This patch series ended up much larger than expected, please bear with me! The goal here is to support vendor extensions, starting at probing the device tree and ending with reporting to userspace.
The main design objective was to allow vendors to operate independently of each other. This has been achieved by delegating vendor extensions to a their own files and then accumulating the extensions in arch/riscv/kernel/vendor_extensions.c.
Each vendor will have their own list of extensions they support.
There is a new hwprobe key RISCV_HWPROBE_KEY_VENDOR_EXT_THEAD_0 that is used to request which thead vendor extensions are supported on the current platform. This allows future vendors to allocate hwprobe keys for their vendor.
On to the xtheadvector specific code. xtheadvector is a custom extension that is based upon riscv vector version 0.7.1 [1]. All of the vector routines have been modified to support this alternative vector version based upon whether xtheadvector was determined to be supported at boot. I have tested this with an Allwinner Nezha board. I ran into issues booting the board on 6.9-rc1 so I applied these patches to 6.8. There are a couple of minor merge conflicts that do arrise when doing that, so please let me know if you have been able to boot this board with a 6.9 kernel. I used SkiffOS [2] to manage building the image, but upgraded the U-Boot version to Samuel Holland's more up-to-date version [3] and changed out the device tree used by U-Boot with the device trees that are present in upstream linux and this series. Thank you Samuel for all of the work you did to make this task possible.
To test the integration, I used the riscv vector kselftests. I modified the test cases to be able to more easily extend them, and then added a xtheadvector target that works by calling hwprobe and swapping out the vector asm if needed.
[1] https://github.com/T-head-Semi/thead-extension-spec/blob/95358cb2cca9489361c... [2] https://github.com/skiffos/SkiffOS/tree/master/configs/allwinner/nezha [3] https://github.com/smaeul/u-boot/commit/2e89b706f5c956a70c989cd31665f1429e9a...
Signed-off-by: Charlie Jenkins charlie@rivosinc.com --- Changes in v5: - Make all vendors have the same size bitmap - Extract vendor hwprobe code into helper macro - Fix bug related to the handling of vendor extensions in the parsing of the isa string (Conor) - Fix bug with the vendor bitmap being incorrectly populated (Evan) - Add vendor extensions to /proc/cpuinfo - Link to v4: https://lore.kernel.org/r/20240426-dev-charlie-support_thead_vector_6_9-v4-0...
Changes in v4: - Disable vector immediately if vlenb from the device tree is not homogeneous - Hide vendor extension code behind a hidden config that vendor extensions select to eliminate the code when kernel is compiled without vendor extensions - Clear up naming conventions and introduce some defines to make the vendor extension code clearer - Link to v3: https://lore.kernel.org/r/20240420-dev-charlie-support_thead_vector_6_9-v3-0...
Changes in v3: - Allow any hardware to support any vendor extension, rather than restricting the vendor extensions to the same vendor as the hardware - Introduce config options to enable/disable a vendor's extensions - Link to v2: https://lore.kernel.org/r/20240415-dev-charlie-support_thead_vector_6_9-v2-0...
Changes in v2: - Added commit hash to xtheadvector - Simplified riscv,isa vector removal fix to not mess with the DT riscv,vendorid - Moved riscv,vendorid parsing into a different patch and cache the value to be used by alternative patching - Reduce riscv,vendorid missing severity to "info" - Separate vendor extension list to vendor files - xtheadvector no longer puts v in the elf_hwcap - Only patch vendor extension if all harts are associated with the same vendor. This is the best chance the kernel has for working properly if there are multiple vendors. - Split hwprobe vendor keys out into vendor file - Add attribution for Heiko's patches - Link to v1: https://lore.kernel.org/r/20240411-dev-charlie-support_thead_vector_6_9-v1-0...
