Re: [PATCH v5 09/23] irqchip/gic-v4.1: Add initial SGI configuration

[Auger Eric]

Hi Marc,

On 3/4/20 9:33 PM, Marc Zyngier wrote:
> The GICv4.1 ITS has yet another new command (VSGI) which allows
> a VPE-targeted SGI to be configured (or have its pending state
> cleared). Add support for this command and plumb it into the
> activate irqdomain callback so that it is ready to be used.
> 
> Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
> Reviewed-by: Zenghui Yu <yuzenghui@xxxxxxxxxx>
> ---
>  drivers/irqchip/irq-gic-v3-its.c   | 79 +++++++++++++++++++++++++++++-
>  include/linux/irqchip/arm-gic-v3.h |  3 +-
>  2 files changed, 80 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
> index 112b452fcb40..e0db3f906f87 100644
> --- a/drivers/irqchip/irq-gic-v3-its.c
> +++ b/drivers/irqchip/irq-gic-v3-its.c
> @@ -380,6 +380,15 @@ struct its_cmd_desc {
>  		struct {
>  			struct its_vpe *vpe;
>  		} its_invdb_cmd;
> +
> +		struct {
> +			struct its_vpe *vpe;
> +			u8 sgi;
> +			u8 priority;
> +			bool enable;
> +			bool group;
> +			bool clear;
> +		} its_vsgi_cmd;
>  	};
>  };
>  
> @@ -528,6 +537,31 @@ static void its_encode_db(struct its_cmd_block *cmd, bool db)
>  	its_mask_encode(&cmd->raw_cmd[2], db, 63, 63);
>  }
>  
> +static void its_encode_sgi_intid(struct its_cmd_block *cmd, u8 sgi)
> +{
> +	its_mask_encode(&cmd->raw_cmd[0], sgi, 35, 32);
> +}
> +
> +static void its_encode_sgi_priority(struct its_cmd_block *cmd, u8 prio)
> +{
> +	its_mask_encode(&cmd->raw_cmd[0], prio >> 4, 23, 20);
> +}
> +
> +static void its_encode_sgi_group(struct its_cmd_block *cmd, bool grp)
> +{
> +	its_mask_encode(&cmd->raw_cmd[0], grp, 10, 10);
> +}
> +
> +static void its_encode_sgi_clear(struct its_cmd_block *cmd, bool clr)
> +{
> +	its_mask_encode(&cmd->raw_cmd[0], clr, 9, 9);
> +}
> +
> +static void its_encode_sgi_enable(struct its_cmd_block *cmd, bool en)
> +{
> +	its_mask_encode(&cmd->raw_cmd[0], en, 8, 8);
> +}
> +
>  static inline void its_fixup_cmd(struct its_cmd_block *cmd)
>  {
>  	/* Let's fixup BE commands */
> @@ -893,6 +927,26 @@ static struct its_vpe *its_build_invdb_cmd(struct its_node *its,
>  	return valid_vpe(its, desc->its_invdb_cmd.vpe);
>  }
>  
> +static struct its_vpe *its_build_vsgi_cmd(struct its_node *its,
> +					  struct its_cmd_block *cmd,
> +					  struct its_cmd_desc *desc)
> +{
> +	if (WARN_ON(!is_v4_1(its)))
> +		return NULL;
> +
> +	its_encode_cmd(cmd, GITS_CMD_VSGI);
> +	its_encode_vpeid(cmd, desc->its_vsgi_cmd.vpe->vpe_id);
> +	its_encode_sgi_intid(cmd, desc->its_vsgi_cmd.sgi);
> +	its_encode_sgi_priority(cmd, desc->its_vsgi_cmd.priority);
> +	its_encode_sgi_group(cmd, desc->its_vsgi_cmd.group);
> +	its_encode_sgi_clear(cmd, desc->its_vsgi_cmd.clear);
> +	its_encode_sgi_enable(cmd, desc->its_vsgi_cmd.enable);
> +
> +	its_fixup_cmd(cmd);
> +
> +	return valid_vpe(its, desc->its_vsgi_cmd.vpe);
> +}
> +
>  static u64 its_cmd_ptr_to_offset(struct its_node *its,
>  				 struct its_cmd_block *ptr)
>  {
> @@ -3870,6 +3924,21 @@ static struct irq_chip its_vpe_4_1_irq_chip = {
>  	.irq_set_vcpu_affinity	= its_vpe_4_1_set_vcpu_affinity,
>  };
>  
> +static void its_configure_sgi(struct irq_data *d, bool clear)
> +{
> +	struct its_vpe *vpe = irq_data_get_irq_chip_data(d);
> +	struct its_cmd_desc desc;
> +
> +	desc.its_vsgi_cmd.vpe = vpe;
> +	desc.its_vsgi_cmd.sgi = d->hwirq;
> +	desc.its_vsgi_cmd.priority = vpe->sgi_config[d->hwirq].priority;
> +	desc.its_vsgi_cmd.enable = vpe->sgi_config[d->hwirq].enabled;
> +	desc.its_vsgi_cmd.group = vpe->sgi_config[d->hwirq].group;
> +	desc.its_vsgi_cmd.clear = clear;
> +
> +	its_send_single_vcommand(find_4_1_its(), its_build_vsgi_cmd, &desc);
I see we pick up the first 4.1 ITS with find_4_1_its(). Can it happen
that not all of them have a mapping for that vPEID and if so we should
rather use one that has this mapping?

