From: Jason Gunthorpe <jgg@nvidia.com>
To: Logan Gunthorpe <logang@deltatee.com>
Cc: 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,
"Stephen Bates" <sbates@raithlin.com>,
"Christoph Hellwig" <hch@lst.de>,
"Dan Williams" <dan.j.williams@intel.com>,
"Christian König" <christian.koenig@amd.com>,
"John Hubbard" <jhubbard@nvidia.com>,
"Don Dutile" <ddutile@redhat.com>,
"Matthew Wilcox" <willy@infradead.org>,
"Daniel Vetter" <daniel.vetter@ffwll.ch>,
"Jakowski Andrzej" <andrzej.jakowski@intel.com>,
"Minturn Dave B" <dave.b.minturn@intel.com>,
"Jason Ekstrand" <jason@jlekstrand.net>,
"Dave Hansen" <dave.hansen@linux.intel.com>,
"Xiong Jianxin" <jianxin.xiong@intel.com>,
"Bjorn Helgaas" <helgaas@kernel.org>,
"Ira Weiny" <ira.weiny@intel.com>,
"Robin Murphy" <robin.murphy@arm.com>,
"Martin Oliveira" <martin.oliveira@eideticom.com>,
"Chaitanya Kulkarni" <ckulkarnilinux@gmail.com>
Subject: Re: [PATCH v3 4/20] PCI/P2PDMA: introduce helpers for dma_map_sg implementations
Date: Wed, 29 Sep 2021 20:40:45 -0300 [thread overview]
Message-ID: <20210929234045.GB964074@nvidia.com> (raw)
In-Reply-To: <fb678f5e-b477-0bd0-334b-a57e771eedc9@deltatee.com>
On Wed, Sep 29, 2021 at 05:00:43PM -0600, Logan Gunthorpe wrote:
>
>
>
> On 2021-09-29 4:46 p.m., Jason Gunthorpe wrote:
> > On Wed, Sep 29, 2021 at 03:30:42PM -0600, Logan Gunthorpe wrote:
> >> On 2021-09-28 4:05 p.m., Jason Gunthorpe wrote:
> >> No, that's not a correct reading of the code. Every time there is a new
> >> pagemap, this code calculates the mapping type and bus offset. If a page
> >> comes along with a different page map,f it recalculates. This just
> >> reduces the overhead so that the calculation is done only every time a
> >> page with a different pgmap comes along and not doing it for every
> >> single page.
> >
> > Each 'struct scatterlist *sg' refers to a range of contiguous pfns
> > starting at page_to_pfn(sg_page()) and going for approx sg->length/PAGE_SIZE
> > pfns long.
> >
>
> Ugh, right. A bit contrived for consecutive pages to have different
> pgmaps and still be next to each other in a DMA transaction. But I guess
> it is technically possible and should be protected against.
I worry it is something a hostile userspace could cookup using mmap
and cause some kind of kernel integrity problem with.
> > @@ -470,7 +470,8 @@ int sg_alloc_append_table_from_pages(struct sg_append_table *sgt_append,
> >
> > /* Merge contiguous pages into the last SG */
> > prv_len = sgt_append->prv->length;
> > - while (n_pages && page_to_pfn(pages[0]) == paddr) {
> > + while (n_pages && page_to_pfn(pages[0]) == paddr &&
> > + sg_page(sgt_append->prv)->pgmap == pages[0]->pgmap) {
>
> I don't think it's correct to use pgmap without first checking if it is
> a zone device page. But your point is taken. I'll try to address this.
Yes
Jason
next prev parent reply other threads:[~2021-09-29 23:40 UTC|newest]
Thread overview: 87+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-16 23:40 [PATCH v3 00/20] Userspace P2PDMA with O_DIRECT NVMe devices Logan Gunthorpe
2021-09-16 23:40 ` [PATCH v3 01/20] lib/scatterlist: add flag for indicating P2PDMA segments in an SGL Logan Gunthorpe
2021-09-28 18:32 ` Jason Gunthorpe
2021-09-29 21:15 ` Logan Gunthorpe
2021-09-30 4:47 ` Chaitanya Kulkarni
2021-09-30 16:49 ` Logan Gunthorpe
2021-09-30 4:57 ` Chaitanya Kulkarni
2021-09-16 23:40 ` [PATCH v3 02/20] PCI/P2PDMA: attempt to set map_type if it has not been set Logan Gunthorpe
2021-09-27 18:50 ` Bjorn Helgaas
2021-09-16 23:40 ` [PATCH v3 03/20] PCI/P2PDMA: make pci_p2pdma_map_type() non-static Logan Gunthorpe
2021-09-27 18:46 ` Bjorn Helgaas
2021-09-28 18:48 ` Jason Gunthorpe
2021-09-16 23:40 ` [PATCH v3 04/20] PCI/P2PDMA: introduce helpers for dma_map_sg implementations Logan Gunthorpe
2021-09-27 18:53 ` Bjorn Helgaas
