[PATCH v2 1/1] lib: sbi: Add support to mask/unmask SSE events

[Anup Patel]

On Mon, Sep 23, 2024 at 11:26 AM Himanshu Chauhan
<hchauhan at ventanamicro.com> wrote:
>
> Add functions to globally mask/unmask supervisor software events
> on the calling hart.
>
> Signed-off-by: Himanshu Chauhan <hchauhan at ventanamicro.com>

LGTM.

Reviewed-by: Anup Patel <anup at brainfault.org>

Applied this patch to the riscv/opensbi repo.

Thanks,
Anup

> ---
>  include/sbi/sbi_ecall_interface.h |  2 ++
>  include/sbi/sbi_sse.h             |  2 ++
>  lib/sbi/sbi_ecall_sse.c           |  6 +++++
>  lib/sbi/sbi_sse.c                 | 43 +++++++++++++++++++++++++++++++
>  4 files changed, 53 insertions(+)
>
> diff --git a/include/sbi/sbi_ecall_interface.h b/include/sbi/sbi_ecall_interface.h
> index e9a81677..40ab32aa 100644
> --- a/include/sbi/sbi_ecall_interface.h
> +++ b/include/sbi/sbi_ecall_interface.h
> @@ -341,6 +341,8 @@ enum sbi_cppc_reg_id {
>  #define SBI_EXT_SSE_DISABLE            0x00000005
>  #define SBI_EXT_SSE_COMPLETE           0x00000006
>  #define SBI_EXT_SSE_INJECT             0x00000007
> +#define SBI_EXT_SSE_HART_UNMASK                0x00000008
> +#define SBI_EXT_SSE_HART_MASK          0x00000009
>
>  /* SBI SSE Event Attributes. */
>  enum sbi_sse_attr_id {
> diff --git a/include/sbi/sbi_sse.h b/include/sbi/sbi_sse.h
> index e5b0ad69..7419698a 100644
> --- a/include/sbi/sbi_sse.h
> +++ b/include/sbi/sbi_sse.h
> @@ -78,6 +78,8 @@ void sbi_sse_exit(struct sbi_scratch *scratch);
>  int sbi_sse_register(uint32_t event_id, unsigned long handler_entry_pc,
>                      unsigned long handler_entry_arg);
>  int sbi_sse_unregister(uint32_t event_id);
> +int sbi_sse_hart_mask(void);
> +int sbi_sse_hart_unmask(void);
>  int sbi_sse_enable(uint32_t event_id);
>  int sbi_sse_disable(uint32_t event_id);
>  int sbi_sse_complete(struct sbi_trap_regs *regs, struct sbi_ecall_return *out);
> diff --git a/lib/sbi/sbi_ecall_sse.c b/lib/sbi/sbi_ecall_sse.c
> index a28a033e..beddc2cd 100644
> --- a/lib/sbi/sbi_ecall_sse.c
> +++ b/lib/sbi/sbi_ecall_sse.c
> @@ -36,6 +36,12 @@ static int sbi_ecall_sse_handler(unsigned long extid, unsigned long funcid,
>         case SBI_EXT_SSE_INJECT:
>                 ret = sbi_sse_inject_from_ecall(regs->a0, regs->a1, out);
>                 break;
> +       case SBI_EXT_SSE_HART_MASK:
> +               ret = sbi_sse_hart_mask();
> +               break;
> +       case SBI_EXT_SSE_HART_UNMASK:
> +               ret = sbi_sse_hart_unmask();
> +               break;
>         default:
>                 ret = SBI_ENOTSUPP;
>         }
> diff --git a/lib/sbi/sbi_sse.c b/lib/sbi/sbi_sse.c
> index 52172fcd..aff64268 100644
> --- a/lib/sbi/sbi_sse.c
> +++ b/lib/sbi/sbi_sse.c
> @@ -141,6 +141,12 @@ struct sse_hart_state {
>          * List of local events allocated at boot time.
>          */
>         struct sbi_sse_event *local_events;
> +
> +       /**
> +        * State to track if the hart is ready to take sse events.
> +        * One hart cannot modify this state of another hart.
> +        */
> +       bool masked;
>  };
>
>  /**
> @@ -608,6 +614,10 @@ void sbi_sse_process_pending_events(struct sbi_trap_regs *regs)
>         struct sbi_sse_event *e;
>         struct sse_hart_state *state = sse_thishart_state_ptr();
>
> +       /* if sse is masked on this hart, do nothing */
> +       if (state->masked)
> +               return;
> +
>         spin_lock(&state->enabled_event_lock);
>
>         sbi_list_for_each_entry(e, &state->enabled_event_list, node) {
> @@ -805,6 +815,36 @@ int sbi_sse_disable(uint32_t event_id)
>         return ret;
>  }
>
> +int sbi_sse_hart_mask(void)
> +{
> +       struct sse_hart_state *state = sse_thishart_state_ptr();
> +
> +       if (!state)
> +               return SBI_EFAIL;
> +
> +       if (state->masked)
> +               return SBI_EALREADY_STARTED;
> +
> +       state->masked = true;
> +
> +       return SBI_SUCCESS;
> +}
> +
> +int sbi_sse_hart_unmask(void)
> +{
> +       struct sse_hart_state *state = sse_thishart_state_ptr();
> +
> +       if (!state)
> +               return SBI_EFAIL;
> +
> +       if (!state->masked)
> +               return SBI_EALREADY_STOPPED;
> +
> +       state->masked = false;
> +
> +       return SBI_SUCCESS;
> +}
> +
>  int sbi_sse_inject_from_ecall(uint32_t event_id, unsigned long hartid,
>                               struct sbi_ecall_return *out)
>  {
> @@ -1123,6 +1163,9 @@ int sbi_sse_init(struct sbi_scratch *scratch, bool cold_boot)
>
>                 shs->local_events = (struct sbi_sse_event *)(shs + 1);
>
> +               /* SSE events are masked until hart unmasks them */
> +               shs->masked = true;
> +
>                 sse_set_hart_state_ptr(scratch, shs);
>         }
>
> --
> 2.43.0
>
>
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