Re: [PATCH v1 2/3] KVM: selftests: aarch64: Move the pmu helper function into lib/

From: Marc Zyngier
Date: Tue Nov 28 2023 - 03:43:26 EST

On 2023-11-27 21:48, Raghavendra Rao Ananta wrote:
Hi Shaoqin,

On Wed, Nov 22, 2023 at 10:39 PM Shaoqin Huang <shahuang@xxxxxxxxxx> wrote:

Move those pmu helper function into lib/, thus it can be used by other
pmu test.

Signed-off-by: Shaoqin Huang <shahuang@xxxxxxxxxx>
---
.../kvm/aarch64/vpmu_counter_access.c | 118 -----------------
.../selftests/kvm/include/aarch64/vpmu.h | 119 ++++++++++++++++++
2 files changed, 119 insertions(+), 118 deletions(-)

diff --git a/tools/testing/selftests/kvm/aarch64/vpmu_counter_access.c b/tools/testing/selftests/kvm/aarch64/vpmu_counter_access.c
index 17305408a334..62d6315790ab 100644
--- a/tools/testing/selftests/kvm/aarch64/vpmu_counter_access.c
+++ b/tools/testing/selftests/kvm/aarch64/vpmu_counter_access.c
@@ -20,12 +20,6 @@
#include <perf/arm_pmuv3.h>
#include <linux/bitfield.h>

-/* The max number of the PMU event counters (excluding the cycle counter) */
-#define ARMV8_PMU_MAX_GENERAL_COUNTERS (ARMV8_PMU_MAX_COUNTERS - 1)
-
-/* The cycle counter bit position that's common among the PMU registers */
-#define ARMV8_PMU_CYCLE_IDX 31
-
static struct vpmu_vm *vpmu_vm;

struct pmreg_sets {
@@ -35,118 +29,6 @@ struct pmreg_sets {

#define PMREG_SET(set, clr) {.set_reg_id = set, .clr_reg_id = clr}

-static uint64_t get_pmcr_n(uint64_t pmcr)
-{
- return (pmcr >> ARMV8_PMU_PMCR_N_SHIFT) & ARMV8_PMU_PMCR_N_MASK;
-}
-
-static void set_pmcr_n(uint64_t *pmcr, uint64_t pmcr_n)
-{
- *pmcr = *pmcr & ~(ARMV8_PMU_PMCR_N_MASK << ARMV8_PMU_PMCR_N_SHIFT);
- *pmcr |= (pmcr_n << ARMV8_PMU_PMCR_N_SHIFT);
-}
-
-static uint64_t get_counters_mask(uint64_t n)
-{
- uint64_t mask = BIT(ARMV8_PMU_CYCLE_IDX);
-
- if (n)
- mask |= GENMASK(n - 1, 0);
- return mask;
-}
-
-/* Read PMEVTCNTR<n>_EL0 through PMXEVCNTR_EL0 */
-static inline unsigned long read_sel_evcntr(int sel)
-{
- write_sysreg(sel, pmselr_el0);
- isb();
- return read_sysreg(pmxevcntr_el0);
-}
-
-/* Write PMEVTCNTR<n>_EL0 through PMXEVCNTR_EL0 */
-static inline void write_sel_evcntr(int sel, unsigned long val)
-{
- write_sysreg(sel, pmselr_el0);
- isb();
- write_sysreg(val, pmxevcntr_el0);
- isb();
-}
-
-/* Read PMEVTYPER<n>_EL0 through PMXEVTYPER_EL0 */
-static inline unsigned long read_sel_evtyper(int sel)
-{
- write_sysreg(sel, pmselr_el0);
- isb();
- return read_sysreg(pmxevtyper_el0);
-}
-
-/* Write PMEVTYPER<n>_EL0 through PMXEVTYPER_EL0 */
-static inline void write_sel_evtyper(int sel, unsigned long val)
-{
- write_sysreg(sel, pmselr_el0);
- isb();
- write_sysreg(val, pmxevtyper_el0);
- isb();
-}
-
-static inline void enable_counter(int idx)
-{
- uint64_t v = read_sysreg(pmcntenset_el0);
-
- write_sysreg(BIT(idx) | v, pmcntenset_el0);
- isb();
-}
-
-static inline void disable_counter(int idx)
-{
- uint64_t v = read_sysreg(pmcntenset_el0);
-
- write_sysreg(BIT(idx) | v, pmcntenclr_el0);
- isb();
-}
-
-static void pmu_disable_reset(void)
-{
- uint64_t pmcr = read_sysreg(pmcr_el0);
-
- /* Reset all counters, disabling them */
- pmcr &= ~ARMV8_PMU_PMCR_E;
- write_sysreg(pmcr | ARMV8_PMU_PMCR_P, pmcr_el0);
- isb();
-}
-
-#define RETURN_READ_PMEVCNTRN(n) \
- return read_sysreg(pmevcntr##n##_el0)
-static unsigned long read_pmevcntrn(int n)
-{
- PMEVN_SWITCH(n, RETURN_READ_PMEVCNTRN);
- return 0;
-}
-
-#define WRITE_PMEVCNTRN(n) \
- write_sysreg(val, pmevcntr##n##_el0)
-static void write_pmevcntrn(int n, unsigned long val)
-{
- PMEVN_SWITCH(n, WRITE_PMEVCNTRN);
- isb();
-}
-
-#define READ_PMEVTYPERN(n) \
- return read_sysreg(pmevtyper##n##_el0)
-static unsigned long read_pmevtypern(int n)
-{
- PMEVN_SWITCH(n, READ_PMEVTYPERN);
- return 0;
-}
-
-#define WRITE_PMEVTYPERN(n) \
- write_sysreg(val, pmevtyper##n##_el0)
-static void write_pmevtypern(int n, unsigned long val)
-{
- PMEVN_SWITCH(n, WRITE_PMEVTYPERN);
- isb();
-}
-
/*
* The pmc_accessor structure has pointers to PMEV{CNTR,TYPER}<n>_EL0
* accessors that test cases will use. Each of the accessors will
diff --git a/tools/testing/selftests/kvm/include/aarch64/vpmu.h b/tools/testing/selftests/kvm/include/aarch64/vpmu.h
index 0a56183644ee..e0cc1ca1c4b7 100644
--- a/tools/testing/selftests/kvm/include/aarch64/vpmu.h
+++ b/tools/testing/selftests/kvm/include/aarch64/vpmu.h
@@ -1,10 +1,17 @@
/* SPDX-License-Identifier: GPL-2.0 */

