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path: root/drivers/xen/grant-dma-ops.c
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2022-10-14xen/virtio: Convert PAGE_SIZE/PAGE_SHIFT/PFN_UP to Xen counterpartsOleksandr Tyshchenko1-12/+12
Currently, a grant ref is always based on the Xen page granularity (4KB), and guest commonly uses the same page granularity. But the guest may use a different page granularity (i.e 64KB). So adopt the code to be able to deal with it. Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> Acked-by: Stefano Stabellini <sstabellini@kernel.org> Reviewed-by: Xenia Ragiadakou <burzalodowa@gmail.com> Link: https://lore.kernel.org/r/20221008151013.2537826-3-olekstysh@gmail.com Signed-off-by: Juergen Gross <jgross@suse.com>
2022-10-14xen/virtio: Handle cases when page offset > PAGE_SIZE properlyOleksandr Tyshchenko1-3/+6
Passed to xen_grant_dma_map_page() offset in the page can be > PAGE_SIZE even if the guest uses the same page granularity as Xen (4KB). Before current patch, if such case happened we ended up providing grants for the whole region in xen_grant_dma_map_page() which was really unnecessary. The more, we ended up not releasing all grants which represented that region in xen_grant_dma_unmap_page(). Current patch updates the code to be able to deal with such cases. Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> Reviewed-by: Stefano Stabellini <sstabellini@kernel.org> Reviewed-by: Xenia Ragiadakou <burzalodowa@gmail.com> Link: https://lore.kernel.org/r/20221008151013.2537826-2-olekstysh@gmail.com Signed-off-by: Juergen Gross <jgross@suse.com>
2022-10-10xen/virtio: enable grant based virtio on x86Juergen Gross1-1/+11
Use an x86-specific virtio_check_mem_acc_cb() for Xen in order to setup the correct DMA ops. Signed-off-by: Juergen Gross <jgross@suse.com> Reviewed-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> # common code Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Signed-off-by: Juergen Gross <jgross@suse.com>
2022-10-07xen/virtio: use dom0 as default backend for CONFIG_XEN_VIRTIO_FORCE_GRANTJuergen Gross1-0/+3
With CONFIG_XEN_VIRTIO_FORCE_GRANT set the default backend domid to 0, enabling to use xen_grant_dma_ops for those devices. Signed-off-by: Juergen Gross <jgross@suse.com> Reviewed-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> Acked-by: Stefano Stabellini <sstabellini@kernel.org> Signed-off-by: Juergen Gross <jgross@suse.com>
2022-10-07xen/virtio: restructure xen grant dma setupJuergen Gross1-25/+43
In order to prepare supporting other means than device tree for setting up virtio devices under Xen, restructure the functions xen_is_grant_dma_device() and xen_grant_setup_dma_ops() a little bit. Signed-off-by: Juergen Gross <jgross@suse.com> Reviewed-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> Tested-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> # Arm64 only Acked-by: Stefano Stabellini <sstabellini@kernel.org> Signed-off-by: Juergen Gross <jgross@suse.com>
2022-10-06xen/virtio: Fix potential deadlock when accessing xen_grant_dma_devicesOleksandr Tyshchenko1-5/+19
As find_xen_grant_dma_data() is called from both interrupt and process contexts, the access to xen_grant_dma_devices XArray must be protected by xa_lock_irqsave to avoid deadlock scenario. As XArray API doesn't provide xa_store_irqsave helper, call lockless __xa_store directly and guard it externally. Also move the storage of the XArray's entry to a separate helper. Fixes: d6aca3504c7d ("xen/grant-dma-ops: Add option to restrict memory access under Xen") Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> Reviewed-by: Stefano Stabellini <sstabellini@kernel.org> Reviewed-by: Juergen Gross <jgross@suse.com> Link: https://lore.kernel.org/r/20221005174823.1800761-3-olekstysh@gmail.com Signed-off-by: Juergen Gross <jgross@suse.com>
2022-10-06xen/virtio: Fix n_pages calculation in xen_grant_dma_map(unmap)_page()Oleksandr Tyshchenko1-2/+3
Take page offset into the account when calculating the number of pages to be granted. Fixes: d6aca3504c7d ("xen/grant-dma-ops: Add option to restrict memory access under Xen") Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> Reviewed-by: Stefano Stabellini <sstabellini@kernel.org> Reviewed-by: Juergen Gross <jgross@suse.com> Link: https://lore.kernel.org/r/20221005174823.1800761-2-olekstysh@gmail.com Signed-off-by: Juergen Gross <jgross@suse.com>
2022-08-01xen: don't require virtio with grants for non-PV guestsJuergen Gross1-0/+10
Commit fa1f57421e0b ("xen/virtio: Enable restricted memory access using Xen grant mappings") introduced a new requirement for using virtio devices: the backend now needs to support the VIRTIO_F_ACCESS_PLATFORM feature. This is an undue requirement for non-PV guests, as those can be operated with existing backends without any problem, as long as those backends are running in dom0. Per default allow virtio devices without grant support for non-PV guests. On Arm require VIRTIO_F_ACCESS_PLATFORM for devices having been listed in the device tree to use grants. Add a new config item to always force use of grants for virtio. Fixes: fa1f57421e0b ("xen/virtio: Enable restricted memory access using Xen grant mappings") Reported-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Juergen Gross <jgross@suse.com> Reviewed-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> Tested-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> # Arm64 guest using Xen Reviewed-by: Stefano Stabellini <sstabellini@kernel.org> Link: https://lore.kernel.org/r/20220622063838.8854-4-jgross@suse.com Signed-off-by: Juergen Gross <jgross@suse.com>
2022-06-06xen/grant-dma-ops: Retrieve the ID of backend's domain for DT devicesOleksandr Tyshchenko1-7/+41
Use the presence of "iommus" property pointed to the IOMMU node with recently introduced "xen,grant-dma" compatible as a clear indicator of enabling Xen grant mappings scheme for that device and read the ID of Xen domain where the corresponding backend is running. The domid (domain ID) is used as an argument to the Xen grant mapping APIs. To avoid the deferred probe timeout which takes place after reusing generic IOMMU device tree bindings (because the IOMMU device never becomes available) enable recently introduced stub IOMMU driver by selecting XEN_GRANT_DMA_IOMMU. Also introduce xen_is_grant_dma_device() to check whether xen-grant DMA ops need to be set for a passed device. Remove the hardcoded domid 0 in xen_grant_setup_dma_ops(). Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> Reviewed-by: Stefano Stabellini <sstabellini@kernel.org> Link: https://lore.kernel.org/r/1654197833-25362-8-git-send-email-olekstysh@gmail.com Signed-off-by: Juergen Gross <jgross@suse.com>
2022-06-06xen/grant-dma-ops: Add option to restrict memory access under XenJuergen Gross1-0/+312
Introduce Xen grant DMA-mapping layer which contains special DMA-mapping routines for providing grant references as DMA addresses to be used by frontends (e.g. virtio) in Xen guests. Add the needed functionality by providing a special set of DMA ops handling the needed grant operations for the I/O pages. The subsequent commit will introduce the use case for xen-grant DMA ops layer to enable using virtio devices in Xen guests in a safe manner. Signed-off-by: Juergen Gross <jgross@suse.com> Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> Reviewed-by: Stefano Stabellini <sstabellini@kernel.org> Link: https://lore.kernel.org/r/1654197833-25362-4-git-send-email-olekstysh@gmail.com Signed-off-by: Juergen Gross <jgross@suse.com>
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