[PATCH v3 1/4] riscv: Improve flush_tlb()

From: Alexandre Ghiti
Date: Tue Aug 01 2023 - 04:56:03 EST


For now, flush_tlb() simply calls flush_tlb_mm() which results in a
flush of the whole TLB. So let's use mmu_gather fields to provide a more
fine-grained flush of the TLB.

Signed-off-by: Alexandre Ghiti <alexghiti@xxxxxxxxxxxx>
Reviewed-by: Andrew Jones <ajones@xxxxxxxxxxxxxxxx>
---
arch/riscv/include/asm/tlb.h | 8 +++++++-
arch/riscv/include/asm/tlbflush.h | 3 +++
arch/riscv/mm/tlbflush.c | 7 +++++++
3 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/arch/riscv/include/asm/tlb.h b/arch/riscv/include/asm/tlb.h
index 120bcf2ed8a8..1eb5682b2af6 100644
--- a/arch/riscv/include/asm/tlb.h
+++ b/arch/riscv/include/asm/tlb.h
@@ -15,7 +15,13 @@ static void tlb_flush(struct mmu_gather *tlb);

static inline void tlb_flush(struct mmu_gather *tlb)
{
- flush_tlb_mm(tlb->mm);
+#ifdef CONFIG_MMU
+ if (tlb->fullmm || tlb->need_flush_all)
+ flush_tlb_mm(tlb->mm);
+ else
+ flush_tlb_mm_range(tlb->mm, tlb->start, tlb->end,
+ tlb_get_unmap_size(tlb));
+#endif
}

#endif /* _ASM_RISCV_TLB_H */
diff --git a/arch/riscv/include/asm/tlbflush.h b/arch/riscv/include/asm/tlbflush.h
index a09196f8de68..f5c4fb0ae642 100644
--- a/arch/riscv/include/asm/tlbflush.h
+++ b/arch/riscv/include/asm/tlbflush.h
@@ -32,6 +32,8 @@ static inline void local_flush_tlb_page(unsigned long addr)
#if defined(CONFIG_SMP) && defined(CONFIG_MMU)
void flush_tlb_all(void);
void flush_tlb_mm(struct mm_struct *mm);
+void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start,
+ unsigned long end, unsigned int page_size);
void flush_tlb_page(struct vm_area_struct *vma, unsigned long addr);
void flush_tlb_range(struct vm_area_struct *vma, unsigned long start,
unsigned long end);
@@ -52,6 +54,7 @@ static inline void flush_tlb_range(struct vm_area_struct *vma,
}

#define flush_tlb_mm(mm) flush_tlb_all()
+#define flush_tlb_mm_range(mm, start, end, page_size) flush_tlb_all()
#endif /* !CONFIG_SMP || !CONFIG_MMU */

/* Flush a range of kernel pages */
diff --git a/arch/riscv/mm/tlbflush.c b/arch/riscv/mm/tlbflush.c
index 77be59aadc73..fa03289853d8 100644
--- a/arch/riscv/mm/tlbflush.c
+++ b/arch/riscv/mm/tlbflush.c
@@ -132,6 +132,13 @@ void flush_tlb_mm(struct mm_struct *mm)
__flush_tlb_range(mm, 0, -1, PAGE_SIZE);
}

+void flush_tlb_mm_range(struct mm_struct *mm,
+ unsigned long start, unsigned long end,
+ unsigned int page_size)
+{
+ __flush_tlb_range(mm, start, end - start, page_size);
+}
+
void flush_tlb_page(struct vm_area_struct *vma, unsigned long addr)
{
__flush_tlb_range(vma->vm_mm, addr, PAGE_SIZE, PAGE_SIZE);
--
2.39.2