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[PATCH 2/4] PCI/MSI: Add startup/shutdown support for per device MSI[X] domains

Inochi Amaoto posted 4 patches 6 months ago
There is a newer version of this series
[PATCH 2/4] PCI/MSI: Add startup/shutdown support for per device MSI[X] domains
Posted by Inochi Amaoto 6 months ago 
As The RISC-V PLIC can not apply affinity setting without calling
irq_enable(), it will make the interrupt unavaible when using as
an underlying irq chip for MSI controller.

Introduce the irq_startup/irq_shutdown for PCI domain template with
new MSI domain flag. This allow the PLIC can be properly configurated
when calling irq_startup().

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Inochi Amaoto <inochiama@gmail.com>
---
 drivers/pci/msi/irqdomain.c | 52 +++++++++++++++++++++++++++++++++++++
 include/linux/msi.h         |  2 ++
 2 files changed, 54 insertions(+)

diff --git a/drivers/pci/msi/irqdomain.c b/drivers/pci/msi/irqdomain.c
index 0938ef7ebabf..f0d18cadbe20 100644
--- a/drivers/pci/msi/irqdomain.c
+++ b/drivers/pci/msi/irqdomain.c
@@ -148,6 +148,23 @@ static void pci_device_domain_set_desc(msi_alloc_info_t *arg, struct msi_desc *d
 	arg->hwirq = desc->msi_index;
 }
 
+static __always_inline void cond_shutdown_parent(struct irq_data *data)
+{
+	struct msi_domain_info *info = data->domain->host_data;
+
+	if (unlikely(info->flags & MSI_FLAG_PCI_MSI_STARTUP_PARENT))
+		irq_chip_shutdown_parent(data);
+}
+
+static __always_inline unsigned int cond_startup_parent(struct irq_data *data)
+{
+	struct msi_domain_info *info = data->domain->host_data;
+
+	if (unlikely(info->flags & MSI_FLAG_PCI_MSI_STARTUP_PARENT))
+		return irq_chip_startup_parent(data);
+	return 0;
+}
+
 static __always_inline void cond_mask_parent(struct irq_data *data)
 {
 	struct msi_domain_info *info = data->domain->host_data;
@@ -164,6 +181,23 @@ static __always_inline void cond_unmask_parent(struct irq_data *data)
 		irq_chip_unmask_parent(data);
 }
 
+static void pci_irq_shutdown_msi(struct irq_data *data)
+{
+	struct msi_desc *desc = irq_data_get_msi_desc(data);
+
+	pci_msi_mask(desc, BIT(data->irq - desc->irq));
+	cond_shutdown_parent(data);
+}
+
+static unsigned int pci_irq_startup_msi(struct irq_data *data)
+{
+	struct msi_desc *desc = irq_data_get_msi_desc(data);
+	unsigned int ret = cond_startup_parent(data);
+
+	pci_msi_unmask(desc, BIT(data->irq - desc->irq));
+	return ret;
+}
+
 static void pci_irq_mask_msi(struct irq_data *data)
 {
 	struct msi_desc *desc = irq_data_get_msi_desc(data);
@@ -194,6 +228,8 @@ static void pci_irq_unmask_msi(struct irq_data *data)
 static const struct msi_domain_template pci_msi_template = {
 	.chip = {
 		.name			= "PCI-MSI",
+		.irq_startup		= pci_irq_startup_msi,
+		.irq_shutdown		= pci_irq_shutdown_msi,
 		.irq_mask		= pci_irq_mask_msi,
 		.irq_unmask		= pci_irq_unmask_msi,
 		.irq_write_msi_msg	= pci_msi_domain_write_msg,
@@ -210,6 +246,20 @@ static const struct msi_domain_template pci_msi_template = {
 	},
 };
 
