From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DA68321B199 for ; Mon, 17 Feb 2025 14:55:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739804140; cv=none; b=GuLvsYlpaZhlaTMxVgF7kl47DPkjHxKPF9l1z+coSBrI0osl5PQfbsDjKaFDm9ntyF3pqFs3xux/6649q2wQlhilx4E5CB4+CEIqOurK7pJAM9+kn8mT3Qsdlmdp7efPXzXAZOFG8yfftxUQEOvVP5rAitIpV2LhXb8MN/gWiIo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739804140; c=relaxed/simple; bh=mCmhZKA69/c2eU7LC9F+MUZq2m9KGbt0EwRoFPfhmtA=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=p0boiNleDAhVaPQM3LbpHA68CPehKFpkWKaIdENPp2cpxLHvW9Xh8zxdS8VQty2C+uSnZ5etq8eAE33bAWzmY9XCghbUjr+EAFbwdVij/1Y3Xo8tqpaRVCro1jdgiyeH5Ur+/YqvEb14UcSJlR49kWBZNLDQAJuft14jqYluclE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 453CDC4CED1; Mon, 17 Feb 2025 14:55:35 +0000 (UTC) Date: Mon, 17 Feb 2025 14:55:32 +0000 From: Catalin Marinas To: Tong Tiangen Cc: Mark Rutland , Jonathan Cameron , Mauro Carvalho Chehab , Will Deacon , Andrew Morton , James Morse , Robin Murphy , Andrey Konovalov , Dmitry Vyukov , Vincenzo Frascino , Michael Ellerman , Nicholas Piggin , Andrey Ryabinin , Alexander Potapenko , Christophe Leroy , "Aneesh Kumar K.V" , "Naveen N. Rao" , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Madhavan Srinivasan , linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, wangkefeng.wang@huawei.com, Guohanjun Subject: Re: [PATCH v13 4/5] arm64: support copy_mc_[user]_highpage() Message-ID: References: <20241209024257.3618492-1-tongtiangen@huawei.com> <20241209024257.3618492-5-tongtiangen@huawei.com> <69955002-c3b1-459d-9b42-8d07475c3fd3@huawei.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Mon, Feb 17, 2025 at 04:07:49PM +0800, Tong Tiangen wrote: > 在 2025/2/15 1:24, Catalin Marinas 写道: > > On Fri, Feb 14, 2025 at 10:49:01AM +0800, Tong Tiangen wrote: > > > 在 2025/2/13 1:11, Catalin Marinas 写道: > > > > On Mon, Dec 09, 2024 at 10:42:56AM +0800, Tong Tiangen wrote: > > > > > Currently, many scenarios that can tolerate memory errors when copying page > > > > > have been supported in the kernel[1~5], all of which are implemented by > > > > > copy_mc_[user]_highpage(). arm64 should also support this mechanism. > > > > > > > > > > Due to mte, arm64 needs to have its own copy_mc_[user]_highpage() > > > > > architecture implementation, macros __HAVE_ARCH_COPY_MC_HIGHPAGE and > > > > > __HAVE_ARCH_COPY_MC_USER_HIGHPAGE have been added to control it. > > > > > > > > > > Add new helper copy_mc_page() which provide a page copy implementation with > > > > > hardware memory error safe. The code logic of copy_mc_page() is the same as > > > > > copy_page(), the main difference is that the ldp insn of copy_mc_page() > > > > > contains the fixup type EX_TYPE_KACCESS_ERR_ZERO_MEM_ERR, therefore, the > > > > > main logic is extracted to copy_page_template.S. In addition, the fixup of > > > > > MOPS insn is not considered at present. > > > > > > > > Could we not add the exception table entry permanently but ignore the > > > > exception table entry if it's not on the do_sea() path? That would save > > > > some code duplication. > > > > > > I'm sorry, I didn't catch your point, that the do_sea() and non do_sea() > > > paths use different exception tables? > > > > No, they would have the same exception table, only that we'd interpret > > it differently depending on whether it's a SEA error or not. Or rather > > ignore the exception table altogether for non-SEA errors. > > You mean to use the same exception type (EX_TYPE_KACCESS_ERR_ZERO) and > then do different processing on SEA errors and non-SEA errors, right? Right. > If so, some instructions of copy_page() did not add to the exception > table will be added to the exception table, and the original logic will > be affected. > > For example, if an instruction is not added to the exception table, the > instruction will panic when it triggers a non-SEA error. If this > instruction is added to the exception table because of SEA processing, > and then a non-SEA error is triggered, should we fix it? No, we shouldn't fix it. The exception table entries have a type associated. For a non-SEA error, we preserve the original behaviour even if we find a SEA-specific entry in the exception table. You already need such logic even if you duplicate the code for configurations where you have MC enabled. -- Catalin