From 119e9db233ad0f4cbd4cfb9f9385a7bca378b37d Mon Sep 17 00:00:00 2001 From: Zeng Chi Date: Mon, 21 Sep 2026 18:24:42 +0800 Subject: KVM: Don't pre-reserve xarray entries when storing empty/NULL attributes Skip the xarray reservation loop when clearing all memory attributes, as storing NULL only erases the entry and never needs to allocate, so no reservation (and no cleanup of a failed one) is required in that case. Suggested-by: Sean Christopherson Cc: David Ballesteros Signed-off-by: Zeng Chi Link: https://patch.msgid.link/20260921102442.1232375-1-zeng_chi911@163.com [sean: split to separate patch] Signed-off-by: Sean Christopherson --- Documentation/gpu/amdgpu/ptl.rst | 94 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 94 insertions(+) create mode 100644 Documentation/gpu/amdgpu/ptl.rst (limited to 'Documentation/gpu/amdgpu/ptl.rst') diff --git a/Documentation/gpu/amdgpu/ptl.rst b/Documentation/gpu/amdgpu/ptl.rst new file mode 100644 index 000000000..c7f16dea7 --- /dev/null +++ b/Documentation/gpu/amdgpu/ptl.rst @@ -0,0 +1,94 @@ +======================================= +Peak Tops Limiter (PTL) sysfs Interface +======================================= + +Overview +-------- +The Peak Tops Limiter (PTL) sysfs interface enables users to control and +configure the PTL feature for each GPU individually. All PTL-related +sysfs files are located under `/sys/class/drm/cardX/device/ptl/`, where +`X` is the GPU index. Through these files, users can enable or disable +PTL, set preferred data formats, and query supported formats for each GPU. + +PTL sysfs files +---------------- +The following files are available under `/sys/class/drm/cardX/device/ptl/`: + +- `ptl_enable` +- `ptl_format` +- `ptl_supported_formats` + +PTL Enable/Disable +------------------ +File: `ptl_enable` +Type: Read/Write (rw) + +Read: Returns the current PTL status as a string: `enabled` if PTL +is active, or `disabled` if inactive. + +Write: + +- Write `1` or `enabled` to enable PTL +- Write `0` or `disabled` to disable PTL + +Examples:: + + # Query PTL status + cat /sys/class/drm/card1/device/ptl/ptl_enable + # Output: enabled + + # Enable PTL + sudo bash -c "echo 1 > /sys/class/drm/card1/device/ptl/ptl_enable" + + # Disable PTL + sudo bash -c "echo 0 > /sys/class/drm/card1/device/ptl/ptl_enable" + +PTL Format (Preferred Data Formats) +----------------------------------- +File: `ptl_format` +Type: Read/Write (rw) + +Read: Returns the two preferred formats, e.g. `I8,F32`. + +Write: Accepts two formats separated by a comma, e.g. `I8,F32`. + +- Both formats must be supported and different. +- If an invalid format is provided (not supported, or both formats are the + same), the driver will return "write error: Invalid argument". + +Examples:: + + # Query PTL formats + cat /sys/class/drm/card1/device/ptl/ptl_format + # Output: I8,F32 + + # Set PTL formats + sudo bash -c "echo I8,F32 > /sys/class/drm/card1/device/ptl/ptl_format" + +Supported Formats +----------------- +File: `ptl_supported_formats` +Type: Read-only (r) + +Read: Returns a comma-separated list of supported formats, e.g. +`I8,F16,BF16,F32,F64`. + +Example:: + + # Check supported formats + cat /sys/class/drm/card1/device/ptl/ptl_supported_formats + # Output: I8,F16,BF16,F32,F64 + +Behavioral Notes +---------------- +- PTL formats can only be set when PTL is enabled. +- If PTL is disabled, `ptl_format` returns `N/A`. +- Only two formats can be set at a time, and they must be from the supported set and different.. +- All commands support per-GPU targeting. +- Root permission is required to enable/disable PTL or change formats. +- If the hardware does not support PTL, the PTL sysfs directory will not + be created. + +Implementation +-------------- +The PTL sysfs nodes are implemented in `drivers/gpu/drm/amd/amdgpu/amdgpu_psp.c`. -- cgit v1.3.1