+static void pci_irq_shutdown_msix(struct irq_data *data)
+{
+	pci_msix_mask(irq_data_get_msi_desc(data));
+	cond_shutdown_parent(data);
+}
+
+static unsigned int pci_irq_startup_msix(struct irq_data *data)
+{
+	unsigned int ret = cond_startup_parent(data);
+
+	pci_msix_unmask(irq_data_get_msi_desc(data));
+	return ret;
+}
+
 static void pci_irq_mask_msix(struct irq_data *data)
 {
 	pci_msix_mask(irq_data_get_msi_desc(data));
@@ -234,6 +284,8 @@ EXPORT_SYMBOL_GPL(pci_msix_prepare_desc);
 static const struct msi_domain_template pci_msix_template = {
 	.chip = {
 		.name			= "PCI-MSIX",
+		.irq_startup		= pci_irq_startup_msix,
+		.irq_shutdown		= pci_irq_shutdown_msix,
 		.irq_mask		= pci_irq_mask_msix,
 		.irq_unmask		= pci_irq_unmask_msix,
 		.irq_write_msi_msg	= pci_msi_domain_write_msg,
diff --git a/include/linux/msi.h b/include/linux/msi.h
index e5e86a8529fb..3111ba95fbde 100644
--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -568,6 +568,8 @@ enum {
 	MSI_FLAG_PARENT_PM_DEV		= (1 << 8),
 	/* Support for parent mask/unmask */
 	MSI_FLAG_PCI_MSI_MASK_PARENT	= (1 << 9),
+	/* Support for parent startup/shutdown */
+	MSI_FLAG_PCI_MSI_STARTUP_PARENT	= (1 << 10),
 
 	/* Mask for the generic functionality */
 	MSI_GENERIC_FLAGS_MASK		= GENMASK(15, 0),
-- 
2.50.1
Re: [PATCH 2/4] PCI/MSI: Add startup/shutdown support for per device MSI[X] domains
Posted by Bjorn Helgaas 6 months ago 
In subject, s/MSI[X]// and s/support for/for/

The "MSI[X]" notation really isn't used anywhere else, and we already
include "PCI/MSI" in the prefix, so I don't think we need it again.

On Thu, Aug 07, 2025 at 07:23:23PM +0800, Inochi Amaoto wrote:
> As The RISC-V PLIC can not apply affinity setting without calling
> irq_enable(), it will make the interrupt unavaible when using as
> an underlying irq chip for MSI controller.

s/As The/As the/
s/unavaible/unavailable/
s/irq chip/IRQ chip/

> Introduce the irq_startup/irq_shutdown for PCI domain template with
> new MSI domain flag. This allow the PLIC can be properly configurated
> when calling irq_startup().

Maybe something like:

  Implement .irq_startup() and .irq_shutdown() for the PCI MSI and
  MSI-X templates.  For chips that specify MSI_FLAG_PCI_MSI_STARTUP_PARENT, 
  these startup and shutdown the parent as well, which allows ...

s/This allow/This allows/
s/can be properly configurated/to be configured/

Evidently PLIC depends on this "parent" connection, but that isn't
explained at all in the commit log.

> Suggested-by: Thomas Gleixner <tglx@linutronix.de>
> Signed-off-by: Inochi Amaoto <inochiama@gmail.com>
> ---
>  drivers/pci/msi/irqdomain.c | 52 +++++++++++++++++++++++++++++++++++++
>  include/linux/msi.h         |  2 ++
>  2 files changed, 54 insertions(+)
> 
> diff --git a/drivers/pci/msi/irqdomain.c b/drivers/pci/msi/irqdomain.c
> index 0938ef7ebabf..f0d18cadbe20 100644
> --- a/drivers/pci/msi/irqdomain.c
> +++ b/drivers/pci/msi/irqdomain.c
> @@ -148,6 +148,23 @@ static void pci_device_domain_set_desc(msi_alloc_info_t *arg, struct msi_desc *d
>  	arg->hwirq = desc->msi_index;
>  }
>  
> +static __always_inline void cond_shutdown_parent(struct irq_data *data)

Is there a functional reason why we need __always_inline?

If not, it seems like this annotation is just clutter, and the compiler
will probably inline it all by itself.

