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

Thomas Gleixner
2021-11-27T01:32:51Z

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);