Messages in this thread | | | Date | Wed, 28 Jul 2021 21:30:19 -0700 (PDT) | Subject | Re: [PATCH v7 1/1] RISC-V: Use SBI SRST extension when available | From | Palmer Dabbelt <> |
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On Sun, 11 Jul 2021 11:59:33 PDT (-0700), Palmer Dabbelt wrote: > On Fri, 09 Jul 2021 22:01:02 PDT (-0700), Anup Patel wrote: >> >> >> On 08/07/21, 9:22 AM, "Anup Patel" <anup@brainfault.org> wrote: >> >> On Wed, Jul 7, 2021 at 1:57 AM Palmer Dabbelt <palmerdabbelt@google.com> wrote: >> > >> > On Mon, 21 Jun 2021 21:46:46 PDT (-0700), anup@brainfault.org wrote: >> > > Hi Palmer, >> > > >> > > On Wed, Jun 9, 2021 at 5:43 PM Anup Patel <anup.patel@wdc.com> wrote: >> > >> >> > >> The SBI SRST extension provides a standard way to poweroff and >> > >> reboot the system irrespective to whether Linux RISC-V S-mode >> > >> is running natively (HS-mode) or inside Guest/VM (VS-mode). >> > >> >> > >> The SBI SRST extension is available in the SBI v0.3 specification. >> > >> (Refer, https://github.com/riscv/riscv-sbi-doc/releases/tag/v0.3.0-rc1) >> > > >> > > Can you please consider this patch for Linux-5.14-rc1 ? >> > > >> > > The SBI v0.3 spec is already frozen and this patch has been >> > > floating on LKML for quite a few months now. >> > >> > I didn't realize that SBI-0.3 had been frozed. That link is to a RC, >> > the cooresponding v0.3.0 tag isn't in that repo. Can you give me a >> > pointer to the frozen spec? >> >> Here's the link to SBI v0.3.0 tag: >> https://github.com/riscv/riscv-sbi-doc/releases/tag/v0.3.0 >> >> We treat RC tags as frozen in SBI spec because no functional >> changes are done in SBI spec after it is tagged as RC. We only >> do typo fixes and clarifications on SBI spec RC release. > > Treating the 0.3.0-rc1 as frozen as soon as it's released is a > terrifying policy: some of the fixes I sent in after I saw rc1 released > change the actual meaning of the text, even if they were meant to change > them to what I thought the intended meaning was supposed to be. That > means the actual text of 0.3.0-rc1 and 0.3.0 conflict with each other. > Given that frozen comes with a guarntee of backwards compatibility, does > that mean that the behavior allowed by 0.3.0-rc1 is compliant with the > SBI, even if it was likely just allowed by a wording mistake? > > If you're going to freeze things at rc1 then you really need to be quite > explicit about that, as generally the point of RCs is to elicit > review/testing. Looks like I was the only person to have provided any > review, so I guess I was the only one who assumed "We don't expect any > significant functional changes. We will wait for any further feedback > and release the official v0.3 in a month or so." actually meant "this is > frozen". > >> Can you take this patch for Linux-5.14 ?? > > No, sorry, it's way too late for that. Please be specific about when > you freeze specifications in the future, so we can all stay on the same > page.
I went and talked to Krste, and he says that there's a whole process for freezing extensions that this hasn't gone through. They don't have anything written down that I can point to, but can you guys please just get on the same page about this? It seems like every time I talk to someone from the RISC-V foundation I get a conflicting description of what's going on, and I'm entirely out of patience when it comes to getting blamed for all the chaos over there.
