Re: [Qemu-devel] [PATCH v5 08/13] target/arm: Finish implementation of PM[X]EVCNTR and PM[X]EVTYPER

[Aaron Lindsay <aclindsa@gmail.com>]

On Jul 17 17:17, Peter Maydell wrote:
> On 22 June 2018 at 21:32, Aaron Lindsay <alindsay@codeaurora.org> wrote:
> > Add arrays to hold the registers, the definitions themselves, access
> > functions, and logic to reset counters when PMCR.P is set. Update
> > filtering code to support counters other than PMCCNTR.
> >
> > Signed-off-by: Aaron Lindsay <alindsay@codeaurora.org>
> > ---
> >  target/arm/cpu.h    |   3 +
> >  target/arm/helper.c | 224 +++++++++++++++++++++++++++++++++++++++++++++++-----
> >  2 files changed, 209 insertions(+), 18 deletions(-)
> >
> > diff --git a/target/arm/cpu.h b/target/arm/cpu.h
> > index 430b8d5..c240b38 100644
> > --- a/target/arm/cpu.h
> > +++ b/target/arm/cpu.h
> > @@ -481,6 +481,9 @@ typedef struct CPUARMState {
> >           * pmccntr_op_finish.
> >           */
> >          uint64_t c15_ccnt_delta;
> > +        uint64_t c14_pmevcntr[31];
> > +        uint64_t c14_pmevcntr_delta[31];
> > +        uint64_t c14_pmevtyper[31];
> >          uint64_t pmccfiltr_el0; /* Performance Monitor Filter Register */
> >          uint64_t vpidr_el2; /* Virtualization Processor ID Register */
> >          uint64_t vmpidr_el2; /* Virtualization Multiprocessor ID Register */
> > diff --git a/target/arm/helper.c b/target/arm/helper.c
> > index 9f81747..f1fd21c 100644
> > --- a/target/arm/helper.c
> > +++ b/target/arm/helper.c
> > @@ -938,6 +938,7 @@ static const ARMCPRegInfo v6_cp_reginfo[] = {
> >  #define PMCRDP  0x10
> >  #define PMCRD   0x8
> >  #define PMCRC   0x4
> > +#define PMCRP   0x2
> >  #define PMCRE   0x1
> >
> >  #define PMXEVTYPER_P          0x80000000
> > @@ -1120,9 +1121,11 @@ static inline bool pmu_counter_enabled(CPUARMState *env, uint8_t counter)
> >          prohibited = env->cp15.c9_pmcr & PMCRDP;
> >      }
> >
> > -    /* TODO Remove assert, set filter to correct PMEVTYPER */
> > -    assert(counter == 31);
> > -    filter = env->cp15.pmccfiltr_el0;
> > +    if (counter == 31) {
> > +        filter = env->cp15.pmccfiltr_el0;
> > +    } else {
> > +        filter = env->cp15.c14_pmevtyper[counter];
> > +    }
> >
> >      p   = filter & PMXEVTYPER_P;
> >      u   = filter & PMXEVTYPER_U;
> > @@ -1142,6 +1145,21 @@ static inline bool pmu_counter_enabled(CPUARMState *env, uint8_t counter)
> >          filtered = m != p;
> >      }
> >
> > +    if (counter != 31) {
> > +        /* If not checking PMCCNTR, ensure the counter is setup to an event we
> > +         * support */
> 
> Please use the right format for multiline comments (here and below).

Fixed.

