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Subject[tip: irq/msi] PCI/MSI: Protect MSI operations
The following commit has been merged into the irq/msi branch of tip:

Commit-ID: 5512c5eaf533a98d33a8dc0dcf415e72773184c8
Gitweb: https://git.kernel.org/tip/5512c5eaf533a98d33a8dc0dcf415e72773184c8
Author: Thomas Gleixner <tglx@linutronix.de>
AuthorDate: Mon, 06 Dec 2021 23:51:13 +01:00
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Thu, 16 Dec 2021 22:22:17 +01:00

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 | 4 +-
drivers/pci/msi/msi.c | 100 +++++++++++++++++++++--------------
2 files changed, 63 insertions(+), 41 deletions(-)

diff --git a/drivers/pci/msi/irqdomain.c b/drivers/pci/msi/irqdomain.c
index 180b2a1..c81793a 100644
--- a/drivers/pci/msi/irqdomain.c
+++ b/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);
}
diff --git a/drivers/pci/msi/msi.c b/drivers/pci/msi/msi.c
index 0909b27..c9a03f9 100644
--- a/drivers/pci/msi/msi.c
+++ b/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);

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