On Mon, Mar 06, 2023 at 05:15:48PM +0100, Gerald Schaefer wrote:
> diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
> index b6ba466e2e8a..0bd18de9fd97 100644
> --- a/arch/arm64/include/asm/pgtable.h
> +++ b/arch/arm64/include/asm/pgtable.h
> @@ -57,7 +57,7 @@ static inline bool arch_thp_swp_supported(void)
> * fault on one CPU which has been handled concurrently by another CPU
> * does not need to perform additional invalidation.
> */
> -#define flush_tlb_fix_spurious_fault(vma, address) do { } while (0)
> +#define flush_tlb_fix_spurious_fault(vma, address, ptep) do { } while (0)
For arm64:
Acked-by: Catalin Marinas <catalin.marinas@xxxxxxx>
> diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h
> index 2c70b4d1263d..c1f6b46ec555 100644
> --- a/arch/s390/include/asm/pgtable.h
> +++ b/arch/s390/include/asm/pgtable.h
> @@ -1239,7 +1239,8 @@ static inline int pte_allow_rdp(pte_t old, pte_t new)
> }
>
> static inline void flush_tlb_fix_spurious_fault(struct vm_area_struct *vma,
> - unsigned long address)
> + unsigned long address,
> + pte_t *ptep)
> {
> /*
> * RDP might not have propagated the PTE protection reset to all CPUs,
> @@ -1247,11 +1248,12 @@ static inline void flush_tlb_fix_spurious_fault(struct vm_area_struct *vma,
> * NOTE: This will also be called when a racing pagetable update on
> * another thread already installed the correct PTE. Both cases cannot
> * really be distinguished.
> - * Therefore, only do the local TLB flush when RDP can be used, to avoid
> - * unnecessary overhead.
> + * Therefore, only do the local TLB flush when RDP can be used, and the
> + * PTE does not have _PAGE_PROTECT set, to avoid unnecessary overhead.
> + * A local RDP can be used to do the flush.
> */
> - if (MACHINE_HAS_RDP)
> - asm volatile("ptlb" : : : "memory");
> + if (MACHINE_HAS_RDP && !(pte_val(*ptep) & _PAGE_PROTECT))
> + __ptep_rdp(address, ptep, 0, 0, 1);
I wonder whether passing the actual entry is somewhat quicker as it
avoids another memory access (though it might already be in the cache).
--
Catalin
