[patch 08/32] PCI/MSI: Protect MSI operations

[Thomas Gleixner <tglx@linutronix.de>]

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>
---
 drivers/pci/msi/irqdomain.c |    4 -
 drivers/pci/msi/msi.c       |  120 ++++++++++++++++++++++++++------------------
 2 files changed, 73 insertions(+), 51 deletions(-)

--- a/drivers/pci/msi/irqdomain.c
+++ b/drivers/pci/msi/irqdomain.c
@@ -14,7 +14,7 @@ int pci_msi_setup_msi_irqs(struct pci_de
 
 	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 pc
 
 	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);
 }
--- a/drivers/pci/msi/msi.c
+++ b/drivers/pci/msi/msi.c
@@ -322,11 +322,13 @@ static void __pci_restore_msix_state(str
 
 	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);
 }
@@ -339,19 +341,15 @@ void pci_restore_msi_state(struct pci_de
 EXPORT_SYMBOL_GPL(pci_restore_msi_state);
 
 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 */
@@ -377,8 +375,7 @@ msi_setup_entry(struct pci_dev *dev, int
 	dev->dev.msi.data->properties = MSI_PROP_PCI_MSI;
 	if (entry->pci.msi_attrib.is_64)
 		dev->dev.msi.data->properties |= MSI_PROP_64BIT;
-out:
-	kfree(masks);
+
 	return entry;
 }
 
@@ -414,14 +411,21 @@ static int msi_verify_entries(struct pci
 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;
 
 	pci_msi_set_enable(dev, 0);	/* Disable MSI during set up */
 
-	entry = msi_setup_entry(dev, nvec, affd);
-	if (!entry)
-		return -ENOMEM;
+	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 unlock;
+	}
 
 	/* All MSIs are unmasked by default; mask them all */
 	pci_msi_mask(entry, msi_multi_mask(entry));
@@ -444,11 +448,14 @@ static int msi_capability_init(struct pc
 
 	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);
+unlock:
+	msi_unlock_descs(&dev->dev);
+	kfree(masks);
 	return ret;
 }
 
@@ -475,23 +482,18 @@ static void __iomem *msix_map_region(str
 
 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;
@@ -520,10 +522,7 @@ static int msix_setup_entries(struct pci
 			curmsk++;
 	}
 	dev->dev.msi.data->properties = MSI_PROP_PCI_MSIX | MSI_PROP_64BIT;
-	ret = 0;
-out:
-	kfree(masks);
-	return ret;
+	return 0;
 }
 
 static void msix_update_entries(struct pci_dev *dev, struct msix_entry *entries)
@@ -550,6 +549,41 @@ static void msix_mask_all(void __iomem *
 		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
@@ -590,20 +624,9 @@ static int msix_capability_init(struct p
 	/* Ensure that all table entries are masked. */
 	msix_mask_all(base, tsize);
 
-	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;
 
 	/* Set MSI-X enabled bits and unmask the function */
 	pci_intx_for_msi(dev, 0);
@@ -613,12 +636,8 @@ static int msix_capability_init(struct p
 	pcibios_free_irq(dev);
 	return 0;
 
-out_free:
-	free_msi_irqs(dev);
-
 out_disable:
 	pci_msix_clear_and_set_ctrl(dev, PCI_MSIX_FLAGS_ENABLE, 0);
-
 	return ret;
 }
 
@@ -723,8 +742,10 @@ 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);
 
@@ -810,8 +831,10 @@ void pci_disable_msix(struct pci_dev *de
 	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);
 
@@ -872,7 +895,6 @@ int pci_enable_msi(struct pci_dev *dev)
 
 	if (!rc)
 		rc = __pci_enable_msi_range(dev, 1, 1, NULL);
-
 	return rc < 0 ? rc : 0;
 }
 EXPORT_SYMBOL(pci_enable_msi);
@@ -959,11 +981,7 @@ int pci_alloc_irq_vectors_affinity(struc
 				   struct irq_affinity *affd)
 {
 	struct irq_affinity msi_default_affd = {0};
-	int ret = msi_setup_device_data(&dev->dev);
-	int nvecs = -ENOSPC;
-
-	if (ret)
-		return ret;
+	int ret, nvecs;
 
 	if (flags & PCI_IRQ_AFFINITY) {
 		if (!affd)
@@ -973,6 +991,10 @@ int pci_alloc_irq_vectors_affinity(struc
 			affd = NULL;
 	}
 
+	ret = msi_setup_device_data(&dev->dev);
+	if (ret)
+		return ret;
+
 	if (flags & PCI_IRQ_MSIX) {
 		nvecs = __pci_enable_msix_range(dev, NULL, min_vecs, max_vecs,
 						affd, flags);
@@ -1001,7 +1023,7 @@ int pci_alloc_irq_vectors_affinity(struc
 		}
 	}
 
-	return nvecs;
+	return -ENOSPC;
 }
 EXPORT_SYMBOL(pci_alloc_irq_vectors_affinity);