PCI/MSI: Use msi_add_msi_desc()

Simplify the allocation of MSI descriptors by using msi_add_msi_desc()
which moves the storage handling to core code and prepares for dynamic
extension of the MSI-X vector space.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Michael Kelley <mikelley@microsoft.com>
Tested-by: Nishanth Menon <nm@ti.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Link: https://lore.kernel.org/r/20211206210748.035348646@linutronix.de

drivers/pci/msi/msi.c

@@ -376,40 +376,41 @@ static int pci_setup_msi_context(struct pci_dev *dev)
 	return ret;
 }
 
-static struct msi_desc *
-msi_setup_entry(struct pci_dev *dev, int nvec, struct irq_affinity_desc *masks)
+static int msi_setup_msi_desc(struct pci_dev *dev, int nvec,
+			      struct irq_affinity_desc *masks)
 {
-	struct msi_desc *entry;
+	struct msi_desc desc;
 	u16 control;
 
 	/* MSI Entry Initialization */
-	entry = alloc_msi_entry(&dev->dev, nvec, masks);
-	if (!entry)
-		return NULL;
+	memset(&desc, 0, sizeof(desc));
 
 	pci_read_config_word(dev, dev->msi_cap + PCI_MSI_FLAGS, &control);
 	/* Lies, damned lies, and MSIs */
 	if (dev->dev_flags & PCI_DEV_FLAGS_HAS_MSI_MASKING)
 		control |= PCI_MSI_FLAGS_MASKBIT;
+	/* Respect XEN's mask disabling */
+	if (pci_msi_ignore_mask)
+		control &= ~PCI_MSI_FLAGS_MASKBIT;
 
-	entry->pci.msi_attrib.is_64	= !!(control & PCI_MSI_FLAGS_64BIT);
-	entry->pci.msi_attrib.can_mask	= !pci_msi_ignore_mask &&
-					  !!(control & PCI_MSI_FLAGS_MASKBIT);
-	entry->pci.msi_attrib.default_irq = dev->irq;
-	entry->pci.msi_attrib.multi_cap	= (control & PCI_MSI_FLAGS_QMASK) >> 1;
-	entry->pci.msi_attrib.multiple	= ilog2(__roundup_pow_of_two(nvec));
+	desc.nvec_used			= nvec;
+	desc.pci.msi_attrib.is_64	= !!(control & PCI_MSI_FLAGS_64BIT);
+	desc.pci.msi_attrib.can_mask	= !!(control & PCI_MSI_FLAGS_MASKBIT);
+	desc.pci.msi_attrib.default_irq	= dev->irq;
+	desc.pci.msi_attrib.multi_cap	= (control & PCI_MSI_FLAGS_QMASK) >> 1;
+	desc.pci.msi_attrib.multiple	= ilog2(__roundup_pow_of_two(nvec));
+	desc.affinity			= masks;
 
 	if (control & PCI_MSI_FLAGS_64BIT)
-		entry->pci.mask_pos = dev->msi_cap + PCI_MSI_MASK_64;
+		desc.pci.mask_pos = dev->msi_cap + PCI_MSI_MASK_64;
 	else
-		entry->pci.mask_pos = dev->msi_cap + PCI_MSI_MASK_32;
+		desc.pci.mask_pos = dev->msi_cap + PCI_MSI_MASK_32;
 
 	/* Save the initial mask status */
-	if (entry->pci.msi_attrib.can_mask)
-		pci_read_config_dword(dev, entry->pci.mask_pos, &entry->pci.msi_mask);
-
+	if (desc.pci.msi_attrib.can_mask)
+		pci_read_config_dword(dev, desc.pci.mask_pos, &desc.pci.msi_mask);
 
-	return entry;
+	return msi_add_msi_desc(&dev->dev, &desc);
 }
 
 static int msi_verify_entries(struct pci_dev *dev)
@@ -459,17 +460,14 @@ static int msi_capability_init(struct pci_dev *dev, int nvec,
 		masks = irq_create_affinity_masks(nvec, affd);
 
 	msi_lock_descs(&dev->dev);
-	entry = msi_setup_entry(dev, nvec, masks);
-	if (!entry) {
-		ret = -ENOMEM;
+	ret = msi_setup_msi_desc(dev, nvec, masks);
+	if (ret)
 		goto fail;
-	}
 
