[patch 09/10] PCI/MSI: Provide pci_msix_expand_vectors[_at]()

Thomas Gleixner
2021-11-27T02:18:52Z

Provide a new interface which allows to expand the MSI-X vector space if
the underlying irq domain implementation supports it.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
drivers/pci/msi/msi.c | 41 +++++++++++++++++++++++++++++++++++++++++
include/linux/pci.h | 13 +++++++++++++
2 files changed, 54 insertions(+)

--- a/drivers/pci/msi/msi.c
+++ b/drivers/pci/msi/msi.c
@@ -1025,6 +1025,47 @@ int pci_alloc_irq_vectors_affinity(struc
EXPORT_SYMBOL(pci_alloc_irq_vectors_affinity);

/**
+ * pci_msix_expand_vectors_at - Expand MSI-X interrupts for a device
+ *
+ * @dev: PCI device to operate on
+ * @at: Allocate at MSI-X index. If @at == PCI_MSI_EXPAND_AUTO
+ * the function expands automatically after the last
+ * active index.
+ * @nvec: Number of vectors to allocate
+ *
+ * Expand the MSI-X vectors of a device after an initial enablement and
+ * allocation.
+ *
+ * Return: 0 if the allocation was successful, an error code otherwise.
+ */
+int pci_msix_expand_vectors_at(struct pci_dev *dev, unsigned int at, unsigned int nvec)
+{
+ struct msi_device_data *md = dev->dev.msi.data;
+ struct msi_range range = { .ndesc = nvec, };
+ unsigned int max_vecs;
+ int ret;
+
+ if (!pci_msi_enable || !dev || !dev->msix_enabled || !md)
+ return -ENOTSUPP;
+
+ if (!pci_msi_domain_supports_expand(dev))
+ return -ENOTSUPP;
+
+ max_vecs = pci_msix_vec_count(dev);
+ if (!nvec || nvec > max_vecs)
+ return -EINVAL;
+
+ range.first = at == PCI_MSIX_EXPAND_AUTO ? md->num_descs : at;
+
+ if (range.first >= max_vecs || nvec > max_vecs - range.first)
+ return -ENOSPC;
+
+ ret = msix_setup_interrupts(dev, dev->msix_base, &range, NULL, NULL, true);
+ return ret <= 0 ? ret : -ENOSPC;;
+}
+EXPORT_SYMBOL_GPL(pci_msix_expand_vectors_at);
+
+/**
* pci_free_irq_vectors - free previously allocated IRQs for a device
* @dev: PCI device to operate on
*
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1534,6 +1534,7 @@ static inline int pci_enable_msix_exact(
int pci_alloc_irq_vectors_affinity(struct pci_dev *dev, unsigned int min_vecs,
unsigned int max_vecs, unsigned int flags,
struct irq_affinity *affd);
+int pci_msix_expand_vectors_at(struct pci_dev *dev, unsigned int at, unsigned int nvec);

void pci_free_irq_vectors(struct pci_dev *dev);
int pci_irq_vector(struct pci_dev *dev, unsigned int nr);
@@ -1565,6 +1566,11 @@ pci_alloc_irq_vectors_affinity(struct pc
return -ENOSPC;
}

+static inline int pci_msix_expand_vectors_at(struct pci_dev *dev, unsigned int at, unsigned int nvec)
+{
+ return -ENOTSUPP;
+}
+
static inline void pci_free_irq_vectors(struct pci_dev *dev)
{
}
@@ -1582,6 +1588,13 @@ static inline const struct cpumask *pci_
}
#endif

+#define PCI_MSIX_EXPAND_AUTO (UINT_MAX)
+
+static inline int pci_msix_expand_vectors(struct pci_dev *dev, unsigned int nvec)
+{
+ return pci_msix_expand_vectors_at(dev, PCI_MSIX_EXPAND_AUTO, nvec);
+}
+
/**
* pci_irqd_intx_xlate() - Translate PCI INTx value to an IRQ domain hwirq
* @d: the INTx IRQ domain