kernel.git/arch/riscv/errata, branch linux-6.10.y

Merge tag 'riscv-for-linus-6.10-mw1' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux

2024-05-22T16:56:00Z

Pull RISC-V updates from Palmer Dabbelt: - Add byte/half-word compare-and-exchange, emulated via LR/SC loops - Support for Rust - Support for Zihintpause in hwprobe - Add PR_RISCV_SET_ICACHE_FLUSH_CTX prctl() - Support lockless lockrefs * tag 'riscv-for-linus-6.10-mw1' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux: (42 commits) riscv: defconfig: Enable CONFIG_CLK_SOPHGO_CV1800 riscv: select ARCH_HAS_FAST_MULTIPLIER riscv: mm: still create swiotlb buffer for kmalloc() bouncing if required riscv: Annotate pgtable_l{4,5}_enabled with __ro_after_init riscv: Remove redundant CONFIG_64BIT from pgtable_l{4,5}_enabled riscv: mm: Always use an ASID to flush mm contexts riscv: mm: Preserve global TLB entries when switching contexts riscv: mm: Make asid_bits a local variable riscv: mm: Use a fixed layout for the MM context ID riscv: mm: Introduce cntx2asid/cntx2version helper macros riscv: Avoid TLB flush loops when affected by SiFive CIP-1200 riscv: Apply SiFive CIP-1200 workaround to single-ASID sfence.vma riscv: mm: Combine the SMP and UP TLB flush code riscv: Only send remote fences when some other CPU is online riscv: mm: Broadcast kernel TLB flushes only when needed riscv: Use IPIs for remote cache/TLB flushes by default riscv: Factor out page table TLB synchronization riscv: Flush the instruction cache during SMP bringup riscv: hwprobe: export Zihintpause ISA extension riscv: misaligned: remove CONFIG_RISCV_M_MODE specific code ...

riscv: Avoid TLB flush loops when affected by SiFive CIP-1200

2024-04-29T17:49:31Z

Implementations affected by SiFive errata CIP-1200 have a bug which forces the kernel to always use the global variant of the sfence.vma instruction. When affected by this errata, do not attempt to flush a range of addresses; each iteration of the loop would actually flush the whole TLB instead. Instead, minimize the overall number of sfence.vma instructions. Signed-off-by: Samuel Holland Reviewed-by: Yunhui Cui Link: https://lore.kernel.org/r/20240327045035.368512-9-samuel.holland@sifive.com Signed-off-by: Palmer Dabbelt

Merge patch series "RISC-V: Test th.sxstatus.MAEE bit before enabling MAEE"

2024-04-26T17:21:57Z

Christoph Müllner says: Currently, the Linux kernel suffers from a boot regression when running on the c906 QEMU emulation. Details have been reported here by Björn Töpel: https://lists.gnu.org/archive/html/qemu-devel/2024-01/msg04766.html The main issue is, that Linux enables XTheadMae for CPUs that have a T-Head mvendorid but QEMU maintainers don't want to emulate a CPU that uses reserved bits in PTEs. See also the following discussion for more context: https://lists.gnu.org/archive/html/qemu-devel/2024-02/msg00775.html This series renames "T-Head PBMT" to "MAE"/"XTheadMae" and only enables it if the th.sxstatus.MAEE bit is set. The th.sxstatus CSR is documented here: https://github.com/T-head-Semi/thead-extension-spec/blob/master/xtheadsxstatus.adoc XTheadMae is documented here: https://github.com/T-head-Semi/thead-extension-spec/blob/master/xtheadmae.adoc The QEMU patch to emulate th.sxstatus with the MAEE bit not set is here: https://lore.kernel.org/all/20240329120427.684677-1-christoph.muellner@vrull.eu/ After applying the referenced QEMU patch, this patchset allows to successfully boot a C906 QEMU system emulation ("-cpu thead-c906"). * b4-shazam-lts: riscv: T-Head: Test availability bit before enabling MAE errata riscv: thead: Rename T-Head PBMT to MAE Link: https://lore.kernel.org/r/20240407213236.2121592-1-christoph.muellner@vrull.eu Signed-off-by: Palmer Dabbelt

