linux-kernel - Re: [PATCH v7 0/7] Fix PF/VF dependency issue

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Date:   Thu, 5 Sep 2019 14:22:25 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     sathyanarayanan.kuppuswamy@...ux.intel.com
Cc:     linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        ashok.raj@...el.com, keith.busch@...el.com
Subject: Re: [PATCH v7 0/7] Fix PF/VF dependency issue

On Wed, Aug 28, 2019 at 03:14:00PM -0700, sathyanarayanan.kuppuswamy@...ux.intel.com wrote:
> From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
> 
> Current implementation of ATS, PASID, PRI does not handle VF dependencies
> correctly. Following patches addresses this issue.
> 
> Changes since v6:
>  * Removed locking interfaces used in v6.
>  * Made necessary changes to PRI/PASID enable/disable calls to allow
>    register changes only for PF.
> 
> Changes since v5:
>  * Created new patches for PRI/PASID capability caching.
>  * Removed individual locks (pri_lock, pasid_lock) and added common
>    resource lock to synchronize PRI/PASID updates between PF/VF.
>  * Addressed comments from Bjorn Helgaas.
> 
> Changes since v4:
>  * Defined empty functions for pci_pri_init() and pci_pasid_init() for cases
>    where CONFIG_PCI_PRI and CONFIG_PCI_PASID are not enabled.
> 
> Changes since v3:
>  * Fixed critical path (lock context) in pci_restore_*_state functions.
> 
> Changes since v2:
>  * Added locking mechanism to synchronize accessing PF registers in VF.
>  * Removed spec compliance checks in patches.
>  * Addressed comments from Bjorn Helgaas.
> 
> Changes since v1:
>  * Added more details about the patches in commit log.
>  * Removed bulk spec check patch.
>  * Addressed comments from Bjorn Helgaas.
> 
> Kuppuswamy Sathyanarayanan (7):
>   PCI/ATS: Fix pci_prg_resp_pasid_required() dependency issues
>   PCI/ATS: Cache PRI capability check result
>   PCI/ATS: Cache PASID capability check result
>   PCI/ATS: Add PRI support for PCIe VF devices
>   PCI/ATS: Add PASID support for PCIe VF devices
>   PCI/ATS: Disable PF/VF ATS service independently
>   PCI: Skip Enhanced Allocation (EA) initialization for VF device

To make it easier to backport things, I think these should be
reordered so the important fixes are first, e.g., like this:

    PCI/ATS: Add PRI support for PCIe VF devices
    PCI/ATS: Add PASID support for PCIe VF devices
    PCI/ATS: Disable PF/VF ATS service independently
    PCI/ATS: Cache PRI capability check result
    PCI/ATS: Cache PASID capability check result

I don't think the following ones are actually needed:

    PCI: Skip Enhanced Allocation (EA) initialization for VF device
    PCI/ATS: Fix pci_prg_resp_pasid_required() dependency issues

I'll post a v8 with my proposal.

>  drivers/pci/ats.c       | 202 ++++++++++++++++++++++++++++------------
>  drivers/pci/pci.c       |   7 ++
>  include/linux/pci-ats.h |  12 ++-
>  include/linux/pci.h     |   3 +-
>  4 files changed, 159 insertions(+), 65 deletions(-)
> 
> -- 
> 2.21.0
>