Re: [RFC PATCH v5 0/5] vfio-pci: Add support for mmapping MSI-X table

Alexey Kardashevskiy
2017-08-14T09:45:20Z

Folks,

Is there anything to change besides those compiler errors and David's
comment in 5/5? Or the while patchset is too bad? Thanks.

On 07/08/17 17:25, Alexey Kardashevskiy wrote:
> This is a followup for "[PATCH kernel v4 0/6] vfio-pci: Add support for mmapping MSI-X table"
> http://www.spinics.net/lists/kvm/msg152232.html
>
> This time it is using "caps" in IOMMU groups. The main question is if PCI
> bus flags or IOMMU domains are still better (and which one).

>
>
>
> Here is some background:
>
> 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.
>
>
> This is based on sha1
> 26c5cebfdb6c "Merge branch 'parisc-4.13-4' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux"
>
> Please comment. Thanks.
>
> Changelog:
>
> v5:
> * redid the whole thing via so-called IOMMU group capabilities
>
> v4:
> * rebased on recent upstream
> * got all 6 patches from v2 (v3 was missing some)
>
>
>
>
> Alexey Kardashevskiy (5):
> iommu: Add capabilities to a group
> iommu: Set IOMMU_GROUP_CAP_ISOLATE_MSIX if MSI controller enables IRQ
> remapping
> iommu/intel/amd: Set IOMMU_GROUP_CAP_ISOLATE_MSIX if IRQ remapping is
> enabled
> powerpc/iommu: Set IOMMU_GROUP_CAP_ISOLATE_MSIX
> vfio-pci: Allow to expose MSI-X table to userspace when safe
>
> include/linux/iommu.h | 20 ++++++++++++++++++++
> include/linux/vfio.h | 1 +
> arch/powerpc/kernel/iommu.c | 1 +
> drivers/iommu/amd_iommu.c | 3 +++
> drivers/iommu/intel-iommu.c | 3 +++
> drivers/iommu/iommu.c | 35 +++++++++++++++++++++++++++++++++++
> drivers/vfio/pci/vfio_pci.c | 20 +++++++++++++++++---
> drivers/vfio/pci/vfio_pci_rdwr.c | 5 ++++-
> drivers/vfio/vfio.c | 15 +++++++++++++++
> 9 files changed, 99 insertions(+), 4 deletions(-)
>

--
Alexey