> 
> >  static void pmuserenr_write(CPUARMState *env, const ARMCPRegInfo *ri,
> >                              uint64_t value)
> >  {
> > @@ -1552,16 +1698,23 @@ static const ARMCPRegInfo v7_cp_reginfo[] = {
> >        .fieldoffset = offsetof(CPUARMState, cp15.pmccfiltr_el0),
> >        .resetvalue = 0, },
> >      { .name = "PMXEVTYPER", .cp = 15, .crn = 9, .crm = 13, .opc1 = 0, .opc2 = 1,
> > -      .access = PL0_RW, .type = ARM_CP_NO_RAW, .accessfn = pmreg_access,
> > +      .access = PL0_RW, .type = ARM_CP_NO_RAW | ARM_CP_IO,
> > +      .accessfn = pmreg_access,
> >        .writefn = pmxevtyper_write, .readfn = pmxevtyper_read },
> >      { .name = "PMXEVTYPER_EL0", .state = ARM_CP_STATE_AA64,
> >        .opc0 = 3, .opc1 = 3, .crn = 9, .crm = 13, .opc2 = 1,
> > -      .access = PL0_RW, .type = ARM_CP_NO_RAW, .accessfn = pmreg_access,
> > +      .access = PL0_RW, .type = ARM_CP_NO_RAW | ARM_CP_IO,
> > +      .accessfn = pmreg_access,
> >        .writefn = pmxevtyper_write, .readfn = pmxevtyper_read },
> > -    /* Unimplemented, RAZ/WI. */
> >      { .name = "PMXEVCNTR", .cp = 15, .crn = 9, .crm = 13, .opc1 = 0, .opc2 = 2,
> > -      .access = PL0_RW, .type = ARM_CP_CONST, .resetvalue = 0,
> > -      .accessfn = pmreg_access_xevcntr },
> > +      .access = PL0_RW, .type = ARM_CP_NO_RAW | ARM_CP_IO,
> > +      .accessfn = pmreg_access_xevcntr,
> > +      .writefn = pmxevcntr_write, .readfn = pmxevcntr_read },
> > +    { .name = "PMXEVCNTR_EL0", .state = ARM_CP_STATE_AA64,
> > +      .opc0 = 3, .opc1 = 3, .crn = 9, .crm = 13, .opc2 = 2,
> > +      .access = PL0_RW, .type = ARM_CP_NO_RAW | ARM_CP_IO,
> > +      .accessfn = pmreg_access_xevcntr,
> > +      .writefn = pmxevcntr_write, .readfn = pmxevcntr_read },
> >      { .name = "PMUSERENR", .cp = 15, .crn = 9, .crm = 14, .opc1 = 0, .opc2 = 0,
> >        .access = PL0_R | PL1_RW, .accessfn = access_tpm,
> >        .fieldoffset = offsetoflow32(CPUARMState, cp15.c9_pmuserenr),
> > @@ -4250,7 +4403,7 @@ static const ARMCPRegInfo el2_cp_reginfo[] = {
> >  #endif
> >      /* The only field of MDCR_EL2 that has a defined architectural reset value
> >       * is MDCR_EL2.HPMN which should reset to the value of PMCR_EL0.N; but we
> > -     * don't impelment any PMU event counters, so using zero as a reset
> > +     * don't implement any PMU event counters, so using zero as a reset
> >       * value for MDCR_EL2 is okay
> >       */
> >      { .name = "MDCR_EL2", .state = ARM_CP_STATE_BOTH,
> > @@ -5062,6 +5215,7 @@ void register_cp_regs_for_features(ARMCPU *cpu)
> >          define_arm_cp_regs(cpu, pmovsset_cp_reginfo);
> >      }
> >      if (arm_feature(env, ARM_FEATURE_V7)) {
> > +        unsigned int i;
> >          /* v7 performance monitor control register: same implementor
> >           * field as main ID register, and we implement only the cycle
> >           * count register.
> > @@ -5086,6 +5240,40 @@ void register_cp_regs_for_features(ARMCPU *cpu)
> >          };
> >          define_one_arm_cp_reg(cpu, &pmcr);
> >          define_one_arm_cp_reg(cpu, &pmcr64);
> > +        for (i = 0; i < 31; i++) {
> > +            char *pmevcntr_name = g_strdup_printf("PMEVCNTR%d", i);
> > +            char *pmevcntr_el0_name = g_strdup_printf("PMEVCNTR%d_EL0", i);
> > +            char *pmevtyper_name = g_strdup_printf("PMEVTYPER%d", i);
> > +            char *pmevtyper_el0_name = g_strdup_printf("PMEVTYPER%d_EL0", i);
> > +            ARMCPRegInfo pmev_regs[] = {
> > +                { .name = pmevcntr_name, .cp = 15, .crn = 15,
> > +                  .crm = 8 | (3 & (i >> 3)), .opc1 = 0, .opc2 = i & 7,
> > +                  .access = PL0_RW, .type = ARM_CP_NO_RAW | ARM_CP_IO,
> > +                  .readfn = pmevcntr_readfn, .writefn = pmevcntr_writefn,
> > +                  .accessfn = pmreg_access },
> > +                { .name = pmevcntr_el0_name, .state = ARM_CP_STATE_AA64,
> > +                  .opc0 = 3, .opc1 = 3, .crn = 15, .crm = 8 | (3 & (i >> 3)),
> > +                  .opc2 = i & 7, .access = PL0_RW, .accessfn = pmreg_access,
> > +                  .type = ARM_CP_NO_RAW | ARM_CP_IO,
> > +                  .readfn = pmevcntr_readfn, .writefn = pmevcntr_writefn },
> > +                { .name = pmevtyper_name, .cp = 15, .crn = 15,
> > +                  .crm = 12 | (3 & (i >> 3)), .opc1 = 0, .opc2 = i & 7,
> > +                  .access = PL0_RW, .type = ARM_CP_NO_RAW | ARM_CP_IO,
> > +                  .readfn = pmevtyper_readfn, .writefn = pmevtyper_writefn,
> > +                  .accessfn = pmreg_access },
> > +                { .name = pmevtyper_el0_name, .state = ARM_CP_STATE_AA64,
> > +                  .opc0 = 3, .opc1 = 3, .crn = 15, .crm = 12 | (3 & (i >> 3)),
> > +                  .opc2 = i & 7, .access = PL0_RW, .accessfn = pmreg_access,
> > +                  .type = ARM_CP_NO_RAW | ARM_CP_IO,
> > +                  .readfn = pmevtyper_readfn, .writefn = pmevtyper_writefn },
> > +                REGINFO_SENTINEL
> > +            };
> > +            define_arm_cp_regs(cpu, pmev_regs);
> > +            g_free(pmevcntr_name);
> > +            g_free(pmevcntr_el0_name);
> > +            g_free(pmevtyper_name);
> > +            g_free(pmevtyper_el0_name);
> > +        }
> >  #endif
> 
> Because all these registers are marked as NO_RAW we're going to fail
> to migrate their state, I think.

A bad copy-paste job from the PMXEVCNTR variants, I'll warrant. Fixed
now.

> This patchset in general needs to address how the extra CPU state
> involved with the PMU is going to be migrated.

I've now commented elsewhere about general ideas for migration, but I'm
wondering if there is a good way to set up unit tests for this code
because I don't trust myself to get migration right (in particular
because it's not my use case, so I won't be "naturally" testing it on my
own).

-Aaron