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Message-ID: <3a26b273-7014-448a-b12c-d8a48b7d8fc6@ghiti.fr> Date: Thu, 5 Jun 2025 09:12:09 +0200 From: Alexandre Ghiti <alex@...ti.fr> To: Charlie Jenkins <charlie@...osinc.com>, Palmer Dabbelt <palmer@...belt.com> Cc: cleger@...osinc.com, Paul Walmsley <paul.walmsley@...ive.com>, anup@...infault.org, atishp@...shpatra.org, shuah@...nel.org, corbet@....net, linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org, kvm@...r.kernel.org, kvm-riscv@...ts.infradead.org, linux-kselftest@...r.kernel.org, samuel.holland@...ive.com, ajones@...tanamicro.com, debug@...osinc.com Subject: Re: [PATCH v8 00/14] riscv: add SBI FWFT misaligned exception delegation support On 6/4/25 21:32, Charlie Jenkins wrote: > On Wed, Jun 04, 2025 at 11:02:35AM -0700, Palmer Dabbelt wrote: >> On Fri, 23 May 2025 03:19:17 PDT (-0700), cleger@...osinc.com wrote: >>> The SBI Firmware Feature extension allows the S-mode to request some >>> specific features (either hardware or software) to be enabled. This >>> series uses this extension to request misaligned access exception >>> delegation to S-mode in order to let the kernel handle it. It also adds >>> support for the KVM FWFT SBI extension based on the misaligned access >>> handling infrastructure. >>> >>> FWFT SBI extension is part of the SBI V3.0 specifications [1]. It can be >>> tested using the qemu provided at [2] which contains the series from >>> [3]. Upstream kvm-unit-tests can be used inside kvm to tests the correct >>> delegation of misaligned exceptions. Upstream OpenSBI can be used. >>> >>> Note: Since SBI V3.0 is not yet ratified, FWFT extension API is split >>> between interface only and implementation, allowing to pick only the >>> interface which do not have hard dependencies on SBI. >>> >>> The tests can be run using the kselftest from series [4]. >>> >>> $ qemu-system-riscv64 \ >>> -cpu rv64,trap-misaligned-access=true,v=true \ >>> -M virt \ >>> -m 1024M \ >>> -bios fw_dynamic.bin \ >>> -kernel Image >>> ... >>> >>> # ./misaligned >>> TAP version 13 >>> 1..23 >>> # Starting 23 tests from 1 test cases. >>> # RUN global.gp_load_lh ... >>> # OK global.gp_load_lh >>> ok 1 global.gp_load_lh >>> # RUN global.gp_load_lhu ... >>> # OK global.gp_load_lhu >>> ok 2 global.gp_load_lhu >>> # RUN global.gp_load_lw ... >>> # OK global.gp_load_lw >>> ok 3 global.gp_load_lw >>> # RUN global.gp_load_lwu ... >>> # OK global.gp_load_lwu >>> ok 4 global.gp_load_lwu >>> # RUN global.gp_load_ld ... >>> # OK global.gp_load_ld >>> ok 5 global.gp_load_ld >>> # RUN global.gp_load_c_lw ... >>> # OK global.gp_load_c_lw >>> ok 6 global.gp_load_c_lw >>> # RUN global.gp_load_c_ld ... >>> # OK global.gp_load_c_ld >>> ok 7 global.gp_load_c_ld >>> # RUN global.gp_load_c_ldsp ... >>> # OK global.gp_load_c_ldsp >>> ok 8 global.gp_load_c_ldsp >>> # RUN global.gp_load_sh ... >>> # OK global.gp_load_sh >>> ok 9 global.gp_load_sh >>> # RUN global.gp_load_sw ... >>> # OK global.gp_load_sw >>> ok 10 global.gp_load_sw >>> # RUN global.gp_load_sd ... >>> # OK global.gp_load_sd >>> ok 11 global.gp_load_sd >>> # RUN global.gp_load_c_sw ... >>> # OK global.gp_load_c_sw >>> ok 12 global.gp_load_c_sw >>> # RUN global.gp_load_c_sd ... >>> # OK global.gp_load_c_sd >>> ok 13 global.gp_load_c_sd >>> # RUN global.gp_load_c_sdsp ... >>> # OK global.gp_load_c_sdsp >>> ok 14 global.gp_load_c_sdsp >>> # RUN global.fpu_load_flw ... >>> # OK global.fpu_load_flw >>> ok 15 global.fpu_load_flw >>> # RUN global.fpu_load_fld ... >>> # OK global.fpu_load_fld >>> ok 16 global.fpu_load_fld >>> # RUN global.fpu_load_c_fld ... >>> # OK global.fpu_load_c_fld >>> ok 17 global.fpu_load_c_fld >>> # RUN global.fpu_load_c_fldsp ... >>> # OK global.fpu_load_c_fldsp >>> ok 18 global.fpu_load_c_fldsp >>> # RUN global.fpu_store_fsw ... >>> # OK global.fpu_store_fsw >>> ok 19 global.fpu_store_fsw >>> # RUN global.fpu_store_fsd ... >>> # OK global.fpu_store_fsd >>> ok 20 global.fpu_store_fsd >>> # RUN global.fpu_store_c_fsd ... >>> # OK global.fpu_store_c_fsd >>> ok 21 global.fpu_store_c_fsd >>> # RUN global.fpu_store_c_fsdsp ... >>> # OK global.fpu_store_c_fsdsp >>> ok 22 global.fpu_store_c_fsdsp >>> # RUN global.gen_sigbus ... >>> [12797.988647] misaligned[618]: unhandled signal 7 code 0x1 at 0x0000000000014dc0 in misaligned[4dc0,10000+76000] >>> [12797.988990] CPU: 0 UID: 0 PID: 618 Comm: misaligned Not tainted 6.13.0-rc6-00008-g4ec4468967c9-dirty #51 >>> [12797.989169] Hardware name: riscv-virtio,qemu (DT) >>> [12797.989264] epc : 0000000000014dc0 ra : 0000000000014d00 sp : 00007fffe165d100 >>> [12797.989407] gp : 000000000008f6e8 tp : 0000000000095760 t0 : 0000000000000008 >>> [12797.989544] t1 : 00000000000965d8 t2 : 000000000008e830 s0 : 00007fffe165d160 >>> [12797.989692] s1 : 000000000000001a a0 : 0000000000000000 a1 : 0000000000000002 >>> [12797.989831] a2 : 0000000000000000 a3 : 0000000000000000 a4 : ffffffffdeadbeef >>> [12797.989964] a5 : 000000000008ef61 a6 : 626769735f6e0000 a7 : fffffffffffff000 >>> [12797.990094] s2 : 0000000000000001 s3 : 00007fffe165d838 s4 : 00007fffe165d848 >>> [12797.990238] s5 : 000000000000001a s6 : 0000000000010442 s7 : 0000000000010200 >>> [12797.990391] s8 : 000000000000003a s9 : 0000000000094508 s10: 0000000000000000 >>> [12797.990526] s11: 0000555567460668 t3 : 00007fffe165d070 t4 : 00000000000965d0 >>> [12797.990656] t5 : fefefefefefefeff t6 : 0000000000000073 >>> [12797.990756] status: 0000000200004020 badaddr: 000000000008ef61 cause: 0000000000000006 >>> [12797.990911] Code: 8793 8791 3423 fcf4 3783 fc84 c737 dead 0713 eef7 (c398) 0001 >>> # OK global.gen_sigbus >>> ok 23 global.gen_sigbus >>> # PASSED: 23 / 23 tests passed. >>> # Totals: pass:23 fail:0 xfail:0 xpass:0 skip:0 error:0 >>> >>> With kvm-tools: >>> >>> # lkvm run -k sbi.flat -m 128 >>> Info: # lkvm run -k sbi.flat -m 128 -c 1 --name guest-97 >>> Info: Removed ghost socket file "/root/.lkvm//guest-97.sock". >>> >>> ########################################################################## >>> # kvm-unit-tests >>> ########################################################################## >>> >>> ... [test messages