From 2bc6b218717b9d08f466f88209251d54bc09b207 Mon Sep 17 00:00:00 2001 From: Fuad Tabba Date: Tue, 22 Sep 2026 19:14:30 +0100 Subject: arm64/boot: Disable trapping of PMZR_EL0 writes to EL2 __init_el2_fgt2() writes one mask to both HDFGRTR2_EL2 and HDFGWTR2_EL2. PMZR_EL0 is write-only, so its trap bit, nPMZR_EL0, exists only in HDFGWTR2_EL2 and is therefore never set: a PMZR_EL0 write from the host traps to EL2, where the nVHE hypervisor has no handler and BUG()s. The kernel never writes PMZR_EL0, but kernel.perf_user_access=1 has the PMU driver set PMUSERENR_EL0.UEN for a task with a user-read event, so a write from EL0 reaches the trap and takes the host down without a panic message. Accumulate the HDFGWTR2_EL2 bits separately, as __init_el2_fgt() already does for HDFGWTR_EL2, and set nPMZR_EL0 with the other FEAT_PMUv3p9 bits. Fixes: 858c7bfcb35e1 ("arm64/boot: Enable EL2 requirements for FEAT_PMUv3p9") Cc: stable@vger.kernel.org Signed-off-by: Fuad Tabba Reviewed-by: Anshuman Khandual Reviewed-by: Oliver Upton Signed-off-by: Will Deacon --- Documentation/driver-api/fpga/fpga-programming.rst | 107 +++++++++++++++++++++ 1 file changed, 107 insertions(+) create mode 100644 Documentation/driver-api/fpga/fpga-programming.rst (limited to 'Documentation/driver-api/fpga/fpga-programming.rst') diff --git a/Documentation/driver-api/fpga/fpga-programming.rst b/Documentation/driver-api/fpga/fpga-programming.rst new file mode 100644 index 000000000..fb4da4240 --- /dev/null +++ b/Documentation/driver-api/fpga/fpga-programming.rst @@ -0,0 +1,107 @@ +In-kernel API for FPGA Programming +================================== + +Overview +-------- + +The in-kernel API for FPGA programming is a combination of APIs from +FPGA manager, bridge, and regions. The actual function used to +trigger FPGA programming is fpga_region_program_fpga(). + +fpga_region_program_fpga() uses functionality supplied by +the FPGA manager and bridges. It will: + + * lock the region's mutex + * lock the mutex of the region's FPGA manager + * build a list of FPGA bridges if a method has been specified to do so + * disable the bridges + * program the FPGA using info passed in :c:expr:`fpga_region->info`. + * re-enable the bridges + * release the locks + +The struct fpga_image_info specifies what FPGA image to program. It is +allocated/freed by fpga_image_info_alloc() and freed with +fpga_image_info_free() + +How to program an FPGA using a region +------------------------------------- + +When the FPGA region driver probed, it was given a pointer to an FPGA manager +driver so it knows which manager to use. The region also either has a list of +bridges to control during programming or it has a pointer to a function that +will generate that list. Here's some sample code of what to do next:: + + #include + #include + + struct fpga_image_info *info; + int ret; + + /* + * First, alloc the struct with information about the FPGA image to + * program. + */ + info = fpga_image_info_alloc(dev); + if (!info) + return -ENOMEM; + + /* Set flags as needed, such as: */ + info->flags = FPGA_MGR_PARTIAL_RECONFIG; + + /* + * Indicate where the FPGA image is. This is pseudo-code; you're + * going to use one of these three. + */ + if (image is in a scatter gather table) { + + info->sgt = [your scatter gather table] + + } else if (image is in a buffer) { + + info->buf = [your image buffer] + info->count = [image buffer size] + + } else if (image is in a firmware file) { + + info->firmware_name = devm_kstrdup(dev, firmware_name, + GFP_KERNEL); + + } + + /* Add info to region and do the programming */ + region->info = info; + ret = fpga_region_program_fpga(region); + + /* Deallocate the image info if you're done with it */ + region->info = NULL; + fpga_image_info_free(info); + + if (ret) + return ret; + + /* Now enumerate whatever hardware has appeared in the FPGA. */ + +API for programming an FPGA +--------------------------- + +* fpga_region_program_fpga() - Program an FPGA +* fpga_image_info() - Specifies what FPGA image to program +* fpga_image_info_alloc() - Allocate an FPGA image info struct +* fpga_image_info_free() - Free an FPGA image info struct + +.. kernel-doc:: drivers/fpga/fpga-region.c + :functions: fpga_region_program_fpga + +FPGA Manager flags + +.. kernel-doc:: include/linux/fpga/fpga-mgr.h + :doc: FPGA Manager flags + +.. kernel-doc:: include/linux/fpga/fpga-mgr.h + :functions: fpga_image_info + +.. kernel-doc:: drivers/fpga/fpga-mgr.c + :functions: fpga_image_info_alloc + +.. kernel-doc:: drivers/fpga/fpga-mgr.c + :functions: fpga_image_info_free -- cgit v1.3.1