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 A4DE61D63F7 for ; Mon, 3 Mar 2025 10:23:41 +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=1740997423; cv=none; b=mJxNNc9SozBRN78FijRQ42KuBgRiv9IHMetXnaUTnNqhXjBG5FBpcaMhjIxhWyQRovhB75ZrduVm17tiqUIBcBUfdOj1PD2IETIEmayiQ7Vr11bfrPGWMmQzwf4gFM3+SL2tLShtGGA5mU6nS3VOBKXwE+duIVdMWcz78onA5/4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740997423; c=relaxed/simple; bh=HMYFcT1D/Mq/XIZ0zFhB6ymz6wEqEq1zIq2vANNrofo=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=EJGrWbRbiCCWF8ku42qZB77I2J45KTqmKC/0c0Ee13oxX10CcF6N/aosDzThhQqk0Ag211IU37md+LjmPbHtDoEkdYyvsFKQzwqJOzOZRWRKMs9QoFFwIsNN58GY+FMkJqgvMDbFyp29T2LUncXm/P7UoisoCN8NjIf+GJL0AGY= 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 6491F12FC; Mon, 3 Mar 2025 02:23:55 -0800 (PST) Received: from [10.1.26.155] (XHFQ2J9959.cambridge.arm.com [10.1.26.155]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 814F63F66E; Mon, 3 Mar 2025 02:23:39 -0800 (PST) Message-ID: <9dd8e02c-9abb-47e6-92df-cf7af6cda99c@arm.com> Date: Mon, 3 Mar 2025 10:23:37 +0000 Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH V2 0/8] arm64/mm: Drop PXD_TABLE_BIT Content-Language: en-GB To: Anshuman Khandual , arm-kernel@lists.infradead.org Cc: Marc Zyngier , Oliver Upton , James Morse , Catalin Marinas , Will Deacon , Ard Biesheuvel , Mark Rutland , kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org References: <20250221044227.1145393-1-anshuman.khandual@arm.com> From: Ryan Roberts In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 03/03/2025 05:02, Anshuman Khandual wrote: > > > On 2/28/25 21:02, Ryan Roberts wrote: >> On 21/02/2025 04:42, Anshuman Khandual wrote: >>> Remove the PXX_TABLE_BIT definitions and instead rely on PXX_TYPE_MASK, >>> PXX_TYPE_SECT and PXX_TYPE_TABLE. The latter versions are more abstract >>> and also include the PTE_VALID bit. >>> >>> This abstraction is valuable for the impending D128 page table support, >>> which doesn't have a single page table bit to determine table vs block. >>> Instead it has the skip level (SKL) field, where it will consider 0 to >>> mean table and any other value to mean a block entry. So PXX_TABLE_BIT >>> therefore doesn't fit into the D128 model well, but the type fields do. >> >> All the patches look logically correct to me and I agree with the intention of >> removing PXX_TABLE_BIT. But personally I'd prefer to see a single patch that >> just does everything that's required to remove PXX_TABLE_BIT. And then a second >> patch for the pud_bad() fix/improvement (currently patch 6) which is orthogonal >> to the removal of PXX_TABLE_BIT. >> >> That would make it much easier to review IMHO, and would also allow for writing >> a single commit log which provides the justification for the change. I find the >> current set of 7 commit logs to not be hugely helpful. > > Dropping PXX_TABLE_BIT from individual functional components which stand on their > own progressively leads to its complete removal from the tree. Even though goal > is PXX_TABLE_BIT mask's complete removal, each patch here could be justified on > its own improving consistent reasoning around various section mapping creation > and identification while keeping the functionality unchanged and also improving > code readability as well. > >> >> But I wrote the original patches and wrote them as I'm suggesting, so I would >> say that :) > > I can understand :) Although it also follows and expands on the previous attempt > in removing this mask that formed a patch series instead. > > https://lore.kernel.org/all/20241005123824.1366397-1-anshuman.khandual@arm.com/ > > TBH this is not a big deal. I can merge all but last one into a single patch as > you have suggested if that's a general consensus. Although I would prefer the > current logically progressive series based approach but that's just me. I guess leave as is for now and see what others say. > >> >> I'm guessing I shouldn't provide a Reviewed-By here, given I wrote the code >> originally... >> >> Thanks, >> Ryan >> >> >>> >>> This series applies on v6.14-rc3. >>> >>> Changes in V2: >>> >>> - Changed pmd_mkhuge() and pud_mkhuge() implementation >>> - Changed pud_bad() implementation with an additional patch >>> >>> Changes in V1: >>> >>> https://lore.kernel.org/all/20241005123824.1366397-1-anshuman.khandual@arm.com/ >>> >>> Cc: Marc Zyngier >>> Cc: Oliver Upton >>> Cc: James Morse >>> Cc: Catalin Marinas >>> Cc: Will Deacon >>> Cc: Ard Biesheuvel >>> Cc: Ryan Roberts >>> Cc: Mark Rutland >>> Cc: kvmarm@lists.linux.dev >>> Cc: linux-arm-kernel@lists.infradead.org >>> Cc: linux-kernel@vger.kernel.org >>> >>> Anshuman Khandual (6): >>> KVM: arm64: ptdump: Test PMD_TYPE_MASK for block mapping >>> arm64/ptdump: Test PMD_TYPE_MASK for block mapping >>> arm64/mm: Clear PXX_TYPE_MASK in mk_[pmd|pud]_sect_prot() >>> arm64/mm: Clear PXX_TYPE_MASK and set PXD_TYPE_SECT in [pmd|pud]_mkhuge() >>> arm64/mm: Check PXD_TYPE_TABLE in [p4d|pgd]_bad() >>> arm64/mm: Drop PXD_TABLE_BIT >>> >>> Ryan Roberts (2): >>> arm64/mm: Check PUD_TYPE_TABLE in pud_bad() >>> arm64/mm: Check pmd_table() in pmd_trans_huge() >>> >>> arch/arm64/include/asm/pgtable-hwdef.h | 5 -- >>> arch/arm64/include/asm/pgtable.h | 65 ++++++++++++++++++-------- >>> arch/arm64/kvm/ptdump.c | 4 +- >>> arch/arm64/mm/ptdump.c | 4 +- >>> 4 files changed, 50 insertions(+), 28 deletions(-) >>> >>