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[76.210.143.223]) by smtp.gmail.com with ESMTPSA id l8sm502367pjb.14.2020.08.04.18.47.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 04 Aug 2020 18:47:51 -0700 (PDT) Date: Tue, 04 Aug 2020 18:47:51 -0700 (PDT) X-Google-Original-Date: Tue, 04 Aug 2020 18:30:52 PDT (-0700) Subject: Re: [PATCH v6 1/4] RISC-V: Add mechanism to provide custom IPI operations In-Reply-To: <20200724071822.126758-2-anup.patel@wdc.com> CC: Paul Walmsley , aou@eecs.berkeley.edu, robh+dt@kernel.org, daniel.lezcano@linaro.org, tglx@linutronix.de, Damien Le Moal , Atish Patra , Alistair Francis , anup@brainfault.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, Anup Patel , kernel@esmil.dk From: Palmer Dabbelt To: Anup Patel Message-ID: Mime-Version: 1.0 (MHng) Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Sender: devicetree-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On Fri, 24 Jul 2020 00:18:19 PDT (-0700), Anup Patel wrote: > We add mechanism to set custom IPI operations so that CLINT driver > from drivers directory can provide custom IPI operations. > > Signed-off-by: Anup Patel > Tested-by: Emil Renner Berhing > Reviewed-by: Atish Patra > --- > arch/riscv/include/asm/clint.h | 25 -------------------- > arch/riscv/include/asm/smp.h | 19 +++++++++++++++ > arch/riscv/kernel/clint.c | 23 ++++++++++++++++-- > arch/riscv/kernel/sbi.c | 14 +++++++++++ > arch/riscv/kernel/smp.c | 43 +++++++++++++++++++--------------- > arch/riscv/kernel/smpboot.c | 3 +-- > 6 files changed, 79 insertions(+), 48 deletions(-) > > diff --git a/arch/riscv/include/asm/clint.h b/arch/riscv/include/asm/clint.h > index a279b17a6aad..adaba98a7d6c 100644 > --- a/arch/riscv/include/asm/clint.h > +++ b/arch/riscv/include/asm/clint.h > @@ -6,34 +6,9 @@ > #include > > #ifdef CONFIG_RISCV_M_MODE > -extern u32 __iomem *clint_ipi_base; > - > void clint_init_boot_cpu(void); > - > -static inline void clint_send_ipi_single(unsigned long hartid) > -{ > - writel(1, clint_ipi_base + hartid); > -} > - > -static inline void clint_send_ipi_mask(const struct cpumask *mask) > -{ > - int cpu; > - > - for_each_cpu(cpu, mask) > - clint_send_ipi_single(cpuid_to_hartid_map(cpu)); > -} > - > -static inline void clint_clear_ipi(unsigned long hartid) > -{ > - writel(0, clint_ipi_base + hartid); > -} > #else /* CONFIG_RISCV_M_MODE */ > #define clint_init_boot_cpu() do { } while (0) > - > -/* stubs to for code is only reachable under IS_ENABLED(CONFIG_RISCV_M_MODE): */ > -void clint_send_ipi_single(unsigned long hartid); > -void clint_send_ipi_mask(const struct cpumask *hartid_mask); > -void clint_clear_ipi(unsigned long hartid); > #endif /* CONFIG_RISCV_M_MODE */ > > #endif /* _ASM_RISCV_CLINT_H */ So this is entirely unrelated to the actual contents of this patch, I'd just forgotten about it before: the scheme used by clint_init_boot_cpu() only works once per system reset (and as far as I can tell, that code only works for two-CPU systems). Not really an issue with this patch set, but we should probably put a sanity check in the code -- the two-CPU thing should be easy, but