diff mbox series

[V2,12/33] PCI/MSI: Add support for per device MSI[X] domains

Message ID 20221121091327.163146917@linutronix.de (mailing list archive)
State Handled Elsewhere
Headers show
Series genirq, PCI/MSI: Support for per device MSI and PCI/IMS - Part 3 implementation | expand

Commit Message

Thomas Gleixner Nov. 21, 2022, 2:38 p.m. UTC 
Provide a template and the necessary callbacks to create PCI/MSI and
PCI/MSI-X domains.

The domains are created when MSI or MSI-X is enabled. The domain's lifetime
is either the device lifetime or in case that e.g. MSI-X was tried first
and failed, then the MSI-X domain is removed and a MSI domain is created as
both are mutually exclusive and reside in the default domain ID slot of the
per device domain pointer array.

Also expand pci_msi_domain_supports() to handle feature checks correctly
even in the case that the per device domain was not yet created by checking
the features supported by the MSI parent.

Add the necessary setup calls into the MSI and MSI-X enable code path.
These setup calls are backwards compatible. They return success when there
is no parent domain found, which means the existing global domains or the
legacy allocation path keep just working.

Co-developed-by: Ahmed S. Darwish <darwi@linutronix.de>
Signed-off-by: Ahmed S. Darwish <darwi@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
---
 drivers/pci/msi/irqdomain.c |  188 +++++++++++++++++++++++++++++++++++++++++++-
 drivers/pci/msi/msi.c       |   16 +++
 drivers/pci/msi/msi.h       |    2 
 3 files changed, 201 insertions(+), 5 deletions(-)

Comments

Tian, Kevin Nov. 23, 2022, 8:08 a.m. UTC | #1 
> From: Thomas Gleixner <tglx@linutronix.de>
> Sent: Monday, November 21, 2022 10:38 PM
> 
> +
> +static void pci_mask_msi(struct irq_data *data)
> +{
> +	struct msi_desc *desc = irq_data_get_msi_desc(data);
> +
> +	pci_msi_mask(desc, BIT(data->irq - desc->irq));

pci_mask_msi() and pci_msi_mask() are confusing.

Probably pci_irq_mask_msi() given the parameter is irq_data.

> +bool pci_setup_msi_device_domain(struct pci_dev *pdev)
> +{
> +	if (WARN_ON_ONCE(pdev->msix_enabled))
> +		return false;

the check already exists in __pci_enable_msi_range()

> +bool pci_setup_msix_device_domain(struct pci_dev *pdev, unsigned int
> hwsize)
> +{
> +	if (WARN_ON_ONCE(pdev->msix_enabled))
> +		return false;

ditto.

btw according to the comment this should check pdev->msi_enabled.

> @@ -152,13 +316,33 @@ bool pci_msi_domain_supports(struct pci_
>  {
>  	struct msi_domain_info *info;
>  	struct irq_domain *domain;
> +	unsigned int supported;
> 
>  	domain = dev_get_msi_domain(&pdev->dev);
> 
>  	if (!domain || !irq_domain_is_hierarchy(domain))
>  		return mode == ALLOW_LEGACY;
> -	info = domain->host_data;
> -	return (info->flags & feature_mask) == feature_mask;
> +
> +	if (!irq_domain_is_msi_parent(domain)) {
> +		/*
> +		 * For "global" PCI/MSI interrupt domains the associated
> +		 * msi_domain_info::flags is the authoritive source of
> +		 * information.
> +		 */
> +		info = domain->host_data;
> +		supported = info->flags;
> +	} else {
> +		/*
> +		 * For MSI parent domains the supported feature set
> +		 * is avaliable in the parent ops. This makes checks
> +		 * possible before actually instantiating the
> +		 * per device domain because the parent is never
> +		 * expanding the PCI/MSI functionality.
> +		 */
> +		supported = domain->msi_parent_ops->supported_flags;

This is general PCI MSI logic. So an open related to my rely to patch02,
is it correct for PCI core to assume that the real parent imposes all the
restrictions and there is no need to further go down the hierarchy?
Thomas Gleixner Nov. 23, 2022, 11:41 a.m. UTC | #2 
On Wed, Nov 23 2022 at 08:08, Kevin Tian wrote:
>> From: Thomas Gleixner <tglx@linutronix.de>
>
> pci_mask_msi() and pci_msi_mask() are confusing.
>
> Probably pci_irq_mask_msi() given the parameter is irq_data.

maybe.

