linux-kernel - [PATCH v5 1/4] riscv: Improve tlb

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Message-Id: <20231019140151.21629-2-alexghiti@rivosinc.com>
Date:   Thu, 19 Oct 2023 16:01:48 +0200
From:   Alexandre Ghiti <alexghiti@...osinc.com>
To:     Will Deacon <will@...nel.org>,
        "Aneesh Kumar K . V" <aneesh.kumar@...ux.ibm.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Nick Piggin <npiggin@...il.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Mayuresh Chitale <mchitale@...tanamicro.com>,
        Vincent Chen <vincent.chen@...ive.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>, linux-arch@...r.kernel.org,
        linux-mm@...ck.org, linux-riscv@...ts.infradead.org,
        linux-kernel@...r.kernel.org, Samuel Holland <samuel@...lland.org>,
        Lad Prabhakar <prabhakar.csengg@...il.com>
Cc:     Alexandre Ghiti <alexghiti@...osinc.com>,
        Andrew Jones <ajones@...tanamicro.com>,
        Samuel Holland <samuel.holland@...ive.com>,
        Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
Subject: [PATCH v5 1/4] riscv: Improve tlb_flush()

For now, tlb_flush() 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@...osinc.com>
Reviewed-by: Andrew Jones <ajones@...tanamicro.com>
Reviewed-by: Samuel Holland <samuel.holland@...ive.com>
Tested-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com> # On RZ/Five SMARC
---
 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