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Received: from s01060023bee90a7d.cg.shawcable.net ([24.64.145.4] helo=[192.168.0.10]) by ale.deltatee.com with esmtpsa (TLS1.3:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.92) (envelope-from ) id 1kb5lh-0003H9-4R; Fri, 06 Nov 2020 10:43:22 -0700 To: Jason Gunthorpe References: <20201106170036.18713-1-logang@deltatee.com> <20201106170036.18713-16-logang@deltatee.com> <20201106173932.GT36674@ziepe.ca> From: Logan Gunthorpe Message-ID: Date: Fri, 6 Nov 2020 10:43:18 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.4.0 MIME-Version: 1.0 In-Reply-To: <20201106173932.GT36674@ziepe.ca> Content-Language: en-US X-SA-Exim-Connect-IP: 24.64.145.4 X-SA-Exim-Rcpt-To: daniel.vetter@ffwll.ch, willy@infradead.org, ddutile@redhat.com, jhubbard@nvidia.com, iweiny@intel.com, christian.koenig@amd.com, 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, jgg@ziepe.ca X-SA-Exim-Mail-From: logang@deltatee.com Subject: Re: [RFC PATCH 15/15] nvme-pci: Allow mmaping the CMB in userspace 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) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201106_124328_074829_CE48CF0D X-CRM114-Status: GOOD ( 22.35 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: =?UTF-8?Q?Christian_K=c3=b6nig?= , linux-pci@vger.kernel.org, Daniel Vetter , Ira Weiny , linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, Stephen Bates , linux-block@vger.kernel.org, linux-mm@kvack.org, iommu@lists.linux-foundation.org, Don Dutile , Matthew Wilcox , John Hubbard , Dan Williams , Christoph Hellwig Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On 2020-11-06 10:39 a.m., Jason Gunthorpe wrote: > On Fri, Nov 06, 2020 at 10:00:36AM -0700, Logan Gunthorpe wrote: >> Allow userspace to obtain CMB memory by mmaping the controller's >> char device. The mmap call allocates and returns a hunk of CMB memory, >> (the offset is ignored) so userspace does not have control over the >> address within the CMB. >> >> A VMA allocated in this way will only be usable by drivers that set >> FOLL_PCI_P2PDMA when calling GUP. And inter-device support will be >> checked the first time the pages are mapped for DMA. >> >> Currently this is only supported by O_DIRECT to an PCI NVMe device >> or through the NVMe passthrough IOCTL. >> >> Signed-off-by: Logan Gunthorpe >> drivers/nvme/host/core.c | 11 +++++++++++ >> drivers/nvme/host/nvme.h | 1 + >> drivers/nvme/host/pci.c | 9 +++++++++ >> 3 files changed, 21 insertions(+) >> >> diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c >> index f14316c9b34a..fc642aba671d 100644 >> +++ b/drivers/nvme/host/core.c >> @@ -3240,12 +3240,23 @@ static long nvme_dev_ioctl(struct file *file, unsigned int cmd, >> } >> } >> >> +static int nvme_dev_mmap(struct file *file, struct vm_area_struct *vma) >> +{ >> + struct nvme_ctrl *ctrl = file->private_data; >> + >> + if (!ctrl->ops->mmap_cmb) >> + return -ENODEV; >> + >> + return ctrl->ops->mmap_cmb(ctrl, vma); >> +} > > This needs to ensure that the VMA created is destroyed before the > driver is unprobed - ie the struct pages backing the BAR memory is > destroyed. > > I don't see anything that synchronizes this in the nvme_dev_release()? Yup, looks like something that needs to be fixed. Though I'd probably do it in the pci_p2pdma helper code instead. Logan _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme