linux-kernel - [PATCH 0/3] PCI: Expose resource resizing through sysfs

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Message-ID: <166067824399.1885802.12557332818208187324.stgit@omen>
Date:   Tue, 16 Aug 2022 13:39:50 -0600
From:   Alex Williamson <alex.williamson@...hat.com>
To:     linux-pci@...r.kernel.org, bhelgaas@...gle.com
Cc:     Christian König <christian.koenig@....com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH 0/3] PCI: Expose resource resizing through sysfs

We have a couple graphics drivers making use of PCIe Resizable BARs
now, but I've been trying to figure out how we can make use of such
features for devices assigned to a VM.  This is a proposal for a
rather basic interface in sysfs such that we have the ability to
pre-enable larger BARs before we bind devices to vfio-pci and
attach them to a VM.

Along the way I found a double-free in the error path of creating
resource attributes, that can certainly be pulled separately (1/).

I'm using an RTX6000 for testing, which unexpectedly only supports
REBAR with smaller than default sizes, which led me to question
why we have such heavy requirements for shrinking resources (2/).

The final patch proposes the sysfs interface and I'll leave the
discussion there for whether this is a good approach.  Thanks,

Alex
---

Alex Williamson (3):
      PCI: Fix double-free in resource attribute error path
      PCI: Skip reassigning bridge resources if reducing BAR size
      PCI: Expose PCIe Resizable BAR support via sysfs

 Documentation/ABI/testing/sysfs-bus-pci |  27 +++++
 drivers/pci/pci-sysfs.c                 | 126 +++++++++++++++++++++++-
 drivers/pci/setup-res.c                 |   2 +-
 include/linux/pci.h                     |   1 +
 4 files changed, 154 insertions(+), 2 deletions(-)