Messages in this thread Patch in this message | | | From | <> | Subject | Re: [PATCH v3] drivers/perf: riscv_pmu_sbi: add support for PMU variant on T-Head C9xx cores | Date | Mon, 5 Sep 2022 19:17:56 +0000 |
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On 05/09/2022 15:16, Heiko Stuebner wrote: > With the T-HEAD C9XX cores being designed before or during the ratification > to the SSCOFPMF extension, it implements functionality very similar but > not equal to it. > > It implements overflow handling and also some privilege-mode filtering. > While SSCOFPMF supports this for all modes, the C9XX only implements the > filtering for M-mode and S-mode but not user-mode. > > So add some adaptions to allow the C9XX to still handle > its PMU through the regular SBI PMU interface instead of defining new > interfaces or drivers. > > To work properly, this requires a matching change in SBI, though the actual > interface between kernel and SBI does not change. > > The main differences are a the overflow CSR and irq number. > > As the reading of the overflow-csr is in the hot-path during irq handling, > use an errata and alternatives to not introduce new conditionals there. > > Signed-off-by: Heiko Stuebner <heiko@sntech.de>
modulo Andreas' question being answered satisfactorially, this is: Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
> --- > changes in v3: > - improve commit message (Atish, Conor) > - IS_ENABLED and BIT() in errata probe (Conor) > > The change depends on my cpufeature/t-head errata probe cleanup series [1]. > > > changes in v2: > - use alternatives for the CSR access > - make the irq num selection a bit nicer > > There is of course a matching opensbi-part whose current implementation can > be found on [0], but as comments show, this needs some more work still. > > > [0] https://patchwork.ozlabs.org/project/opensbi/cover/20220817112004.745776-1-heiko@sntech.de/ > [1] https://lore.kernel.org/all/20220905111027.2463297-1-heiko@sntech.de/ > > arch/riscv/Kconfig.erratas | 14 ++++++++++++ > arch/riscv/errata/thead/errata.c | 18 ++++++++++++++++ > arch/riscv/include/asm/errata_list.h | 16 +++++++++++++- > drivers/perf/riscv_pmu_sbi.c | 32 +++++++++++++++++++--------- > 4 files changed, 69 insertions(+), 11 deletions(-) > > diff --git a/arch/riscv/Kconfig.erratas b/arch/riscv/Kconfig.erratas > index 6850e9389930..f1eaac4c0073 100644 > --- a/arch/riscv/Kconfig.erratas > +++ b/arch/riscv/Kconfig.erratas > @@ -66,4 +66,18 @@ config ERRATA_THEAD_CMO > > If you don't know what to do here, say "Y". > > +config ERRATA_THEAD_PMU > + bool "Apply T-Head PMU errata" > + depends on ERRATA_THEAD > + depends on RISCV_PMU_SBI > + default y > + help > + The T-Head C9xx cores implement a PMU overflow extension very > + similar to the core SSCOFPMF extension. > + > + This will apply the overflow errata to handle the non-standard > + behaviour via the regular SBI PMU driver and interface. > + > + If you don't know what to do here, say "Y". > + > endmenu # "CPU errata selection" > diff --git a/arch/riscv/errata/thead/errata.c b/arch/riscv/errata/thead/errata.c > index 902e12452821..d4b1526538ad 100644 > --- a/arch/riscv/errata/thead/errata.c > +++ b/arch/riscv/errata/thead/errata.c > @@ -46,6 +46,21 @@ static bool errata_probe_cmo(unsigned int stage, > return true; > } > > +static bool errata_probe_pmu(unsigned int stage, > + unsigned long arch_id, unsigned long impid) > +{ > + if (!IS_ENABLED(CONFIG_ERRATA_THEAD_PMU)) > + return false; > + > + if (arch_id != 0 || impid != 0) > + return false; > + > + if (stage == RISCV_ALTERNATIVES_EARLY_BOOT) > + return false; > + > + return true; > +} > + > static u32 thead_errata_probe(unsigned int stage, > unsigned long archid, unsigned long impid) > { > @@ -57,6 +72,9 @@ static u32 thead_errata_probe(unsigned int stage, > if (errata_probe_cmo(stage, archid, impid)) > cpu_req_errata |= BIT(ERRATA_THEAD_CMO); > > + if (errata_probe_pmu(stage, archid, impid)) > + cpu_req_errata |= BIT(ERRATA_THEAD_PMU); > + > return cpu_req_errata; > } > > diff --git a/arch/riscv/include/asm/errata_list.h b/arch/riscv/include/asm/errata_list.h > index 19a771085781..4180312d2a70 100644 > --- a/arch/riscv/include/asm/errata_list.h > +++ b/arch/riscv/include/asm/errata_list.h > @@ -6,6 +6,7 @@ > #define ASM_ERRATA_LIST_H > > #include <asm/alternative.h> > +#include <asm/csr.h> > #include <asm/vendorid_list.h> > > #ifdef CONFIG_ERRATA_SIFIVE > @@ -17,7 +18,8 @@ > #ifdef CONFIG_ERRATA_THEAD > #define ERRATA_THEAD_PBMT 0 > #define ERRATA_THEAD_CMO 1 > -#define ERRATA_THEAD_NUMBER 2 > +#define ERRATA_THEAD_PMU 2 > +#define ERRATA_THEAD_NUMBER 3 > #endif > > #define CPUFEATURE_SVPBMT 0 > @@ -142,6 +144,18 @@ asm volatile(ALTERNATIVE_2( \ > "r"((unsigned long)(_start) + (_size)) \ > : "a0") > > +#define THEAD_C9XX_RV_IRQ_PMU 17 > +#define THEAD_C9XX_CSR_SCOUNTEROF 0x5c5 > + > +#define ALT_SBI_PMU_OVERFLOW(__ovl) \ > +asm volatile(ALTERNATIVE( \ > + "csrr %0, " __stringify(CSR_SSCOUNTOVF), \ > + "csrr %0, " __stringify(THEAD_C9XX_CSR_SCOUNTEROF), \ > + THEAD_VENDOR_ID, ERRATA_THEAD_PMU, \ > + CONFIG_ERRATA_THEAD_PMU) \ > + : "=r" (__ovl) : \ > + : "memory") > + > #endif /* __ASSEMBLY__ */ > > #endif > diff --git a/drivers/perf/riscv_pmu_sbi.c b/drivers/perf/riscv_pmu_sbi.c > index 6f6681bbfd36..f814d3ce5ba2 100644 > --- a/drivers/perf/riscv_pmu_sbi.c > +++ b/drivers/perf/riscv_pmu_sbi.c > @@ -19,6 +19,7 @@ > #include <linux/of.h> > #include <linux/cpu_pm.h> > > +#include <asm/errata_list.h> > #include <asm/sbi.h> > #include <asm/hwcap.h> > > @@ -46,6 +47,8 @@ static const struct attribute_group *riscv_pmu_attr_groups[] = { > * per_cpu in case of harts with different pmu counters > */ > static union sbi_pmu_ctr_info *pmu_ctr_list; > +static bool riscv_pmu_use_irq; > +static unsigned int riscv_pmu_irq_num; > static unsigned int riscv_pmu_irq; > > struct sbi_pmu_event_data { > @@ -575,7 +578,7 @@ static irqreturn_t pmu_sbi_ovf_handler(int irq, void *dev) > fidx = find_first_bit(cpu_hw_evt->used_hw_ctrs, RISCV_MAX_COUNTERS); > event = cpu_hw_evt->events[fidx]; > if (!event) { > - csr_clear(CSR_SIP, SIP_LCOFIP); > + csr_clear(CSR_SIP, BIT(riscv_pmu_irq_num)); > return IRQ_NONE; > } > > @@ -583,13 +586,13 @@ static irqreturn_t pmu_sbi_ovf_handler(int irq, void *dev) > pmu_sbi_stop_hw_ctrs(pmu); > > /* Overflow status register should only be read after counter are stopped */ > - overflow = csr_read(CSR_SSCOUNTOVF); > + ALT_SBI_PMU_OVERFLOW(overflow); > > /* > * Overflow interrupt pending bit should only be cleared after stopping > * all the counters to avoid any race condition. > */ > - csr_clear(CSR_SIP, SIP_LCOFIP); > + csr_clear(CSR_SIP, BIT(riscv_pmu_irq_num)); > > /* No overflow bit is set */ > if (!overflow) > @@ -651,10 +654,10 @@ static int pmu_sbi_starting_cpu(unsigned int cpu, struct hlist_node *node) > /* Stop all the counters so that they can be enabled from perf */ > pmu_sbi_stop_all(pmu); > > - if (riscv_isa_extension_available(NULL, SSCOFPMF)) { > + if (riscv_pmu_use_irq) { > cpu_hw_evt->irq = riscv_pmu_irq; > - csr_clear(CSR_IP, BIT(RV_IRQ_PMU)); > - csr_set(CSR_IE, BIT(RV_IRQ_PMU)); > + csr_clear(CSR_IP, BIT(riscv_pmu_irq_num)); > + csr_set(CSR_IE, BIT(riscv_pmu_irq_num)); > enable_percpu_irq(riscv_pmu_irq, IRQ_TYPE_NONE); > } > > @@ -663,9 +666,9 @@ static int pmu_sbi_starting_cpu(unsigned int cpu, struct hlist_node *node) > > static int pmu_sbi_dying_cpu(unsigned int cpu, struct hlist_node *node) > { > - if (riscv_isa_extension_available(NULL, SSCOFPMF)) { > + if (riscv_pmu_use_irq) { > disable_percpu_irq(riscv_pmu_irq); > - csr_clear(CSR_IE, BIT(RV_IRQ_PMU)); > + csr_clear(CSR_IE, BIT(riscv_pmu_irq_num)); > } > > /* Disable all counters access for user mode now */ > @@ -681,7 +684,16 @@ static int pmu_sbi_setup_irqs(struct riscv_pmu *pmu, struct platform_device *pde > struct device_node *cpu, *child; > struct irq_domain *domain = NULL; > > - if (!riscv_isa_extension_available(NULL, SSCOFPMF)) > + if (riscv_isa_extension_available(NULL, SSCOFPMF)) { > + riscv_pmu_irq_num = RV_IRQ_PMU; > + riscv_pmu_use_irq = true; > + } else if (sbi_get_mvendorid() == THEAD_VENDOR_ID && > + sbi_get_marchid() == 0 && sbi_get_mimpid() == 0) { > + riscv_pmu_irq_num = THEAD_C9XX_RV_IRQ_PMU; > + riscv_pmu_use_irq = true; > + } > + > + if (!riscv_pmu_use_irq) > return -EOPNOTSUPP; > > for_each_of_cpu_node(cpu) { > @@ -703,7 +715,7 @@ static int pmu_sbi_setup_irqs(struct riscv_pmu *pmu, struct platform_device *pde > return -ENODEV; > } > > - riscv_pmu_irq = irq_create_mapping(domain, RV_IRQ_PMU); > + riscv_pmu_irq = irq_create_mapping(domain, riscv_pmu_irq_num); > if (!riscv_pmu_irq) { > pr_err("Failed to map PMU interrupt for node\n"); > return -ENODEV;
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