the "only use the CLINT init trick once" thing need some sort of platform interface. > diff --git a/arch/riscv/include/asm/smp.h b/arch/riscv/include/asm/smp.h > index 40bb1c15a731..68de78a8eba6 100644 > --- a/arch/riscv/include/asm/smp.h > +++ b/arch/riscv/include/asm/smp.h > @@ -15,6 +15,11 @@ > struct seq_file; > extern unsigned long boot_cpu_hartid; > > +struct riscv_ipi_ops { > + void (*ipi_inject)(const struct cpumask *target); > + void (*ipi_clear)(void); > +}; > + > #ifdef CONFIG_SMP > /* > * Mapping between linux logical cpu index and hartid. > @@ -40,6 +45,12 @@ void arch_send_call_function_single_ipi(int cpu); > int riscv_hartid_to_cpuid(int hartid); > void riscv_cpuid_to_hartid_mask(const struct cpumask *in, struct cpumask *out); > > +/* Set custom IPI operations */ > +void riscv_set_ipi_ops(struct riscv_ipi_ops *ops); > + > +/* Clear IPI for current CPU */ > +void riscv_clear_ipi(void); > + > /* > * Obtains the hart ID of the currently executing task. This relies on > * THREAD_INFO_IN_TASK, but we define that unconditionally. > @@ -78,6 +89,14 @@ static inline void riscv_cpuid_to_hartid_mask(const struct cpumask *in, > cpumask_set_cpu(boot_cpu_hartid, out); > } > > +static inline void riscv_set_ipi_ops(struct riscv_ipi_ops *ops) > +{ > +} It's a bit pedantic, but it seems like this should do something as of this patch -- even though there's only a single driver, it's odd to have this both exist and do nothing. > + > +static inline void riscv_clear_ipi(void) > +{ > +} > + > #endif /* CONFIG_SMP */ > > #if defined(CONFIG_HOTPLUG_CPU) && (CONFIG_SMP) > diff --git a/arch/riscv/kernel/clint.c b/arch/riscv/kernel/clint.c > index 3647980d14c3..a9845ee023e2 100644 > --- a/arch/riscv/kernel/clint.c > +++ b/arch/riscv/kernel/clint.c > @@ -5,11 +5,11 @@ > > #include > #include > +#include > #include > #include > #include > #include > -#include > > /* > * This is the layout used by the SiFive clint, which is also shared by the qemu > @@ -21,6 +21,24 @@ > > u32 __iomem *clint_ipi_base; > > +static void clint_send_ipi(const struct cpumask *target) > +{ > + unsigned int cpu; > + > + for_each_cpu(cpu, target) > + writel(1, clint_ipi_base + cpuid_to_hartid_map(cpu)); > +} > + > +static void clint_clear_ipi(void) > +{ > + writel(0, clint_ipi_base + cpuid_to_hartid_map(smp_processor_id())); > +} > + > +static struct riscv_ipi_ops clint_ipi_ops = { > + .ipi_inject = clint_send_ipi, > + .ipi_clear = clint_clear_ipi, > +}; > + > void clint_init_boot_cpu(void) > { > struct device_node *np; > @@ -40,5 +58,6 @@ void clint_init_boot_cpu(void) > riscv_time_cmp = base + CLINT_TIME_CMP_OFF; > riscv_time_val = base + CLINT_TIME_VAL_OFF; > > - clint_clear_ipi(boot_cpu_hartid); > + clint_clear_ipi(); > + riscv_set_ipi_ops(&clint_ipi_ops); > } > diff --git a/arch/riscv/kernel/sbi.c b/arch/riscv/kernel/sbi.c > index f383ef5672b2..226ccce0f9e0 100644 > --- a/arch/riscv/kernel/sbi.c > +++ b/arch/riscv/kernel/sbi.c > @@ -547,6 +547,18 @@ static inline long sbi_get_firmware_version(void) > return __sbi_base_ecall(SBI_EXT_BASE_GET_IMP_VERSION); > } > > +static void sbi_send_cpumask_ipi(const