lkml.org 
[lkml]   [2021]   [Jul]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    SubjectRe: [PATCH v7 1/1] RISC-V: Use SBI SRST extension when available
    From
    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
    >> > >>
    >>

    \
     
     \ /
      Last update: 2021-07-29 06:31    [W:6.712 / U:0.012 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site