Re: [PATCH v4 5/6] lib: utils/irqchip/imsic: track IRQ enable state and restore EIE on warm init

On Tue, Jul 21, 2026 at 2:38 AM Pawandeep Oza
<[email protected]> wrote:
>
> Add an irq_state field to struct sbi_irqchip_hwirq_data with a single
> IRQ_ENABLED flag (bit 0) to track whether a hardware interrupt has been
> enabled via the irqchip framework. Set IRQ_ENABLED in
> sbi_irqchip_unmask_hwirq() when the unmask callback is invoked.
>
> Add sbi_irqchip_get_irq_state() as a private inline accessor and expose
> sbi_irqchip_is_irq_enabled() as a public API for drivers to query the
> enabled state of a hardware interrupt by chip pointer and hwirq number.
>
> Refactor imsic_local_eix_update() to operate on a single interrupt ID
> instead of a base+count range, simplifying the CSR bit manipulation to
> a direct BIT(id) write without the inner loop. Update all call sites
> accordingly.
>
> Use sbi_irqchip_is_irq_enabled() in imsic_warm_irqchip_init() to
> restore per-EIID EIE CSR state on warm boot and HSM resume based on
> the saved irq_state, replacing the previous blanket disable of all
> interrupts. This ensures that EIIDs enabled during hotplug/warminit
> cycle are correctly re-enabled on the resuming hart without requiring
> software to re-register or re-unmask each interrupt.
>
> Signed-off-by: Oza Pawandeep <[email protected]>
> ---
>  include/sbi/sbi_irqchip.h |  4 +++
>  lib/sbi/sbi_irqchip.c     | 33 +++++++++++++++++++++++
>  lib/utils/irqchip/imsic.c | 55 ++++++++++++++++++---------------------
>  3 files changed, 63 insertions(+), 29 deletions(-)
>
> diff --git a/include/sbi/sbi_irqchip.h b/include/sbi/sbi_irqchip.h
> index 7f6c763c..4fd5f780 100644
> --- a/include/sbi/sbi_irqchip.h
> +++ b/include/sbi/sbi_irqchip.h
> @@ -165,4 +165,8 @@ int sbi_irqchip_init(struct sbi_scratch *scratch, bool cold_boot);
>  /** Exit interrupt controllers */
>  void sbi_irqchip_exit(struct sbi_scratch *scratch);
>
> +/** Check if the interrupt is enabled */
> +bool sbi_irqchip_is_hwirq_enabled(struct sbi_irqchip_device *chip,
> +                                              u32 hwirq);
> +
>  #endif
> diff --git a/lib/sbi/sbi_irqchip.c b/lib/sbi/sbi_irqchip.c
> index 8923d2a2..9d14c39e 100644
> --- a/lib/sbi/sbi_irqchip.c
> +++ b/lib/sbi/sbi_irqchip.c
> @@ -20,6 +20,11 @@ struct sbi_irqchip_hwirq_data {
>         /** raw hardware interrupt handler */
>         int (*raw_handler)(struct sbi_irqchip_device *chip, u32 hwirq);
>
> +#define IRQ_ENABLED    BIT(0)
> +       /** interrupt state
> +        * bit 0 - 1: enabled, 0: disabled */
> +       u32 irq_state;
> +
>         /** target hart index */
>         u32 hart_index;
>  };
> @@ -77,23 +82,51 @@ int sbi_irqchip_process_hwirq(struct sbi_irqchip_device *chip, u32 hwirq)
>         return data->raw_handler(chip, hwirq);
>  }
>
> +static inline u32 sbi_irqchip_get_irq_state(struct sbi_irqchip_device *chip,
> +                                            u32 hwirq)
> +{
> +       if (!chip || !chip->hwirqs || hwirq >= chip->num_hwirq)
> +               return 0;
> +
> +       return chip->hwirqs[hwirq].irq_state;
> +}
> +
> +bool sbi_irqchip_is_hwirq_enabled(struct sbi_irqchip_device *chip,
> +                                              u32 hwirq)
> +{
> +       return !!(sbi_irqchip_get_irq_state(chip, hwirq) & IRQ_ENABLED);
> +}
> +
>  int sbi_irqchip_unmask_hwirq(struct sbi_irqchip_device *chip, u32 hwirq)
>  {
> +       struct sbi_irqchip_hwirq_data *data;
> +
>         if (!chip || chip->num_hwirq <= hwirq)
>                 return SBI_EINVAL;
>
> +       data = &chip->hwirqs[hwirq];
> +       if (data->irq_state & IRQ_ENABLED)
> +               return SBI_EALREADY;

Re-use sbi_irqchip_is_hwirq_enabled() over here.

> +
>         if (chip->hwirq_unmask)
>                 chip->hwirq_unmask(chip, hwirq);
> +
> +       data->irq_state |= IRQ_ENABLED;
>         return 0;
>  }
>
>  int sbi_irqchip_mask_hwirq(struct sbi_irqchip_device *chip, u32 hwirq)
>  {
> +       struct sbi_irqchip_hwirq_data *data;
> +
>         if (!chip || chip->num_hwirq <= hwirq)
>                 return SBI_EINVAL;

Check and return SBI_EALREADY, if hwirq is already
masked (i.e. !sbi_irqchip_is_hwirq_enabled()) .

