[PATCH v7 5/7] xen/PMU: Intercept PMU-related MSR and APIC accesses

From: Boris Ostrovsky
Date: Mon Aug 10 2015 - 16:36:31 EST


Provide interfaces for recognizing accesses to PMU-related MSRs and
LVTPC APIC and process these accesses in Xen PMU code.

(The interrupt handler performs XENPMU_flush right away in the beginning
since no PMU emulation is available. It will be added with a later patch).

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Reviewed-by: David Vrabel <david.vrabel@xxxxxxxxxx>
---
arch/x86/xen/apic.c | 5 ++-
arch/x86/xen/enlighten.c | 11 +++--
arch/x86/xen/pmu.c | 95 +++++++++++++++++++++++++++++++++++++++++-
arch/x86/xen/pmu.h | 4 ++
include/xen/interface/xenpmu.h | 2 +
5 files changed, 109 insertions(+), 8 deletions(-)

diff --git a/arch/x86/xen/apic.c b/arch/x86/xen/apic.c
index d03ebfa..acda713 100644
--- a/arch/x86/xen/apic.c
+++ b/arch/x86/xen/apic.c
@@ -7,6 +7,7 @@
#include <xen/xen.h>
#include <xen/interface/physdev.h>
#include "xen-ops.h"
+#include "pmu.h"
#include "smp.h"

static unsigned int xen_io_apic_read(unsigned apic, unsigned reg)
@@ -72,8 +73,10 @@ static u32 xen_apic_read(u32 reg)

static void xen_apic_write(u32 reg, u32 val)
{
- if (reg == APIC_LVTPC)
+ if (reg == APIC_LVTPC) {
+ (void)pmu_apic_update(reg);
return;
+ }

/* Warn to see if there's any stray references */
WARN(1,"register: %x, value: %x\n", reg, val);
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index cf46416..623f8ad 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -991,6 +991,9 @@ static u64 xen_read_msr_safe(unsigned int msr, int *err)
{
u64 val;

+ if (pmu_msr_read(msr, &val, err))
+ return val;
+
val = native_read_msr_safe(msr, err);
switch (msr) {
case MSR_IA32_APICBASE:
@@ -1037,17 +1040,13 @@ static int xen_write_msr_safe(unsigned int msr, unsigned low, unsigned high)
Xen console noise. */

default:
- ret = native_write_msr_safe(msr, low, high);
+ if (!pmu_msr_write(msr, low, high, &ret))
+ ret = native_write_msr_safe(msr, low, high);
}

return ret;
}

-unsigned long long xen_read_pmc(int counter)
-{
- return 0;
-}
-
void xen_setup_shared_info(void)
{
if (!xen_feature(XENFEAT_auto_translated_physmap)) {
diff --git a/arch/x86/xen/pmu.c b/arch/x86/xen/pmu.c
index 2b2e7df..cbd68dd 100644
--- a/arch/x86/xen/pmu.c
+++ b/arch/x86/xen/pmu.c
@@ -51,6 +51,8 @@ static __read_mostly int amd_num_counters;
/* Alias registers (0x4c1) for full-width writes to PMCs */
#define MSR_PMC_ALIAS_MASK (~(MSR_IA32_PERFCTR0 ^ MSR_IA32_PMC0))

+#define INTEL_PMC_TYPE_SHIFT 30
+
static __read_mostly int intel_num_arch_counters, intel_num_fixed_counters;


@@ -167,6 +169,91 @@ static int is_intel_pmu_msr(u32 msr_index, int *type, int *index)
}
}

