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

Alexey Kardashevskiy
2017-08-29T02:58:59Z

On 21/08/17 12:47, Alexey Kardashevskiy wrote:
> 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.

Anyone, any help? How do we proceed with this? 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