Re: [PATCH] vfio: selftests: Add vfio_dma_mapping_mmio_test

On Wed, Jan 07, 2026 at 02:13:28PM -0800, Alex Mastro wrote:

@@ -124,20 +127,43 @@ static void vfio_pci_region_get(struct vfio_pci_device *device, int index, static void vfio_pci_bar_map(struct vfio_pci_device *device, int index) { struct vfio_pci_bar *bar = &device->bars[index];

• size_t align, size;
• void *map_base, *map_align; int prot = 0;

VFIO_ASSERT_LT(index, PCI_STD_NUM_BARS); VFIO_ASSERT_NULL(bar->vaddr); VFIO_ASSERT_TRUE(bar->info.flags & VFIO_REGION_INFO_FLAG_MMAP);

• VFIO_ASSERT_GT(bar->info.size, 0);

if (bar->info.flags & VFIO_REGION_INFO_FLAG_READ) prot |= PROT_READ; if (bar->info.flags & VFIO_REGION_INFO_FLAG_WRITE) prot |= PROT_WRITE;

• bar->vaddr = mmap(NULL, bar->info.size, prot, MAP_FILE | MAP_SHARED,

• /*

• * Align the mmap for more efficient IOMMU mapping.
  

• * The largest PUD size supporting huge pfnmap is 1GiB.
  

• */
  

• size = bar->info.size;
• align = min_t(u64, 1ULL << __builtin_ctzll(size), SZ_1G);
• map_base = mmap(NULL, size + align, PROT_NONE,

• 	MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
  

• VFIO_ASSERT_NE(map_base, MAP_FAILED);
• map_align = (void *)ALIGN((uintptr_t)map_base, align);
• if (map_align > map_base)

• munmap(map_base, map_align - map_base);
  

• if (align > (size_t)(map_align - map_base))

I realized that this is tautological. Will fix in v2.

• munmap(map_align + size, align - (map_align - map_base));
  

• bar->vaddr = mmap(map_align, size, prot, MAP_SHARED | MAP_FIXED, device->fd, bar->info.offset); VFIO_ASSERT_NE(bar->vaddr, MAP_FAILED);
• madvise(bar->vaddr, size, MADV_HUGEPAGE);

}