Date: Wed, 18 Jul 2018 02:02:21 +0000 From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 229852] [PATCH] bhyve: IOMMU (Intel VTd) PCI passthrough attempt locks up some systems Message-ID: <bug-229852-227@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=229852 Bug ID: 229852 Summary: [PATCH] bhyve: IOMMU (Intel VTd) PCI passthrough attempt locks up some systems Product: Base System Version: 11.2-RELEASE Hardware: amd64 OS: Any Status: New Severity: Affects Some People Priority: --- Component: kern Assignee: bugs@FreeBSD.org Reporter: callum@aitchison.org Created attachment 195225 --> https://bugs.freebsd.org/bugzilla/attachment.cgi?id=195225&action=edit Patch for VT-d capability detection on chipsets that have multiple translation units with differing capabilities When an attempt is made to passthrough a PCI device to a bhyve VM (causing initialisation of IOMMU) on certain Intel chipsets using VT-d the PCI bus stops working entirely. This issue occurs on the E3-1275 v5 processor on C236 chipset and has also been encountered by others on the forums with different hardware in the Skylake series. The chipset has two VT-d translation units. The issue is caused by an attempt to use the VT-d device-IOTLB capability that is supported by only the first unit for devices attached to the second unit which lacks that capability. Only the capabilities of the first unit are checked and are assumed to be the same for all units. Attached is a patch to rectify this issue by determining which unit is responsible for the device being added to a domain and then checking that unit's device-IOTLB capability. In addition to this a few fixes have been made to other instances where the first unit's capabilities are assumed for all units for domains they share. In these cases a mutual set of capabilities is determined. The patch should hopefully fix any bugs for current/future hardware with multiple translation units supporting different capabilities. A description is on the forums at https://forums.freebsd.org/threads/pci-passthrough-bhyve-usb-xhci.65235 The thread includes observations by other users of the bug occurring, and description as well as confirmation of the fix. I'd also like to thank Ordoban for their help. The attached patch applies to 11.2-RELEASE and the current 11-STABLE. It will also apply to 12.0-CURRENT since the only difference in source at present is an extra 2 lines of licensing comment. Although I have personally only tested the patch on 11.2-RELEASE there's no reason results should differ on 12.0-CURRENT. -- You are receiving this mail because: You are the assignee for the bug.
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