diff mbox series

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

Message ID 20221111135205.951710169@linutronix.de (mailing list archive)
State Superseded
Headers show
Series genirq, PCI/MSI: Support for per device MSI and PCI/IMS - Part 3 implementation | expand

Commit Message

Thomas Gleixner Nov. 11, 2022, 1:58 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 domains lifetime
is either the device life time 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>
---
 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

Jason Gunthorpe Nov. 16, 2022, 7:13 p.m. UTC | #1 
On Fri, Nov 11, 2022 at 02:58:30PM +0100, Thomas Gleixner wrote:
> +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,
> +	},
> +};

I like this splitting alot, it makes the whole thing make so much more
sense.

> +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);

Hardwired to one 1? What about multi-msi?

Jason
Bjorn Helgaas Nov. 16, 2022, 8:22 p.m. UTC | #2 
Comment below uses [-X] (not [X]).

On Fri, Nov 11, 2022 at 02:58:30PM +0100, Thomas Gleixner wrote:
> 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 domains lifetime

domain's

> is either the device life time or in case that e.g. MSI-X was tried first

lifetime (as used above)

> 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.

ID?

> 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>

A couple typos below.

> ---
>  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(-)
> 
> --- 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

authoritative

> +		 * 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

available

> +		 * 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 */
>  
>
Thomas Gleixner Nov. 16, 2022, 10:38 p.m. UTC | #3 
On Wed, Nov 16 2022 at 15:13, Jason Gunthorpe wrote:
> On Fri, Nov 11, 2022 at 02:58:30PM +0100, Thomas Gleixner wrote:
>> +	.info = {
>> +		.flags			= MSI_COMMON_FLAGS | MSI_FLAG_PCI_MSIX,
>> +		.bus_token		= DOMAIN_BUS_PCI_DEVICE_MSIX,
>> +	},
>> +};
>
> I like this splitting alot, it makes the whole thing make so much more
> sense.

:)

>> +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);
>
> Hardwired to one 1? What about multi-msi?

MSI has exactly ONE descriptor whether it's single or multi-MSI.

Multi-MSI can have several interrupts hanging off the same descriptor,
but that's not how MSI looks at it because you write ONE message and the
hardware does the substitution of the low bits depending on which vector
is raised.

I pondered to change that, but that would have required to create yet
another code path for the 20years legacy and to adjust every single
implementation of PCI/MSI domains or the underlying parents to handle
this new world order. About 5 years later we might talk about per device
domains then.

Thanks,

        tglx
Jason Gunthorpe Nov. 17, 2022, 12:22 a.m. UTC | #4 
On Wed, Nov 16, 2022 at 11:38:52PM +0100, Thomas Gleixner wrote:

> >> +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);
> >
> > Hardwired to one 1? What about multi-msi?
> 
> MSI has exactly ONE descriptor whether it's single or multi-MSI.
> 
> Multi-MSI can have several interrupts hanging off the same descriptor,
> but that's not how MSI looks at it because you write ONE message and the
> hardware does the substitution of the low bits depending on which vector
> is raised.

Okay, that is very clear, maybe this in a comment right here ?

Jason
Thomas Gleixner Nov. 17, 2022, 8:45 a.m. UTC | #5 
On Wed, Nov 16 2022 at 20:22, Jason Gunthorpe wrote:
> On Wed, Nov 16, 2022 at 11:38:52PM +0100, Thomas Gleixner wrote:
>
>> >> +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);
>> >
>> > Hardwired to one 1? What about multi-msi?
>> 
>> MSI has exactly ONE descriptor whether it's single or multi-MSI.
>> 
>> Multi-MSI can have several interrupts hanging off the same descriptor,
>> but that's not how MSI looks at it because you write ONE message and the
>> hardware does the substitution of the low bits depending on which vector
>> is raised.
>
> Okay, that is very clear, maybe this in a comment right here ?

Sure.
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 */