riscv: T-Head: Test availability bit before enabling MAE errata

2024-04-25T17:22:34Z

T-Head's memory attribute extension (XTheadMae) (non-compatible equivalent of RVI's Svpbmt) is currently assumed for all T-Head harts. However, QEMU recently decided to drop acceptance of guests that write reserved bits in PTEs. As XTheadMae uses reserved bits in PTEs and Linux applies the MAE errata for all T-Head harts, this broke the Linux startup on QEMU emulations of the C906 emulation. This patch attempts to address this issue by testing the MAE-enable bit in the th.sxstatus CSR. This CSR is available in HW and can be emulated in QEMU. This patch also makes the XTheadMae probing mechanism reliable, because a test for the right combination of mvendorid, marchid, and mimpid is not sufficient to enable MAE. Reviewed-by: Conor Dooley Signed-off-by: Christoph Müllner Link: https://lore.kernel.org/r/20240407213236.2121592-3-christoph.muellner@vrull.eu Signed-off-by: Palmer Dabbelt

riscv: thead: Rename T-Head PBMT to MAE

2024-04-25T17:22:33Z

T-Head's vendor extension to set page attributes has the name MAE (memory attribute extension). Let's rename it, so it is clear what this referes to. Link: https://github.com/T-head-Semi/thead-extension-spec/blob/master/xtheadmae.adoc Reviewed-by: Conor Dooley Signed-off-by: Christoph Müllner Link: https://lore.kernel.org/r/20240407213236.2121592-2-christoph.muellner@vrull.eu Signed-off-by: Palmer Dabbelt

riscv: errata: Rename defines for Andes

2024-03-12T14:13:12Z

Use "ANDES" rather than "ANDESTECH" to unify the naming convention with directory, file names, Kconfig options and other definitions. Signed-off-by: Yu Chien Peter Lin Reviewed-by: Charles Ci-Jyun Wu Reviewed-by: Leo Yu-Chi Liang Acked-by: Conor Dooley Reviewed-by: Lad Prabhakar Link: https://lore.kernel.org/r/20240222083946.3977135-2-peterlin@andestech.com Signed-off-by: Palmer Dabbelt

Merge patch series "riscv: errata: thead: use riscv_nonstd_cache_ops for CMO"

2024-01-11T15:36:30Z

Jisheng Zhang says: Previously, we use alternative mechanism to dynamically patch the CMO operations for THEAD C906/C910 during boot for performance reason. But as pointed out by Arnd, "there is already a significant cost in accessing the invalidated cache lines afterwards, which is likely going to be much higher than the cost of an indirect branch". And indeed, there's no performance difference with GMAC and EMMC per my test on Sipeed Lichee Pi 4A board. Use riscv_nonstd_cache_ops for THEAD C906/C910 CMO to simplify the alternative code, and to acchieve Arnd's goal -- "I think moving the THEAD ops at the same level as all nonstandard operations makes sense, but I'd still leave CMO as an explicit fast path that avoids the indirect branch. This seems like the right thing to do both for readability and for platforms on which the indirect branch has a noticeable overhead." To make bisect easy, I use two patches here: patch1 does the conversion which just mimics current CMO behavior via. riscv_nonstd_cache_ops, I assume no functionalities changes. patch2 uses T-HEAD PA based CMO instructions so that we don't need to covert PA to VA. * b4-shazam-merge: riscv: errata: thead: use pa based instructions for CMO riscv: errata: thead: use riscv_nonstd_cache_ops for CMO Link: https://lore.kernel.org/r/20231114143338.2406-1-jszhang@kernel.org Signed-off-by: Palmer Dabbelt

riscv: errata: thead: use pa based instructions for CMO

2024-01-10T17:54:27Z

T-HEAD CPUs such as C906/C910/C920 support phy address based CMO, use them so that we don't need to convert to virt address. Signed-off-by: Jisheng Zhang Reviewed-by: Guo Ren Link: https://lore.kernel.org/r/20231114143338.2406-3-jszhang@kernel.org Signed-off-by: Palmer Dabbelt

riscv: errata: thead: use riscv_nonstd_cache_ops for CMO

2024-01-10T17:54:26Z

Previously, we use alternative mechanism to dynamically patch the CMO operations for THEAD C906/C910 during boot for performance reason. But as pointed out by Arnd, "there is already a significant cost in accessing the invalidated cache lines afterwards, which is likely going to be much higher than the cost of an indirect branch". And indeed, there's no performance difference with GMAC and EMMC per my test on Sipeed Lichee Pi 4A board. Use riscv_nonstd_cache_ops for THEAD C906/C910 CMO to simplify the alternative code, and to acchieve Arnd's goal -- "I think moving the THEAD ops at the same level as all nonstandard operations makes sense, but I'd still leave CMO as an explicit fast path that avoids the indirect branch. This seems like the right thing to do both for readability and for platforms on which the indirect branch has a noticeable overhead." Signed-off-by: Jisheng Zhang Tested-by: Emil Renner Berthing Reviewed-by: Conor Dooley Link: https://lore.kernel.org/r/20231114143338.2406-2-jszhang@kernel.org Signed-off-by: Palmer Dabbelt

