From: Nicolin Chen <nicolinc@nvidia.com> To: Christoph Hellwig <hch@infradead.org>, <jgg@nvidia.com> Cc: <kwankhede@nvidia.com>, <corbet@lwn.net>, <hca@linux.ibm.com>, <gor@linux.ibm.com>, <agordeev@linux.ibm.com>, <borntraeger@linux.ibm.com>, <svens@linux.ibm.com>, <zhenyuw@linux.intel.com>, <zhi.a.wang@intel.com>, <jani.nikula@linux.intel.com>, <joonas.lahtinen@linux.intel.com>, <rodrigo.vivi@intel.com>, <tvrtko.ursulin@linux.intel.com>, <airlied@linux.ie>, <daniel@ffwll.ch>, <farman@linux.ibm.com>, <mjrosato@linux.ibm.com>, <pasic@linux.ibm.com>, <vneethv@linux.ibm.com>, <oberpar@linux.ibm.com>, <freude@linux.ibm.com>, <akrowiak@linux.ibm.com>, <jjherne@linux.ibm.com>, <alex.williamson@redhat.com>, <cohuck@redhat.com>, <kevin.tian@intel.com>, <jchrist@linux.ibm.com>, <kvm@vger.kernel.org>, <linux-doc@vger.kernel.org>, <linux-kernel@vger.kernel.org>, <linux-s390@vger.kernel.org>, <intel-gvt-dev@lists.freedesktop.org>, <intel-gfx@lists.freedesktop.org>, <dri-devel@lists.freedesktop.org> Subject: Re: [RFT][PATCH v1 6/6] vfio: Replace phys_pfn with phys_page for vfio_pin_pages() Date: Sat, 18 Jun 2022 23:41:30 -0700 [thread overview] Message-ID: <Yq7FGti2byQCelPN@Asurada-Nvidia> (raw) In-Reply-To: <Yq6/qS+AE1LfO+/q@infradead.org> On Sat, Jun 18, 2022 at 11:18:17PM -0700, Christoph Hellwig wrote: > > > There is a bunch of code an comments in the iommu type1 code that > > > suggest we can pin memory that is not page backed. > > > > Would you mind explaining the use case for pinning memory that > > isn't page backed? And do we have such use case so far? > > Sorry, I should have deleted that sentence. I wrote it before spending > some more time to dig through the code and all the locked memory has > page backing. There just seem to be a lot of checks left inbetween > if a pfn is page backed, mostly due to the pfn based calling convetions. OK. We'd be safe to move on then. Thanks for the clarification. > > I can do that. I tried once, but there were just too much changes > > inside type1 code that felt like a chain reaction. If we plan to > > eventually replace with IOMMUFD implementations, these changes in > > type1 might not be necessary, I thought. > > To make sure we keep full compatibility I suspect the final iommufd > implementation has to be gradutally created from the existing code > anyway. Hmm. I think Jason can give some insight. Meanwhile, I will try to add a patch to type1 code, in case we'd end up with what you suspected.
WARNING: multiple messages have this Message-ID (diff)
From: Nicolin Chen <nicolinc@nvidia.com> To: Christoph Hellwig <hch@infradead.org>, <jgg@nvidia.com> Cc: mjrosato@linux.ibm.com, linux-doc@vger.kernel.org, airlied@linux.ie, kevin.tian@intel.com, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, kwankhede@nvidia.com, vneethv@linux.ibm.com, agordeev@linux.ibm.com, linux-s390@vger.kernel.org, kvm@vger.kernel.org, corbet@lwn.net, pasic@linux.ibm.com, borntraeger@linux.ibm.com, intel-gfx@lists.freedesktop.org, zhi.a.wang@intel.com, jjherne@linux.ibm.com, farman@linux.ibm.com, jchrist@linux.ibm.com, gor@linux.ibm.com, hca@linux.ibm.com, alex.williamson@redhat.com, freude@linux.ibm.com, rodrigo.vivi@intel.com, intel-gvt-dev@lists.freedesktop.org, akrowiak@linux.ibm.com, tvrtko.ursulin@linux.intel.com, cohuck@redhat.com, oberpar@linux.ibm.com, svens@linux.ibm.com Subject: Re: [RFT][PATCH v1 6/6] vfio: Replace phys_pfn with phys_page for vfio_pin_pages() Date: Sat, 18 Jun 2022 23:41:30 -0700 [thread overview] Message-ID: <Yq7FGti2byQCelPN@Asurada-Nvidia> (raw) In-Reply-To: <Yq6/qS+AE1LfO+/q@infradead.org> On Sat, Jun 18, 2022 at 11:18:17PM -0700, Christoph Hellwig wrote: > > > There is a bunch of code an comments in the iommu type1 code that > > > suggest we can pin memory that is not page backed. > > > > Would you mind explaining the use case for pinning memory that > > isn't page backed? And do we have such use case so far? > > Sorry, I should have deleted that sentence. I wrote it before spending > some more time to dig through the code and all the locked memory has > page backing. There just seem to be a lot of checks left inbetween > if a pfn is page backed, mostly due to the pfn based calling convetions. OK. We'd be safe to move on then. Thanks for the clarification. > > I can do that. I tried once, but there were just too much changes > > inside type1 code that felt like a chain reaction. If we plan to > > eventually replace with IOMMUFD implementations, these changes in > > type1 might not be necessary, I thought. > > To make sure we keep full compatibility I suspect the final iommufd > implementation has to be gradutally created from the existing code > anyway. Hmm. I think Jason can give some insight. Meanwhile, I will try to add a patch to type1 code, in case we'd end up with what you suspected.