>
>         if (chip->hwirq_mask)
>                 chip->hwirq_mask(chip, hwirq);
> +
> +       data = &chip->hwirqs[hwirq];
> +       data->irq_state &= ~IRQ_ENABLED;
>         return 0;
>  }
>
> diff --git a/lib/utils/irqchip/imsic.c b/lib/utils/irqchip/imsic.c
> index 40bffcc0..82a74f43 100644
> --- a/lib/utils/irqchip/imsic.c
> +++ b/lib/utils/irqchip/imsic.c
> @@ -225,29 +225,20 @@ static struct sbi_ipi_device imsic_ipi_device = {
>         .ipi_send       = imsic_ipi_send
>  };
>
> -static void imsic_local_eix_update(unsigned long base_id,
> -                                  unsigned long num_id, bool pend, bool val)
> +static void imsic_local_eix_update(unsigned long id,
> +                                  bool pend, bool val)
>  {
> -       unsigned long i, isel, ireg;
> -       unsigned long id = base_id, last_id = base_id + num_id;
> -
> -       while (id < last_id) {
> -               isel = id / __riscv_xlen;
> -               isel *= __riscv_xlen / IMSIC_EIPx_BITS;
> -               isel += (pend) ? IMSIC_EIP0 : IMSIC_EIE0;
> -
> -               ireg = 0;
> -               for (i = id & (__riscv_xlen - 1);
> -                    (id < last_id) && (i < __riscv_xlen); i++) {
> -                       ireg |= BIT(i);
> -                       id++;
> -               }
> +       unsigned long isel, ireg = 0;
>
> -               if (val)
> -                       imsic_csr_set(isel, ireg);
> -               else
> -                       imsic_csr_clear(isel, ireg);
> -       }
> +       isel = id / __riscv_xlen;
> +       isel *= __riscv_xlen / IMSIC_EIPx_BITS;
> +       isel += (pend) ? IMSIC_EIP0 : IMSIC_EIE0;
> +       ireg |= BIT(id);
> +
> +       if (val)
> +               imsic_csr_set(isel, ireg);
> +       else
> +               imsic_csr_clear(isel, ireg);
>  }
>
>  void imsic_local_irqchip_init(void)
> @@ -275,13 +266,14 @@ void imsic_local_irqchip_init(void)
>         imsic_csr_write(IMSIC_EIDELIVERY, IMSIC_ENABLE_EIDELIVERY);
>
>         /* Enable IPI */
> -       imsic_local_eix_update(IMSIC_IPI_ID, 1, false, true);
> +       imsic_local_eix_update(IMSIC_IPI_ID, false, true);
>  }
>
>  static int imsic_warm_irqchip_init(struct sbi_irqchip_device *dev)
>  {
>         struct imsic_data *imsic;
>         struct imsic_data *hart_imsic;
> +       int i;
>
>         imsic = container_of(dev, struct imsic_data, irqchip);
>         hart_imsic = imsic_get_data(current_hartindex());
> @@ -291,11 +283,16 @@ static int imsic_warm_irqchip_init(struct sbi_irqchip_device *dev)
>                 !hart_imsic->targets_mmode)
>                 return SBI_EINVAL;
>
> -       /* Disable all interrupts */
> -       imsic_local_eix_update(1, imsic->num_ids, false, false);
> +       /* enable interrutps based on the irq state */
> +       for (i = 1; i < imsic->num_ids; i++) {
> +               if (sbi_irqchip_is_hwirq_enabled(&imsic->irqchip, i) == true)
> +                       imsic_local_eix_update(i, true, true);
> +               else
> +                       imsic_local_eix_update(i, false, false);
> +       }
>
>         /* Clear IPI pending */
> -       imsic_local_eix_update(IMSIC_IPI_ID, 1, true, false);
> +       imsic_local_eix_update(IMSIC_IPI_ID, true, false);
>
>         /* Local IMSIC initialization */
>         imsic_local_irqchip_init();
> @@ -395,8 +392,8 @@ static void imsic_hwirq_cleanup(struct sbi_irqchip_device *chip, u32 hwirq)
>         if (!imsic || !imsic->targets_mmode)
>                 return;
>
> -       imsic_local_eix_update(hwirq, 1, false, false);
> -       imsic_local_eix_update(hwirq, 1, true, false);
> +       imsic_local_eix_update(hwirq, false, false);
> +       imsic_local_eix_update(hwirq, true, false);
>  }
>
>  static void imsic_hwirq_eoi(struct sbi_irqchip_device *chip, u32 hwirq)
> @@ -535,7 +532,7 @@ static void imsic_hwirq_mask(struct sbi_irqchip_device *chip, u32 hwirq)
>         if (!imsic || !imsic->targets_mmode)
>                 return;
>
> -       imsic_local_eix_update(hwirq, 1, false, false);
> +       imsic_local_eix_update(hwirq, false, false);
>  }
>
>  static void imsic_hwirq_unmask(struct sbi_irqchip_device *chip, u32 hwirq)
> @@ -552,7 +549,7 @@ static void imsic_hwirq_unmask(struct sbi_irqchip_device *chip, u32 hwirq)
>         if (!hwirq || hwirq == IMSIC_IPI_ID)
>                 return;
>
> -       imsic_local_eix_update(hwirq, 1, false, true);
> +       imsic_local_eix_update(hwirq, false, true);
>  }
>
>  static struct sbi_irqchip_device imsic_device = {
> --
> 2.43.0
>
>
> --
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Regards,
Anup

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