 	/* All MSIs are unmasked by default; mask them all */
+	entry = first_pci_msi_entry(dev);
 	pci_msi_mask(entry, msi_multi_mask(entry));
 
-	list_add_tail(&entry->list, dev_to_msi_list(&dev->dev));
-
 	/* Configure MSI capability structure */
 	ret = pci_msi_setup_msi_irqs(dev, nvec, PCI_CAP_ID_MSI);
 	if (ret)
@@ -519,48 +517,40 @@ static void __iomem *msix_map_region(struct pci_dev *dev,
 	return ioremap(phys_addr, nr_entries * PCI_MSIX_ENTRY_SIZE);
 }
 
-static int msix_setup_entries(struct pci_dev *dev, void __iomem *base,
-			      struct msix_entry *entries, int nvec,
-			      struct irq_affinity_desc *masks)
+static int msix_setup_msi_descs(struct pci_dev *dev, void __iomem *base,
+				struct msix_entry *entries, int nvec,
+				struct irq_affinity_desc *masks)
 {
-	int i, vec_count = pci_msix_vec_count(dev);
+	int ret = 0, i, vec_count = pci_msix_vec_count(dev);
 	struct irq_affinity_desc *curmsk;
-	struct msi_desc *entry;
+	struct msi_desc desc;
 	void __iomem *addr;
 
-	for (i = 0, curmsk = masks; i < nvec; i++) {
-		entry = alloc_msi_entry(&dev->dev, 1, curmsk);
-		if (!entry) {
-			/* No enough memory. Don't try again */
-			return -ENOMEM;
-		}
-
-		entry->pci.msi_attrib.is_msix	= 1;
-		entry->pci.msi_attrib.is_64	= 1;
+	memset(&desc, 0, sizeof(desc));
 
-		if (entries)
-			entry->msi_index = entries[i].entry;
-		else
-			entry->msi_index = i;
+	desc.nvec_used			= 1;
+	desc.pci.msi_attrib.is_msix	= 1;
+	desc.pci.msi_attrib.is_64	= 1;
+	desc.pci.msi_attrib.default_irq	= dev->irq;
+	desc.pci.mask_base		= base;
 
-		entry->pci.msi_attrib.is_virtual = entry->msi_index >= vec_count;
+	for (i = 0, curmsk = masks; i < nvec; i++, curmsk++) {
+		desc.msi_index = entries ? entries[i].entry : i;
+		desc.affinity = masks ? curmsk : NULL;
+		desc.pci.msi_attrib.is_virtual = desc.msi_index >= vec_count;
+		desc.pci.msi_attrib.can_mask = !pci_msi_ignore_mask &&
+					       !desc.pci.msi_attrib.is_virtual;
 
-		entry->pci.msi_attrib.can_mask	= !pci_msi_ignore_mask &&
-						  !entry->pci.msi_attrib.is_virtual;
-
-		entry->pci.msi_attrib.default_irq	= dev->irq;
-		entry->pci.mask_base			= base;
-
-		if (entry->pci.msi_attrib.can_mask) {
-			addr = pci_msix_desc_addr(entry);
-			entry->pci.msix_ctrl = readl(addr + PCI_MSIX_ENTRY_VECTOR_CTRL);
+		if (!desc.pci.msi_attrib.can_mask) {
+			addr = pci_msix_desc_addr(&desc);
+			desc.pci.msix_ctrl = readl(addr + PCI_MSIX_ENTRY_VECTOR_CTRL);
 		}
 
-		list_add_tail(&entry->list, dev_to_msi_list(&dev->dev));
-		if (masks)
-			curmsk++;
+		ret = msi_add_msi_desc(&dev->dev, &desc);
+		if (ret)
+			break;
 	}
-	return 0;
+	return ret;
 }
 
 static void msix_update_entries(struct pci_dev *dev, struct msix_entry *entries)
@@ -598,7 +588,7 @@ static int msix_setup_interrupts(struct pci_dev *dev, void __iomem *base,
 		masks = irq_create_affinity_masks(nvec, affd);
 
 	msi_lock_descs(&dev->dev);
-	ret = msix_setup_entries(dev, base, entries, nvec, masks);
+	ret = msix_setup_msi_descs(dev, base, entries, nvec, masks);
 	if (ret)
 		goto out_free;