Here is a patchset which Yongji was working on before leaving IBM LTC. Since we still want to have this functionality in the kernel (DPDK is the first user), here is a rebase on the current upstream. Current vfio-pci implementation disallows to mmap the page containing MSI-X table in case that users can write directly to MSI-X table and generate an incorrect MSIs. However, this will cause some performance issue when there are some critical device registers in the same page as the MSI-X table. We have to handle the mmio access to these registers in QEMU emulation rather than in guest. To solve this issue, this series allows to expose MSI-X table to userspace when hardware enables the capability of interrupt remapping which can ensure that a given PCI device can only shoot the MSIs assigned for it. And we introduce a new bus_flags PCI_BUS_FLAGS_MSI_REMAP to test this capability on PCI side for different archs. The patch 3 are based on the proposed patchset[1]. Changelog v3: - rebased on the current upstream v2: - Make the commit log more clear - Replace pci_bus_check_msi_remapping() with pci_bus_msi_isolated() so that we could clearly know what the function does - Set PCI_BUS_FLAGS_MSI_REMAP in pci_create_root_bus() instead of iommu_bus_notifier() - Reserve VFIO_REGION_INFO_FLAG_CAPS when we allow to mmap MSI-X table so that we can know whether we allow to mmap MSI-X table in QEMU [1] https://www.mail-archive.com/linux-kernel%40vger.kernel.org/msg1138820.html This is based on sha1 63f700aab4c1 Linus Torvalds "Merge tag 'xtensa-20170612' of git://github.com/jcmvbkbc/linux-xtensa". Please comment. Thanks. Yongji Xie (3): PCI: Add a new PCI_BUS_FLAGS_MSI_REMAP flag pci-ioda: Set PCI_BUS_FLAGS_MSI_REMAP for IODA host bridge vfio-pci: Allow to expose MSI-X table to userspace if interrupt remapping is enabled include/linux/pci.h | 1 + arch/powerpc/platforms/powernv/pci-ioda.c | 8 ++++++++ drivers/vfio/pci/vfio_pci.c | 18 +++++++++++++++--- drivers/vfio/pci/vfio_pci_rdwr.c | 3 ++- 4 files changed, 26 insertions(+), 4 deletions(-) -- 2.11.0
