PCI/MSI: Protect MSI operations

To prepare for dynamic extension of MSI-X vectors, protect the MSI
operations for MSI and MSI-X. This requires to move the invocation of
irq_create_affinity_masks() out of the descriptor lock section to avoid
reverse lock ordering vs. CPU hotplug lock as some callers of the PCI/MSI
allocation interfaces already hold it.
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/20211206210747.982292705@linutronix.de

drivers/pci/msi/irqdomain.c

@@ -14,7 +14,7 @@ int pci_msi_setup_msi_irqs(struct pci_dev *dev, int nvec, int type)
 
 	domain = dev_get_msi_domain(&dev->dev);
 	if (domain && irq_domain_is_hierarchy(domain))
-		return msi_domain_alloc_irqs(domain, &dev->dev, nvec);
+		return msi_domain_alloc_irqs_descs_locked(domain, &dev->dev, nvec);
 
 	return pci_msi_legacy_setup_msi_irqs(dev, nvec, type);
 }
@@ -25,7 +25,7 @@ void pci_msi_teardown_msi_irqs(struct pci_dev *dev)
 
 	domain = dev_get_msi_domain(&dev->dev);
 	if (domain && irq_domain_is_hierarchy(domain))
-		msi_domain_free_irqs(domain, &dev->dev);
+		msi_domain_free_irqs_descs_locked(domain, &dev->dev);
 	else
 		pci_msi_legacy_teardown_msi_irqs(dev);
 }

drivers/pci/msi/msi.c

@@ -320,11 +320,13 @@ static void __pci_restore_msix_state(struct pci_dev *dev)
 
 	write_msg = arch_restore_msi_irqs(dev);
 
+	msi_lock_descs(&dev->dev);
 	for_each_pci_msi_entry(entry, dev) {
 		if (write_msg)
 			__pci_write_msi_msg(entry, &entry->msg);
 		pci_msix_write_vector_ctrl(entry, entry->pci.msix_ctrl);
 	}
+	msi_unlock_descs(&dev->dev);
 
 	pci_msix_clear_and_set_ctrl(dev, PCI_MSIX_FLAGS_MASKALL, 0);
 }
@@ -375,19 +377,15 @@ static int pci_setup_msi_context(struct pci_dev *dev)
 }
 
 static struct msi_desc *
-msi_setup_entry(struct pci_dev *dev, int nvec, struct irq_affinity *affd)
+msi_setup_entry(struct pci_dev *dev, int nvec, struct irq_affinity_desc *masks)
 {
-	struct irq_affinity_desc *masks = NULL;
 	struct msi_desc *entry;
 	u16 control;
 
-	if (affd)
-		masks = irq_create_affinity_masks(nvec, affd);
-
 	/* MSI Entry Initialization */
 	entry = alloc_msi_entry(&dev->dev, nvec, masks);
 	if (!entry)
-		goto out;
+		return NULL;
 
 	pci_read_config_word(dev, dev->msi_cap + PCI_MSI_FLAGS, &control);
 	/* Lies, damned lies, and MSIs */
@@ -410,8 +408,7 @@ msi_setup_entry(struct pci_dev *dev, int nvec, struct irq_affinity *affd)
 	if (entry->pci.msi_attrib.can_mask)
 		pci_read_config_dword(dev, entry->pci.mask_pos, &entry->pci.msi_mask);
 
-out:
-	kfree(masks);
+
 	return entry;
 }
 
@@ -447,6 +444,7 @@ static int msi_verify_entries(struct pci_dev *dev)
 static int msi_capability_init(struct pci_dev *dev, int nvec,
 			       struct irq_affinity *affd)
 {
+	struct irq_affinity_desc *masks = NULL;
 	struct msi_desc *entry;
 	int ret;
 
@@ -457,7 +455,11 @@ static int msi_capability_init(struct pci_dev *dev, int nvec,
 	pci_msi_set_enable(dev, 0);
 	dev->msi_enabled = 1;
 
-	entry = msi_setup_entry(dev, nvec, affd);
+	if (affd)
+		masks = irq_create_affinity_masks(nvec, affd);
+
+	msi_lock_descs(&dev->dev);
+	entry = msi_setup_entry(dev, nvec, masks);
 	if (!entry) {
 		ret = -ENOMEM;
 		goto fail;
@@ -483,13 +485,16 @@ static int msi_capability_init(struct pci_dev *dev, int nvec,
 
 	pcibios_free_irq(dev);
 	dev->irq = entry->irq;
-	return 0;
+	goto unlock;
 
 err:
 	pci_msi_unmask(entry, msi_multi_mask(entry));
 	free_msi_irqs(dev);
 fail:
 	dev->msi_enabled = 0;
+unlock:
+	msi_unlock_descs(&dev->dev);
+	kfree(masks);
 	return ret;
 }
 
