[kvmtool PATCH v2 4/6] riscv: Add IRQFD support for in-kernel AIA irqchip

[Andrew Jones <ajones@ventanamicro.com>]

On Mon, Sep 18, 2023 at 06:27:28PM +0530, Anup Patel wrote:
> To use irqfd with in-kernel AIA irqchip, we add custom
> irq__add_irqfd and irq__del_irqfd functions. This allows
> us to defer actual KVM_IRQFD ioctl() until AIA irqchip
> is initialized by KVMTOOL.
> 
> Signed-off-by: Anup Patel <apatel@ventanamicro.com>
> ---
>  riscv/include/kvm/kvm-arch.h | 11 ++++++
>  riscv/irq.c                  | 73 ++++++++++++++++++++++++++++++++++++
>  2 files changed, 84 insertions(+)
> 
> diff --git a/riscv/include/kvm/kvm-arch.h b/riscv/include/kvm/kvm-arch.h
> index cd37fc6..1a8af6a 100644
> --- a/riscv/include/kvm/kvm-arch.h
> +++ b/riscv/include/kvm/kvm-arch.h
> @@ -98,11 +98,22 @@ extern void (*riscv_irqchip_generate_fdt_node)(void *fdt, struct kvm *kvm);
>  extern u32 riscv_irqchip_phandle;
>  extern u32 riscv_irqchip_msi_phandle;
>  extern bool riscv_irqchip_line_sensing;
> +extern bool riscv_irqchip_irqfd_ready;
>  
>  void plic__create(struct kvm *kvm);
>  
>  void pci__generate_fdt_nodes(void *fdt);
>  
> +int riscv__add_irqfd(struct kvm *kvm, unsigned int gsi, int trigger_fd,
> +		     int resample_fd);
> +
> +void riscv__del_irqfd(struct kvm *kvm, unsigned int gsi, int trigger_fd);
> +
> +#define irq__add_irqfd riscv__add_irqfd
> +#define irq__del_irqfd riscv__del_irqfd
> +
> +int riscv__setup_irqfd_lines(struct kvm *kvm);
> +
>  void riscv__generate_irq_prop(void *fdt, u8 irq, enum irq_type irq_type);
>  
>  void riscv__irqchip_create(struct kvm *kvm);
> diff --git a/riscv/irq.c b/riscv/irq.c
> index b608a2f..e6c0939 100644
> --- a/riscv/irq.c
> +++ b/riscv/irq.c
> @@ -12,6 +12,7 @@ void (*riscv_irqchip_generate_fdt_node)(void *fdt, struct kvm *kvm) = NULL;
>  u32 riscv_irqchip_phandle = PHANDLE_RESERVED;
>  u32 riscv_irqchip_msi_phandle = PHANDLE_RESERVED;
>  bool riscv_irqchip_line_sensing = false;
> +bool riscv_irqchip_irqfd_ready = false;
>  
>  void kvm__irq_line(struct kvm *kvm, int irq, int level)
>  {
> @@ -46,6 +47,78 @@ void kvm__irq_trigger(struct kvm *kvm, int irq)
>  	}
>  }
>  
> +struct riscv_irqfd_line {
> +	unsigned int		gsi;
> +	int			trigger_fd;
> +	int			resample_fd;
> +	struct list_head	list;
> +};
> +
> +static LIST_HEAD(irqfd_lines);
> +
> +int riscv__add_irqfd(struct kvm *kvm, unsigned int gsi, int trigger_fd,
> +		     int resample_fd)
> +{
> +	struct riscv_irqfd_line *line;
> +
> +	if (riscv_irqchip_irqfd_ready)
> +		return irq__common_add_irqfd(kvm, gsi, trigger_fd,
> +					     resample_fd);
> +
> +	/* Postpone the routing setup until we have a distributor */

This comment comes from the Arm code. We probably want to replace
distributor with "until the AIA is initialized" or something.

> +	line = malloc(sizeof(*line));
> +	if (!line)
> +		return -ENOMEM;
> +
> +	*line = (struct riscv_irqfd_line) {
> +		.gsi		= gsi,
> +		.trigger_fd	= trigger_fd,
> +		.resample_fd	= resample_fd,
> +	};
> +	list_add(&line->list, &irqfd_lines);
> +
> +	return 0;
> +}
> +
> +void riscv__del_irqfd(struct kvm *kvm, unsigned int gsi, int trigger_fd)
> +{
> +	struct riscv_irqfd_line *line;
> +
> +	if (riscv_irqchip_irqfd_ready) {
> +		irq__common_del_irqfd(kvm, gsi, trigger_fd);
> +		return;
> +	}
> +
> +	list_for_each_entry(line, &irqfd_lines, list) {
> +		if (line->gsi != gsi)
> +			continue;
> +
> +		list_del(&line->list);
> +		free(line);
> +		break;
> +	}
> +}
> +
> +int riscv__setup_irqfd_lines(struct kvm *kvm)
> +{
> +	int ret;
> +	struct riscv_irqfd_line *line, *tmp;
> +
> +	list_for_each_entry_safe(line, tmp, &irqfd_lines, list) {
> +		ret = irq__common_add_irqfd(kvm, line->gsi, line->trigger_fd,
> +					    line->resample_fd);
> +		if (ret < 0) {
> +			pr_err("Failed to register IRQFD");
> +			return ret;
> +		}
> +
> +		list_del(&line->list);
> +		free(line);
> +	}
> +
> +	return 0;
> +}
> +
>  void riscv__generate_irq_prop(void *fdt, u8 irq, enum irq_type irq_type)
>  {
>  	u32 prop[2], size;
> -- 
> 2.34.1
>

Other than the comment,

Reviewed-by: Andrew Jones <ajones@ventanamicro.com>