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Sat, 28 Oct 2023 16:13:45 -0700 (PDT) Received: from sw06.internal.sifive.com ([4.53.31.132]) by smtp.gmail.com with ESMTPSA id u17-20020a17090341d100b001b8622c1ad2sm3679345ple.130.2023.10.28.16.13.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 28 Oct 2023 16:13:45 -0700 (PDT) From: Samuel Holland To: Palmer Dabbelt , Alexandre Ghiti , linux-riscv@lists.infradead.org Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Mayuresh Chitale , Andrew Jones , Lad Prabhakar , Samuel Holland Subject: [PATCH v2 03/11] riscv: Make __flush_tlb_range() loop over pte instead of flushing the whole tlb Date: Sat, 28 Oct 2023 16:12:01 -0700 Message-ID: <20231028231339.3116618-4-samuel.holland@sifive.com> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20231028231339.3116618-1-samuel.holland@sifive.com> References: <20231028231339.3116618-1-samuel.holland@sifive.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20231028_161347_019263_65DA4560 X-CRM114-Status: GOOD ( 22.02 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org From: Alexandre Ghiti Currently, when the range to flush covers more than one page (a 4K page or a hugepage), __flush_tlb_range() flushes the whole tlb. Flushing the whole tlb comes with a greater cost than flushing a single entry so we should flush single entries up to a certain threshold so that: threshold * cost of flushing a single entry < cost of flushing the whole tlb. Co-developed-by: Mayuresh Chitale Signed-off-by: Mayuresh Chitale Signed-off-by: Alexandre Ghiti Reviewed-by: Andrew Jones Tested-by: Lad Prabhakar # On RZ/Five SMARC [Samuel: Fixed type of nr_ptes_in_range] Signed-off-by: Samuel Holland --- Changes in v2: - Rebase on Alexandre's "riscv: tlb flush improvements" series v5 arch/riscv/include/asm/sbi.h | 3 - arch/riscv/include/asm/tlbflush.h | 3 + arch/riscv/kernel/sbi.c | 32 +++------ arch/riscv/mm/tlbflush.c | 115 +++++++++++++++--------------- 4 files changed, 72 insertions(+), 81 deletions(-) diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h index 5b4a1bf5f439..b79d0228144f 100644 --- a/arch/riscv/include/asm/sbi.h +++ b/arch/riscv/include/asm/sbi.h @@ -273,9 +273,6 @@ void sbi_set_timer(uint64_t stime_value); void sbi_shutdown(void); void sbi_send_ipi(unsigned int cpu); int sbi_remote_fence_i(const struct cpumask *cpu_mask); -int sbi_remote_sfence_vma(const struct cpumask *cpu_mask, - unsigned long start, - unsigned long size); int sbi_remote_sfence_vma_asid(const struct cpumask *cpu_mask, unsigned long start, diff --git a/arch/riscv/include/asm/tlbflush.h b/arch/riscv/include/asm/tlbflush.h index f5c4fb0ae642..170a49c531c6 100644 --- a/arch/riscv/include/asm/tlbflush.h +++ b/arch/riscv/include/asm/tlbflush.h @@ -11,6 +11,9 @@ #include #include +#define FLUSH_TLB_MAX_SIZE ((unsigned long)-1) +#define FLUSH_TLB_NO_ASID ((unsigned long)-1) + #ifdef CONFIG_MMU extern unsigned long asid_mask; diff --git a/arch/riscv/kernel/sbi.c b/arch/riscv/kernel/sbi.c index c672c8ba9a2a..5a62ed1da453 100644 --- a/arch/riscv/kernel/sbi.c +++ b/arch/riscv/kernel/sbi.c @@ -11,6 +11,7 @@ #include #include #include +#include /* default SBI version is 0.1 */ unsigned long sbi_spec_version __ro_after_init = SBI_SPEC_VERSION_DEFAULT; @@ -376,32 +377,15 @@ int sbi_remote_fence_i(const struct cpumask *cpu_mask) } EXPORT_SYMBOL(sbi_remote_fence_i); -/** - * sbi_remote_sfence_vma() - Execute SFENCE.VMA instructions on given remote - * harts for the specified virtual address range. - * @cpu_mask: A cpu mask containing all the target harts. - * @start: Start of the virtual address - * @size: Total size of the virtual address range. - * - * Return: 0 on success, appropriate linux error code otherwise. - */ -int sbi_remote_sfence_vma(const struct cpumask *cpu_mask, - unsigned long start, - unsigned long size) -{ - return __sbi_rfence(SBI_EXT_RFENCE_REMOTE_SFENCE_VMA, - cpu_mask, start, size, 0, 0); -} -EXPORT_SYMBOL(sbi_remote_sfence_vma); - /** * sbi_remote_sfence_vma_asid() - Execute SFENCE.VMA instructions on given - * remote harts for a virtual address range belonging to a specific ASID. + * remote harts for a virtual address range belonging to a specific ASID or not. * * @cpu_mask: A cpu mask containing all the target harts. * @start: Start of the virtual address * @size: Total size of the virtual address range. - * @asid: The value of address space identifier (ASID). + * @asid: The value of address space identifier (ASID), or FLUSH_TLB_NO_ASID + * for flushing all address spaces. * * Return: 0 on success, appropriate linux error code otherwise. */ @@ -410,8 +394,12 @@ int sbi_remote_sfence_vma_asid(const struct cpumask *cpu_mask, unsigned long size, unsigned long asid) { - return __sbi_rfence(SBI_EXT_RFENCE_REMOTE_SFENCE_VMA_ASID, - cpu_mask, start, size, asid, 0); + if (asid == FLUSH_TLB_NO_ASID) + return __sbi_rfence(SBI_EXT_RFENCE_REMOTE_SFENCE_VMA, + cpu_mask, start, size, 0, 0); + else + return __sbi_rfence(SBI_EXT_RFENCE_REMOTE_SFENCE_VMA_ASID, + cpu_mask, start, size, asid, 0); } EXPORT_SYMBOL(sbi_remote_sfence_vma_asid); diff --git a/arch/riscv/mm/tlbflush.c b/arch/riscv/mm/tlbflush.c index b6d712a82306..e46fefc70927 100644 --- a/arch/riscv/mm/tlbflush.c +++ b/arch/riscv/mm/tlbflush.c @@ -9,28 +9,50 @@ static inline void local_flush_tlb_all_asid(unsigned long asid) { - __asm__ __volatile__ ("sfence.vma x0, %0" - : - : "r" (asid) - : "memory"); + if (asid != FLUSH_TLB_NO_ASID) + __asm__ __volatile__ ("sfence.vma x0, %0" + : + : "r" (asid) + : "memory"); + else + local_flush_tlb_all(); } static inline void local_flush_tlb_page_asid(unsigned long addr, unsigned long asid) { - __asm__ __volatile__ ("sfence.vma %0, %1" - : - : "r" (addr), "r" (asid) - : "memory"); + if (asid != FLUSH_TLB_NO_ASID) + __asm__ __volatile__ ("sfence.vma %0, %1" + : + : "r" (addr), "r" (asid) + : "memory"); + else + local_flush_tlb_page(addr); } -static inline void local_flush_tlb_range(unsigned long start, - unsigned long size, unsigned long stride) +/* + * Flush entire TLB if number of entries to be flushed is greater + * than the threshold below. + */ +static unsigned long tlb_flush_all_threshold __read_mostly = 64; + +static void local_flush_tlb_range_threshold_asid(unsigned long start, + unsigned long size, + unsigned long stride, + unsigned long asid) { - if (size <= stride) - local_flush_tlb_page(start); - else - local_flush_tlb_all(); + unsigned long nr_ptes_in_range = DIV_ROUND_UP(size, stride); + int