4.20-stable review patch. If anyone has any objections, please let me know.
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From: Alexander Shishkin alexander.shishkin@linux.intel.com
commit 2e095ce7b6ecce2f3e2ff330527f12056ed1e1a1 upstream.
On Denverton's integration of the Intel(R) Trace Hub (for a reference and overview see Documentation/trace/intel_th.rst) the reported size of one of its resources (RTIT_BAR) doesn't match its actual size, which leads to overlaps with other devices' resources.
In practice, it overlaps with XHCI MMIO space, which results in the xhci driver bailing out after seeing its registers as 0xffffffff, and perceived disappearance of all USB devices:
intel_th_pci 0000:00:1f.7: enabling device (0004 -> 0006) xhci_hcd 0000:00:15.0: xHCI host controller not responding, assume dead xhci_hcd 0000:00:15.0: xHC not responding in xhci_irq, assume controller is dead xhci_hcd 0000:00:15.0: HC died; cleaning up usb 1-1: USB disconnect, device number 2
For this reason, we need to resize the RTIT_BAR on Denverton to its actual size, which in this case is 4MB. The corresponding erratum is DNV36 at the link below:
DNV36. Processor Host Root Complex May Incorrectly Route Memory Accesses to Intel® Trace Hub
Problem: The Intel® Trace Hub RTIT_BAR (B0:D31:F7 offset 20h) is reported as a 2KB memory range. Due to this erratum, the processor Host Root Complex will forward addresses from RTIT_BAR to RTIT_BAR + 4MB -1 to Intel® Trace Hub.
Implication: Devices assigned within the RTIT_BAR to RTIT_BAR + 4MB -1 space may not function correctly.
Workaround: A BIOS code change has been identified and may be implemented as a workaround for this erratum.
Status: No Fix.
Note that 5118ccd34780 ("intel_th: pci: Add Denverton SOC support") updates the Trace Hub driver so it claims the Denverton device, but the resource overlap exists regardless of whether that driver is loaded or that commit is included.
Link: https://www.intel.com/content/dam/www/public/us/en/documents/specification-u... Signed-off-by: Alexander Shishkin alexander.shishkin@linux.intel.com [bhelgaas: include erratum text, clarify relationship with 5118ccd34780] Signed-off-by: Bjorn Helgaas bhelgaas@google.com Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/x86/pci/fixup.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+)
--- a/arch/x86/pci/fixup.c +++ b/arch/x86/pci/fixup.c @@ -635,6 +635,22 @@ static void quirk_no_aersid(struct pci_d DECLARE_PCI_FIXUP_CLASS_EARLY(PCI_VENDOR_ID_INTEL, PCI_ANY_ID, PCI_CLASS_BRIDGE_PCI, 8, quirk_no_aersid);
+static void quirk_intel_th_dnv(struct pci_dev *dev) +{ + struct resource *r = &dev->resource[4]; + + /* + * Denverton reports 2k of RTIT_BAR (intel_th resource 4), which + * appears to be 4 MB in reality. + */ + if (r->end == r->start + 0x7ff) { + r->start = 0; + r->end = 0x3fffff; + r->flags |= IORESOURCE_UNSET; + } +} +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x19e1, quirk_intel_th_dnv); + #ifdef CONFIG_PHYS_ADDR_T_64BIT
#define AMD_141b_MMIO_BASE(x) (0x80 + (x) * 0x8)