From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id E97FBC021A7 for ; Thu, 13 Feb 2025 05:01:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=yMQidJxq5pOpDUJEPxMXD+3QeoOWt7cGeE2UAXIIdt8=; b=vri0cYpl6IcQbX+DTzEDQMxAlN 0XJkkQRZfc5B9lDlL6wJ27jZ+veN5MFb79pkcy1C6yHjjXpPhm454NaOtHLNGjO02lHjCawbdVAum Raqmt5Ukkp14hX++Br1xJk59e1J8EtIYGNhNfRn9AD7JG/Aj8q39dD29Nu61V3CuJJ9CeWC8B3ms4 RjpGZnv5pqoF6VNID/+7qhO3fwP5DAApGxs1OHjgmIQc0miH0ScXUKNSa0uhMSwzM8EfvuOE+ukiF ygJcsCvaolM3yZWe40YOK3N/cJ/smG5IgShjPM/oa67Cyb3zhGiwROMwHadT/QN+kL2T8UuWXotDv XoWwCoMg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tiRM2-00000009lt6-3qsR; Thu, 13 Feb 2025 05:01:38 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tiRIL-00000009lRM-2AZE for linux-arm-kernel@lists.infradead.org; Thu, 13 Feb 2025 04:57:50 +0000 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 914621756; Wed, 12 Feb 2025 20:58:08 -0800 (PST) Received: from [10.162.16.135] (a077893.blr.arm.com [10.162.16.135]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id CFAC93F6A8; Wed, 12 Feb 2025 20:57:42 -0800 (PST) Message-ID: <49149fa7-4775-4d44-91f6-ce67c1b0ac2c@arm.com> Date: Thu, 13 Feb 2025 10:27:40 +0530 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 03/16] arm64: hugetlb: Fix flush_hugetlb_tlb_range() invalidation level To: Ryan Roberts , Catalin Marinas , Will Deacon , Muchun Song , Pasha Tatashin , Andrew Morton , Uladzislau Rezki , Christoph Hellwig , Mark Rutland , Ard Biesheuvel , Dev Jain , Alexandre Ghiti , Steve Capper , Kevin Brodsky Cc: linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org References: <20250205151003.88959-1-ryan.roberts@arm.com> <20250205151003.88959-4-ryan.roberts@arm.com> Content-Language: en-US From: Anshuman Khandual In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250212_205749_700121_E2B84BF5 X-CRM114-Status: GOOD ( 20.97 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 2/6/25 18:34, Ryan Roberts wrote: > On 06/02/2025 06:46, Anshuman Khandual wrote: >> >> >> On 2/5/25 20:39, Ryan Roberts wrote: >>> commit c910f2b65518 ("arm64/mm: Update tlb invalidation routines for >>> FEAT_LPA2") changed the "invalidation level unknown" hint from 0 to >>> TLBI_TTL_UNKNOWN (INT_MAX). But the fallback "unknown level" path in >>> flush_hugetlb_tlb_range() was not updated. So as it stands, when trying >>> to invalidate CONT_PMD_SIZE or CONT_PTE_SIZE hugetlb mappings, we will >>> spuriously try to invalidate at level 0 on LPA2-enabled systems. >>> >>> Fix this so that the fallback passes TLBI_TTL_UNKNOWN, and while we are >>> at it, explicitly use the correct stride and level for CONT_PMD_SIZE and >>> CONT_PTE_SIZE, which should provide a minor optimization. >>> >>> Cc: >>> Fixes: c910f2b65518 ("arm64/mm: Update tlb invalidation routines for FEAT_LPA2") >>> Signed-off-by: Ryan Roberts >>> --- >>> arch/arm64/include/asm/hugetlb.h | 20 ++++++++++++++------ >>> 1 file changed, 14 insertions(+), 6 deletions(-) >>> >>> diff --git a/arch/arm64/include/asm/hugetlb.h b/arch/arm64/include/asm/hugetlb.h >>> index 03db9cb21ace..8ab9542d2d22 100644 >>> --- a/arch/arm64/include/asm/hugetlb.h >>> +++ b/arch/arm64/include/asm/hugetlb.h >>> @@ -76,12 +76,20 @@ static inline void flush_hugetlb_tlb_range(struct vm_area_struct *vma, >>> { >>> unsigned long stride = huge_page_size(hstate_vma(vma)); >>> >>> - if (stride == PMD_SIZE) >>> - __flush_tlb_range(vma, start, end, stride, false, 2); >>> - else if (stride == PUD_SIZE) >>> - __flush_tlb_range(vma, start, end, stride, false, 1); >>> - else >>> - __flush_tlb_range(vma, start, end, PAGE_SIZE, false, 0); >>> + switch (stride) { >>> + case PUD_SIZE: >>> + __flush_tlb_range(vma, start, end, PUD_SIZE, false, 1); >>> + break; >> >> Just wondering - should not !__PAGETABLE_PMD_FOLDED and pud_sect_supported() >> checks also be added here for this PUD_SIZE case ? > > Yeah I guess so. TBH, it's never been entirely clear to me what the benefit is? > Is it just to remove (a tiny amount of) dead code when we know we don't support > blocks at the level? Or is there something more fundamental going on that I've > missed? There is a generic fallback for PUD_SIZE in include/asm-generic/pgtable-nopud.h when it is not defined on arm64 platform and pud_sect_supported() might also get optimized by the compiler. static inline bool pud_sect_supported(void) { return PAGE_SIZE == SZ_4K; } IIUC this just saves dead code from being compiled as you mentioned. > > We seem to be quite inconsistent with the use of pud_sect_supported() in > hugetlbpage.c. PUD_SIZE switch cases in hugetlb_mask_last_page() and arch_make_huge_pte() ? Those should be fixed. > > Anyway, I'll add this in, I guess it's preferable to follow the established pattern. Agreed. > > Thanks, > Ryan > >> >>> + case CONT_PMD_SIZE: >>> + case PMD_SIZE: >>> + __flush_tlb_range(vma, start, end, PMD_SIZE, false, 2); >>> + break; >>> + case CONT_PTE_SIZE: >>> + __flush_tlb_range(vma, start, end, PAGE_SIZE, false, 3); >>> + break; >>> + default: >>> + __flush_tlb_range(vma, start, end, PAGE_SIZE, false, TLBI_TTL_UNKNOWN); >>> + } >>> } >>> >>> #endif /* __ASM_HUGETLB_H */ >