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Message-ID: <621ea04b-ae10-c2a5-8711-dcb8c6d2b322@redhat.com>
Date: Wed, 29 Nov 2023 11:51:53 +0800
From: Shaoqin Huang <shahuang@...hat.com>
To: Marc Zyngier <maz@...nel.org>,
Raghavendra Rao Ananta <rananta@...gle.com>
Cc: Oliver Upton <oliver.upton@...ux.dev>, kvmarm@...ts.linux.dev,
James Morse <james.morse@....com>,
Suzuki K Poulose <suzuki.poulose@....com>,
Zenghui Yu <yuzenghui@...wei.com>,
Paolo Bonzini <pbonzini@...hat.com>,
Shuah Khan <shuah@...nel.org>,
linux-arm-kernel@...ts.infradead.org, kvm@...r.kernel.org,
linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 2/3] KVM: selftests: aarch64: Move the pmu helper
function into lib/
Hi Marc,
On 11/28/23 16:43, Marc Zyngier wrote:
> On 2023-11-27 21:48, Raghavendra Rao Ananta wrote:
>> Hi Shaoqin,
>>
>> On Wed, Nov 22, 2023 at 10:39 PM Shaoqin Huang <shahuang@...hat.com>
>> wrote:
>>>
>>> Move those pmu helper function into lib/, thus it can be used by other
>>> pmu test.
>>>
>>> Signed-off-by: Shaoqin Huang <shahuang@...hat.com>
>>> ---
>>> .../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 for your explaination. I will fix the enable_counter together
with the disable_counter.
Thanks,
Shaoqin
> Thanks,
>
> M.
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