[PATCH 2/2] hisi_acc_vfio_pci: fix VF BAR2 mmap on 64KB page size

[Longfang Liu <liulongfang@huawei.com>]

    On HW_ACC_MIG_VF_CTRL hardware, VF BAR2 is split into functional
and migration register regions. When kernel page size exceeds the
functional region size (e.g. 64KB pages vs 32KB functional region),
guest mmap operations get rounded up to page size, causing the VMA
to exceed functional boundaries and fail validation.
    The solution aligns mmap boundaries to page size while maintaining
byte-granularity access control through hisi_acc_pci_rw_access_check()
for read/write operations and accurate region size reporting via
hisi_acc_vfio_ioctl_get_region(), ensuring migration registers remain
protected from non-mmap access while resolving compatibility issues.

Signed-off-by: Longfang Liu <liulongfang@huawei.com>
---
 drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c b/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
index 36490be7a61a..44b3e7d8fef5 100644
--- a/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
+++ b/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
@@ -1355,14 +1355,21 @@ static int hisi_acc_vfio_pci_mmap(struct vfio_device *core_vdev,
 	index = vma->vm_pgoff >> (VFIO_PCI_OFFSET_SHIFT - PAGE_SHIFT);
 	if (index == VFIO_PCI_BAR2_REGION_INDEX) {
 		u64 req_len, pgoff, req_start;
-		resource_size_t end;
+		resource_size_t end, dev_len;
 
-		end = hisi_acc_get_resource_len(vdev, index);
+		dev_len = hisi_acc_get_resource_len(vdev, index);
 		req_len = vma->vm_end - vma->vm_start;
 		pgoff = vma->vm_pgoff &
 			((1U << (VFIO_PCI_OFFSET_SHIFT - PAGE_SHIFT)) - 1);
 		req_start = pgoff << PAGE_SHIFT;
-
+		/*
+		 * The BAR2 functional region (dev_len) may be smaller than the
+		 * kernel page size. Align it to PAGE_SIZE so a page-rounded
+		 * guest mmap is not rejected, which would make the VF unusable.
+		 * The read/write path still truncates at the real functional
+		 * boundary, keeping the migration registers inaccessible.
+		 */
+		end = PAGE_ALIGN(dev_len);
 		if (req_start + req_len > end)
 			return -EINVAL;
 	}
-- 
2.43.0