user/sven/linux.git/drivers/xen/gntdev.c, branch v4.9.296

Xen/gntdev: correct error checking in gntdev_map_grant_pages()

2021-02-23T12:59:17Z

commit ebee0eab08594b2bd5db716288a4f1ae5936e9bc upstream. Failure of the kernel part of the mapping operation should also be indicated as an error to the caller, or else it may assume the respective kernel VA is okay to access. Furthermore gnttab_map_refs() failing still requires recording successfully mapped handles, so they can be unmapped subsequently. This in turn requires there to be a way to tell full hypercall failure from partial success - preset map_op status fields such that they won't "happen" to look as if the operation succeeded. Also again use GNTST_okay instead of implying its value (zero). This is part of XSA-361. Signed-off-by: Jan Beulich Cc: stable@vger.kernel.org Reviewed-by: Juergen Gross Signed-off-by: Juergen Gross Signed-off-by: Greg Kroah-Hartman

Xen/gntdev: correct dev_bus_addr handling in gntdev_map_grant_pages()

2021-02-23T12:59:17Z

commit dbe5283605b3bc12ca45def09cc721a0a5c853a2 upstream. We may not skip setting the field in the unmap structure when GNTMAP_device_map is in use - such an unmap would fail to release the respective resources (a page ref in the hypervisor). Otoh the field doesn't need setting at all when GNTMAP_device_map is not in use. To record the value for unmapping, we also better don't use our local p2m: In particular after a subsequent change it may not have got updated for all the batch elements. Instead it can simply be taken from the respective map's results. We can additionally avoid playing this game altogether for the kernel part of the mappings in (x86) PV mode. This is part of XSA-361. Signed-off-by: Jan Beulich Cc: stable@vger.kernel.org Reviewed-by: Stefano Stabellini Signed-off-by: Juergen Gross Signed-off-by: Greg Kroah-Hartman

xen/gntdev: Fix partial gntdev_mmap() cleanup

2018-03-03T09:23:28Z

[ Upstream commit cf2acf66ad43abb39735568f55e1f85f9844e990 ] When cleaning up after a partially successful gntdev_mmap(), unmap the successfully mapped grant pages otherwise Xen will kill the domain if in debug mode (Attempt to implicitly unmap a granted PTE) or Linux will kill the process and emit "BUG: Bad page map in process" if Xen is in release mode. This is only needed when use_ptemod is true because gntdev_put_map() will unmap grant pages itself when use_ptemod is false. Signed-off-by: Ross Lagerwall Reviewed-by: Boris Ostrovsky Signed-off-by: Boris Ostrovsky Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

xen/gntdev: Fix off-by-one error when unmapping with holes

2018-03-03T09:23:28Z

[ Upstream commit 951a010233625b77cde3430b4b8785a9a22968d1 ] If the requested range has a hole, the calculation of the number of pages to unmap is off by one. Fix it. Signed-off-by: Ross Lagerwall Reviewed-by: Boris Ostrovsky Signed-off-by: Boris Ostrovsky Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

xen/gntdev: avoid out of bounds access in case of partial gntdev_mmap()

2017-11-02T08:49:13Z

commit 298d275d4d9bea3524ff4bc76678c140611d8a8d upstream. In case gntdev_mmap() succeeds only partially in mapping grant pages it will leave some vital information uninitialized needed later for cleanup. This will lead to an out of bounds array access when unmapping the already mapped pages. So just initialize the data needed for unmapping the pages a little bit earlier. Reported-by: Arthur Borsboom Signed-off-by: Juergen Gross Reviewed-by: Boris Ostrovsky Signed-off-by: Boris Ostrovsky Signed-off-by: Greg Kroah-Hartman

xen/gntdev: Use VM_MIXEDMAP instead of VM_IO to avoid NUMA balancing

2017-01-06T09:40:17Z

commit 30faaafdfa0c754c91bac60f216c9f34a2bfdf7e upstream. Commit 9c17d96500f7 ("xen/gntdev: Grant maps should not be subject to NUMA balancing") set VM_IO flag to prevent grant maps from being subjected to NUMA balancing. It was discovered recently that this flag causes get_user_pages() to always fail with -EFAULT. check_vma_flags __get_user_pages __get_user_pages_locked __get_user_pages_unlocked get_user_pages_fast iov_iter_get_pages dio_refill_pages do_direct_IO do_blockdev_direct_IO do_blockdev_direct_IO ext4_direct_IO_read generic_file_read_iter aio_run_iocb (which can happen if guest's vdisk has direct-io-safe option). To avoid this let's use VM_MIXEDMAP flag instead --- it prevents NUMA balancing just as VM_IO does and has no effect on check_vma_flags(). Reported-by: Olaf Hering Suggested-by: Hugh Dickins Signed-off-by: Boris Ostrovsky Acked-by: Hugh Dickins Tested-by: Olaf Hering Signed-off-by: Juergen Gross Signed-off-by: Greg Kroah-Hartman

xen: use vma_pages().

2016-07-06T09:34:47Z

Replace explicit computation of vma page count by a call to vma_pages(). Signed-off-by: Muhammad Falak R Wani Reviewed-by: Boris Ostrovsky Signed-off-by: David Vrabel

xen/gntdev: reduce copy batch size to 16

2016-05-24T11:58:17Z

IOCTL_GNTDEV_GRANT_COPY batches copy operations to reduce the number of hypercalls. The stack is used to avoid a memory allocation in a hot path. However, a batch size of 24 requires more than 1024 bytes of stack which in some configurations causes a compiler warning. xen/gntdev.c: In function ‘gntdev_ioctl_grant_copy’: xen/gntdev.c:949:1: warning: the frame size of 1248 bytes is larger than 1024 bytes [-Wframe-larger-than=] This is a harmless warning as there is still plenty of stack spare, but people keep trying to "fix" it. Reduce the batch size to 16 to reduce stack usage to less than 1024 bytes. This should have minimal impact on performance. Signed-off-by: David Vrabel

xen/gntdev: add ioctl for grant copy

2016-01-07T13:21:53Z

Add IOCTL_GNTDEV_GRANT_COPY to allow applications to copy between user space buffers and grant references. This interface is similar to the GNTTABOP_copy hypercall ABI except the local buffers are provided using a virtual address (instead of a GFN and offset). To avoid userspace from having to page align its buffers the driver will use two or more ops if required. If the ioctl returns 0, the application must check the status of each segment with the segments status field. If the ioctl returns a -ve error code (EINVAL or EFAULT), the status of individual ops is undefined. Signed-off-by: David Vrabel Reviewed-by: Boris Ostrovsky

xen/gntdev: constify mmu_notifier_ops structures

2015-12-21T14:41:01Z

This mmu_notifier_ops structure is never modified, so declare it as const, like the other mmu_notifier_ops structures. Done with the help of Coccinelle. Signed-off-by: Julia Lawall Signed-off-by: David Vrabel