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 F22BF1F7084; Thu, 24 Oct 2024 16:04:08 +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=1729785849; cv=none; b=YOL3UJ3Ow/++4ZlzPcsfyF0HeYZh/CdvSCIhPXjX4vhMAwtsM4Hp3g+RY5npcsyIuhzH7ZtkeLzr759Ley1cuc9Tx4UTYNImbEUg1GjhHa/M4fO2Vi2/KyagJcq7ojKjG5B9KlSGmi+ZDJvSLPKAOnlK5maJR2ZK532s5J0v1Fs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729785849; c=relaxed/simple; bh=Myjz9JYsX77B7JYfT/JXdIOgce90SWSzlxORYDjC8oA=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=JaylMTbmXbH0AuBk9vixVcbEZTq70umKGoSZjr9yYvDTuMsf1rXJEvFLID4EEYJBnDWjWelAox6WZhD+TpPafBnE93vsmC0o6MjYZx6K0t6Pl7Z5Up9B8pzD1/gbh76V1HjxYQ7Fyrgz9ivWa65NR5r/hkXH1pYnbhiHCaU+QU8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=HEu7Igyh; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="HEu7Igyh" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 16525C4CEC7; Thu, 24 Oct 2024 16:04:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1729785848; bh=Myjz9JYsX77B7JYfT/JXdIOgce90SWSzlxORYDjC8oA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=HEu7Igyh7nj3naMU5ewRp2bwWjflOn8o/POIpUa6Oe75xASEzF8dGSuvc9eWQZGUV TOk4L6DZZzpz2gDhvEGhev8TEsz7Nw3kQIglKNgLuMkVFHstd+K5JcTvK8qjthcQ0R FC80nS1GtXxZi5KcmRo2iVv8loA/2lSy8PMhxh0NDWfzuo3cz0D3xT7sAiqN30knWo UjcCScpsimQjYig5mMr4oEtp4aTnNK+ANCn0f6A7iiOLnxcP/GcOFvqSVPMXSONXL5 1l8Vli5eqfO7nloEi7YtxL2eBC8mF+oVBe/JInQVkAAf08KmLrD2BoH+mCAiBrKlfC B4zl8KA9Wmv0g== Date: Thu, 24 Oct 2024 17:04:04 +0100 From: Simon Horman To: Jijie Shao Cc: Paolo Abeni , davem@davemloft.net, edumazet@google.com, kuba@kernel.org, shenjian15@huawei.com, salil.mehta@huawei.com, liuyonglong@huawei.com, wangpeiyang1@huawei.com, lanhao@huawei.com, chenhao418@huawei.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH V2 net 1/9] net: hns3: default enable tx bounce buffer when smmu enabled Message-ID: <20241024160404.GC1202098@kernel.org> References: <20241018101059.1718375-1-shaojijie@huawei.com> <20241018101059.1718375-2-shaojijie@huawei.com> <50874428-b4ef-4e65-b60b-1bd917f1933c@redhat.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Thu, Oct 24, 2024 at 04:31:46PM +0800, Jijie Shao wrote: > > on 2024/10/24 16:26, Paolo Abeni wrote: > > On 10/18/24 12:10, Jijie Shao wrote: > > > From: Peiyang Wang > > > > > > The SMMU engine on HIP09 chip has a hardware issue. > > > SMMU pagetable prefetch features may prefetch and use a invalid PTE > > > even the PTE is valid at that time. This will cause the device trigger > > > fake pagefaults. The solution is to avoid prefetching by adding a > > > SYNC command when smmu mapping a iova. But the performance of nic has a > > > sharp drop. Then we do this workaround, always enable tx bounce buffer, > > > avoid mapping/unmapping on TX path. > > > > > > This issue only affects HNS3, so we always enable > > > tx bounce buffer when smmu enabled to improve performance. > > > > > > Signed-off-by: Peiyang Wang > > > Signed-off-by: Jian Shen > > > Signed-off-by: Jijie Shao > > I'm sorry to nick pick on somewhat small details, but we really need a > > fixes tag here to make 110% clear is a bugfix. I guess it could be the > > commit introducing the support for the buggy H/W. > > > > Thanks, > > > > Paolo > > I have a little doubt that this patch is about H/W problem, > so how can we write the the fixes tag? Hi Jijie, That is a good point. But the much point of the Fixes tag is to indicate how far back the fix should be backported. So I would say the ID of the patch where the user would have first seen this problem - possibly the patch that added the driver.