next prev parent reply other threads:[~2022-06-19 6:41 UTC|newest] Thread overview: 75+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-06-16 23:52 [RFT][PATCH v1 0/6] Update vfio_pin/unpin_pages API Nicolin Chen 2022-06-16 23:52 ` Nicolin Chen 2022-06-16 23:52 ` [RFT][PATCH v1 1/6] vfio/ap: Pass in physical address of ind to ap_aqic() Nicolin Chen 2022-06-16 23:52 ` Nicolin Chen 2022-06-20 10:00 ` Harald Freudenberger 2022-06-20 10:00 ` Harald Freudenberger 2022-06-21 21:01 ` Nicolin Chen 2022-06-21 21:01 ` [Intel-gfx] " Nicolin Chen 2022-06-21 21:01 ` Nicolin Chen 2022-06-16 23:52 ` [RFT][PATCH v1 2/6] vfio/ccw: Only pass in contiguous pages Nicolin Chen 2022-06-16 23:52 ` Nicolin Chen 2022-06-16 23:52 ` [RFT][PATCH v1 3/6] vfio: Pass in starting IOVA to vfio_pin/unpin_pages API Nicolin Chen 2022-06-16 23:52 ` Nicolin Chen 2022-06-17 8:42 ` Christoph Hellwig 2022-06-17 8:42 ` [Intel-gfx] " Christoph Hellwig 2022-06-17 21:57 ` Nicolin Chen 2022-06-17 21:57 ` Nicolin Chen 2022-06-22 1:18 ` Nicolin Chen 2022-06-22 1:18 ` [Intel-gfx] " Nicolin Chen 2022-06-22 1:18 ` Nicolin Chen 2022-06-16 23:52 ` [RFT][PATCH v1 4/6] vfio: Rename user_iova of vfio_dma_rw() Nicolin Chen 2022-06-16 23:52 ` Nicolin Chen 2022-06-16 23:52 ` [RFT][PATCH v1 5/6] vfio/ccw: Add kmap_local_page() for memcpy Nicolin Chen 2022-06-16 23:52 ` Nicolin Chen 2022-06-17 8:44 ` Christoph Hellwig 2022-06-17 8:44 ` [Intel-gfx] " Christoph Hellwig 2022-06-17 21:58 ` Nicolin Chen 2022-06-17 21:58 ` Nicolin Chen 2022-06-20 2:57 ` Jason Gunthorpe 2022-06-20 2:57 ` [Intel-gfx] " Jason Gunthorpe 2022-06-20 2:57 ` Jason Gunthorpe 2022-06-20 6:32 ` Christoph Hellwig 2022-06-20 6:32 ` [Intel-gfx] " Christoph Hellwig 2022-06-20 15:39 ` Jason Gunthorpe 2022-06-20 15:39 ` [Intel-gfx] " Jason Gunthorpe 2022-06-20 15:39 ` Jason Gunthorpe 2022-06-21 21:21 ` Nicolin Chen 2022-06-21 21:21 ` [Intel-gfx] " Nicolin Chen 2022-06-21 21:21 ` Nicolin Chen 2022-06-24 13:56 ` Jason Gunthorpe 2022-06-24 13:56 ` [Intel-gfx] " Jason Gunthorpe 2022-06-24 13:56 ` Jason Gunthorpe 2022-06-24 19:22 ` Nicolin Chen 2022-06-24 19:22 ` Nicolin Chen 2022-06-24 19:30 ` Jason Gunthorpe 2022-06-24 19:30 ` [Intel-gfx] " Jason Gunthorpe 2022-06-24 19:30 ` Jason Gunthorpe 2022-06-24 20:12 ` Nicolin Chen 2022-06-24 20:12 ` Nicolin Chen 2022-06-24 22:42 ` Jason Gunthorpe 2022-06-24 22:42 ` [Intel-gfx] " Jason Gunthorpe 2022-06-24 22:42 ` Jason Gunthorpe 2022-06-16 23:52 ` [RFT][PATCH v1 6/6] vfio: Replace phys_pfn with phys_page for vfio_pin_pages() Nicolin Chen 2022-06-16 23:52 ` Nicolin Chen 2022-06-17 8:54 ` Christoph Hellwig 2022-06-17 8:54 ` [Intel-gfx] " Christoph Hellwig 2022-06-17 22:06 ` Nicolin Chen 2022-06-17 22:06 ` Nicolin Chen 2022-06-19 6:18 ` Christoph Hellwig 2022-06-19 6:18 ` [Intel-gfx] " Christoph Hellwig 2022-06-19 6:41 ` Nicolin Chen [this message] 2022-06-19 6:41 ` Nicolin Chen 2022-06-20 3:00 ` Jason Gunthorpe 2022-06-20 3:00 ` [Intel-gfx] " Jason Gunthorpe 2022-06-20 3:00 ` Jason Gunthorpe 2022-06-20 5:51 ` Christoph Hellwig 2022-06-20 5:51 ` [Intel-gfx] " Christoph Hellwig 2022-06-20 6:37 ` Christoph Hellwig 2022-06-20 6:37 ` [Intel-gfx] " Christoph Hellwig 2022-06-20 15:36 ` Jason Gunthorpe 2022-06-20 15:36 ` [Intel-gfx] " Jason Gunthorpe 2022-06-20 15:36 ` Jason Gunthorpe 2022-06-21 21:47 ` Nicolin Chen 2022-06-21 21:47 ` [Intel-gfx] " Nicolin Chen 2022-06-21 21:47 ` Nicolin Chen
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