>> +bool pci_setup_msi_device_domain(struct pci_dev *pdev)
>> +{
>> +	if (WARN_ON_ONCE(pdev->msix_enabled))
>> +		return false;
>
> the check already exists in __pci_enable_msi_range()
>
>> +bool pci_setup_msix_device_domain(struct pci_dev *pdev, unsigned int
>> hwsize)
>> +{
>> +	if (WARN_ON_ONCE(pdev->msix_enabled))
>> +		return false;
>
> ditto.
>
> btw according to the comment this should check pdev->msi_enabled.

Yeah, those are probably redundant.

>
>> @@ -152,13 +316,33 @@ bool pci_msi_domain_supports(struct pci_
>>  {
>>  	struct msi_domain_info *info;
>>  	struct irq_domain *domain;
>> +	unsigned int supported;
>> 
>>  	domain = dev_get_msi_domain(&pdev->dev);
>> 
>>  	if (!domain || !irq_domain_is_hierarchy(domain))
>>  		return mode == ALLOW_LEGACY;
>> -	info = domain->host_data;
>> -	return (info->flags & feature_mask) == feature_mask;
>> +
>> +	if (!irq_domain_is_msi_parent(domain)) {
>> +		/*
>> +		 * For "global" PCI/MSI interrupt domains the associated
>> +		 * msi_domain_info::flags is the authoritive source of
>> +		 * information.
>> +		 */
>> +		info = domain->host_data;
>> +		supported = info->flags;
>> +	} else {
>> +		/*
>> +		 * For MSI parent domains the supported feature set
>> +		 * is avaliable in the parent ops. This makes checks
>> +		 * possible before actually instantiating the
>> +		 * per device domain because the parent is never
>> +		 * expanding the PCI/MSI functionality.
>> +		 */
>> +		supported = domain->msi_parent_ops->supported_flags;
>
> This is general PCI MSI logic. So an open related to my rely to patch02,
> is it correct for PCI core to assume that the real parent imposes all the
> restrictions and there is no need to further go down the hierarchy?

That was my working assumption and it turned out to be correct with both
x86 and ARM.

Thanks,

        tglx
Thomas Gleixner Nov. 23, 2022, 9:50 p.m. UTC | #3 
On Wed, Nov 23 2022 at 12:41, Thomas Gleixner wrote:
> On Wed, Nov 23 2022 at 08:08, Kevin Tian wrote:
>>> +bool pci_setup_msi_device_domain(struct pci_dev *pdev)
>>> +{
>>> +	if (WARN_ON_ONCE(pdev->msix_enabled))
>>> +		return false;
>>
>> the check already exists in __pci_enable_msi_range()
>>
>>> +bool pci_setup_msix_device_domain(struct pci_dev *pdev, unsigned int
>>> hwsize)
>>> +{
>>> +	if (WARN_ON_ONCE(pdev->msix_enabled))
>>> +		return false;
>>
>> ditto.
>>
>> btw according to the comment this should check pdev->msi_enabled.
>
> Yeah, those are probably redundant.

I fixed the MSIX check and kept them for paranoia reasons, so changes in
the calling code get caught.

>> This is general PCI MSI logic. So an open related to my rely to patch02,
>> is it correct for PCI core to assume that the real parent imposes all the
>> restrictions and there is no need to further go down the hierarchy?
>
> That was my working assumption and it turned out to be correct with both
> x86 and ARM.

