Messages in this thread | | | From | Anup Patel <> | Date | Thu, 29 Jul 2021 10:14:44 +0530 | Subject | Re: [PATCH v7 1/1] RISC-V: Use SBI SRST extension when available |
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On Thu, Jul 29, 2021 at 10:00 AM Palmer Dabbelt <palmer@dabbelt.com> wrote: > > 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.
The RISC-V SBI is a pure software specification and not a ISA specification. In fact, this is not even non-ISA specification dealing with a MMIO (or hardware) device. There is no process defined for RISC-V software specifications.
The last SBI v0.2 release was done by you (Palmer). At that time, you simply tagged the SBI v0.2 release and announced it everywhere.
Regards, Anup
> > > > >> > >> 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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