>From 6d814685b907980b4cae5c27c57fb4bdea13d5bb Mon Sep 17 00:00:00 2001 From: Piotr Gregor <piotrgregor@rsyncme.org> Date: Fri, 26 May 2017 22:02:25 +0100 Subject: [PATCH] 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> --- drivers/pci/pci.c | 42 +----------------------------------------- drivers/pci/probe.c | 30 ++++++++++++++++++++++++++++++ include/linux/pci.h | 12 ++++++++++-- 3 files changed, 41 insertions(+), 43 deletions(-) diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index b01bd5b..7c4e1aa 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -3708,46 +3708,6 @@ void pci_intx(struct pci_dev *pdev, int enable) } EXPORT_SYMBOL_GPL(pci_intx); -/** - * pci_intx_mask_supported - probe for INTx masking support - * @dev: the PCI device to operate on - * - * Check if the device dev support INTx masking via the config space - * command word. - */ -bool pci_intx_mask_supported(struct pci_dev *dev) -{ - bool mask_supported = false; - u16 orig, new; - - if (dev->broken_intx_masking) - return false; - - pci_cfg_access_lock(dev); - - pci_read_config_word(dev, PCI_COMMAND, &orig); - pci_write_config_word(dev, PCI_COMMAND, - orig ^ PCI_COMMAND_INTX_DISABLE); - pci_read_config_word(dev, PCI_COMMAND, &new); - - /* - * There's no way to protect against hardware bugs or detect them - * reliably, but as long as we know what the value should be, let's - * go ahead and check it. - */ - if ((new ^ orig) & ~PCI_COMMAND_INTX_DISABLE) { - dev_err(&dev->dev, "Command register changed from 0x%x to 0x%x: driver or hardware bug?\n", - orig, new); - } else if ((new ^ orig) & PCI_COMMAND_INTX_DISABLE) { - mask_supported = true; - pci_write_config_word(dev, PCI_COMMAND, orig); - } - - pci_cfg_access_unlock(dev); - return mask_supported; -} -EXPORT_SYMBOL_GPL(pci_intx_mask_supported); - static bool pci_check_and_set_intx_mask(struct pci_dev *dev, bool mask) { struct pci_bus *bus = dev->bus; @@ -3798,7 +3758,7 @@ static bool pci_check_and_set_intx_mask(struct pci_dev *dev, bool mask) * @dev: the PCI device to operate on * * Check if the device dev has its INTx line asserted, mask it and - * return true in that case. False is returned if not interrupt was + * return true in that case. False is returned if no interrupt was * pending. */ bool pci_check_and_mask_intx(struct pci_dev *dev) diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index 19c8950..e2c2650 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. + */ + 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) diff --git a/include/linux/pci.h b/include/linux/pci.h index 33c2b0b..4f0613d 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -366,7 +366,7 @@ struct pci_dev { unsigned int is_thunderbolt:1; /* Thunderbolt controller */ unsigned int __aer_firmware_first_valid:1; unsigned int __aer_firmware_first:1; - unsigned int broken_intx_masking:1; + unsigned int broken_intx_masking:1; /* INTx masking can't be used */ unsigned int io_window_1k:1; /* Intel P2P bridge 1K I/O windows */ unsigned int irq_managed:1; unsigned int has_secondary_link:1; @@ -1003,6 +1003,15 @@ int __must_check pci_reenable_device(struct pci_dev *); int __must_check pcim_enable_device(struct pci_dev *pdev); void pcim_pin_device(struct pci_dev *pdev); +static inline bool pci_intx_mask_supported(struct pci_dev *pdev) +{ + /* + * INTx masking is supported if PCI_COMMAND_INTX_DISABLE is + * writable and no quirk has marked the feature broken. + */ + return !pdev->broken_intx_masking; +} + static inline int pci_is_enabled(struct pci_dev *pdev) { return (atomic_read(&pdev->enable_cnt) > 0); @@ -1026,7 +1035,6 @@ int __must_check pci_set_mwi(struct pci_dev *dev); int pci_try_set_mwi(struct pci_dev *dev); void pci_clear_mwi(struct pci_dev *dev); void pci_intx(struct pci_dev *dev, int enable); -bool pci_intx_mask_supported(struct pci_dev *dev); bool pci_check_and_mask_intx(struct pci_dev *dev); bool pci_check_and_unmask_intx(struct pci_dev *dev); int pci_wait_for_pending(struct pci_dev *dev, int pos, u16 mask); -- 2.1.4