[RFC PATCH v2 02/11] riscv: asid: Add ASID-based tlbflushing methods

guoren
2021-06-06T09:05:17Z

From: Guo Ren <guoren@linux.alibaba.com>

Implement optimized version of the tlb flushing routines for systems
using ASIDs. These are behind the use_asid_allocator static branch to
not affect existing systems not using ASIDs.

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Signed-off-by: Liu Shaohua <liush@allwinnertech.com>
Reviewed-by: Anup Patel <anup.patel@wdc.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Chen-Yu Tsai <wens@csie.org>
Cc: Drew Fustini <drew@beagleboard.org>
Cc: Maxime Ripard <maxime@cerno.tech>
Cc: Palmer Dabbelt <palmerdabbelt@google.com>
Cc: Wei Fu <wefu@redhat.com>
Cc: Wei Wu <lazyparser@gmail.com>
---
arch/riscv/include/asm/mmu_context.h | 2 ++
arch/riscv/include/asm/tlbflush.h | 22 +++++++++++++++++
arch/riscv/mm/context.c | 2 +-
arch/riscv/mm/tlbflush.c | 46 +++++++++++++++++++++++++++++++++---
4 files changed, 68 insertions(+), 4 deletions(-)

diff --git a/arch/riscv/include/asm/mmu_context.h b/arch/riscv/include/asm/mmu_context.h
index b065941..7030837 100644
--- a/arch/riscv/include/asm/mmu_context.h
+++ b/arch/riscv/include/asm/mmu_context.h
@@ -33,6 +33,8 @@ static inline int init_new_context(struct task_struct *tsk,
return 0;
}

+DECLARE_STATIC_KEY_FALSE(use_asid_allocator);
+
#include <asm-generic/mmu_context.h>

#endif /* _ASM_RISCV_MMU_CONTEXT_H */
diff --git a/arch/riscv/include/asm/tlbflush.h b/arch/riscv/include/asm/tlbflush.h
index c84218a..894cf75 100644
--- a/arch/riscv/include/asm/tlbflush.h
+++ b/arch/riscv/include/asm/tlbflush.h
@@ -22,9 +22,31 @@ static inline void local_flush_tlb_page(unsigned long addr)
{
ALT_FLUSH_TLB_PAGE(__asm__ __volatile__ ("sfence.vma %0" : : "r" (addr) : "memory"));
}
+
+static inline void local_flush_tlb_all_asid(unsigned long asid)
+{
+ __asm__ __volatile__ ("sfence.vma x0, %0"
+ :
+ : "r" (asid)
+ : "memory");
+}
+
+static inline void local_flush_tlb_range_asid(unsigned long start,
+ unsigned long size, unsigned long asid)
+{
+ unsigned long tmp, end = ALIGN(start + size, PAGE_SIZE);
+
+ for (tmp = start & PAGE_MASK; tmp < end; tmp += PAGE_SIZE) {
+ __asm__ __volatile__ ("sfence.vma %0, %1"
+ :
+ : "r" (tmp), "r" (asid)
+ : "memory");
+ }
+}
#else /* CONFIG_MMU */
#define local_flush_tlb_all() do { } while (0)
#define local_flush_tlb_page(addr) do { } while (0)
+#define local_flush_tlb_range_asid(addr) do { } while (0)
#endif /* CONFIG_MMU */

#if defined(CONFIG_SMP) && defined(CONFIG_MMU)
diff --git a/arch/riscv/mm/context.c b/arch/riscv/mm/context.c
index 68aa312..45c1b04 100644
--- a/arch/riscv/mm/context.c
+++ b/arch/riscv/mm/context.c
@@ -18,7 +18,7 @@

#ifdef CONFIG_MMU

-static DEFINE_STATIC_KEY_FALSE(use_asid_allocator);
+DEFINE_STATIC_KEY_FALSE(use_asid_allocator);

static unsigned long asid_bits;
static unsigned long num_asids;
diff --git a/arch/riscv/mm/tlbflush.c b/arch/riscv/mm/tlbflush.c
index 720b443..87b4e52 100644
--- a/arch/riscv/mm/tlbflush.c
+++ b/arch/riscv/mm/tlbflush.c
@@ -4,6 +4,7 @@
#include <linux/smp.h>
#include <linux/sched.h>
#include <asm/sbi.h>
+#include <asm/mmu_context.h>

void flush_tlb_all(void)
{
@@ -39,18 +40,57 @@ static void __sbi_tlb_flush_range(struct cpumask *cmask, unsigned long start,
put_cpu();
}

+static void __sbi_tlb_flush_range_asid(struct cpumask *cmask,
+ unsigned long start,
+ unsigned long size,
+ unsigned long asid)
+{
+ struct cpumask hmask;
+ unsigned int cpuid;
+
+ if (cpumask_empty(cmask))
+ return;
+
+ cpuid = get_cpu();
+
+ if (cpumask_any_but(cmask, cpuid) >= nr_cpu_ids) {
+ if (size == -1)
+ local_flush_tlb_all_asid(asid);
+ else
+ local_flush_tlb_range_asid(start, size, asid);
+ } else {
+ riscv_cpuid_to_hartid_mask(cmask, &hmask);
+ sbi_remote_sfence_vma_asid(cpumask_bits(&hmask),
+ start, size, asid);
+ }
+
+ put_cpu();
+}
+
void flush_tlb_mm(struct mm_struct *mm)
{
- __sbi_tlb_flush_range(mm_cpumask(mm), 0, -1);
+ if (static_branch_unlikely(&use_asid_allocator))
+ __sbi_tlb_flush_range_asid(mm_cpumask(mm), 0, -1,
+ atomic_long_read(&mm->context.id));
+ else
+ __sbi_tlb_flush_range(mm_cpumask(mm), 0, -1);
}

void flush_tlb_page(struct vm_area_struct *vma, unsigned long addr)
{
- __sbi_tlb_flush_range(mm_cpumask(vma->vm_mm), addr, PAGE_SIZE);
+ if (static_branch_unlikely(&use_asid_allocator))
+ __sbi_tlb_flush_range_asid(mm_cpumask(vma->vm_mm), addr, PAGE_SIZE,
+ atomic_long_read(&vma->vm_mm->context.id));
+ else
+ __sbi_tlb_flush_range(mm_cpumask(vma->vm_mm), addr, PAGE_SIZE);
}

void flush_tlb_range(struct vm_area_struct *vma, unsigned long start,
unsigned long end)
{
- __sbi_tlb_flush_range(mm_cpumask(vma->vm_mm), start, end - start);
+ if (static_branch_unlikely(&use_asid_allocator))
+ __sbi_tlb_flush_range_asid(mm_cpumask(vma->vm_mm), start, end - start,
+ atomic_long_read(&vma->vm_mm->context.id));
+ else
+ __sbi_tlb_flush_range(mm_cpumask(vma->vm_mm), start, end - start);
}
--
2.7.4