
+
+static void __init parse_vpmu_params(char *s)
+{
+ char *sep, *p = s;
+
switch ( parse_bool(s) )
{
case 0:
break;
default:
- if ( !strcmp(s, "bts") )
- vpmu_features |= XENPMU_FEATURE_INTEL_BTS;
- else if ( *s )
+ while (1)
{
- printk("VPMU: unknown flag: %s - vpmu disabled!\n", s);
- break;
+ sep = strchr(p, ',');
+ if ( sep == NULL )
+ sep = strchr(p, 0);
+ if ( parse_vpmu_param(p, sep - p) )
+ goto error;
+ if ( *sep == 0 )
+ /* reached end of flags */
+ break;
+ p = sep + 1;
}
/* fall through */
case 1:
@@ -79,6 +104,10 @@ static void __init parse_vpmu_param(char *s)
opt_vpmu_enabled = 1;
break;
}
+ return;
+
+ error:
+ printk("VPMU: unknown flags: %s - vpmu disabled!\n", s);
}
void vpmu_lvtpc_update(uint32_t val)
diff --git a/xen/arch/x86/cpu/vpmu_intel.c b/xen/arch/x86/cpu/vpmu_intel.c
index 8d83a1a..0ba0f1f 100644
--- a/xen/arch/x86/cpu/vpmu_intel.c
+++ b/xen/arch/x86/cpu/vpmu_intel.c
@@ -602,12 +602,19 @@ static int core2_vpmu_do_wrmsr(unsigned int msr, uint64_t
msr_content,
"MSR_PERF_GLOBAL_STATUS(0x38E)!\n");
return -EINVAL;
case MSR_IA32_PEBS_ENABLE:
+ if ( vpmu_features & (XENPMU_FEATURE_IPC_ONLY |
+ XENPMU_FEATURE_ARCH_ONLY) )
+ return -EINVAL;
if ( msr_content & 1 )
gdprintk(XENLOG_WARNING, "Guest is trying to enable PEBS, "
"which is not supported.\n");
core2_vpmu_cxt->pebs_enable = msr_content;
return 0;
case MSR_IA32_DS_AREA:
+ if ( (vpmu_features & (XENPMU_FEATURE_IPC_ONLY |
+ XENPMU_FEATURE_ARCH_ONLY)) &&
+ !(vpmu_features & XENPMU_FEATURE_INTEL_BTS) )
+ return -EINVAL;
if ( vpmu_is_set(vpmu, VPMU_CPU_HAS_DS) )
{
if ( !is_canonical_address(msr_content) )
@@ -652,12 +659,54 @@ static int core2_vpmu_do_wrmsr(unsigned int msr, uint64_t
msr_content,
tmp = msr - MSR_P6_EVNTSEL(0);
if ( tmp >= 0 && tmp < arch_pmc_cnt )
{
+ bool_t blocked = 0;
+ uint64_t umaskevent;
struct xen_pmu_cntr_pair *xen_pmu_cntr_pair =
vpmu_reg_pointer(core2_vpmu_cxt, arch_counters);
if ( msr_content & ARCH_CTRL_MASK )
return -EINVAL;
+ /* PMC filters */
+ umaskevent = msr_content & MSR_IA32_CMT_EVTSEL_UE_MASK;
+ if ( vpmu_features & XENPMU_FEATURE_IPC_ONLY ||
+ vpmu_features & XENPMU_FEATURE_ARCH_ONLY )
+ {
+ blocked = 1;
+ switch ( umaskevent )
+ {
+ /*
+ * See Table 18-1 from the Intel 64 and IA-32 Architectures
+ * Software Developer's Manual, Volume 3B, System Programming
+ * Guide, Part 2.
+ */
+ case 0x003c: /* unhalted core cycles */
+ case 0x013c: /* unhalted ref cycles */
+ case 0x00c0: /* instruction retired */
+ blocked = 0;
+ default:
+ break;
+ }
+ }
+
+ if ( vpmu_features & XENPMU_FEATURE_ARCH_ONLY )
+ {
+ /* additional counters beyond IPC only; blocked already set */
+ switch ( umaskevent )
+ {
+ case 0x4f2e: /* LLC reference */
+ case 0x412e: /* LLC misses */
+ case 0x00c4: /* branch instruction retired */
+ case 0x00c5: /* branch */
+ blocked = 0;
+ default:
+ break;
+ }
+ }
+
+ if ( blocked )
+ return -EINVAL;
+
if ( has_hvm_container_vcpu(v) )
vmx_read_guest_msr(MSR_CORE_PERF_GLOBAL_CTRL,
&core2_vpmu_cxt->global_ctrl);
diff --git a/xen/include/asm-x86/msr-index.h b/xen/include/asm-x86/msr-index.h
index b8ad93c..0542064 100644
--- a/xen/include/asm-x86/msr-index.h
+++ b/xen/include/asm-x86/msr-index.h
@@ -328,6 +328,7 @@
/* Platform Shared Resource MSRs */
#define MSR_IA32_CMT_EVTSEL 0x00000c8d
+#define MSR_IA32_CMT_EVTSEL_UE_MASK 0x0000ffff
#define MSR_IA32_CMT_CTR 0x00000c8e
#define MSR_IA32_PSR_ASSOC 0x00000c8f
#define MSR_IA32_PSR_L3_QOS_CFG 0x00000c81
diff --git a/xen/include/public/pmu.h b/xen/include/public/pmu.h
index 7753df0..c7b5648 100644
--- a/xen/include/public/pmu.h
+++ b/xen/include/public/pmu.h
@@ -84,9 +84,19 @@ DEFINE_XEN_GUEST_HANDLE(xen_pmu_params_t);
/*
* PMU features:
- * - XENPMU_FEATURE_INTEL_BTS: Intel BTS support (ignored on AMD)
+ * - XENPMU_FEATURE_INTEL_BTS: Intel BTS support (ignored on AMD)
+ * - XENPMU_FEATURE_IPC_ONLY: Restrict PMC to the most minimum set possible.
+ * Instructions, cycles, and ref cycles. Can be
+ * used to calculate instructions-per-cycle (IPC)
+ * (ignored on AMD).
+ * - XENPMU_FEATURE_ARCH_ONLY: Restrict PMCs to the Intel pre-defined
+ * architecteral events exposed by cpuid and
+ * listed in Table 18-1 of the developer's manual
+ * (ignored on AMD).
*/
-#define XENPMU_FEATURE_INTEL_BTS 1
+#define XENPMU_FEATURE_INTEL_BTS (1<<0)
+#define XENPMU_FEATURE_IPC_ONLY (1<<1)
+#define XENPMU_FEATURE_ARCH_ONLY (1<<2)
/*
* Shared PMU data between hypervisor and PV(H) domains.
--
1.9.1
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