elided] >>> PASS: sbi: fwft: FWFT extension probing no error >>> PASS: sbi: fwft: get/set reserved feature 0x6 error == SBI_ERR_DENIED >>> PASS: sbi: fwft: get/set reserved feature 0x3fffffff error == SBI_ERR_DENIED >>> PASS: sbi: fwft: get/set reserved feature 0x80000000 error == SBI_ERR_DENIED >>> PASS: sbi: fwft: get/set reserved feature 0xbfffffff error == SBI_ERR_DENIED >>> PASS: sbi: fwft: misaligned_deleg: Get misaligned deleg feature no error >>> PASS: sbi: fwft: misaligned_deleg: Set misaligned deleg feature invalid value error >>> PASS: sbi: fwft: misaligned_deleg: Set misaligned deleg feature invalid value error >>> PASS: sbi: fwft: misaligned_deleg: Set misaligned deleg feature value no error >>> PASS: sbi: fwft: misaligned_deleg: Set misaligned deleg feature value 0 >>> PASS: sbi: fwft: misaligned_deleg: Set misaligned deleg feature value no error >>> PASS: sbi: fwft: misaligned_deleg: Set misaligned deleg feature value 1 >>> PASS: sbi: fwft: misaligned_deleg: Verify misaligned load exception trap in supervisor >>> SUMMARY: 50 tests, 2 unexpected failures, 12 skipped >>> >>> This series is available at [5]. >>> >>> Link: https://github.com/riscv-non-isa/riscv-sbi-doc/releases/download/vv3.0-rc2/riscv-sbi.pdf [1] >>> Link: https://github.com/rivosinc/qemu/tree/dev/cleger/misaligned [2] >>> Link: https://lore.kernel.org/all/20241211211933.198792-3-fkonrad@amd.com/T/ [3] >>> Link: https://lore.kernel.org/linux-riscv/20250414123543.1615478-1-cleger@rivosinc.com [4] >>> Link: https://github.com/rivosinc/linux/tree/dev/cleger/fwft [5] >>> --- >>> >>> V8: >>> - Move misaligned_access_speed under CONFIG_RISCV_MISALIGNED and add a >>> separate commit for that. >>> >>> V7: >>> - Fix ifdefery build problems >>> - Move sbi_fwft_is_supported with fwft_set_req struct >>> - Added Atish Reviewed-by >>> - Updated KVM vcpu cfg hedeleg value in set_delegation >>> - Changed SBI ETIME error mapping to ETIMEDOUT >>> - Fixed a few typo reported by Alok >>> >>> V6: >>> - Rename FWFT interface to remove "_local" >>> - Fix test for MEDELEG values in KVM FWFT support >>> - Add __init for unaligned_access_init() >>> - Rebased on master >>> >>> V5: >>> - Return ERANGE as mapping for SBI_ERR_BAD_RANGE >>> - Removed unused sbi_fwft_get() >>> - Fix kernel for sbi_fwft_local_set_cpumask() >>> - Fix indentation for sbi_fwft_local_set() >>> - Remove spurious space in kvm_sbi_fwft_ops. >>> - Rebased on origin/master >>> - Remove fixes commits and sent them as a separate series [4] >>> >>> V4: >>> - Check SBI version 3.0 instead of 2.0 for FWFT presence >>> - Use long for kvm_sbi_fwft operation return value >>> - Init KVM sbi extension even if default_disabled >>> - Remove revert_on_fail parameter for sbi_fwft_feature_set(). >>> - Fix comments for sbi_fwft_set/get() >>> - Only handle local features (there are no globals yet in the spec) >>> - Add new SBI errors to sbi_err_map_linux_errno() >>> >>> V3: >>> - Added comment about kvm sbi fwft supported/set/get callback >>> requirements >>> - Move struct kvm_sbi_fwft_feature in kvm_sbi_fwft.c >>> - Add a