As a follow up, I went through some of the other architectures,
especially the places which have extra limitations and it turns out that
the restriction comes always from the direct parent.

If that ever changes then we need a callback which lets us evaluate the
resulting capabilities through the hierarchy. That's nothing which can
be evaluated directly.

Just look at the x86 hierarchy with IR. IR allows multi PCI-MSI, but the
vector domain does not. Who is right? That's a decision which is made in
the particular hierarchy.

For now it's valid that the direct MSI parent has the proper set
available.

Thanks,

        tglx
Tian, Kevin Nov. 24, 2022, 1:08 a.m. UTC | #4 
> From: Thomas Gleixner <tglx@linutronix.de>
> Sent: Thursday, November 24, 2022 5:50 AM
> 
> >> This is general PCI MSI logic. So an open related to my rely to patch02,
> >> is it correct for PCI core to assume that the real parent imposes all the
> >> restrictions and there is no need to further go down the hierarchy?
> >
> > That was my working assumption and it turned out to be correct with both
> > x86 and ARM.
> 
> As a follow up, I went through some of the other architectures,
> especially the places which have extra limitations and it turns out that
> the restriction comes always from the direct parent.
> 
> If that ever changes then we need a callback which lets us evaluate the
> resulting capabilities through the hierarchy. That's nothing which can
> be evaluated directly.
> 
> Just look at the x86 hierarchy with IR. IR allows multi PCI-MSI, but the
> vector domain does not. Who is right? That's a decision which is made in
> the particular hierarchy.

make sense.

> 
> For now it's valid that the direct MSI parent has the proper set
> available.
> 

probably above can be marked out in the comment.
diff mbox series

Patch

--- a/drivers/pci/msi/irqdomain.c
+++ b/drivers/pci/msi/irqdomain.c
@@ -139,6 +139,170 @@  struct irq_domain *pci_msi_create_irq_do
 }
 EXPORT_SYMBOL_GPL(pci_msi_create_irq_domain);
 
