Commit df749be3 authored Jun 22, 2021 by Sandor Bodo-Merle Committed by Greg Kroah-Hartman Jul 20, 2021

PCI: iproc: Support multi-MSI only on uniprocessor kernel

[ Upstream commit 2dc0a201d0f59e6818ef443609f0850a32910844 ]

The interrupt affinity scheme used by this driver is incompatible with
multi-MSI as it implies moving the doorbell address to that of another MSI
group.  This isn't possible for multi-MSI, as all the MSIs must have the
same doorbell address. As such it is restricted to systems with a single
CPU.

Link: https://lore.kernel.org/r/20210622152630.40842-2-sbodomerle@gmail.com


Fixes: fc54bae2 ("PCI: iproc: Allow allocation of multiple MSIs")
Reported-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Sandor Bodo-Merle <sbodomerle@gmail.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Acked-by: Pali Rohár <pali@kernel.org>
Acked-by: Ray Jui <ray.jui@broadcom.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

parent 25bff167

drivers/pci/controller/pcie-iproc-msi.c

+7 −1

Original line number	Diff line number	Diff line
		@@ -171,7 +171,7 @@ static struct irq_chip iproc_msi_irq_chip = {

		static struct msi_domain_info iproc_msi_domain_info = {
		.flags = MSI_FLAG_USE_DEF_DOM_OPS \| MSI_FLAG_USE_DEF_CHIP_OPS \|
		MSI_FLAG_MULTI_PCI_MSI \| MSI_FLAG_PCI_MSIX,
		MSI_FLAG_PCI_MSIX,
		.chip = &iproc_msi_irq_chip,
		};

		@@ -250,6 +250,9 @@ static int iproc_msi_irq_domain_alloc(struct irq_domain *domain,
		struct iproc_msi *msi = domain->host_data;
		int hwirq, i;

		if (msi->nr_cpus > 1 && nr_irqs > 1)
		return -EINVAL;

		mutex_lock(&msi->bitmap_lock);

		/*
		@@ -539,6 +542,9 @@ int iproc_msi_init(struct iproc_pcie pcie, struct device_node node)
		mutex_init(&msi->bitmap_lock);
		msi->nr_cpus = num_possible_cpus();

		if (msi->nr_cpus == 1)
		iproc_msi_domain_info.flags \|= MSI_FLAG_MULTI_PCI_MSI;

		msi->nr_irqs = of_irq_count(node);
		if (!msi->nr_irqs) {
		dev_err(pcie->dev, "found no MSI GIC interrupt\n");