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| author | Piotr Gregor <piotrgregor@rsyncme.org> | 2017-05-27 00:02:25 +0300 |
|---|---|---|
| committer | Bjorn Helgaas <bhelgaas@google.com> | 2017-06-17 00:12:37 +0300 |
| commit | 99b3c58f7ba7fae801e501b45c5fcf6e08d9247f (patch) | |
| tree | 092b76f6111502eb56c044bdb1fa173e4a91a737 /drivers/pci/probe.c | |
| parent | 2ea659a9ef488125eb46da6eb571de5eae5c43f6 (diff) | |
| download | linux-99b3c58f7ba7fae801e501b45c5fcf6e08d9247f.tar.xz | |
PCI: Test INTx masking during enumeration, not at run-time
The test for INTx masking via PCI_COMMAND_INTX_DISABLE performed in
pci_intx_mask_supported() should be done before the device can be used.
This is to avoid writing PCI_COMMAND while the driver owns the device, in
case that has any effect on MSI/MSI-X interrupts.
Move the content of pci_intx_mask_supported() to pci_intx_mask_broken() and
call it from pci_setup_device().
The test result can be queried at any time later using the same
pci_intx_mask_supported() interface as before (though with changed
implementation), so callers (uio, vfio) should be unaffected.
Signed-off-by: Piotr Gregor <piotrgregor@rsyncme.org>
[bhelgaas: changelog, remove quirk check, remove locking, move
dev->broken_intx_masking assignment to caller]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Diffstat (limited to 'drivers/pci/probe.c')
| -rw-r--r-- | drivers/pci/probe.c | 30 |
1 files changed, 30 insertions, 0 deletions
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index 19c8950c6c38..8b8826b9a398 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -1330,6 +1330,34 @@ static void pci_msi_setup_pci_dev(struct pci_dev *dev) } /** + * pci_intx_mask_broken - test PCI_COMMAND_INTX_DISABLE writability + * @dev: PCI device + * + * Test whether PCI_COMMAND_INTX_DISABLE is writable for @dev. Check this + * at enumeration-time to avoid modifying PCI_COMMAND at run-time. + */ +static int pci_intx_mask_broken(struct pci_dev *dev) +{ + u16 orig, toggle, new; + + pci_read_config_word(dev, PCI_COMMAND, &orig); + toggle = orig ^ PCI_COMMAND_INTX_DISABLE; + pci_write_config_word(dev, PCI_COMMAND, toggle); + pci_read_config_word(dev, PCI_COMMAND, &new); + + pci_write_config_word(dev, PCI_COMMAND, orig); + + /* + * PCI_COMMAND_INTX_DISABLE was reserved and read-only prior to PCI + * r2.3, so strictly speaking, a device is not *broken* if it's not + * writable. But we'll live with the misnomer for now. + */ + if (new != toggle) + return 1; + return 0; +} + +/** * pci_setup_device - fill in class and map information of a device * @dev: the device structure to fill * @@ -1399,6 +1427,8 @@ int pci_setup_device(struct pci_dev *dev) } } + dev->broken_intx_masking = pci_intx_mask_broken(dev); + switch (dev->hdr_type) { /* header type */ case PCI_HEADER_TYPE_NORMAL: /* standard header */ if (class == PCI_CLASS_BRIDGE_PCI) |