struct cpumask *target) > +{ > + struct cpumask hartid_mask; > + > + riscv_cpuid_to_hartid_mask(target, &hartid_mask); > + > + sbi_send_ipi(cpumask_bits(&hartid_mask)); > +} > + > +static struct riscv_ipi_ops sbi_ipi_ops = { > + .ipi_inject = sbi_send_cpumask_ipi > +}; > > int __init sbi_init(void) > { > @@ -587,5 +599,7 @@ int __init sbi_init(void) > __sbi_rfence = __sbi_rfence_v01; > } > > + riscv_set_ipi_ops(&sbi_ipi_ops); > + > return 0; > } > diff --git a/arch/riscv/kernel/smp.c b/arch/riscv/kernel/smp.c > index b1d4f452f843..8b85683ce203 100644 > --- a/arch/riscv/kernel/smp.c > +++ b/arch/riscv/kernel/smp.c > @@ -84,9 +84,25 @@ static void ipi_stop(void) > wait_for_interrupt(); > } > > +static struct riscv_ipi_ops *ipi_ops; > + > +void riscv_set_ipi_ops(struct riscv_ipi_ops *ops) > +{ > + ipi_ops = ops; > +} > +EXPORT_SYMBOL_GPL(riscv_set_ipi_ops); > + > +void riscv_clear_ipi(void) > +{ > + if (ipi_ops && ipi_ops->ipi_clear) > + ipi_ops->ipi_clear(); > + > + csr_clear(CSR_IP, IE_SIE); > +} > +EXPORT_SYMBOL_GPL(riscv_clear_ipi); > + > static void send_ipi_mask(const struct cpumask *mask, enum ipi_message_type op) > { > - struct cpumask hartid_mask; > int cpu; > > smp_mb__before_atomic(); > @@ -94,33 +110,22 @@ static void send_ipi_mask(const struct cpumask *mask, enum ipi_message_type op) > set_bit(op, &ipi_data[cpu].bits); > smp_mb__after_atomic(); > > - riscv_cpuid_to_hartid_mask(mask, &hartid_mask); > - if (IS_ENABLED(CONFIG_RISCV_SBI)) > - sbi_send_ipi(cpumask_bits(&hartid_mask)); > + if (ipi_ops && ipi_ops->ipi_inject) > + ipi_ops->ipi_inject(mask); > else > - clint_send_ipi_mask(mask); > + pr_warn("SMP: IPI inject method not available\n"); > } > > static void send_ipi_single(int cpu, enum ipi_message_type op) > { > - int hartid = cpuid_to_hartid_map(cpu); > - > smp_mb__before_atomic(); > set_bit(op, &ipi_data[cpu].bits); > smp_mb__after_atomic(); > > - if (IS_ENABLED(CONFIG_RISCV_SBI)) > - sbi_send_ipi(cpumask_bits(cpumask_of(hartid))); > - else > - clint_send_ipi_single(hartid); > -} > - > -static inline void clear_ipi(void) > -{ > - if (IS_ENABLED(CONFIG_RISCV_SBI)) > - csr_clear(CSR_IP, IE_SIE); > + if (ipi_ops && ipi_ops->ipi_inject) > + ipi_ops->ipi_inject(cpumask_of(cpu)); > else > - clint_clear_ipi(cpuid_to_hartid_map(smp_processor_id())); > + pr_warn("SMP: IPI inject method not available\n"); > } > > void handle_IPI(struct pt_regs *regs) > @@ -131,7 +136,7 @@ void handle_IPI(struct pt_regs *regs) > > irq_enter(); > > - clear_ipi(); > + riscv_clear_ipi(); > > while (true) { > unsigned long ops; > diff --git a/arch/riscv/kernel/smpboot.c b/arch/riscv/kernel/smpboot.c > index 4e9922790f6e..5fe849791bf0 100644 > --- a/arch/riscv/kernel/smpboot.c > +++ b/arch/riscv/kernel/smpboot.c > @@ -147,8 +147,7 @@ asmlinkage __visible void smp_callin(void) > { > struct mm_struct *mm = &init_mm; > > - if (!IS_ENABLED(CONFIG_RISCV_SBI)) > - clint_clear_ipi(cpuid_to_hartid_map(smp_processor_id())); > + riscv_clear_ipi(); > > /* All kernel threads share the same mm context. */ > mmgrab(mm); I don't really care that much, though, so: Reviewed-by: Palmer Dabbelt