kernel/include/xen/xen-ops.h, branch linux-6.18.y

xen: replace XENFEAT_auto_translated_physmap with xen_pv_domain()

2025-09-08T15:01:36Z

Instead of testing the XENFEAT_auto_translated_physmap feature, just use !xen_pv_domain() which is equivalent. This has the advantage that a kernel not built with CONFIG_XEN_PV will be smaller due to dead code elimination. Reviewed-by: Jason Andryuk Signed-off-by: Juergen Gross Message-ID: <20250826145608.10352-3-jgross@suse.com>

xen: Remove some deadcode (x)

2025-07-14T07:55:52Z

Remove three uncalled functions: xenbus_mkdir() was added in 2007 by commit 4bac07c993d0 ("xen: add the Xenbus sysfs and virtual device hotplug driver") but has remained unused. xen_get_runstate_snapshot() last use was removed in 2016 by commit 6ba286ad8457 ("xen: support runqueue steal time on xen") which replaces the use by the _cpu version. xen_resume_notifier_unregister() last use was removed in 2017 by commit 1914f0cd203c ("xen/acpi: upload PM state from init-domain to Xen") Remove them. Signed-off-by: "Dr. David Alan Gilbert" Reviewed-by: Juergen Gross Signed-off-by: Juergen Gross Message-ID: <20250713132625.164728-1-linux@treblig.org>

xen/virtio: Optimize the setup of "xen-grant-dma" devices

2022-12-05T11:59:49Z

This is needed to avoid having to parse the same device-tree several times for a given device. For this to work we need to install the xen_virtio_restricted_mem_acc callback in Arm's xen_guest_init() which is same callback as x86's PV and HVM modes already use and remove the manual assignment in xen_setup_dma_ops(). Also we need to split the code to initialize backend_domid into a separate function. Prior to current patch we parsed the device-tree three times: 1. xen_setup_dma_ops()->...->xen_is_dt_grant_dma_device() 2. xen_setup_dma_ops()->...->xen_dt_grant_init_backend_domid() 3. xen_virtio_mem_acc()->...->xen_is_dt_grant_dma_device() With current patch we parse the device-tree only once in xen_virtio_restricted_mem_acc()->...->xen_dt_grant_init_backend_domid() Other benefits are: - Not diverge from x86 when setting up Xen grant DMA ops - Drop several global functions Signed-off-by: Oleksandr Tyshchenko Reviewed-by: Xenia Ragiadakou Reviewed-by: Stefano Stabellini Link: https://lore.kernel.org/r/20221025162004.8501-2-olekstysh@gmail.com Signed-off-by: Juergen Gross

xen/virtio: enable grant based virtio on x86

2022-10-10T12:31:26Z

Use an x86-specific virtio_check_mem_acc_cb() for Xen in order to setup the correct DMA ops. Signed-off-by: Juergen Gross Reviewed-by: Oleksandr Tyshchenko # common code Reviewed-by: Boris Ostrovsky Signed-off-by: Juergen Gross

xen: don't require virtio with grants for non-PV guests

2022-08-01T05:43:03Z

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 Signed-off-by: Juergen Gross Reviewed-by: Oleksandr Tyshchenko Tested-by: Oleksandr Tyshchenko # Arm64 guest using Xen Reviewed-by: Stefano Stabellini Link: https://lore.kernel.org/r/20220622063838.8854-4-jgross@suse.com Signed-off-by: Juergen Gross

xen/grant-dma-ops: Retrieve the ID of backend's domain for DT devices

2022-06-06T14:07:30Z

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 Reviewed-by: Stefano Stabellini Link: https://lore.kernel.org/r/1654197833-25362-8-git-send-email-olekstysh@gmail.com Signed-off-by: Juergen Gross

xen/grant-dma-ops: Add option to restrict memory access under Xen

2022-06-06T06:54:52Z

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 Signed-off-by: Oleksandr Tyshchenko Reviewed-by: Stefano Stabellini Link: https://lore.kernel.org/r/1654197833-25362-4-git-send-email-olekstysh@gmail.com Signed-off-by: Juergen Gross

swiotlb-xen: fix DMA_ATTR_NO_KERNEL_MAPPING on arm

2022-05-11T17:48:32Z

swiotlb-xen uses very different ways to allocate coherent memory on x86 vs arm. On the former it allocates memory from the page allocator, while on the later it reuses the dma-direct allocator the handles the complexities of non-coherent DMA on arm platforms. Unfortunately the complexities of trying to deal with the two cases in the swiotlb-xen.c code lead to a bug in the handling of DMA_ATTR_NO_KERNEL_MAPPING on arm. With the DMA_ATTR_NO_KERNEL_MAPPING flag the coherent memory allocator does not actually allocate coherent memory, but just a DMA handle for some memory that is DMA addressable by the device, but which does not have to have a kernel mapping. Thus dereferencing the return value will lead to kernel crashed and memory corruption. Fix this by using the dma-direct allocator directly for arm, which works perfectly fine because on arm swiotlb-xen is only used when the domain is 1:1 mapped, and then simplifying the remaining code to only cater for the x86 case with DMA coherent device. Reported-by: Rahul Singh Signed-off-by: Christoph Hellwig Reviewed-by: Rahul Singh Reviewed-by: Stefano Stabellini Tested-by: Rahul Singh

xen/privcmd: drop "pages" parameter from xen_remap_pfn()

2021-10-05T06:20:27Z

The function doesn't use it and all of its callers say in a comment that their respective arguments are to be non-NULL only in auto-translated mode. Since xen_remap_domain_mfn_array() isn't supposed to be used by non-PV, drop the parameter there as well. It was bogusly passed as non- NULL (PRIV_VMA_LOCKED) by its only caller anyway. For xen_remap_domain_gfn_range(), otoh, it's not clear at all why this wouldn't want / might not need to gain auto-translated support down the road, so the parameter is retained there despite now remaining unused (and the only caller passing NULL); correct a respective comment as well. Signed-off-by: Jan Beulich Reviewed-by: Boris Ostrovsky Link: https://lore.kernel.org/r/036ad8a2-46f9-ac3d-6219-bdc93ab9e10b@suse.com Signed-off-by: Juergen Gross

swiotlb-xen: this is PV-only on x86

2021-09-20T15:01:21Z

The code is unreachable for HVM or PVH, and it also makes little sense in auto-translated environments. On Arm, with xen_{create,destroy}_contiguous_region() both being stubs, I have a hard time seeing what good the Xen specific variant does - the generic one ought to be fine for all purposes there. Still Arm code explicitly references symbols here, so the code will continue to be included there. Instead of making PCI_XEN's "select" conditional, simply drop it - SWIOTLB_XEN will be available unconditionally in the PV case anyway, and is - as explained above - dead code in non-PV environments. This in turn allows dropping the stubs for xen_{create,destroy}_contiguous_region(), the former of which was broken anyway - it failed to set the DMA handle output. Signed-off-by: Jan Beulich Reviewed-by: Christoph Hellwig Reviewed-by: Stefano Stabellini Link: https://lore.kernel.org/r/5947b8ae-fdc7-225c-4838-84712265fc1e@suse.com Signed-off-by: Juergen Gross