> >> >> Regards, >> Anup >> >> Regards, >> Anup >> >> > >> > > >> > > Regards, >> > > Anup >> > > >> > >> >> > >> This patch extends Linux RISC-V SBI implementation to detect >> > >> and use SBI SRST extension. >> > >> >> > >> Signed-off-by: Anup Patel <anup.patel@wdc.com> >> > >> Reviewed-by: Atish Patra <atish.patra@wdc.com> >> > >> --- >> > >> arch/riscv/include/asm/sbi.h | 24 ++++++++++++++++++++++++ >> > >> arch/riscv/kernel/sbi.c | 35 +++++++++++++++++++++++++++++++++++ >> > >> 2 files changed, 59 insertions(+) >> > >> >> > >> diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h >> > >> index 0d42693cb65e..289621da4a2a 100644 >> > >> --- a/arch/riscv/include/asm/sbi.h >> > >> +++ b/arch/riscv/include/asm/sbi.h >> > >> @@ -27,6 +27,7 @@ enum sbi_ext_id { >> > >> SBI_EXT_IPI = 0x735049, >> > >> SBI_EXT_RFENCE = 0x52464E43, >> > >> SBI_EXT_HSM = 0x48534D, >> > >> + SBI_EXT_SRST = 0x53525354, >> > >> }; >> > >> >> > >> enum sbi_ext_base_fid { >> > >> @@ -70,6 +71,21 @@ enum sbi_hsm_hart_status { >> > >> SBI_HSM_HART_STATUS_STOP_PENDING, >> > >> }; >> > >> >> > >> +enum sbi_ext_srst_fid { >> > >> + SBI_EXT_SRST_RESET = 0, >> > >> +}; >> > >> + >> > >> +enum sbi_srst_reset_type { >> > >> + SBI_SRST_RESET_TYPE_SHUTDOWN = 0, >> > >> + SBI_SRST_RESET_TYPE_COLD_REBOOT, >> > >> + SBI_SRST_RESET_TYPE_WARM_REBOOT, >> > >> +}; >> > >> + >> > >> +enum sbi_srst_reset_reason { >> > >> + SBI_SRST_RESET_REASON_NONE = 0, >> > >> + SBI_SRST_RESET_REASON_SYS_FAILURE, >> > >> +}; >> > >> + >> > >> #define SBI_SPEC_VERSION_DEFAULT 0x1 >> > >> #define SBI_SPEC_VERSION_MAJOR_SHIFT 24 >> > >> #define SBI_SPEC_VERSION_MAJOR_MASK 0x7f >> > >> @@ -148,6 +164,14 @@ static inline unsigned long sbi_minor_version(void) >> > >> return sbi_spec_version & SBI_SPEC_VERSION_MINOR_MASK; >> > >> } >> > >> >> > >> +/* Make SBI version */ >> > >> +static inline unsigned long sbi_mk_version(unsigned long major, >> > >> + unsigned long minor) >> > >> +{ >> > >> + return ((major & SBI_SPEC_VERSION_MAJOR_MASK) << >> > >> + SBI_SPEC_VERSION_MAJOR_SHIFT) | minor; >> > >> +} >> > >> + >> > >> int sbi_err_map_linux_errno(int err); >> > >> #else /* CONFIG_RISCV_SBI */ >> > >> static inline int sbi_remote_fence_i(const unsigned long *hart_mask) { return -1; } >> > >> diff --git a/arch/riscv/kernel/sbi.c b/arch/riscv/kernel/sbi.c >> > >> index 7402a417f38e..9a84f0cb5175 100644 >> > >> --- a/arch/riscv/kernel/sbi.c >> > >> +++ b/arch/riscv/kernel/sbi.c >> > >> @@ -7,6 +7,7 @@ >> > >> >> > >> #include <linux/init.h> >> > >> #include <linux/pm.h> >> > >> +#include <linux/reboot.h> >> > >> #include <asm/sbi.h> >> > >> #include <asm/smp.h> >> > >> >> > >> @@ -501,6 +502,32 @@ int sbi_remote_hfence_vvma_asid(const unsigned long *hart_mask, >> > >> } >> > >> EXPORT_SYMBOL(sbi_remote_hfence_vvma_asid); >> > >> >> > >> +static void sbi_srst_reset(unsigned long type, unsigned long reason) >> > >> +{ >> > >> + sbi_ecall(SBI_EXT_SRST, SBI_EXT_SRST_RESET, type, reason, >> > >> + 0, 0, 0, 0); >> > >> + pr_warn("%s: type=0x%lx reason=0x%lx failed\n", >> > >> + __func__, type, reason); >> > >> +} >> > >> + >> > >> +static int sbi_srst_reboot(struct notifier_block *this, >> > >> + unsigned long mode, void *cmd) >> > >> +{ >> > >> + sbi_srst_reset((mode == REBOOT_WARM || mode == REBOOT_SOFT) ? >> > >> + SBI_SRST_RESET_TYPE_WARM_REBOOT : >> > >> + SBI_SRST_RESET_TYPE_COLD_REBOOT, >> > >> + SBI_SRST_RESET_REASON_NONE); >> > >> + return NOTIFY_DONE; >> > >> +} >> > >> + >> > >> +static struct notifier_block sbi_srst_reboot_nb; >> > >> + >> > >> +static void sbi_srst_power_off(void) >> > >> +{ >> > >> + sbi_srst_reset(SBI_SRST_RESET_TYPE_SHUTDOWN, >> > >> + SBI_SRST_RESET_REASON_NONE); >> > >> +} >> > >> + >> > >> /** >> > >> * sbi_probe_extension() - Check if an SBI extension ID is supported or not. >> > >> * @extid: The extension ID to be probed. >> > >> @@ -608,6 +635,14 @@ void __init sbi_init(void) >> > >> } else { >> > >> __sbi_rfence = __sbi_rfence_v01; >> > >> } >> > >> + if ((sbi_spec_version >= sbi_mk_version(0, 3)) && >> > >> + (sbi_probe_extension(SBI_EXT_SRST) > 0)) { >> > >> + pr_info("SBI SRST extension detected\n"); >> > >> + pm_power_off = sbi_srst_power_off; >> > >> + sbi_srst_reboot_nb.notifier_call = sbi_srst_reboot; >> > >> + sbi_srst_reboot_nb.priority = 192; >> > >> + register_restart_handler(&sbi_srst_reboot_nb); >> > >> + } >> > >> } else { >> > >> __sbi_set_timer = __sbi_set_timer_v01; >> > >> __sbi_send_ipi = __sbi_send_ipi_v01; >> > >> -- >> > >> 2.25.1 >> > >> >>
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