@@ -516,23 +521,18 @@ static void __iomem *msix_map_region(struct pci_dev *dev,
 
 static int msix_setup_entries(struct pci_dev *dev, void __iomem *base,
 			      struct msix_entry *entries, int nvec,
-			      struct irq_affinity *affd)
+			      struct irq_affinity_desc *masks)
 {
-	struct irq_affinity_desc *curmsk, *masks = NULL;
+	int i, vec_count = pci_msix_vec_count(dev);
+	struct irq_affinity_desc *curmsk;
 	struct msi_desc *entry;
 	void __iomem *addr;
-	int ret, i;
-	int vec_count = pci_msix_vec_count(dev);
-
-	if (affd)
-		masks = irq_create_affinity_masks(nvec, affd);
 
 	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 */
-			ret = -ENOMEM;
-			goto out;
+			return -ENOMEM;
 		}
 
 		entry->pci.msi_attrib.is_msix	= 1;
@@ -560,10 +560,7 @@ static int msix_setup_entries(struct pci_dev *dev, void __iomem *base,
 		if (masks)
 			curmsk++;
 	}
-	ret = 0;
-out:
-	kfree(masks);
-	return ret;
+	return 0;
 }
 
 static void msix_update_entries(struct pci_dev *dev, struct msix_entry *entries)
@@ -590,6 +587,41 @@ static void msix_mask_all(void __iomem *base, int tsize)
 		writel(ctrl, base + PCI_MSIX_ENTRY_VECTOR_CTRL);
 }
 
+static int msix_setup_interrupts(struct pci_dev *dev, void __iomem *base,
+				 struct msix_entry *entries, int nvec,
+				 struct irq_affinity *affd)
+{
+	struct irq_affinity_desc *masks = NULL;
+	int ret;
+
+	if (affd)
+		masks = irq_create_affinity_masks(nvec, affd);
+
+	msi_lock_descs(&dev->dev);
+	ret = msix_setup_entries(dev, base, entries, nvec, masks);
+	if (ret)
+		goto out_free;
+
+	ret = pci_msi_setup_msi_irqs(dev, nvec, PCI_CAP_ID_MSIX);
+	if (ret)
+		goto out_free;
+
+	/* Check if all MSI entries honor device restrictions */
+	ret = msi_verify_entries(dev);
+	if (ret)
+		goto out_free;
+
+	msix_update_entries(dev, entries);
+	goto out_unlock;
+
+out_free:
+	free_msi_irqs(dev);
+out_unlock:
+	msi_unlock_descs(&dev->dev);
+	kfree(masks);
+	return ret;
+}
+
 /**
  * msix_capability_init - configure device's MSI-X capability
  * @dev: pointer to the pci_dev data structure of MSI-X device function
@@ -630,20 +662,9 @@ static int msix_capability_init(struct pci_dev *dev, struct msix_entry *entries,
 
 	dev->msix_base = base;
 
-	ret = msix_setup_entries(dev, base, entries, nvec, affd);
+	ret = msix_setup_interrupts(dev, base, entries, nvec, affd);
 	if (ret)
-		goto out_free;
-
-	ret = pci_msi_setup_msi_irqs(dev, nvec, PCI_CAP_ID_MSIX);
-	if (ret)
-		goto out_free;
-
-	/* Check if all MSI entries honor device restrictions */
-	ret = msi_verify_entries(dev);
-	if (ret)
-		goto out_free;
-
-	msix_update_entries(dev, entries);
+		goto out_disable;
 
 	/* Disable INTX */
 	pci_intx_for_msi(dev, 0);
@@ -662,9 +683,6 @@ static int msix_capability_init(struct pci_dev *dev, struct msix_entry *entries,
 	pcibios_free_irq(dev);
 	return 0;
 
-out_free:
-	free_msi_irqs(dev);
-
 out_disable:
 	dev->msix_enabled = 0;
 	pci_msix_clear_and_set_ctrl(dev, PCI_MSIX_FLAGS_MASKALL | PCI_MSIX_FLAGS_ENABLE, 0);
@@ -773,8 +791,10 @@ void pci_disable_msi(struct pci_dev *dev)
 	if (!pci_msi_enable || !dev || !dev->msi_enabled)
 		return;
 
+	msi_lock_descs(&dev->dev);
 	pci_msi_shutdown(dev);
 	free_msi_irqs(dev);
+	msi_unlock_descs(&dev->dev);
 }
 EXPORT_SYMBOL(pci_disable_msi);
 
@@ -860,8 +880,10 @@ void pci_disable_msix(struct pci_dev *dev)
 	if (!pci_msi_enable || !dev || !dev->msix_enabled)
 		return;
 
+	msi_lock_descs(&dev->dev);
 	pci_msix_shutdown(dev);
 	free_msi_irqs(dev);
+	msi_unlock_descs(&dev->dev);
 }
 EXPORT_SYMBOL(pci_disable_msix);