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PCI/MSI: Reject multi-MSI early

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When hierarchical MSI interrupt domains are enabled then there is no point
to do tons of work and detect the missing support for multi-MSI late in the
allocation path.

Just query the domain feature flags right away. The query function is going
to be used for other purposes later and has a mode argument which influences
the result:

  ALLOW_LEGACY returns true when:
     - there is no irq domain attached (legacy support)
     - there is a irq domain attached which has the feature flag set

  DENY_LEGACY returns only true when:
     - there is a irq domain attached which has the feature flag set

This allows to use the function universally without ifdeffery in the
calling code.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Link: https://lore.kernel.org/r/20221111122015.574339988@linutronix.de
This commit is contained in:
Thomas Gleixner
2022-11-11 14:55:09 +01:00
parent bab65e48cb
commit d2a463b297
3 changed files with 35 additions and 0 deletions
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22
drivers/pci/msi/irqdomain.c
View File

@@ -187,6 +187,28 @@ struct irq_domain *pci_msi_create_irq_domain(struct fwnode_handle *fwnode,
}
EXPORT_SYMBOL_GPL(pci_msi_create_irq_domain);
/**
* pci_msi_domain_supports - Check for support of a particular feature flag
* @pdev: The PCI device to operate on
* @feature_mask: The feature mask to check for (full match)
* @mode: If ALLOW_LEGACY this grants the feature when there is no irq domain
* associated to the device. If DENY_LEGACY the lack of an irq domain
* makes the feature unsupported
*/
bool pci_msi_domain_supports(struct pci_dev *pdev, unsigned int feature_mask,
enum support_mode mode)
{
struct msi_domain_info *info;
struct irq_domain *domain;
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;
}
/*
* Users of the generic MSI infrastructure expect a device to have a single ID,
* so with DMA aliases we have to pick the least-worst compromise. Devices with

4
drivers/pci/msi/msi.c
View File

@@ -347,6 +347,10 @@ static int msi_capability_init(struct pci_dev *dev, int nvec,
struct msi_desc *entry;
int ret;
/* Reject multi-MSI early on irq domain enabled architectures */
if (nvec > 1 && !pci_msi_domain_supports(dev, MSI_FLAG_MULTI_PCI_MSI, ALLOW_LEGACY))
return 1;
/*
* Disable MSI during setup in the hardware, but mark it enabled
* so that setup code can evaluate it.

9
drivers/pci/msi/msi.h
View File

@@ -97,6 +97,15 @@ int __pci_enable_msix_range(struct pci_dev *dev, struct msix_entry *entries, int
void __pci_restore_msi_state(struct pci_dev *dev);
void __pci_restore_msix_state(struct pci_dev *dev);
/* irq_domain related functionality */
enum support_mode {
ALLOW_LEGACY,
DENY_LEGACY,
};
bool pci_msi_domain_supports(struct pci_dev *dev, unsigned int feature_mask, enum support_mode mode);
/* Legacy (!IRQDOMAIN) fallbacks */
#ifdef CONFIG_PCI_MSI_ARCH_FALLBACKS