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| author | Alex Williamson <alex.williamson@nvidia.com> | 2026-06-15 13:12:34 -0600 |
|---|---|---|
| committer | Alex Williamson <alex@shazbot.org> | 2026-06-29 14:26:31 -0600 |
| commit | 586a989d8b0db75d6f97c80a4f588d46e1df6881 (patch) | |
| tree | 2a0439cccff5e8cdea5ff7e66bdb5b49e0031480 /Documentation | |
| parent | dc7fe87de492ea7f33a72b78d26650b75bf37f4f (diff) | |
| download | linux-586a989d8b0db75d6f97c80a4f588d46e1df6881.tar.gz linux-586a989d8b0db75d6f97c80a4f588d46e1df6881.zip | |
vfio/pci: Expose latched module parameter policy in debugfs
The nointxmask and disable_idle_d3 module parameters remain writable,
but vfio-pci now latches their values into each device at init. Once a
device is registered, changing the module parameter only affects future
devices, leaving no direct way to confirm the effective policy for an
existing device.
Add a pci debugfs directory under the VFIO device debugfs root and
report the per-device nointxmask and disable_idle_d3 values. These are
read-only debugfs views and use the same Y/N bool output convention as
the module parameters.
Read-only vfio-pci parameters, such as disable_vga, are not exposed here
because they cannot drift from the latched device value, therefore the
existing module parameter exposure via sysfs is sufficient.
Note that while only vfio-pci currently provides these options, the
implementation is in vfio-pci-core and therefore properly reflects the
device policy in the core, regardless of driver.
Assisted-by: OpenAI Codex:gpt-5
Cc: Guixin Liu <kanie@linux.alibaba.com>
Signed-off-by: Alex Williamson <alex.williamson@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/20260615191241.688297-7-alex.williamson@nvidia.com
Signed-off-by: Alex Williamson <alex@shazbot.org>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/ABI/testing/debugfs-vfio | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/debugfs-vfio b/Documentation/ABI/testing/debugfs-vfio index 70ec2d454686..ed2f29c3a9b4 100644 --- a/Documentation/ABI/testing/debugfs-vfio +++ b/Documentation/ABI/testing/debugfs-vfio @@ -29,3 +29,29 @@ Date: Oct 2025 KernelVersion: 6.18 Contact: Cédric Le Goater <clg@redhat.com> Description: Read the migration features of the vfio device. + +What: /sys/kernel/debug/vfio/<device>/pci +Date: June 2026 +KernelVersion: 7.2 +Contact: Alex Williamson <alex.williamson@nvidia.com> +Description: This debugfs file directory is used for debugging + VFIO PCI devices. + +What: /sys/kernel/debug/vfio/<device>/pci/nointxmask +Date: June 2026 +KernelVersion: 7.2 +Contact: Alex Williamson <alex.williamson@nvidia.com> +Description: Read the nointxmask policy latched for this device. This + policy governs whether the device may use PCI 2.3 style + INTx masking when supported, reporting a value of "N", or + requires APIC level INTx masking, reporting a value of "Y". + +What: /sys/kernel/debug/vfio/<device>/pci/disable_idle_d3 +Date: June 2026 +KernelVersion: 7.2 +Contact: Alex Williamson <alex.williamson@nvidia.com> +Description: Read the disable_idle_d3 policy latched for this device. This + policy governs whether the device PM runtime usage count is + kept elevated while the device is bound to the driver and + unused, reporting a value of "Y", or decremented to allow the + device to enter a low power state, reporting a value of "N". |