+bool pmu_msr_read(unsigned int msr, uint64_t *val, int *err)
+{
+
+ if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD) {
+ if (is_amd_pmu_msr(msr)) {
+ *val = native_read_msr_safe(msr, err);
+ return true;
+ }
+ } else {
+ int type, index;
+
+ if (is_intel_pmu_msr(msr, &type, &index)) {
+ *val = native_read_msr_safe(msr, err);
+ return true;
+ }
+ }
+
+ return false;
+}
+
+bool pmu_msr_write(unsigned int msr, uint32_t low, uint32_t high, int *err)
+{
+ if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD) {
+ if (is_amd_pmu_msr(msr)) {
+ *err = native_write_msr_safe(msr, low, high);
+ return true;
+ }
+ } else {
+ int type, index;
+
+ if (is_intel_pmu_msr(msr, &type, &index)) {
+ *err = native_write_msr_safe(msr, low, high);
+ return true;
+ }
+ }
+
+ return false;
+}
+
+unsigned long long xen_amd_read_pmc(int counter)
+{
+ uint32_t msr;
+ int err;
+
+ msr = amd_counters_base + (counter * amd_msr_step);
+ return native_read_msr_safe(msr, &err);
+}
+
+unsigned long long xen_intel_read_pmc(int counter)
+{
+ int err;
+ uint32_t msr;
+
+ if (counter & (1<<INTEL_PMC_TYPE_SHIFT))
+ msr = MSR_CORE_PERF_FIXED_CTR0 + (counter & 0xffff);
+ else
+ msr = MSR_IA32_PERFCTR0 + counter;
+
+ return native_read_msr_safe(msr, &err);
+}
+
+unsigned long long xen_read_pmc(int counter)
+{
+ if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD)
+ return xen_amd_read_pmc(counter);
+ else
+ return xen_intel_read_pmc(counter);
+}
+
+int pmu_apic_update(uint32_t val)
+{
+ int ret;
+ struct xen_pmu_data *xenpmu_data = get_xenpmu_data();
+
+ if (!xenpmu_data) {
+ pr_warn_once("%s: pmudata not initialized\n", __func__);
+ return -EINVAL;
+ }
+
+ xenpmu_data->pmu.l.lapic_lvtpc = val;
+ ret = HYPERVISOR_xenpmu_op(XENPMU_lvtpc_set, NULL);
+
+ return ret;
+}
+
/* perf callbacks */
static int xen_is_in_guest(void)
{
@@ -239,7 +326,7 @@ static void xen_convert_regs(const struct xen_pmu_regs *xen_regs,

irqreturn_t xen_pmu_irq_handler(int irq, void *dev_id)
{
- int ret = IRQ_NONE;
+ int err, ret = IRQ_NONE;
struct pt_regs regs;
const struct xen_pmu_data *xenpmu_data = get_xenpmu_data();

@@ -248,6 +335,12 @@ irqreturn_t xen_pmu_irq_handler(int irq, void *dev_id)
return ret;
}

+ err = HYPERVISOR_xenpmu_op(XENPMU_flush, NULL);
+ if (err) {
+ pr_warn_once("%s: failed hypercall, err: %d\n", __func__, err);
+ return ret;
+ }
+
xen_convert_regs(&xenpmu_data->pmu.r.regs, &regs,
xenpmu_data->pmu.pmu_flags);
if (x86_pmu.handle_irq(&regs))
diff --git a/arch/x86/xen/pmu.h b/arch/x86/xen/pmu.h
index a76d2cf..af5f0ad 100644
--- a/arch/x86/xen/pmu.h
+++ b/arch/x86/xen/pmu.h
@@ -7,5 +7,9 @@ irqreturn_t xen_pmu_irq_handler(int irq, void *dev_id);
void xen_pmu_init(int cpu);
void xen_pmu_finish(int cpu);
bool is_xen_pmu(int cpu);
+bool pmu_msr_read(unsigned int msr, uint64_t *val, int *err);
+bool pmu_msr_write(unsigned int msr, uint32_t low, uint32_t high, int *err);
+int pmu_apic_update(uint32_t reg);
+unsigned long long xen_read_pmc(int counter);

#endif /* __XEN_PMU_H */
diff --git a/include/xen/interface/xenpmu.h b/include/xen/interface/xenpmu.h
index ca42301..139efc9 100644
--- a/include/xen/interface/xenpmu.h
+++ b/include/xen/interface/xenpmu.h
@@ -20,6 +20,8 @@
#define XENPMU_feature_set 3
#define XENPMU_init 4
#define XENPMU_finish 5
+#define XENPMU_lvtpc_set 6
+#define XENPMU_flush 7

/* ` } */

--
1.8.1.4

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