From 58ccf0190d19d9a8a41f8a02b9e06742b58df4a1 Mon Sep 17 00:00:00 2001 From: Joao Martins Date: Thu, 8 Sep 2022 21:34:42 +0300 Subject: vfio: Add an IOVA bitmap support The new facility adds a bunch of wrappers that abstract how an IOVA range is represented in a bitmap that is granulated by a given page_size. So it translates all the lifting of dealing with user pointers into its corresponding kernel addresses backing said user memory into doing finally the (non-atomic) bitmap ops to change various bits. The formula for the bitmap is: data[(iova / page_size) / 64] & (1ULL << (iova % 64)) Where 64 is the number of bits in a unsigned long (depending on arch) It introduces an IOVA iterator that uses a windowing scheme to minimize the pinning overhead, as opposed to pinning it on demand 4K at a time. Assuming a 4K kernel page and 4K requested page size, we can use a single kernel page to hold 512 page pointers, mapping 2M of bitmap, representing 64G of IOVA space. An example usage of these helpers for a given @base_iova, @page_size, @length and __user @data: bitmap = iova_bitmap_alloc(base_iova, page_size, length, data); if (IS_ERR(bitmap)) return -ENOMEM; ret = iova_bitmap_for_each(bitmap, arg, dirty_reporter_fn); iova_bitmap_free(bitmap); Each iteration of the @dirty_reporter_fn is called with a unique @iova and @length argument, indicating the current range available through the iova_bitmap. The @dirty_reporter_fn uses iova_bitmap_set() to mark dirty areas (@iova_length) within that provided range, as following: iova_bitmap_set(bitmap, iova, iova_length); The facility is intended to be used for user bitmaps representing dirtied IOVAs by IOMMU (via IOMMUFD) and PCI Devices (via vfio-pci). Signed-off-by: Joao Martins Signed-off-by: Yishai Hadas Link: https://lore.kernel.org/r/20220908183448.195262-5-yishaih@nvidia.com Signed-off-by: Alex Williamson --- drivers/vfio/Makefile | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'drivers/vfio/Makefile') diff --git a/drivers/vfio/Makefile b/drivers/vfio/Makefile index 1a32357592e3..d67c604d0407 100644 --- a/drivers/vfio/Makefile +++ b/drivers/vfio/Makefile @@ -1,9 +1,11 @@ # SPDX-License-Identifier: GPL-2.0 vfio_virqfd-y := virqfd.o -vfio-y += vfio_main.o - obj-$(CONFIG_VFIO) += vfio.o + +vfio-y += vfio_main.o \ + iova_bitmap.o \ + obj-$(CONFIG_VFIO_VIRQFD) += vfio_virqfd.o obj-$(CONFIG_VFIO_IOMMU_TYPE1) += vfio_iommu_type1.o obj-$(CONFIG_VFIO_IOMMU_SPAPR_TCE) += vfio_iommu_spapr_tce.o -- cgit v1.2.3