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PCI/P2PDMA: Avoid returning a provider for non_mappable_bars

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Extend the checks in pcim_p2pdma_init() and pcim_p2pdma_provider() to
exclude functions that have pdev->non_mappable_bars set.

Consumers such as VFIO were previously able to map these for access by the
CPU or P2P.  Update the comment on non_mappable_bars to show it refers to
any access, not just userspace CPU access.

Fixes: 372d6d1b8a ("PCI/P2PDMA: Refactor to separate core P2P functionality from memory allocation")
Suggested-by: Alex Williamson <alex@shazbot.org>
Signed-off-by: Matt Evans <mattev@meta.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Niklas Schnelle <schnelle@linux.ibm.com>
Reviewed-by: Alex Williamson <alex@shazbot.org>
Link: https://patch.msgid.link/20260423173051.1999679-1-mattev@meta.com
This commit is contained in:
Matt Evans 2026-04-23 10:30:51 -07:00 committed by Bjorn Helgaas
parent 254f49634e
commit 951ebc18d1
2 changed files with 6 additions and 2 deletions
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6
drivers/pci/p2pdma.c
View File

@ -262,6 +262,9 @@ int pcim_p2pdma_init(struct pci_dev *pdev)
struct pci_p2pdma *p2p;
int i, ret;
if (pdev->non_mappable_bars)
return -EOPNOTSUPP;
p2p = rcu_dereference_protected(pdev->p2pdma, 1);
if (p2p)
return 0;
@ -318,7 +321,8 @@ struct p2pdma_provider *pcim_p2pdma_provider(struct pci_dev *pdev, int bar)
{
struct pci_p2pdma *p2p;
if (!(pci_resource_flags(pdev, bar) & IORESOURCE_MEM))
if (!(pci_resource_flags(pdev, bar) & IORESOURCE_MEM) ||
pdev->non_mappable_bars)
return NULL;
p2p = rcu_dereference_protected(pdev->p2pdma, 1);

2
include/linux/pci.h
View File

@ -508,7 +508,7 @@ struct pci_dev {
unsigned int no_command_memory:1; /* No PCI_COMMAND_MEMORY */
unsigned int rom_bar_overlap:1; /* ROM BAR disable broken */
unsigned int rom_attr_enabled:1; /* Display of ROM attribute enabled? */
unsigned int non_mappable_bars:1; /* BARs can't be mapped to user-space */
unsigned int non_mappable_bars:1; /* BARs can't be mapped by CPU or peers */
pci_dev_flags_t dev_flags;
atomic_t enable_cnt; /* pci_enable_device has been called */