Re: [PATCH V2 2/4] RISC-V: KVM: AIA: Replace global HGEI count with simple enabled bool

On Sat, Apr 25, 2026 at 6:29 AM <[email protected]> wrote:
>
> From: "Guo Ren (Alibaba DAMO Academy)" <[email protected]>
>
> Now that HGEI line management is fully per-CPU (via struct
> aia_hgei_control::nr_hgei), the global `kvm_riscv_aia_nr_hgei`
> is no longer needed. Replace it with a simple `bool
> kvm_riscv_aia_hgei_enabled` that only indicates whether HGEI
> support is available at all.

As mentioned in PATCH1, this PATCH is not required.

>
> Signed-off-by: Guo Ren (Alibaba DAMO Academy) <[email protected]>
> ---
>  arch/riscv/include/asm/kvm_aia.h |  2 +-
>  arch/riscv/kvm/aia.c             | 18 ++++++++----------
>  arch/riscv/kvm/aia_device.c      |  4 ++--
>  arch/riscv/kvm/main.c            |  3 +--
>  4 files changed, 12 insertions(+), 15 deletions(-)
>
> diff --git a/arch/riscv/include/asm/kvm_aia.h b/arch/riscv/include/asm/kvm_aia.h
> index b04ecdd1a860..e8749ac6bed7 100644
> --- a/arch/riscv/include/asm/kvm_aia.h
> +++ b/arch/riscv/include/asm/kvm_aia.h
> @@ -79,7 +79,7 @@ struct kvm_vcpu_aia {
>
>  #define irqchip_in_kernel(k)           ((k)->arch.aia.in_kernel)
>
> -extern unsigned int kvm_riscv_aia_nr_hgei;
> +extern bool kvm_riscv_aia_hgei_enabled;
>  extern unsigned int kvm_riscv_aia_max_ids;
>  DECLARE_STATIC_KEY_FALSE(kvm_riscv_aia_available);
>  #define kvm_riscv_aia_available() \
> diff --git a/arch/riscv/kvm/aia.c b/arch/riscv/kvm/aia.c
> index a23729052cfb..70ff1d25dd99 100644
> --- a/arch/riscv/kvm/aia.c
> +++ b/arch/riscv/kvm/aia.c
> @@ -28,7 +28,7 @@ struct aia_hgei_control {
>  static DEFINE_PER_CPU(struct aia_hgei_control, aia_hgei);
>  static int hgei_parent_irq;
>
> -unsigned int kvm_riscv_aia_nr_hgei;
> +bool kvm_riscv_aia_hgei_enabled;
>  unsigned int kvm_riscv_aia_max_ids;
>  DEFINE_STATIC_KEY_FALSE(kvm_riscv_aia_available);
>
> @@ -491,7 +491,7 @@ static int aia_hgei_init(void)
>         struct irq_domain *domain;
>
>         /* Skip SGEI interrupt setup for zero guest external interrupts */
> -       if (!kvm_riscv_aia_nr_hgei)
> +       if (!kvm_riscv_aia_hgei_enabled)
>                 goto skip_sgei_interrupt;
>
>         /* Find INTC irq domain */
> @@ -524,7 +524,7 @@ static int aia_hgei_init(void)
>  static void aia_hgei_exit(void)
>  {
>         /* Do nothing for zero guest external interrupts */
> -       if (!kvm_riscv_aia_nr_hgei)
> +       if (!kvm_riscv_aia_hgei_enabled)
>                 return;
>
>         /* Free per-CPU SGEI interrupt */
> @@ -631,6 +631,7 @@ int kvm_riscv_aia_init(void)
>  {
>         int rc;
>         const struct imsic_global_config *gc;
> +       unsigned int kvm_riscv_aia_nr_hgei;
>
>         if (!riscv_isa_extension_available(NULL, SxAIA))
>                 return -ENODEV;
> @@ -641,21 +642,18 @@ int kvm_riscv_aia_init(void)
>         kvm_riscv_aia_nr_hgei = fls_long(csr_read(CSR_HGEIE));
>         csr_write(CSR_HGEIE, 0);
>         if (kvm_riscv_aia_nr_hgei)
> -               kvm_riscv_aia_nr_hgei--;
> +               kvm_riscv_aia_hgei_enabled = true;
>
>         /*
>          * Number of usable HGEI lines should be minimum of per-HART
>          * IMSIC guest files and number of bits in HGEIE
>          */
> -       if (gc)
> -               kvm_riscv_aia_nr_hgei = min((ulong)kvm_riscv_aia_nr_hgei,
> -                                           gc->nr_guest_files);
> -       else
> -               kvm_riscv_aia_nr_hgei = 0;
> +       if (!gc)
> +               kvm_riscv_aia_hgei_enabled = 0;
>
>         /* Find number of guest MSI IDs */
>         kvm_riscv_aia_max_ids = IMSIC_MAX_ID;
> -       if (gc && kvm_riscv_aia_nr_hgei)
> +       if (gc && kvm_riscv_aia_hgei_enabled)
>                 kvm_riscv_aia_max_ids = gc->nr_guest_ids + 1;
>
>         /* Initialize guest external interrupt line management */
> diff --git a/arch/riscv/kvm/aia_device.c b/arch/riscv/kvm/aia_device.c
> index 3d1e81e2a36b..5b45b1114425 100644
> --- a/arch/riscv/kvm/aia_device.c
> +++ b/arch/riscv/kvm/aia_device.c
> @@ -71,7 +71,7 @@ static int aia_config(struct kvm *kvm, unsigned long type,
>                                  * external interrupts (i.e. non-zero
>                                  * VS-level IMSIC pages).
>                                  */
> -                               if (!kvm_riscv_aia_nr_hgei)
> +                               if (!kvm_riscv_aia_hgei_enabled)
>                                         return -EINVAL;
>                                 break;
>                         default:
> @@ -628,7 +628,7 @@ void kvm_riscv_aia_init_vm(struct kvm *kvm)
>          */
>
>         /* Initialize default values in AIA global context */
> -       aia->mode = (kvm_riscv_aia_nr_hgei) ?
> +       aia->mode = (kvm_riscv_aia_hgei_enabled) ?
>                 KVM_DEV_RISCV_AIA_MODE_AUTO : KVM_DEV_RISCV_AIA_MODE_EMUL;
>         aia->nr_ids = kvm_riscv_aia_max_ids - 1;
>         aia->nr_sources = 0;
> diff --git a/arch/riscv/kvm/main.c b/arch/riscv/kvm/main.c
> index cb8a65273c1f..bcfa139f4871 100644
> --- a/arch/riscv/kvm/main.c
> +++ b/arch/riscv/kvm/main.c
> @@ -169,8 +169,7 @@ static int __init riscv_kvm_init(void)
>         kvm_info("VMID %ld bits available\n", kvm_riscv_gstage_vmid_bits());
>
>         if (kvm_riscv_aia_available())
> -               kvm_info("AIA available with %d guest external interrupts\n",
> -                        kvm_riscv_aia_nr_hgei);
> +               kvm_info("AIA available with guest external interrupts\n");
>
>         kvm_riscv_setup_vendor_features();
>
> --
> 2.43.0
>

Regards,
Anup

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