2021-09-27 19:59 ` Logan Gunthorpe
2021-09-28 18:55 ` Jason Gunthorpe
2021-09-29 21:26 ` Logan Gunthorpe
2021-09-28 22:05 ` [PATCH v3 4/20] " Jason Gunthorpe
2021-09-29 21:30 ` Logan Gunthorpe
2021-09-29 22:46 ` Jason Gunthorpe
2021-09-29 23:00 ` Logan Gunthorpe
2021-09-29 23:40 ` Jason Gunthorpe [this message]
2021-09-16 23:40 ` [PATCH v3 05/20] dma-mapping: allow EREMOTEIO return code for P2PDMA transfers Logan Gunthorpe
2021-09-28 18:57 ` Jason Gunthorpe
2021-09-16 23:40 ` [PATCH v3 06/20] dma-direct: support PCI P2PDMA pages in dma-direct map_sg Logan Gunthorpe
2021-09-28 19:08 ` Jason Gunthorpe
2021-09-16 23:40 ` [PATCH v3 07/20] dma-mapping: add flags to dma_map_ops to indicate PCI P2PDMA support Logan Gunthorpe
2021-09-28 19:11 ` Jason Gunthorpe
2021-09-16 23:40 ` [PATCH v3 08/20] iommu/dma: support PCI P2PDMA pages in dma-iommu map_sg Logan Gunthorpe
2021-09-28 19:15 ` Jason Gunthorpe
2021-09-16 23:40 ` [PATCH v3 09/20] nvme-pci: check DMA ops when indicating support for PCI P2PDMA Logan Gunthorpe
2021-09-30 5:06 ` Chaitanya Kulkarni
2021-09-30 16:51 ` Logan Gunthorpe
2021-09-30 17:19 ` Chaitanya Kulkarni
2021-09-16 23:40 ` [PATCH v3 10/20] nvme-pci: convert to using dma_map_sgtable() Logan Gunthorpe
2021-10-05 22:29 ` Max Gurtovoy
2021-09-16 23:40 ` [PATCH v3 11/20] RDMA/core: introduce ib_dma_pci_p2p_dma_supported() Logan Gunthorpe
2021-09-28 19:17 ` Jason Gunthorpe
2021-10-05 22:31 ` Max Gurtovoy
2021-09-16 23:40 ` [PATCH v3 12/20] RDMA/rw: use dma_map_sgtable() Logan Gunthorpe
2021-09-28 19:43 ` Jason Gunthorpe
2021-09-29 22:56 ` Logan Gunthorpe
2021-10-05 22:40 ` Max Gurtovoy
2021-09-16 23:40 ` [PATCH v3 13/20] PCI/P2PDMA: remove pci_p2pdma_[un]map_sg() Logan Gunthorpe
2021-09-27 18:50 ` Bjorn Helgaas
2021-09-28 19:43 ` Jason Gunthorpe
2021-10-05 22:42 ` Max Gurtovoy
2021-09-16 23:40 ` [PATCH v3 14/20] mm: introduce FOLL_PCI_P2PDMA to gate getting PCI P2PDMA pages Logan Gunthorpe
2021-09-28 19:47 ` Jason Gunthorpe
2021-09-29 21:34 ` Logan Gunthorpe
2021-09-29 22:48 ` Jason Gunthorpe
2021-09-16 23:40 ` [PATCH v3 15/20] iov_iter: introduce iov_iter_get_pages_[alloc_]flags() Logan Gunthorpe
2021-09-16 23:40 ` [PATCH v3 16/20] block: set FOLL_PCI_P2PDMA in __bio_iov_iter_get_pages() Logan Gunthorpe
2021-09-16 23:40 ` [PATCH v3 17/20] block: set FOLL_PCI_P2PDMA in bio_map_user_iov() Logan Gunthorpe
2021-09-16 23:40 ` [PATCH v3 18/20] mm: use custom page_free for P2PDMA pages Logan Gunthorpe
2021-09-16 23:40 ` [PATCH v3 19/20] PCI/P2PDMA: introduce pci_mmap_p2pmem() Logan Gunthorpe
2021-09-27 18:49 ` Bjorn Helgaas
2021-09-28 19:55 ` Jason Gunthorpe
2021-09-29 21:42 ` Logan Gunthorpe
2021-09-29 23:05 ` Jason Gunthorpe
2021-09-29 23:27 ` Logan Gunthorpe
2021-09-29 23:35 ` Jason Gunthorpe
2021-09-29 23:49 ` Logan Gunthorpe
2021-09-30 0:36 ` Jason Gunthorpe
2021-10-01 13:48 ` Jason Gunthorpe
2021-10-01 17:01 ` Logan Gunthorpe
2021-10-01 17:45 ` Jason Gunthorpe
2021-10-01 20:13 ` Logan Gunthorpe
2021-10-01 22:14 ` Jason Gunthorpe
2021-10-01 22:22 ` Logan Gunthorpe
2021-10-01 22:46 ` Jason Gunthorpe
2021-10-01 23:27 ` John Hubbard
2021-10-01 23:34 ` Logan Gunthorpe
2021-10-04 6:58 ` Christian König
2021-10-04 13:11 ` Jason Gunthorpe
2021-10-04 13:22 ` Christian König
2021-10-04 13:27 ` Jason Gunthorpe
2021-10-04 14:54 ` Christian König
2021-09-28 20:05 ` Jason Gunthorpe
2021-09-29 21:46 ` Logan Gunthorpe
2021-09-16 23:41 ` [PATCH v3 20/20] nvme-pci: allow mmaping the CMB in userspace Logan Gunthorpe
2021-09-28 20:02 ` [PATCH v3 00/20] Userspace P2PDMA with O_DIRECT NVMe devices Jason Gunthorpe
2021-09-29 21:50 ` Logan Gunthorpe
2021-09-29 23:21 ` Jason Gunthorpe
2021-09-29 23:28 ` Logan Gunthorpe
2021-09-29 23:36 ` Jason Gunthorpe
2021-09-29 23:52 ` Logan Gunthorpe
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