linux-kernel - [PATCH v2 2/2] vfio/pci: Disable qword access to the VGA region

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Message-ID: <20251218081650.555015-3-kevin.tian@intel.com>
Date: Thu, 18 Dec 2025 08:16:50 +0000
From: Kevin Tian <kevin.tian@...el.com>
To: Alex Williamson <alex@...zbot.org>,
	Ankit Agrawal <ankita@...dia.com>
Cc: Jason Gunthorpe <jgg@...pe.ca>,
	Yishai Hadas <yishaih@...dia.com>,
	Shameer Kolothum <skolothumtho@...dia.com>,
	Kevin Tian <kevin.tian@...el.com>,
	Ramesh Thomas <ramesh.thomas@...el.com>,
	Yunxiang Li <Yunxiang.Li@....com>,
	kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH v2 2/2] vfio/pci: Disable qword access to the VGA region

Seems no reason to allow qword access to the old VGA resource. Better
restrict it to dword access as before.

Suggested-by: Alex Williamson <alex@...zbot.org>
Signed-off-by: Kevin Tian <kevin.tian@...el.com>
---
 drivers/vfio/pci/vfio_pci_rdwr.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/vfio/pci/vfio_pci_rdwr.c b/drivers/vfio/pci/vfio_pci_rdwr.c
index 25380b7dfe18..b38627b35c35 100644
--- a/drivers/vfio/pci/vfio_pci_rdwr.c
+++ b/drivers/vfio/pci/vfio_pci_rdwr.c
@@ -363,7 +363,7 @@ ssize_t vfio_pci_vga_rw(struct vfio_pci_core_device *vdev, char __user *buf,
 	 * to the memory enable bit in the command register.
 	 */
 	done = vfio_pci_core_do_io_rw(vdev, false, iomem, buf, off, count,
-				      0, 0, iswrite, VFIO_PCI_IO_WIDTH_8);
+				      0, 0, iswrite, VFIO_PCI_IO_WIDTH_4);
 
 	vga_put(vdev->pdev, rsrc);
 
-- 
2.43.0