Re: [PATCH v5 0/4] PCI: Introduce a way to enforce all MMIO BARs not to share PAGE_SIZE

[Yongji Xie <xyjxie@linux.vnet.ibm.com>]

Hi Bjorn,

Kindly Ping... Any comment on V5?

Thanks,
Yongji

On 2016/9/13 17:00, Yongji Xie wrote:
> This series introduces a way for PCI resource allocator to force
> MMIO BARs not to share PAGE_SIZE. This would make sense to VFIO
> driver. Because current VFIO implementation disallows to mmap
> sub-page(size < PAGE_SIZE) MMIO BARs which may share the same page
> with other BARs for security reasons. Thus, we have to handle mmio
> access to these BARs in QEMU emulation rather than in guest which
> will cause some performance loss.
>
> In our solution, we try to make use of the existing code path of
> resource_alignment kernel parameter and add a macro to set default
> alignment for it. Thus we can define this macro by default on some
> archs which may easily hit the performance issue because of their
> 64K page.
>
> In this series, patch 1,2 fixed bugs of using resource_alignment;
> patch 3 tried to add a new option for resource_alignment to use
> IORESOURCE_STARTALIGN to specify the alignment of PCI BARs; patch 4
> adds a macro to set the default alignment of all MMIO BARs.
>
> Changelog v5:
> - Rebased against v4.8-rc6
> - Drop the patch that forbidding disable memory decoding in
>    pci_reassigndev_resource_alignment()
>
> Changelog v4:
> - Rebased against v4.8-rc1
> - Drop one irrelevant patch
> - Drop the patch that adding wildcard to resource_alignment to enforce
>    the alignment of all MMIO BARs to be at least PAGE_SIZE
> - Change the format of option "noresize" of resource_alignment
> - Code style improvements
>
> Changelog v3:
> - Ignore enforced alignment to fixed BARs
> - Fix issue that disabling memory decoding when reassigning the alignment
> - Only enable default alignment on PowerNV platform
>
> Changelog v2:
> - Ignore enforced alignment to VF BARs on pci_reassigndev_resource_alignment()
>
> Yongji Xie (4):
>    PCI: Ignore enforced alignment when kernel uses existing firmware setup
>    PCI: Ignore enforced alignment to VF BARs
>    PCI: Add a new option for resource_alignment to reassign alignment
>    PCI: Add a macro to set default alignment for all PCI devices
>
>   Documentation/kernel-parameters.txt |    9 +++--
>   arch/powerpc/include/asm/pci.h      |    4 +++
>   drivers/pci/pci.c                   |   63 +++++++++++++++++++++++++++++------
>   3 files changed, 63 insertions(+), 13 deletions(-)
>