v3: - repost with the correct tree v2: - rebase to master [Eric] - add r-bs for Eric - remove RFC tag
The VT-d code has some defects, one of them is that we cannot detect the misuse of vIOMMU and vfio-pci early enough. For example, logically this is not allowed: -device intel-iommu,caching-mode=off \ -device vfio-pci,host=05:00.0 Because the caching mode is required to make vfio-pci devices functional. Previously we did this sanity check in vtd_iommu_notify_flag_changed() as when the memory regions change their attributes. However that's too late in most cases! Because the memory region layouts will only change after IOMMU is enabled, and that's in most cases during the guest OS boots. So when the configuration is wrong, we will only bail out during the guest boots rather than simply telling the user before QEMU starts. The same problem happens on device hotplug, say, when we have this: -device intel-iommu,caching-mode=off Then we do something like: (HMP) device_add vfio-pci,host=05:00.0,bus=pcie.1 If at that time the vIOMMU is enabled in the guest then the QEMU process will simply quit directly due to this hotplug event. This is a bit insane... This series tries to solve above two problems by introducing two sanity checks upon these places separately: - machine done - hotplug device This is a bit awkward but I hope this could be better than before. There is of course other solutions like hard-code the check into vfio-pci but I feel it even more unpretty. I didn't think out any better way to do this, if there is please kindly shout out. Please have a look to see whether this would be acceptable, thanks. Peter Xu (4): intel_iommu: Sanity check vfio-pci config on machine init done qdev/machine: Introduce hotplug_allowed hook pc/q35: Disallow vfio-pci hotplug without VT-d caching mode intel_iommu: Remove the caching-mode check during flag change hw/core/qdev.c | 17 +++++++++++++++++ hw/i386/intel_iommu.c | 41 +++++++++++++++++++++++++++++++++++------ hw/i386/pc.c | 21 +++++++++++++++++++++ include/hw/boards.h | 9 +++++++++ include/hw/qdev-core.h | 1 + qdev-monitor.c | 7 +++++++ 6 files changed, 90 insertions(+), 6 deletions(-) -- 2.21.0
