[PATCH 5.13 232/351] PCI: iproc: Support multi-MSI only on uniprocessor kernel

Greg Kroah-Hartman
2021-07-19T17:43:00Z

From: Sandor Bodo-Merle <sbodomerle@gmail.com>

[ 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: fc54bae28818 ("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>
---
drivers/pci/controller/pcie-iproc-msi.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/controller/pcie-iproc-msi.c b/drivers/pci/controller/pcie-iproc-msi.c
index 557d93dcb3bc..81b4effeb130 100644
--- a/drivers/pci/controller/pcie-iproc-msi.c
+++ b/drivers/pci/controller/pcie-iproc-msi.c
@@ -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);

/*
@@ -540,6 +543,9 @@ 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");
--
2.30.2