+/*
+ * Per device MSI[-X] domain functionality
+ */
+static void pci_device_domain_set_desc(msi_alloc_info_t *arg, struct msi_desc *desc)
+{
+	arg->desc = desc;
+	arg->hwirq = desc->msi_index;
+}
+
+static void pci_mask_msi(struct irq_data *data)
+{
+	struct msi_desc *desc = irq_data_get_msi_desc(data);
+
+	pci_msi_mask(desc, BIT(data->irq - desc->irq));
+}
+
+static void pci_unmask_msi(struct irq_data *data)
+{
+	struct msi_desc *desc = irq_data_get_msi_desc(data);
+
+	pci_msi_unmask(desc, BIT(data->irq - desc->irq));
+}
+
+#ifdef CONFIG_GENERIC_IRQ_RESERVATION_MODE
+# define MSI_REACTIVATE		MSI_FLAG_MUST_REACTIVATE
+#else
+# define MSI_REACTIVATE		0
+#endif
+
+#define MSI_COMMON_FLAGS	(MSI_FLAG_FREE_MSI_DESCS |	\
+				 MSI_FLAG_ACTIVATE_EARLY |	\
+				 MSI_FLAG_DEV_SYSFS |		\
+				 MSI_REACTIVATE)
+
+static struct msi_domain_template pci_msi_template = {
+	.chip = {
+		.name			= "PCI-MSI",
+		.irq_mask		= pci_mask_msi,
+		.irq_unmask		= pci_unmask_msi,
+		.irq_write_msi_msg	= pci_msi_domain_write_msg,
+		.flags			= IRQCHIP_ONESHOT_SAFE,
+	},
+
+	.ops = {
+		.set_desc		= pci_device_domain_set_desc,
+	},
+
+	.info = {
+		.flags			= MSI_COMMON_FLAGS | MSI_FLAG_MULTI_PCI_MSI,
+		.bus_token		= DOMAIN_BUS_PCI_DEVICE_MSI,
+	},
+};
+
+static void pci_mask_msix(struct irq_data *data)
+{
+	pci_msix_mask(irq_data_get_msi_desc(data));
+}
+
+static void pci_unmask_msix(struct irq_data *data)
+{
+	pci_msix_unmask(irq_data_get_msi_desc(data));
+}
+
+static struct msi_domain_template pci_msix_template = {
+	.chip = {
+		.name			= "PCI-MSIX",
+		.irq_mask		= pci_mask_msix,
+		.irq_unmask		= pci_unmask_msix,
+		.irq_write_msi_msg	= pci_msi_domain_write_msg,
+		.flags			= IRQCHIP_ONESHOT_SAFE,
+	},
+
+	.ops = {
+		.set_desc		= pci_device_domain_set_desc,
+	},
+
+	.info = {
+		.flags			= MSI_COMMON_FLAGS | MSI_FLAG_PCI_MSIX,
+		.bus_token		= DOMAIN_BUS_PCI_DEVICE_MSIX,
+	},
+};
+
+static bool pci_match_device_domain(struct pci_dev *pdev, enum irq_domain_bus_token bus_token)
+{
+	return msi_match_device_irq_domain(&pdev->dev, MSI_DEFAULT_DOMAIN, bus_token);
+}
+
+static bool pci_create_device_domain(struct pci_dev *pdev, struct msi_domain_template *tmpl,
+				     unsigned int hwsize)
+{
+	struct irq_domain *domain = dev_get_msi_domain(&pdev->dev);
+
+	if (!domain || !irq_domain_is_msi_parent(domain))
+		return true;
+
+	return msi_create_device_irq_domain(&pdev->dev, MSI_DEFAULT_DOMAIN, tmpl,
+					    hwsize, NULL, NULL);
+}
+
+/**
+ * pci_setup_msi_device_domain - Setup a device MSI interrupt domain
+ * @pdev:	The PCI device to create the domain on
+ *
+ * Return:
+ *  True when:
+ *	- The device does not have a MSI parent irq domain associated,
+ *	  which keeps the legacy architecture specific and the global
+ *	  PCI/MSI domain models working
+ *	- The MSI domain exists already
+ *	- The MSI domain was successfully allocated
+ *  False when:
+ *	- MSI-X is enabled
+ *	- The domain creation fails.
+ *
+ * The created MSI domain is preserved until:
+ *	- The device is removed
+ *	- MSI is disabled and a MSI-X domain is created
+ */
+bool pci_setup_msi_device_domain(struct pci_dev *pdev)
+{
+	if (WARN_ON_ONCE(pdev->msix_enabled))
+		return false;
+
+	if (pci_match_device_domain(pdev, DOMAIN_BUS_PCI_DEVICE_MSI))
+		return true;
+	if (pci_match_device_domain(pdev, DOMAIN_BUS_PCI_DEVICE_MSIX))
+		msi_remove_device_irq_domain(&pdev->dev, MSI_DEFAULT_DOMAIN);
+
+	return pci_create_device_domain(pdev, &pci_msi_template, 1);
+}
+
+/**
+ * pci_setup_msix_device_domain - Setup a device MSI-X interrupt domain
+ * @pdev:	The PCI device to create the domain on
+ * @hwsize:	The size of the MSI-X vector table
+ *
+ * Return:
+ *  True when:
+ *	- The device does not have a MSI parent irq domain associated,
+ *	  which keeps the legacy architecture specific and the global
+ *	  PCI/MSI domain models working
+ *	- The MSI-X domain exists already
+ *	- The MSI-X domain was successfully allocated
+ *  False when:
+ *	- MSI is enabled
+ *	- The domain creation fails.
+ *
+ * The created MSI-X domain is preserved until:
+ *	- The device is removed
+ *	- MSI-X is disabled and a MSI domain is created
+ */
+bool pci_setup_msix_device_domain(struct pci_dev *pdev, unsigned int hwsize)
+{
+	if (WARN_ON_ONCE(pdev->msix_enabled))
+		return false;
+
+	if (pci_match_device_domain(pdev, DOMAIN_BUS_PCI_DEVICE_MSIX))
+		return true;
+	if (pci_match_device_domain(pdev, DOMAIN_BUS_PCI_DEVICE_MSI))
+		msi_remove_device_irq_domain(&pdev->dev, MSI_DEFAULT_DOMAIN);
+
+	return pci_create_device_domain(pdev, &pci_msix_template, hwsize);
+}
+
 /**
  * pci_msi_domain_supports - Check for support of a particular feature flag
  * @pdev:		The PCI device to operate on
@@ -152,13 +316,33 @@  bool pci_msi_domain_supports(struct pci_
 {
 	struct msi_domain_info *info;
 	struct irq_domain *domain;
+	unsigned int supported;
 
