From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 092952E62D1 for ; Fri, 4 Apr 2025 03:50:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743738649; cv=none; b=QpSeyJym0ExP0CeuwupmYLxLmkUcZ7agdKLD1DFRa6uwevfTRX59ioUMfCfR9o7/smf6yc2U/esaKBEVrqP2ZKZcn8dJAKjJqa6Pih+aHthyuMKjKlFWa4yXE9XS/y/kFILgQdrxA0IkBdfHUvXkElK15whh3ef/3iUFXUHGito= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743738649; c=relaxed/simple; bh=831a3b/szRXFhs4u6BKC5Yc43cN0QKhK1rfCUJc1Hd0=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=KvLFRKSnoLZX1ymJK71CfQDo8nTe5aijyLHVB+4mOa0ZoOs3RlHdwwdtuI/Rj3EvWptPXkMJIEh1QwLePlrmvrA6udGpEiISGxWuE+cctjoW/H78aQ5Zmx2tH4ep5Joo7vr7pblYf38dK+5ePxvB8J4/vlqoxwzR9W+/eevx+2M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 5DE041516; Thu, 3 Apr 2025 20:50:48 -0700 (PDT) Received: from [10.162.40.17] (a077893.blr.arm.com [10.162.40.17]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 10FBC3F694; Thu, 3 Apr 2025 20:50:40 -0700 (PDT) Message-ID: <6e4e11ef-d0d2-48e8-9ecd-4ba6575c8e52@arm.com> Date: Fri, 4 Apr 2025 09:20:37 +0530 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 02/11] arm64: hugetlb: Refine tlb maintenance scope To: Ryan Roberts , Catalin Marinas , Will Deacon , Pasha Tatashin , Andrew Morton , Uladzislau Rezki , Christoph Hellwig , David Hildenbrand , "Matthew Wilcox (Oracle)" , Mark Rutland , Alexandre Ghiti , Kevin Brodsky Cc: linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20250304150444.3788920-1-ryan.roberts@arm.com> <20250304150444.3788920-3-ryan.roberts@arm.com> Content-Language: en-US From: Anshuman Khandual In-Reply-To: <20250304150444.3788920-3-ryan.roberts@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 3/4/25 20:34, Ryan Roberts wrote: > When operating on contiguous blocks of ptes (or pmds) for some hugetlb > sizes, we must honour break-before-make requirements and clear down the > block to invalid state in the pgtable then invalidate the relevant tlb > entries before making the pgtable entries valid again. > > However, the tlb maintenance is currently always done assuming the worst > case stride (PAGE_SIZE), last_level (false) and tlb_level > (TLBI_TTL_UNKNOWN). We can do much better with the hinting; In reality, > we know the stride from the huge_pte pgsize, we are always operating > only on the last level, and we always know the tlb_level, again based on > pgsize. So let's start providing these hints. > > Additionally, avoid tlb maintenace in set_huge_pte_at(). > Break-before-make is only required if we are transitioning the > contiguous pte block from valid -> valid. So let's elide the > clear-and-flush ("break") if the pte range was previously invalid. > > Signed-off-by: Ryan Roberts > --- > arch/arm64/include/asm/hugetlb.h | 29 +++++++++++++++++++---------- > arch/arm64/mm/hugetlbpage.c | 9 ++++++--- > 2 files changed, 25 insertions(+), 13 deletions(-) > > diff --git a/arch/arm64/include/asm/hugetlb.h b/arch/arm64/include/asm/hugetlb.h > index 07fbf5bf85a7..2a8155c4a882 100644 > --- a/arch/arm64/include/asm/hugetlb.h > +++ b/arch/arm64/include/asm/hugetlb.h > @@ -69,29 +69,38 @@ extern void huge_ptep_modify_prot_commit(struct vm_area_struct *vma, > > #include > > -#define __HAVE_ARCH_FLUSH_HUGETLB_TLB_RANGE > -static inline void flush_hugetlb_tlb_range(struct vm_area_struct *vma, > - unsigned long start, > - unsigned long end) > +static inline void __flush_hugetlb_tlb_range(struct vm_area_struct *vma, > + unsigned long start, > + unsigned long end, > + unsigned long stride, > + bool last_level) > { > - unsigned long stride = huge_page_size(hstate_vma(vma)); > - > switch (stride) { > #ifndef __PAGETABLE_PMD_FOLDED > case PUD_SIZE: > - __flush_tlb_range(vma, start, end, PUD_SIZE, false, 1); > + __flush_tlb_range(vma, start, end, PUD_SIZE, last_level, 1); > break; > #endif > case CONT_PMD_SIZE: > case PMD_SIZE: > - __flush_tlb_range(vma, start, end, PMD_SIZE, false, 2); > + __flush_tlb_range(vma, start, end, PMD_SIZE, last_level, 2); > break; > case CONT_PTE_SIZE: > - __flush_tlb_range(vma, start, end, PAGE_SIZE, false, 3); > + __flush_tlb_range(vma, start, end, PAGE_SIZE, last_level, 3); > break; > default: > - __flush_tlb_range(vma, start, end, PAGE_SIZE, false, TLBI_TTL_UNKNOWN); > + __flush_tlb_range(vma, start, end, PAGE_SIZE, last_level, TLBI_TTL_UNKNOWN); > } > } > > +#define __HAVE_ARCH_FLUSH_HUGETLB_TLB_RANGE > +static inline void flush_hugetlb_tlb_range(struct vm_area_struct *vma, > + unsigned long start, > + unsigned long end) > +{ > + unsigned long stride = huge_page_size(hstate_vma(vma)); > + > + __flush_hugetlb_tlb_range(vma, start, end, stride, false); > +} > + > #endif /* __ASM_HUGETLB_H */ > diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c > index 6a2af9fb2566..065be8650aa5 100644 > --- a/arch/arm64/mm/hugetlbpage.c > +++ b/arch/arm64/mm/hugetlbpage.c > @@ -183,8 +183,9 @@ static pte_t get_clear_contig_flush(struct mm_struct *mm, > { > pte_t orig_pte = get_clear_contig(mm, addr, ptep, pgsize, ncontig); > struct vm_area_struct vma = TLB_FLUSH_VMA(mm, 0); > + unsigned long end = addr + (pgsize * ncontig); > > - flush_tlb_range(&vma, addr, addr + (pgsize * ncontig)); > + __flush_hugetlb_tlb_range(&vma, addr, end, pgsize, true); > return orig_pte; > } > > @@ -209,7 +210,7 @@ static void clear_flush(struct mm_struct *mm, > for (i = 0; i < ncontig; i++, addr += pgsize, ptep++) > __ptep_get_and_clear(mm, addr, ptep); > > - flush_tlb_range(&vma, saddr, addr); > + __flush_hugetlb_tlb_range(&vma, saddr, addr, pgsize, true); > } > > void set_huge_pte_at(struct mm_struct *mm, unsigned long addr, > @@ -238,7 +239,9 @@ void set_huge_pte_at(struct mm_struct *mm, unsigned long addr, > dpfn = pgsize >> PAGE_SHIFT; > hugeprot = pte_pgprot(pte); > > - clear_flush(mm, addr, ptep, pgsize, ncontig); > + /* Only need to "break" if transitioning valid -> valid. */ > + if (pte_valid(__ptep_get(ptep))) > + clear_flush(mm, addr, ptep, pgsize, ncontig); > > for (i = 0; i < ncontig; i++, ptep++, addr += pgsize, pfn += dpfn) > __set_ptes(mm, addr, ptep, pfn_pte(pfn, hugeprot), 1); LGTM Reviewed-by: Anshuman Khandual