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

Alexey Kardashevskiy
2017-08-21T02:48:11Z

Folks,

Ok, people did talk, exchanged ideas, lovely :) What happens now? Do I
repost this or go back to PCI bus flags or something else? Thanks.

On 14/08/17 19:45, Alexey Kardashevskiy wrote:
> 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