FWFT interface >>> >>> V2: >>> - Added Kselftest for misaligned testing >>> - Added get_user() usage instead of __get_user() >>> - Reenable interrupt when possible in misaligned access handling >>> - Document that riscv supports unaligned-traps >>> - Fix KVM extension state when an init function is present >>> - Rework SBI misaligned accesses trap delegation code >>> - Added support for CPU hotplugging >>> - Added KVM SBI reset callback >>> - Added reset for KVM SBI FWFT lock >>> - Return SBI_ERR_DENIED_LOCKED when LOCK flag is set >>> >>> Clément Léger (14): >>> riscv: sbi: add Firmware Feature (FWFT) SBI extensions definitions >>> riscv: sbi: remove useless parenthesis >>> riscv: sbi: add new SBI error mappings >>> riscv: sbi: add FWFT extension interface >>> riscv: sbi: add SBI FWFT extension calls >>> riscv: misaligned: request misaligned exception from SBI >>> riscv: misaligned: use on_each_cpu() for scalar misaligned access >>> probing >>> riscv: misaligned: declare misaligned_access_speed under >>> CONFIG_RISCV_MISALIGNED >>> riscv: misaligned: move emulated access uniformity check in a function >>> riscv: misaligned: add a function to check misalign trap delegability >>> RISC-V: KVM: add SBI extension init()/deinit() functions >>> RISC-V: KVM: add SBI extension reset callback >>> RISC-V: KVM: add support for FWFT SBI extension >>> RISC-V: KVM: add support for SBI_FWFT_MISALIGNED_DELEG >>> >>> arch/riscv/include/asm/cpufeature.h | 14 +- >>> arch/riscv/include/asm/kvm_host.h | 5 +- >>> arch/riscv/include/asm/kvm_vcpu_sbi.h | 12 + >>> arch/riscv/include/asm/kvm_vcpu_sbi_fwft.h | 29 +++ >>> arch/riscv/include/asm/sbi.h | 60 +++++ >>> arch/riscv/include/uapi/asm/kvm.h | 1 + >>> arch/riscv/kernel/sbi.c | 81 ++++++- >>> arch/riscv/kernel/traps_misaligned.c | 112 ++++++++- >>> arch/riscv/kernel/unaligned_access_speed.c | 8 +- >>> arch/riscv/kvm/Makefile | 1 + >>> arch/riscv/kvm/vcpu.c | 4 +- >>> arch/riscv/kvm/vcpu_sbi.c | 54 +++++ >>> arch/riscv/kvm/vcpu_sbi_fwft.c | 257 +++++++++++++++++++++ >>> arch/riscv/kvm/vcpu_sbi_sta.c | 3 +- >>> 14 files changed, 620 insertions(+), 21 deletions(-) >>> create mode 100644 arch/riscv/include/asm/kvm_vcpu_sbi_fwft.h >>> create mode 100644 arch/riscv/kvm/vcpu_sbi_fwft.c >> Sorry I'm still kind of out of it here, but I think Alex was saying this has >> dependencies in the patchwork call this morning? Yes, you need this patchset too: https://lore.kernel.org/linux-riscv/20250602193918.868962-1-cleger@rivosinc.com/ I prepared a PR that does not merge the KVM parts and I checked with Anup, he will merge them in the next MW. My PR with FWFT passed the CI, so I'll send it now anyway. Thanks, Alex > The "dependency" is that the kvm tree will not accept patches this late. > The KVM patches can be dropped and the riscv patches can be merged, but > it is pretty late now. > > - Charlie > > > _______________________________________________ > linux-riscv mailing list > linux-riscv@...ts.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-riscv
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