James Clark <james.clark@xxxxxxxxxx> writes:
On 13/02/2025 6:03 pm, Colton Lewis wrote:
If the PMU is partitioned, keep the driver out of the guest counter
partition and only use the host counter partition. Partitioning is
defined by the MDCR_EL2.HPMN register field and saved in
cpu_pmu->hpmn. The range 0..HPMN-1 is accessible by EL1 and EL0 while
HPMN..PMCR.N is reserved for EL2.
Define some macros that take HPMN as an argument and construct
mutually exclusive bitmaps for testing which partition a particular
counter is in. Note that despite their different position in the
bitmap, the cycle and instruction counters are always in the guest
partition.
Signed-off-by: Colton Lewis <coltonlewis@xxxxxxxxxx>
---
arch/arm/include/asm/arm_pmuv3.h | 2 +
arch/arm64/include/asm/kvm_pmu.h | 5 +++
arch/arm64/kvm/pmu-part.c | 16 +++++++
drivers/perf/arm_pmuv3.c | 73 +++++++++++++++++++++++++++-----
include/linux/perf/arm_pmuv3.h | 8 ++++
5 files changed, 94 insertions(+), 10 deletions(-)
diff --git a/arch/arm/include/asm/arm_pmuv3.h
b/arch/arm/include/asm/arm_pmuv3.h
index 2ec0e5e83fc9..dadd4ddf51af 100644
--- a/arch/arm/include/asm/arm_pmuv3.h
+++ b/arch/arm/include/asm/arm_pmuv3.h
@@ -227,6 +227,8 @@ static inline bool kvm_set_pmuserenr(u64 val)
}
static inline void kvm_vcpu_pmu_resync_el0(void) {}
+static inline void kvm_pmu_host_counters_enable(void) {}
+static inline void kvm_pmu_host_counters_disable(void) {}
/* PMU Version in DFR Register */
#define ARMV8_PMU_DFR_VER_NI 0
diff --git a/arch/arm64/include/asm/kvm_pmu.h
b/arch/arm64/include/asm/kvm_pmu.h
index 174b7f376d95..8f25754fde47 100644
--- a/arch/arm64/include/asm/kvm_pmu.h
+++ b/arch/arm64/include/asm/kvm_pmu.h
@@ -25,6 +25,8 @@ void kvm_host_pmu_init(struct arm_pmu *pmu);
u8 kvm_pmu_get_reserved_counters(void);
u8 kvm_pmu_hpmn(u8 nr_counters);
void kvm_pmu_partition(struct arm_pmu *pmu);
+void kvm_pmu_host_counters_enable(void);
+void kvm_pmu_host_counters_disable(void);
#else
@@ -37,6 +39,9 @@ static inline bool kvm_set_pmuserenr(u64 val)
static inline void kvm_vcpu_pmu_resync_el0(void) {}
static inline void kvm_host_pmu_init(struct arm_pmu *pmu) {}
+static inline void kvm_pmu_host_counters_enable(void) {}
+static inline void kvm_pmu_host_counters_disable(void) {}
+
#endif
#endif
diff --git a/arch/arm64/kvm/pmu-part.c b/arch/arm64/kvm/pmu-part.c
index e74fecc67e37..51da65c678f9 100644
--- a/arch/arm64/kvm/pmu-part.c
+++ b/arch/arm64/kvm/pmu-part.c
@@ -45,3 +45,19 @@ void kvm_pmu_partition(struct arm_pmu *pmu)
pmu->partitioned = false;
}
}
+
+void kvm_pmu_host_counters_enable(void)
+{
+ u64 mdcr = read_sysreg(mdcr_el2);
+
+ mdcr |= MDCR_EL2_HPME;
+ write_sysreg(mdcr, mdcr_el2);
+}
+
+void kvm_pmu_host_counters_disable(void)
+{
+ u64 mdcr = read_sysreg(mdcr_el2);
+
+ mdcr &= ~MDCR_EL2_HPME;
+ write_sysreg(mdcr, mdcr_el2);
+}
diff --git a/drivers/perf/arm_pmuv3.c b/drivers/perf/arm_pmuv3.c
index 0e360feb3432..442dcff56d5b 100644
--- a/drivers/perf/arm_pmuv3.c
+++ b/drivers/perf/arm_pmuv3.c
@@ -730,15 +730,19 @@ static void armv8pmu_disable_event_irq(struct
perf_event *event)
armv8pmu_disable_intens(BIT(event->hw.idx));
}
-static u64 armv8pmu_getreset_flags(void)
+static u64 armv8pmu_getreset_flags(struct arm_pmu *cpu_pmu)
{
u64 value;
/* Read */
value = read_pmovsclr();
+ if (cpu_pmu->partitioned)
+ value &= ARMV8_PMU_HOST_CNT_PART(cpu_pmu->hpmn);
+ else
+ value &= ARMV8_PMU_OVERFLOWED_MASK;
+
/* Write to clear flags */
- value &= ARMV8_PMU_OVERFLOWED_MASK;
write_pmovsclr(value);
return value;
@@ -765,6 +769,18 @@ static void armv8pmu_disable_user_access(void)
update_pmuserenr(0);
}
+static bool armv8pmu_is_guest_part(struct arm_pmu *cpu_pmu, u8 idx)
+{
+ return cpu_pmu->partitioned &&
+ (BIT(idx) & ARMV8_PMU_GUEST_CNT_PART(cpu_pmu->hpmn));
+}
+
+static bool armv8pmu_is_host_part(struct arm_pmu *cpu_pmu, u8 idx)
+{
+ return !cpu_pmu->partitioned ||
+ (BIT(idx) & ARMV8_PMU_HOST_CNT_PART(cpu_pmu->hpmn));
+}
+
static void armv8pmu_enable_user_access(struct arm_pmu *cpu_pmu)
{
int i;
@@ -773,6 +789,8 @@ static void armv8pmu_enable_user_access(struct
arm_pmu *cpu_pmu)
if (is_pmuv3p9(cpu_pmu->pmuver)) {
u64 mask = 0;
for_each_set_bit(i, cpuc->used_mask, ARMPMU_MAX_HWEVENTS) {
+ if (armv8pmu_is_guest_part(cpu_pmu, i))
+ continue;
Hi Colton,
Is it possible to keep the guest bits out of used_mask and cntr_mask in
the first place? Then all these loops don't need to have the logic for
is_guest_part()/is_host_part().
It should be possible.
That leads me to wonder about updating the printout:
hw perfevents: enabled with armv8_pmuv3_0 PMU driver, 7 (0,8000003f)
counters available
It might be a bit confusing if that doesn't quite reflect reality anymore.
Good point.