The spec says:
The ITS controls must only be used on an ITS that has a mapping for that
vPEID.
Where multiple ITSs have a mapping for the vPEID, any ITS with a mapping
may be used.

> +}
> +
>  static int its_sgi_set_affinity(struct irq_data *d,
>  				const struct cpumask *mask_val,
>  				bool force)
> @@ -3915,13 +3984,21 @@ static void its_sgi_irq_domain_free(struct irq_domain *domain,
>  static int its_sgi_irq_domain_activate(struct irq_domain *domain,
>  				       struct irq_data *d, bool reserve)
>  {
> +	/* Write out the initial SGI configuration */
> +	its_configure_sgi(d, false);
>  	return 0;
>  }
>  
>  static void its_sgi_irq_domain_deactivate(struct irq_domain *domain,
>  					  struct irq_data *d)
>  {
> -	/* Nothing to do */
> +	struct its_vpe *vpe = irq_data_get_irq_chip_data(d);
> +
> +	/* First disable the SGI */
> +	vpe->sgi_config[d->hwirq].enabled = false;
> +	its_configure_sgi(d, false);
> +	/* Now clear the potential pending bit (yes, this is clunky) */
nit: Without carefuly reading the VSGI cmd notes, it is difficult to
understand why those 2 steps are needed: maybe replace this comment by
something like:
to change the config, clear must be set to false. Then clear is set and
this leaves the config unchanged. Both steps cannot be done concurrently.

"
> +	its_configure_sgi(d, true);
>  }
>  
>  static struct irq_domain_ops its_sgi_domain_ops = {
> diff --git a/include/linux/irqchip/arm-gic-v3.h b/include/linux/irqchip/arm-gic-v3.h
> index b28acfa71f82..fd3be49ac9a5 100644
> --- a/include/linux/irqchip/arm-gic-v3.h
> +++ b/include/linux/irqchip/arm-gic-v3.h
> @@ -502,8 +502,9 @@
>  #define GITS_CMD_VMAPTI			GITS_CMD_GICv4(GITS_CMD_MAPTI)
>  #define GITS_CMD_VMOVI			GITS_CMD_GICv4(GITS_CMD_MOVI)
>  #define GITS_CMD_VSYNC			GITS_CMD_GICv4(GITS_CMD_SYNC)
> -/* VMOVP and INVDB are the odd ones, as they dont have a physical counterpart */
> +/* VMOVP, VSGI and INVDB are the odd ones, as they dont have a physical counterpart */
>  #define GITS_CMD_VMOVP			GITS_CMD_GICv4(2)
> +#define GITS_CMD_VSGI			GITS_CMD_GICv4(3)
>  #define GITS_CMD_INVDB			GITS_CMD_GICv4(0xe)
>  
>  /*
> 
Thanks

Eric