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Date: Fri, 11 Nov 2022 14:55:09 +0100 (CET)
From: Thomas Gleixner <tglx@...utronix.de>
To: LKML <linux-kernel@...r.kernel.org>
Cc: x86@...nel.org, Joerg Roedel <joro@...tes.org>,
Will Deacon <will@...nel.org>, linux-pci@...r.kernel.org,
Bjorn Helgaas <bhelgaas@...gle.com>,
Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
Marc Zyngier <maz@...nel.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Jason Gunthorpe <jgg@...lanox.com>,
Dave Jiang <dave.jiang@...el.com>,
Alex Williamson <alex.williamson@...hat.com>,
Kevin Tian <kevin.tian@...el.com>,
Dan Williams <dan.j.williams@...el.com>,
Logan Gunthorpe <logang@...tatee.com>,
Ashok Raj <ashok.raj@...el.com>, Jon Mason <jdmason@...zu.us>,
Allen Hubbe <allenbh@...il.com>,
Michael Ellerman <mpe@...erman.id.au>,
Christophe Leroy <christophe.leroy@...roup.eu>,
linuxppc-dev@...ts.ozlabs.org,
"Ahmed S. Darwish" <darwi@...utronix.de>,
Reinette Chatre <reinette.chatre@...el.com>
Subject: [patch 34/39] PCI/MSI: Reject multi-MSI early
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@...utronix.de>
---
drivers/pci/msi/irqdomain.c | 22 ++++++++++++++++++++++
drivers/pci/msi/msi.c | 4 ++++
drivers/pci/msi/msi.h | 9 +++++++++
3 files changed, 35 insertions(+)
--- a/drivers/pci/msi/irqdomain.c
+++ b/drivers/pci/msi/irqdomain.c
@@ -187,6 +187,28 @@ struct irq_domain *pci_msi_create_irq_do
}
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
--- a/drivers/pci/msi/msi.c
+++ b/drivers/pci/msi/msi.c
@@ -347,6 +347,10 @@ static int msi_capability_init(struct pc
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.
--- a/drivers/pci/msi/msi.h
+++ b/drivers/pci/msi/msi.h
@@ -97,6 +97,15 @@ int __pci_enable_msix_range(struct pci_d
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
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