riscv: errata: andes: Probe for IOCP only once in boot stage

2023-12-06T15:18:58Z

We need to probe for IOCP only once during boot stage, as we were probing for IOCP for all the stages this caused the below issue during module-init stage, [9.019104] Unable to handle kernel paging request at virtual address ffffffff8100d3a0 [9.027153] Oops [#1] [9.029421] Modules linked in: rcar_canfd renesas_usbhs i2c_riic can_dev spi_rspi i2c_core [9.037686] CPU: 0 PID: 90 Comm: udevd Not tainted 6.7.0-rc1+ #57 [9.043756] Hardware name: Renesas SMARC EVK based on r9a07g043f01 (DT) [9.050339] epc : riscv_noncoherent_supported+0x10/0x3e [9.055558] ra : andes_errata_patch_func+0x4a/0x52 [9.060418] epc : ffffffff8000d8c2 ra : ffffffff8000d95c sp : ffffffc8003abb00 [9.067607] gp : ffffffff814e25a0 tp : ffffffd80361e540 t0 : 0000000000000000 [9.074795] t1 : 000000000900031e t2 : 0000000000000001 s0 : ffffffc8003abb20 [9.081984] s1 : ffffffff015b57c7 a0 : 0000000000000000 a1 : 0000000000000001 [9.089172] a2 : 0000000000000000 a3 : 0000000000000000 a4 : ffffffff8100d8be [9.096360] a5 : 0000000000000001 a6 : 0000000000000001 a7 : 000000000900031e [9.103548] s2 : ffffffff015b57d7 s3 : 0000000000000001 s4 : 000000000000031e [9.110736] s5 : 8000000000008a45 s6 : 0000000000000500 s7 : 000000000000003f [9.117924] s8 : ffffffc8003abd48 s9 : ffffffff015b1140 s10: ffffffff8151a1b0 [9.125113] s11: ffffffff015b1000 t3 : 0000000000000001 t4 : fefefefefefefeff [9.132301] t5 : ffffffff015b57c7 t6 : ffffffd8b63a6000 [9.137587] status: 0000000200000120 badaddr: ffffffff8100d3a0 cause: 000000000000000f [9.145468] [] riscv_noncoherent_supported+0x10/0x3e [9.151972] [] _apply_alternatives+0x84/0x86 [9.157784] [] apply_module_alternatives+0x10/0x1a [9.164113] [] module_finalize+0x5e/0x7a [9.169583] [] load_module+0xfd8/0x179c [9.174965] [] init_module_from_file+0x76/0xaa [9.180948] [] __riscv_sys_finit_module+0x176/0x2a8 [9.187365] [] do_trap_ecall_u+0xbe/0x130 [9.192922] [] ret_from_exception+0x0/0x64 [9.198573] Code: 0009 b7e9 6797 014d a783 85a7 c799 4785 0717 0100 (0123) aef7 [9.205994] ---[ end trace 0000000000000000 ]--- This is because we called riscv_noncoherent_supported() for all the stages during IOCP probe. riscv_noncoherent_supported() function sets noncoherent_supported variable to true which has an annotation set to "__ro_after_init" due to which we were seeing the above splat. Fix this by probing for IOCP only once in boot stage by having a boolean variable "done" which will be set to true upon IOCP probe in errata_probe_iocp() and we bail out early if "done" is set to true. While at it make return type of errata_probe_iocp() to void as we were not checking the return value in andes_errata_patch_func(). Fixes: e021ae7f5145 ("riscv: errata: Add Andes alternative ports") Signed-off-by: Lad Prabhakar Reviewed-by: Geert Uytterhoeven Reviewed-by: Yu Chien Peter Lin Link: https://lore.kernel.org/r/20231130212647.108746-1-prabhakar.mahadev-lad.rj@bp.renesas.com Signed-off-by: Palmer Dabbelt