From 25c429dd117854b46cf515e28cb910c66742688e Mon Sep 17 00:00:00 2001 From: Kommula Shiva Shankar Date: Fri, 2 Jan 2026 12:27:03 +0530 Subject: [PATCH] vhost: fix caching attributes of MMIO regions by setting them explicitly [ Upstream commit 5145b277309f3818e2db507f525d19ac3b910922 ] Explicitly set non-cached caching attributes for MMIO regions. Default write-back mode can cause CPU to cache device memory, causing invalid reads and unpredictable behavior. Invalid read and write issues were observed on ARM64 when mapping the notification area to userspace via mmap. Signed-off-by: Kommula Shiva Shankar Acked-by: Jason Wang Reviewed-by: Jason Gunthorpe Signed-off-by: Michael S. Tsirkin Message-Id: <20260102065703.656255-1-kshankar@marvell.com> Signed-off-by: Sasha Levin --- drivers/vhost/vdpa.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c index 05a481e4c385..b0179e8567ab 100644 --- a/drivers/vhost/vdpa.c +++ b/drivers/vhost/vdpa.c @@ -1527,6 +1527,7 @@ static int vhost_vdpa_mmap(struct file *file, struct vm_area_struct *vma) if (vma->vm_end - vma->vm_start != notify.size) return -ENOTSUPP; + vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot); vm_flags_set(vma, VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP); vma->vm_ops = &vhost_vdpa_vm_ops; return 0;