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

Zenghui Yu
2020-03-17T02:02:41Z

Hi Eric,

On 2020/3/17 1:53, Auger Eric wrote:
> 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@kernel.org>
>> Reviewed-by: Zenghui Yu <yuzenghui@huawei.com>
>> ---
>> 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?

It can't happen in GICv4.1, and you may find the answer in patch #16
("Eagerly vmap vPEs"). I also failed to follow this logic the first
time looking at it [*], so I think it may worth adding some comments
on top of find_4_1_its()?

[*]
https://lore.kernel.org/lkml/c94061be-d029-69c8-d34f-4d21081d5aba@huawei.com/

>
> 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.
>
> "

I think it makes sense.

Thanks,
Zenghui

>> + 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
>
>
> .
>