From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7AE1D338590; Tue, 6 Jan 2026 18:03:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767722620; cv=none; b=gowKeK+ZXnopBxsDVPJW/4bW9WRTXU0mcdJ9znbSI/B0tSDwplalwMYNHWT05bnolD9YXs2P8RD0juDwvdLmWm1xo7KQcJQFt7KNuQMROislM7fqKVD3G8svhIQhivJOBs+8IRWd+rZgaLQ3OvHjZeWZqgrHGUBBftdvOtCH8nY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767722620; c=relaxed/simple; bh=Jp1tzmtgFW2DbYtIxUmJPYD+ibWBxWy8WEtJoOI/TmY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=XpSi1unC4CDcvjR1zRIo5TIICyCOPZTqhD5M3xLFX1u4LWAc/TU8CagQ3sFhpsQqd8FhyCV5DkXoam9xwBW3io9yj5BGJ9+JerMs5tBz6/H+s5NGX612VxEhzOSvqtmZ3R2uSD++Bl7ZDdYrWfBrHP/5hlrgjRsEjPcsz94mcvc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=fhr59/HY; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="fhr59/HY" Received: by smtp.kernel.org (Postfix) with ESMTPSA id ED193C116C6; Tue, 6 Jan 2026 18:03:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1767722620; bh=Jp1tzmtgFW2DbYtIxUmJPYD+ibWBxWy8WEtJoOI/TmY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fhr59/HYZRrWoURlzEoe5ybj4TkZJwvfqypUoygm/WLVnahsT41LkSRMhs1PbmZQm kwPesqeikiT5f3pbfQoVTtCnEIOUF6RVgla+ZYzNRrAhSagQxgRPpjg8MXLtEL1ZY0 G3TIZ9nCUy1mabywVTSnmm+ORYmbwvKv+6wLdNzs= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Farrah Chen , Kevin Tian , Alex Williamson Subject: [PATCH 6.18 310/312] vfio/pci: Disable qword access to the PCI ROM bar Date: Tue, 6 Jan 2026 18:06:24 +0100 Message-ID: <20260106170559.074694065@linuxfoundation.org> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260106170547.832845344@linuxfoundation.org> References: <20260106170547.832845344@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Kevin Tian [ Upstream commit dc85a46928c41423ad89869baf05a589e2975575 ] Commit 2b938e3db335 ("vfio/pci: Enable iowrite64 and ioread64 for vfio pci") enables qword access to the PCI bar resources. However certain devices (e.g. Intel X710) are observed with problem upon qword accesses to the rom bar, e.g. triggering PCI aer errors. This is triggered by Qemu which caches the rom content by simply does a pread() of the remaining size until it gets the full contents. The other bars would only perform operations at the same access width as their guest drivers. Instead of trying to identify all broken devices, universally disable qword access to the rom bar i.e. going back to the old way which worked reliably for years. Reported-by: Farrah Chen Closes: https://bugzilla.kernel.org/show_bug.cgi?id=220740 Fixes: 2b938e3db335 ("vfio/pci: Enable iowrite64 and ioread64 for vfio pci") Cc: stable@vger.kernel.org Signed-off-by: Kevin Tian Tested-by: Farrah Chen Link: https://lore.kernel.org/r/20251218081650.555015-2-kevin.tian@intel.com Signed-off-by: Alex Williamson Signed-off-by: Greg Kroah-Hartman --- drivers/vfio/pci/nvgrace-gpu/main.c | 4 ++-- drivers/vfio/pci/vfio_pci_rdwr.c | 25 ++++++++++++++++++------- include/linux/vfio_pci_core.h | 10 +++++++++- 3 files changed, 29 insertions(+), 10 deletions(-) --- a/drivers/vfio/pci/nvgrace-gpu/main.c +++ b/drivers/vfio/pci/nvgrace-gpu/main.c @@ -491,7 +491,7 @@ nvgrace_gpu_map_and_read(struct nvgrace_ ret = vfio_pci_core_do_io_rw(&nvdev->core_device, false, nvdev->resmem.ioaddr, buf, offset, mem_count, - 0, 0, false); + 0, 0, false, VFIO_PCI_IO_WIDTH_8); } return ret; @@ -609,7 +609,7 @@ nvgrace_gpu_map_and_write(struct nvgrace ret = vfio_pci_core_do_io_rw(&nvdev->core_device, false, nvdev->resmem.ioaddr, (char __user *)buf, pos, mem_count, - 0, 0, true); + 0, 0, true, VFIO_PCI_IO_WIDTH_8); } return ret; --- a/drivers/vfio/pci/vfio_pci_rdwr.c +++ b/drivers/vfio/pci/vfio_pci_rdwr.c @@ -135,7 +135,8 @@ VFIO_IORDWR(64) ssize_t vfio_pci_core_do_io_rw(struct vfio_pci_core_device *vdev, bool test_mem, void __iomem *io, char __user *buf, loff_t off, size_t count, size_t x_start, - size_t x_end, bool iswrite) + size_t x_end, bool iswrite, + enum vfio_pci_io_width max_width) { ssize_t done = 0; int ret; @@ -150,20 +151,19 @@ ssize_t vfio_pci_core_do_io_rw(struct vf else fillable = 0; - if (fillable >= 8 && !(off % 8)) { + if (fillable >= 8 && !(off % 8) && max_width >= 8) { ret = vfio_pci_iordwr64(vdev, iswrite, test_mem, io, buf, off, &filled); if (ret) return ret; - } else - if (fillable >= 4 && !(off % 4)) { + } else if (fillable >= 4 && !(off % 4) && max_width >= 4) { ret = vfio_pci_iordwr32(vdev, iswrite, test_mem, io, buf, off, &filled); if (ret) return ret; - } else if (fillable >= 2 && !(off % 2)) { + } else if (fillable >= 2 && !(off % 2) && max_width >= 2) { ret = vfio_pci_iordwr16(vdev, iswrite, test_mem, io, buf, off, &filled); if (ret) @@ -234,6 +234,7 @@ ssize_t vfio_pci_bar_rw(struct vfio_pci_ void __iomem *io; struct resource *res = &vdev->pdev->resource[bar]; ssize_t done; + enum vfio_pci_io_width max_width = VFIO_PCI_IO_WIDTH_8; if (pci_resource_start(pdev, bar)) end = pci_resource_len(pdev, bar); @@ -262,6 +263,16 @@ ssize_t vfio_pci_bar_rw(struct vfio_pci_ if (!io) return -ENOMEM; x_end = end; + + /* + * Certain devices (e.g. Intel X710) don't support qword + * access to the ROM bar. Otherwise PCI AER errors might be + * triggered. + * + * Disable qword access to the ROM bar universally, which + * worked reliably for years before qword access is enabled. + */ + max_width = VFIO_PCI_IO_WIDTH_4; } else { int ret = vfio_pci_core_setup_barmap(vdev, bar); if (ret) { @@ -278,7 +289,7 @@ ssize_t vfio_pci_bar_rw(struct vfio_pci_ } done = vfio_pci_core_do_io_rw(vdev, res->flags & IORESOURCE_MEM, io, buf, pos, - count, x_start, x_end, iswrite); + count, x_start, x_end, iswrite, max_width); if (done >= 0) *ppos += done; @@ -352,7 +363,7 @@ ssize_t vfio_pci_vga_rw(struct vfio_pci_ * 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); + 0, 0, iswrite, VFIO_PCI_IO_WIDTH_8); vga_put(vdev->pdev, rsrc); --- a/include/linux/vfio_pci_core.h +++ b/include/linux/vfio_pci_core.h @@ -102,6 +102,13 @@ struct vfio_pci_core_device { struct rw_semaphore memory_lock; }; +enum vfio_pci_io_width { + VFIO_PCI_IO_WIDTH_1 = 1, + VFIO_PCI_IO_WIDTH_2 = 2, + VFIO_PCI_IO_WIDTH_4 = 4, + VFIO_PCI_IO_WIDTH_8 = 8, +}; + /* Will be exported for vfio pci drivers usage */ int vfio_pci_core_register_dev_region(struct vfio_pci_core_device *vdev, unsigned int type, unsigned int subtype, @@ -139,7 +146,8 @@ pci_ers_result_t vfio_pci_core_aer_err_d ssize_t vfio_pci_core_do_io_rw(struct vfio_pci_core_device *vdev, bool test_mem, void __iomem *io, char __user *buf, loff_t off, size_t count, size_t x_start, - size_t x_end, bool iswrite); + size_t x_end, bool iswrite, + enum vfio_pci_io_width max_width); bool vfio_pci_core_range_intersect_range(loff_t buf_start, size_t buf_cnt, loff_t reg_start, size_t reg_cnt, loff_t *buf_offset,