From 6192a3f77c97dea8a594bd6c186fc440ec08c71a Mon Sep 17 00:00:00 2001 From: Xincheng Zhang Date: Tue, 28 Jul 2026 13:41:00 +0800 Subject: [PATCH] usb: xhci-pci: Limit VIA VL805 DMA addressing to 36 bits commit 1fc50f1ecde39feb4fccdaf4bc71aa6c0eb25c49 upstream. The VIA VL805/806 xHCI controller advertises AC64, but fails to handle DMA addresses at or above 0x1000000000. On systems with large amounts of RAM, this can cause USB device failures when the controller is given DMA addresses beyond its usable address width. Do not use XHCI_NO_64BIT_SUPPORT for this controller. That quirk clears the cached AC64 capability and limits DMA to 32 bits, causing unnecessary bouncing for addresses between 4GiB and 64GiB and hiding the controller's real AC64 capability from code that may need to distinguish register access width from usable DMA address width. Track the usable DMA address width separately from the AC64 capability. Initialize the generic xhci->dma_mask_bits field to 64 and let PCI quirks reduce it for controllers with narrower DMA support. Set VIA VL805/806 to 36 bits so the DMA API only hands it addresses in the range it can handle while keeping HCCPARAMS1.AC64 visible. Cc: stable@kernel.org Signed-off-by: Xincheng Zhang Link: https://patch.msgid.link/20260630-xhci-via-dma-fix-v3-1-690dcb8cf75a@ultrarisc.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/usb/host/xhci-pci.c | 1 + drivers/usb/host/xhci.c | 15 ++++++++++----- drivers/usb/host/xhci.h | 1 + 3 files changed, 12 insertions(+), 5 deletions(-) diff --git a/drivers/usb/host/xhci-pci.c b/drivers/usb/host/xhci-pci.c index 5abc48f148dc..d5ba5a34625b 100644 --- a/drivers/usb/host/xhci-pci.c +++ b/drivers/usb/host/xhci-pci.c @@ -510,6 +510,7 @@ static void xhci_pci_quirks(struct device *dev, struct xhci_hcd *xhci) if (pdev->vendor == PCI_VENDOR_ID_VIA && pdev->device == PCI_DEVICE_ID_VIA_VL805) { xhci->quirks |= XHCI_LPM_SUPPORT; xhci->quirks |= XHCI_TRB_OVERFETCH; + xhci->dma_mask_bits = 36; } if (pdev->vendor == PCI_VENDOR_ID_ASMEDIA && diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c index 31509845594e..210b5727d1a6 100644 --- a/drivers/usb/host/xhci.c +++ b/drivers/usb/host/xhci.c @@ -5267,6 +5267,7 @@ int xhci_gen_setup(struct usb_hcd *hcd, xhci_get_quirks_t get_quirks) if (xhci->hci_version > 0x100) xhci->hcc_params2 = readl(&xhci->cap_regs->hcc_params2); + xhci->dma_mask_bits = 64; /* xhci-plat or xhci-pci might have set max_interrupters already */ if ((!xhci->max_interrupters) || xhci->max_interrupters > HCS_MAX_INTRS(xhci->hcs_params1)) @@ -5308,12 +5309,16 @@ int xhci_gen_setup(struct usb_hcd *hcd, xhci_get_quirks_t get_quirks) if (xhci->quirks & XHCI_NO_64BIT_SUPPORT) xhci->hcc_params &= ~BIT(0); - /* Set dma_mask and coherent_dma_mask to 64-bits, - * if xHC supports 64-bit addressing */ + /* + * Set dma_mask and coherent_dma_mask to 64-bits if xHC supports + * 64-bit addressing, unless a controller-specific quirk callback + * limits the usable address width. + */ if (HCC_64BIT_ADDR(xhci->hcc_params) && - !dma_set_mask(dev, DMA_BIT_MASK(64))) { - xhci_dbg(xhci, "Enabling 64-bit DMA addresses.\n"); - dma_set_coherent_mask(dev, DMA_BIT_MASK(64)); + !dma_set_mask(dev, DMA_BIT_MASK(xhci->dma_mask_bits))) { + xhci_dbg(xhci, "Enabling %u-bit DMA addresses.\n", + xhci->dma_mask_bits); + dma_set_coherent_mask(dev, DMA_BIT_MASK(xhci->dma_mask_bits)); } else { /* * This is to avoid error in cases where a 32-bit USB diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h index 849a83e4013c..bb7e73df297a 100644 --- a/drivers/usb/host/xhci.h +++ b/drivers/usb/host/xhci.h @@ -1538,6 +1538,7 @@ struct xhci_hcd { int event_ring_max; /* 4KB min, 128MB max */ int page_size; + unsigned int dma_mask_bits; /* Valid values are 12 to 20, inclusive */ int page_shift; /* msi-x vectors */