> +{
> +	struct msi_domain_info *info = data->domain->host_data;
> +
> +	if (unlikely(info->flags & MSI_FLAG_PCI_MSI_STARTUP_PARENT))
> +		irq_chip_shutdown_parent(data);
> +}
> +
> +static __always_inline unsigned int cond_startup_parent(struct irq_data *data)
> +{
> +	struct msi_domain_info *info = data->domain->host_data;
> +
> +	if (unlikely(info->flags & MSI_FLAG_PCI_MSI_STARTUP_PARENT))
> +		return irq_chip_startup_parent(data);
> +	return 0;
> +}
> +
>  static __always_inline void cond_mask_parent(struct irq_data *data)
>  {
>  	struct msi_domain_info *info = data->domain->host_data;
> @@ -164,6 +181,23 @@ static __always_inline void cond_unmask_parent(struct irq_data *data)
>  		irq_chip_unmask_parent(data);
>  }
>  
> +static void pci_irq_shutdown_msi(struct irq_data *data)
> +{
> +	struct msi_desc *desc = irq_data_get_msi_desc(data);
> +
> +	pci_msi_mask(desc, BIT(data->irq - desc->irq));
> +	cond_shutdown_parent(data);
> +}
> +
> +static unsigned int pci_irq_startup_msi(struct irq_data *data)
> +{
> +	struct msi_desc *desc = irq_data_get_msi_desc(data);
> +	unsigned int ret = cond_startup_parent(data);
> +
> +	pci_msi_unmask(desc, BIT(data->irq - desc->irq));
> +	return ret;
> +}
> +
>  static void pci_irq_mask_msi(struct irq_data *data)
>  {
>  	struct msi_desc *desc = irq_data_get_msi_desc(data);
> @@ -194,6 +228,8 @@ static void pci_irq_unmask_msi(struct irq_data *data)
>  static const struct msi_domain_template pci_msi_template = {
>  	.chip = {
>  		.name			= "PCI-MSI",
> +		.irq_startup		= pci_irq_startup_msi,
> +		.irq_shutdown		= pci_irq_shutdown_msi,
>  		.irq_mask		= pci_irq_mask_msi,
>  		.irq_unmask		= pci_irq_unmask_msi,
>  		.irq_write_msi_msg	= pci_msi_domain_write_msg,
> @@ -210,6 +246,20 @@ static const struct msi_domain_template pci_msi_template = {
>  	},
>  };
>  
> +static void pci_irq_shutdown_msix(struct irq_data *data)
> +{
> +	pci_msix_mask(irq_data_get_msi_desc(data));
> +	cond_shutdown_parent(data);
> +}
> +
> +static unsigned int pci_irq_startup_msix(struct irq_data *data)
> +{
> +	unsigned int ret = cond_startup_parent(data);
> +
> +	pci_msix_unmask(irq_data_get_msi_desc(data));
> +	return ret;
> +}
> +
>  static void pci_irq_mask_msix(struct irq_data *data)
>  {
>  	pci_msix_mask(irq_data_get_msi_desc(data));
> @@ -234,6 +284,8 @@ EXPORT_SYMBOL_GPL(pci_msix_prepare_desc);
>  static const struct msi_domain_template pci_msix_template = {
>  	.chip = {
>  		.name			= "PCI-MSIX",
> +		.irq_startup		= pci_irq_startup_msix,
> +		.irq_shutdown		= pci_irq_shutdown_msix,
>  		.irq_mask		= pci_irq_mask_msix,
>  		.irq_unmask		= pci_irq_unmask_msix,
>  		.irq_write_msi_msg	= pci_msi_domain_write_msg,
> diff --git a/include/linux/msi.h b/include/linux/msi.h
> index e5e86a8529fb..3111ba95fbde 100644
> --- a/include/linux/msi.h
> +++ b/include/linux/msi.h
> @@ -568,6 +568,8 @@ enum {
>  	MSI_FLAG_PARENT_PM_DEV		= (1 << 8),
>  	/* Support for parent mask/unmask */
>  	MSI_FLAG_PCI_MSI_MASK_PARENT	= (1 << 9),
> +	/* Support for parent startup/shutdown */
> +	MSI_FLAG_PCI_MSI_STARTUP_PARENT	= (1 << 10),
>  
>  	/* Mask for the generic functionality */
>  	MSI_GENERIC_FLAGS_MASK		= GENMASK(15, 0),
> -- 
> 2.50.1
>
Re: [PATCH 2/4] PCI/MSI: Add startup/shutdown support for per device MSI[X] domains
Posted by Inochi Amaoto 6 months ago 
On Thu, Aug 07, 2025 at 11:25:21AM -0500, Bjorn Helgaas wrote:
> In subject, s/MSI[X]// and s/support for/for/
> 
> The "MSI[X]" notation really isn't used anywhere else, and we already
> include "PCI/MSI" in the prefix, so I don't think we need it again.
> 
> On Thu, Aug 07, 2025 at 07:23:23PM +0800, Inochi Amaoto wrote:
> > As The RISC-V PLIC can not apply affinity setting without calling
> > irq_enable(), it will make the interrupt unavaible when using as
> > an underlying irq chip for MSI controller.
> 
> s/As The/As the/
> s/unavaible/unavailable/
> s/irq chip/IRQ chip/
> 

