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CXL Reset is device scoped, requires affected memory to be idle, invalidates CPU caches, restores cached HDM decoder state, and does not request Memory Clear. Signed-off-by: Srirangan Madhavan --- Documentation/ABI/testing/sysfs-bus-pci | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/Documentation/ABI/testing/sysfs-bus-pci b/Documentation/ABI/testing/sysfs-bus-pci index b767db2c52cb..92e3f5840775 100644 --- a/Documentation/ABI/testing/sysfs-bus-pci +++ b/Documentation/ABI/testing/sysfs-bus-pci @@ -153,6 +153,22 @@ Description: "default" enables all supported reset methods in the default ordering. + If present, "cxl_reset" selects CXL Reset for CXL Type 2 + devices that advertise CXL Reset support. The method is only + listed for single-function devices so CXL Reset is not exposed + when the reset could affect another PCI function. + + Before issuing CXL Reset, the kernel rejects the operation if + cached HDM state is unavailable or affected CXL memory is busy. + On architectures that support explicit CPU cache invalidation for + memory ranges, the kernel invalidates CPU caches for enabled HDM + ranges; otherwise it warns and continues without that step. The + kernel then disables CXL.cache, initiates cache write-back where + supported, quiesces the PCI function, and issues CXL Reset. After + reset, the kernel restores PCI config state needed to access HDM + MMIO, restores cached HDM decoder state, and completes PCI reset + recovery. "cxl_reset" does not request CXL Reset Memory Clear. + What: /sys/bus/pci/devices/.../reset Date: July 2009 Contact: Michael S. Tsirkin -- 2.43.0