#include <kvm_util.h>
+#include <perf/arm_pmuv3.h>

#define GICD_BASE_GPA 0x8000000ULL
#define GICR_BASE_GPA 0x80A0000ULL

+/* The max number of the PMU event counters (excluding the cycle counter) */
+#define ARMV8_PMU_MAX_GENERAL_COUNTERS (ARMV8_PMU_MAX_COUNTERS - 1)
+
+/* The cycle counter bit position that's common among the PMU registers */
+#define ARMV8_PMU_CYCLE_IDX 31
+
struct vpmu_vm {
struct kvm_vm *vm;
struct kvm_vcpu *vcpu;
@@ -14,3 +21,115 @@ struct vpmu_vm {
struct vpmu_vm *create_vpmu_vm(void *guest_code);

void destroy_vpmu_vm(struct vpmu_vm *vpmu_vm);
+
+static inline uint64_t get_pmcr_n(uint64_t pmcr)
+{
+ return (pmcr >> ARMV8_PMU_PMCR_N_SHIFT) & ARMV8_PMU_PMCR_N_MASK;
+}
+
+static inline void set_pmcr_n(uint64_t *pmcr, uint64_t pmcr_n)
+{
+ *pmcr = *pmcr & ~(ARMV8_PMU_PMCR_N_MASK << ARMV8_PMU_PMCR_N_SHIFT);
+ *pmcr |= (pmcr_n << ARMV8_PMU_PMCR_N_SHIFT);
+}
+
+static inline uint64_t get_counters_mask(uint64_t n)
+{
+ uint64_t mask = BIT(ARMV8_PMU_CYCLE_IDX);
+
+ if (n)
+ mask |= GENMASK(n - 1, 0);
+ return mask;
+}
+
+/* Read PMEVTCNTR<n>_EL0 through PMXEVCNTR_EL0 */
+static inline unsigned long read_sel_evcntr(int sel)
+{
+ write_sysreg(sel, pmselr_el0);
+ isb();
+ return read_sysreg(pmxevcntr_el0);
+}
+
+/* Write PMEVTCNTR<n>_EL0 through PMXEVCNTR_EL0 */
+static inline void write_sel_evcntr(int sel, unsigned long val)
+{
+ write_sysreg(sel, pmselr_el0);
+ isb();
+ write_sysreg(val, pmxevcntr_el0);
+ isb();
+}
+
+/* Read PMEVTYPER<n>_EL0 through PMXEVTYPER_EL0 */
+static inline unsigned long read_sel_evtyper(int sel)
+{
+ write_sysreg(sel, pmselr_el0);
+ isb();
+ return read_sysreg(pmxevtyper_el0);
+}
+
+/* Write PMEVTYPER<n>_EL0 through PMXEVTYPER_EL0 */
+static inline void write_sel_evtyper(int sel, unsigned long val)
+{
+ write_sysreg(sel, pmselr_el0);
+ isb();
+ write_sysreg(val, pmxevtyper_el0);
+ isb();
+}
+
+static inline void enable_counter(int idx)
+{
+ uint64_t v = read_sysreg(pmcntenset_el0);
+
+ write_sysreg(BIT(idx) | v, pmcntenset_el0);
+ isb();
+}
+
+static inline void disable_counter(int idx)
+{
+ uint64_t v = read_sysreg(pmcntenset_el0);
+
+ write_sysreg(BIT(idx) | v, pmcntenclr_el0);
+ isb();
+}
+
As mentioned in [1], the current implementation of disable_counter()
is buggy and would end up disabling all the counters.
However if you intend to keep it (even though it would remain unused),
may be change the definition something to:

static inline void disable_counter(int idx)
{
write_sysreg(BIT(idx), pmcntenclr_el0);
isb();
}

Same thing for the enable_counter() function, by the way.
It doesn't have the same disastrous effect, but it is
buggy (imagine an interrupt disabling a counter between
the read and the write...).

In general, the set/clr registers should always be used
in their write form, never in a RMW form.

Thanks,

M.
--
Jazz is not dead. It just smells funny...