--- Charlie Jenkins (15): dt-bindings: riscv: Add xtheadvector ISA extension description riscv: vector: Use vlenb from DT riscv: dts: allwinner: Add xtheadvector to the D1/D1s devicetree riscv: Extend cpufeature.c to detect vendor extensions riscv: Add vendor extensions to /proc/cpuinfo riscv: Introduce vendor variants of extension helpers riscv: cpufeature: Extract common elements from extension checking riscv: Convert xandespmu to use the vendor extension framework riscv: csr: Add CSR encodings for VCSR_VXRM/VCSR_VXSAT riscv: Add xtheadvector instruction definitions riscv: vector: Support xtheadvector save/restore riscv: hwprobe: Add thead vendor extension probing riscv: hwprobe: Document thead vendor extensions and xtheadvector extension selftests: riscv: Fix vector tests selftests: riscv: Support xtheadvector in vector tests
Conor Dooley (1): dt-bindings: riscv: cpus: add a vlen register length property
Heiko Stuebner (1): RISC-V: define the elements of the VCSR vector CSR
Documentation/arch/riscv/hwprobe.rst | 10 + Documentation/devicetree/bindings/riscv/cpus.yaml | 6 + .../devicetree/bindings/riscv/extensions.yaml | 10 + arch/riscv/Kconfig | 2 + arch/riscv/Kconfig.vendor | 44 +++ arch/riscv/boot/dts/allwinner/sun20i-d1s.dtsi | 3 +- arch/riscv/errata/andes/errata.c | 2 + arch/riscv/errata/sifive/errata.c | 3 + arch/riscv/errata/thead/errata.c | 3 + arch/riscv/include/asm/cpufeature.h | 98 ++++--- arch/riscv/include/asm/csr.h | 13 + arch/riscv/include/asm/hwcap.h | 1 - arch/riscv/include/asm/hwprobe.h | 4 +- arch/riscv/include/asm/switch_to.h | 2 +- arch/riscv/include/asm/vector.h | 247 +++++++++++++---- arch/riscv/include/asm/vendor_extensions.h | 103 +++++++ arch/riscv/include/asm/vendor_extensions/andes.h | 19 ++ arch/riscv/include/asm/vendor_extensions/thead.h | 42 +++ .../include/asm/vendor_extensions/thead_hwprobe.h | 18 ++ .../include/asm/vendor_extensions/vendor_hwprobe.h | 34 +++ arch/riscv/include/uapi/asm/hwprobe.h | 3 +- arch/riscv/include/uapi/asm/vendor/thead.h | 3 + arch/riscv/kernel/Makefile | 2 + arch/riscv/kernel/cpu.c | 35 ++- arch/riscv/kernel/cpufeature.c | 171 +++++++++--- arch/riscv/kernel/kernel_mode_vector.c | 8 +- arch/riscv/kernel/process.c | 4 +- arch/riscv/kernel/signal.c | 6 +- arch/riscv/kernel/sys_hwprobe.c | 5 + arch/riscv/kernel/vector.c | 25 +- arch/riscv/kernel/vendor_extensions.c | 66 +++++ arch/riscv/kernel/vendor_extensions/Makefile | 5 + arch/riscv/kernel/vendor_extensions/andes.c | 18 ++ arch/riscv/kernel/vendor_extensions/thead.c | 18 ++ .../riscv/kernel/vendor_extensions/thead_hwprobe.c | 19 ++ drivers/perf/riscv_pmu_sbi.c | 9 +- tools/testing/selftests/riscv/vector/.gitignore | 3 +- tools/testing/selftests/riscv/vector/Makefile | 17 +- .../selftests/riscv/vector/v_exec_initval_nolibc.c | 93 +++++++ tools/testing/selftests/riscv/vector/v_helpers.c | 67 +++++ tools/testing/selftests/riscv/vector/v_helpers.h | 7 + tools/testing/selftests/riscv/vector/v_initval.c | 22 ++ .../selftests/riscv/vector/v_initval_nolibc.c | 68 ----- .../selftests/riscv/vector/vstate_exec_nolibc.c | 20 +- .../testing/selftests/riscv/vector/vstate_prctl.c | 295 ++++++++++++--------- 45 files changed, 1312 insertions(+), 341 deletions(-) --- base-commit: 4cece764965020c22cff7665b18a012006359095 change-id: 20240411-dev-charlie-support_thead_vector_6_9-1591fc2a431d