2023-07-27 19:16:05

by Alexandre Ghiti

Subject: [PATCH v2 2/4] riscv: Improve flush_tlb_range() for hugetlb pages

flush_tlb_range() uses a fixed stride of PAGE_SIZE and in its current form,
when a hugetlb mapping needs to be flushed, flush_tlb_range() flushes the
whole tlb: so set a stride of the size of the hugetlb mapping in order to
only flush the hugetlb mapping.

Note that THPs are directly handled by flush_pmd_tlb_range().

Signed-off-by: Alexandre Ghiti <[email protected]>
---
arch/riscv/mm/tlbflush.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/arch/riscv/mm/tlbflush.c b/arch/riscv/mm/tlbflush.c
index fa03289853d8..3e4acef1f6bc 100644
--- a/arch/riscv/mm/tlbflush.c
+++ b/arch/riscv/mm/tlbflush.c
@@ -3,6 +3,7 @@
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/sched.h>
+#include <linux/hugetlb.h>
#include <asm/sbi.h>
#include <asm/mmu_context.h>

@@ -147,7 +148,14 @@ 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)
{
- __flush_tlb_range(vma->vm_mm, start, end - start, PAGE_SIZE);
+ unsigned long stride_shift;
+
+ stride_shift = is_vm_hugetlb_page(vma) ?
+ huge_page_shift(hstate_vma(vma)) :
+ PAGE_SHIFT;
+
+ __flush_tlb_range(vma->vm_mm,
+ start, end - start, 1 << stride_shift);
}
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
void flush_pmd_tlb_range(struct vm_area_struct *vma, unsigned long start,
--
2.39.2

2023-07-28 15:10:40

by Andrew Jones

Subject: Re: [PATCH v2 2/4] riscv: Improve flush_tlb_range() for hugetlb pages

On Thu, Jul 27, 2023 at 08:55:51PM +0200, Alexandre Ghiti wrote:
> flush_tlb_range() uses a fixed stride of PAGE_SIZE and in its current form,
> when a hugetlb mapping needs to be flushed, flush_tlb_range() flushes the
> whole tlb: so set a stride of the size of the hugetlb mapping in order to
> only flush the hugetlb mapping.
>
> Note that THPs are directly handled by flush_pmd_tlb_range().
>
> Signed-off-by: Alexandre Ghiti <[email protected]>
> ---
> arch/riscv/mm/tlbflush.c | 10 +++++++++-
> 1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/arch/riscv/mm/tlbflush.c b/arch/riscv/mm/tlbflush.c
> index fa03289853d8..3e4acef1f6bc 100644
> --- a/arch/riscv/mm/tlbflush.c
> +++ b/arch/riscv/mm/tlbflush.c
> @@ -3,6 +3,7 @@
> #include <linux/mm.h>
> #include <linux/smp.h>
> #include <linux/sched.h>
> +#include <linux/hugetlb.h>
> #include <asm/sbi.h>
> #include <asm/mmu_context.h>
>
> @@ -147,7 +148,14 @@ 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)
> {
> - __flush_tlb_range(vma->vm_mm, start, end - start, PAGE_SIZE);
> + unsigned long stride_shift;
> +
> + stride_shift = is_vm_hugetlb_page(vma) ?
> + huge_page_shift(hstate_vma(vma)) :
> + PAGE_SHIFT;

We want the size below instead of the shift, so we can just use
huge_page_size() and PAGE_SIZE here.

> +
> + __flush_tlb_range(vma->vm_mm,
> + start, end - start, 1 << stride_shift);

Shouldn't need to wrap this line.

> }
> #ifdef CONFIG_TRANSPARENT_HUGEPAGE
> void flush_pmd_tlb_range(struct vm_area_struct *vma, unsigned long start,
> --
> 2.39.2
>

Otherwise,

Reviewed-by: Andrew Jones <[email protected]>

Thanks,
drew