 	domain = dev_get_msi_domain(&pdev->dev);
 
 	if (!domain || !irq_domain_is_hierarchy(domain))
 		return mode == ALLOW_LEGACY;
-	info = domain->host_data;
-	return (info->flags & feature_mask) == feature_mask;
+
+	if (!irq_domain_is_msi_parent(domain)) {
+		/*
+		 * For "global" PCI/MSI interrupt domains the associated
+		 * msi_domain_info::flags is the authoritive source of
+		 * information.
+		 */
+		info = domain->host_data;
+		supported = info->flags;
+	} else {
+		/*
+		 * For MSI parent domains the supported feature set
+		 * is avaliable in the parent ops. This makes checks
+		 * possible before actually instantiating the
+		 * per device domain because the parent is never
+		 * expanding the PCI/MSI functionality.
+		 */
+		supported = domain->msi_parent_ops->supported_flags;
+	}
+
+	return (supported & feature_mask) == feature_mask;
 }
 
 /*
--- a/drivers/pci/msi/msi.c
+++ b/drivers/pci/msi/msi.c
@@ -436,6 +436,9 @@  int __pci_enable_msi_range(struct pci_de
 	if (rc)
 		return rc;
 
+	if (!pci_setup_msi_device_domain(dev))
+		return -ENODEV;
+
 	for (;;) {
 		if (affd) {
 			nvec = irq_calc_affinity_vectors(minvec, nvec, affd);
@@ -787,9 +790,13 @@  int __pci_enable_msix_range(struct pci_d
 	if (!pci_msix_validate_entries(dev, entries, nvec, hwsize))
 		return -EINVAL;
 
-	/* PCI_IRQ_VIRTUAL is a horrible hack! */
-	if (nvec > hwsize && !(flags & PCI_IRQ_VIRTUAL))
-		nvec = hwsize;
+	if (hwsize < nvec) {
+		/* Keep the IRQ virtual hackery working */
+		if (flags & PCI_IRQ_VIRTUAL)
+			hwsize = nvec;
+		else
+			nvec = hwsize;
+	}
 
 	if (nvec < minvec)
 		return -ENOSPC;
@@ -798,6 +805,9 @@  int __pci_enable_msix_range(struct pci_d
 	if (rc)
 		return rc;
 
+	if (!pci_setup_msix_device_domain(dev, hwsize))
+		return -ENODEV;
+
 	for (;;) {
 		if (affd) {
 			nvec = irq_calc_affinity_vectors(minvec, nvec, affd);
--- a/drivers/pci/msi/msi.h
+++ b/drivers/pci/msi/msi.h
@@ -105,6 +105,8 @@  enum support_mode {
 };
 
 bool pci_msi_domain_supports(struct pci_dev *dev, unsigned int feature_mask, enum support_mode mode);
+bool pci_setup_msi_device_domain(struct pci_dev *pdev);
+bool pci_setup_msix_device_domain(struct pci_dev *pdev, unsigned int hwsize);
 
 /* Legacy (!IRQDOMAIN) fallbacks */