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a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=deltatee.com; s=20200525; h=Subject:In-Reply-To:MIME-Version:Date: Message-ID:From:References:Cc:To:content-disposition; bh=KRREYiID4nTLAcd30iCtMu5qS4tYGdizddy6etGFynA=; b=QX2vn+ZSnkNIea3oIqxWCrg9tp n1sCb9KHpJoIaRXdY0nYk+A55R5+bJzf7lAUrmRIP+9tYXPMAY9zVdmvTrY8Zi4CN+nP4mJCwlXNi 9EpP4/ubF7Zt56WkMmsltDxbS59EjBO3rKE9BgbNkI4JufYuR4lLRmoNsuerG4uBi5CFZyekeuaGh adS2eOEVb6LeYpnv785vjeHILX6oPibI9iYigpRsbyKCGjWpq95W7BYMUn3Ez26qYJDbXa8bQ4t+g 9GEhUUbscgDYfAy9KDF7uFUAETOgR5Z55BuzayN3e/GMBH3ziI+KwOOahICDS35fDS9iJbAZ4bRN1 OGZR8Z+g==; Received: from guinness.priv.deltatee.com ([172.16.1.162]) by ale.deltatee.com with esmtp (Exim 4.92) (envelope-from ) id 1lgV65-0006go-Tm; Tue, 11 May 2021 10:19:02 -0600 To: Don Dutile , linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, linux-block@vger.kernel.org, linux-pci@vger.kernel.org, linux-mm@kvack.org, iommu@lists.linux-foundation.org Cc: Stephen Bates , Christoph Hellwig , Dan Williams , Jason Gunthorpe , =?UTF-8?Q?Christian_K=c3=b6nig?= , John Hubbard , Matthew Wilcox , Daniel Vetter , Jakowski Andrzej , Minturn Dave B , Jason Ekstrand , Dave Hansen , Xiong Jianxin , Bjorn Helgaas , Ira Weiny , Robin Murphy References: <20210408170123.8788-1-logang@deltatee.com> <20210408170123.8788-11-logang@deltatee.com> <92704199-4cee-3811-3902-08ccf6cc1f5f@redhat.com> From: Logan Gunthorpe Message-ID: <185f39c0-d71c-5d24-9d87-951a72c3532d@deltatee.com> Date: Tue, 11 May 2021 10:19:01 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.10.0 MIME-Version: 1.0 In-Reply-To: <92704199-4cee-3811-3902-08ccf6cc1f5f@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-CA Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 172.16.1.162 X-SA-Exim-Rcpt-To: robin.murphy@arm.com, ira.weiny@intel.com, helgaas@kernel.org, jianxin.xiong@intel.com, dave.hansen@linux.intel.com, jason@jlekstrand.net, dave.b.minturn@intel.com, andrzej.jakowski@intel.com, daniel.vetter@ffwll.ch, willy@infradead.org, jhubbard@nvidia.com, christian.koenig@amd.com, jgg@ziepe.ca, dan.j.williams@intel.com, hch@lst.de, sbates@raithlin.com, iommu@lists.linux-foundation.org, linux-mm@kvack.org, linux-pci@vger.kernel.org, linux-block@vger.kernel.org, linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org, ddutile@redhat.com X-SA-Exim-Mail-From: logang@deltatee.com Subject: Re: [PATCH 10/16] dma-mapping: Add flags to dma_map_ops to indicate PCI P2PDMA support X-SA-Exim-Version: 4.2.1 (built Wed, 08 May 2019 21:11:16 +0000) X-SA-Exim-Scanned: Yes (on ale.deltatee.com) Authentication-Results: imf02.hostedemail.com; dkim=pass header.d=deltatee.com header.s=20200525 header.b=QX2vn+ZS; dmarc=none; spf=pass (imf02.hostedemail.com: domain of logang@deltatee.com designates 204.191.154.188 as permitted sender) smtp.mailfrom=logang@deltatee.com X-Stat-Signature: fxpk7r5s3fdx6kaukfkihhot7hgf4q7u X-Rspamd-Queue-Id: 4430E40002D6 X-Rspamd-Server: rspam02 Received-SPF: none (deltatee.com>: No applicable sender policy available) receiver=imf02; identity=mailfrom; envelope-from=""; helo=ale.deltatee.com; client-ip=204.191.154.188 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1620749917-377684 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 2021-05-11 10:06 a.m., Don Dutile wrote: > On 4/8/21 1:01 PM, Logan Gunthorpe wrote: >> Add a flags member to the dma_map_ops structure with one flag to >> indicate support for PCI P2PDMA. >> >> Also, add a helper to check if a device supports PCI P2PDMA. >> >> Signed-off-by: Logan Gunthorpe >> --- >> include/linux/dma-map-ops.h | 3 +++ >> include/linux/dma-mapping.h | 5 +++++ >> kernel/dma/mapping.c | 18 ++++++++++++++++++ >> 3 files changed, 26 insertions(+) >> >> diff --git a/include/linux/dma-map-ops.h b/include/linux/dma-map-ops.h >> index 51872e736e7b..481892822104 100644 >> --- a/include/linux/dma-map-ops.h >> +++ b/include/linux/dma-map-ops.h >> @@ -12,6 +12,9 @@ >> struct cma; >> >> struct dma_map_ops { >> + unsigned int flags; >> +#define DMA_F_PCI_P2PDMA_SUPPORTED (1 << 0) >> + > I'm not a fan of in-line define's; if we're going to add a flags field to the dma-ops > -- and logically it'd be good to have p2pdma go through the dma-ops struct -- > then let's move this up in front of the dma-ops description. Already changed for v2. > And now that the dma-ops struct is being 'opened' for p2pdma, should p2pdma ops be added > to this struct, so all this work can be mimic'd/reflected/leveraged/refactored for CXL, GenZ, etc. p2pdma in (the near?) future? v2 no longer has a specific op for p2pdma. We are now using dma_map_sgtable() which already has the error return we need. I think any work to support CXL, GenZ, etc will need to be done when they add their own support. I can't and shouldn't guess at their needs now. Logan