i; + + if (nr_ptes_in_range > tlb_flush_all_threshold) { + local_flush_tlb_all_asid(asid); + return; + } + + for (i = 0; i < nr_ptes_in_range; ++i) { + local_flush_tlb_page_asid(start, asid); + start += stride; + } } static inline void local_flush_tlb_range_asid(unsigned long start, @@ -38,8 +60,10 @@ static inline void local_flush_tlb_range_asid(unsigned long start, { if (size <= stride) local_flush_tlb_page_asid(start, asid); - else + else if (size == FLUSH_TLB_MAX_SIZE) local_flush_tlb_all_asid(asid); + else + local_flush_tlb_range_threshold_asid(start, size, stride, asid); } static void __ipi_flush_tlb_all(void *info) @@ -52,7 +76,7 @@ void flush_tlb_all(void) if (riscv_use_ipi_for_rfence()) on_each_cpu(__ipi_flush_tlb_all, NULL, 1); else - sbi_remote_sfence_vma(NULL, 0, -1); + sbi_remote_sfence_vma_asid(NULL, 0, FLUSH_TLB_MAX_SIZE, FLUSH_TLB_NO_ASID); } struct flush_tlb_range_data { @@ -69,18 +93,12 @@ static void __ipi_flush_tlb_range_asid(void *info) local_flush_tlb_range_asid(d->start, d->size, d->stride, d->asid); } -static void __ipi_flush_tlb_range(void *info) -{ - struct flush_tlb_range_data *d = info; - - local_flush_tlb_range(d->start, d->size, d->stride); -} - static void __flush_tlb_range(struct mm_struct *mm, unsigned long start, unsigned long size, unsigned long stride) { struct flush_tlb_range_data ftd; struct cpumask *cmask = mm_cpumask(mm); + unsigned long asid = FLUSH_TLB_NO_ASID; unsigned int cpuid; bool broadcast; @@ -90,39 +108,24 @@ static void __flush_tlb_range(struct mm_struct *mm, unsigned long start, cpuid = get_cpu(); /* check if the tlbflush needs to be sent to other CPUs */ broadcast = cpumask_any_but(cmask, cpuid) < nr_cpu_ids; - if (static_branch_unlikely(&use_asid_allocator)) { - unsigned long asid = atomic_long_read(&mm->context.id) & asid_mask; - - if (broadcast) { - if (riscv_use_ipi_for_rfence()) { - ftd.asid = asid; - ftd.start = start; - ftd.size = size; - ftd.stride = stride; - on_each_cpu_mask(cmask, - __ipi_flush_tlb_range_asid, - &ftd, 1); - } else - sbi_remote_sfence_vma_asid(cmask, - start, size, asid); - } else { - local_flush_tlb_range_asid(start, size, stride, asid); - } + + if (static_branch_unlikely(&use_asid_allocator)) + asid = atomic_long_read(&mm->context.id) & asid_mask; + + if (broadcast) { + if (riscv_use_ipi_for_rfence()) { + ftd.asid = asid; + ftd.start = start; + ftd.size = size; + ftd.stride = stride; + on_each_cpu_mask(cmask, + __ipi_flush_tlb_range_asid, + &ftd, 1); + } else + sbi_remote_sfence_vma_asid(cmask, + start, size, asid); } else { - if (broadcast) { - if (riscv_use_ipi_for_rfence()) { - ftd.asid = 0; - ftd.start = start; - ftd.size = size; - ftd.stride = stride; - on_each_cpu_mask(cmask, - __ipi_flush_tlb_range, - &ftd, 1); - } else - sbi_remote_sfence_vma(cmask, start, size); - } else { - local_flush_tlb_range(start, size, stride); - } + local_flush_tlb_range_asid(start, size, stride, asid); } put_cpu(); @@ -130,7 +133,7 @@ static void __flush_tlb_range(struct mm_struct *mm, unsigned long start, void flush_tlb_mm(struct mm_struct *mm) { - __flush_tlb_range(mm, 0, -1, PAGE_SIZE); + __flush_tlb_range(mm, 0, FLUSH_TLB_MAX_SIZE, PAGE_SIZE); } void flush_tlb_mm_range(struct mm_struct *mm,