lkml.org 
[lkml]   [2017]   [Jun]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Subject[PATCH kernel 0/3] vfio-pci: Add support for mmapping MSI-X table
Date
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

\
 
 \ /
  Last update: 2017-06-15 07:07    [W:0.047 / U:0.156 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site