These are good for me. I will take it.

> > Introduce the irq_startup/irq_shutdown for PCI domain template with
> > new MSI domain flag. This allow the PLIC can be properly configurated
> > when calling irq_startup().
> 
> Maybe something like:
> 
>   Implement .irq_startup() and .irq_shutdown() for the PCI MSI and
>   MSI-X templates.  For chips that specify MSI_FLAG_PCI_MSI_STARTUP_PARENT, 
>   these startup and shutdown the parent as well, which allows ...
> 
> s/This allow/This allows/
> s/can be properly configurated/to be configured/
> 

Thanks, I will update my commit log.

> Evidently PLIC depends on this "parent" connection, but that isn't
> explained at all in the commit log.
> 

When call irq_startup, the PLIC is called irq_enable() instead of 
irq_unmask(), the the irq on PLIC can be enabled.

I will add this to the commit log.

> > Suggested-by: Thomas Gleixner <tglx@linutronix.de>
> > Signed-off-by: Inochi Amaoto <inochiama@gmail.com>
> > ---
> >  drivers/pci/msi/irqdomain.c | 52 +++++++++++++++++++++++++++++++++++++
> >  include/linux/msi.h         |  2 ++
> >  2 files changed, 54 insertions(+)
> > 
> > diff --git a/drivers/pci/msi/irqdomain.c b/drivers/pci/msi/irqdomain.c
> > index 0938ef7ebabf..f0d18cadbe20 100644
> > --- a/drivers/pci/msi/irqdomain.c
> > +++ b/drivers/pci/msi/irqdomain.c
> > @@ -148,6 +148,23 @@ static void pci_device_domain_set_desc(msi_alloc_info_t *arg, struct msi_desc *d
> >  	arg->hwirq = desc->msi_index;
> >  }
> >  
> > +static __always_inline void cond_shutdown_parent(struct irq_data *data)
> 
> Is there a functional reason why we need __always_inline?
> 

I am not sure for this. As I found other cond_[mask/unmask]_parent()
also have this attribute, I added this as well.

> If not, it seems like this annotation is just clutter, and the compiler
> will probably inline it all by itself.
> 

I will see if someone know the reason. If there is no other objection,
I will remove this in the next version

Regards,
Inochi
Re: [PATCH 2/4] PCI/MSI: Add startup/shutdown support for per device MSI[X] domains
Posted by Thomas Gleixner 6 months ago 
On Fri, Aug 08 2025 at 07:18, Inochi Amaoto wrote:
> On Thu, Aug 07, 2025 at 11:25:21AM -0500, Bjorn Helgaas wrote:
>> >  
>> > +static __always_inline void cond_shutdown_parent(struct irq_data *data)
>> 
>> Is there a functional reason why we need __always_inline?
>>
> I am not sure for this. As I found other cond_[mask/unmask]_parent()
> also have this attribute, I added this as well.
>
>> If not, it seems like this annotation is just clutter, and the compiler
>> will probably inline it all by itself.

Most of the time, but yes in this case it's irrelevant.

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