From: Leon Romanovsky <[email protected]> pci_acs_flags_enabled() and the Intel SPT PCH quirk use ACS registers without checking config-space read errors. A failed read may leave control state indeterminate yet allow the device to satisfy requested isolation controls. So can a read that returns all ones with a successful status, which is what a device that does not answer usually produces.
Return false when either ACS capability or control state cannot be read or reads as all ones, which neither register can legitimately hold. An unknown state cannot prove isolation. Reviewed-by: Logan Gunthorpe <[email protected]> Tested-by: Tushar Dave <[email protected]> Signed-off-by: Leon Romanovsky <[email protected]> --- drivers/pci/pci.c | 4 +++- drivers/pci/quirks.c | 8 ++++++-- 2 files changed, 9 insertions(+), 3 deletions(-) diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 7c6f2aba8144..6d677695c0f5 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -3627,7 +3627,9 @@ static bool pci_acs_flags_enabled(struct pci_dev *pdev, u16 acs_flags) */ acs_flags &= (pdev->acs_capabilities | PCI_ACS_EC); - pci_read_config_word(pdev, pos + PCI_ACS_CTRL, &ctrl); + if (pci_read_config_word(pdev, pos + PCI_ACS_CTRL, &ctrl) || + PCI_POSSIBLE_ERROR(ctrl)) + return false; return (ctrl & acs_flags) == acs_flags; } diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c index 7f1f47ea2ee4..05605c3afe08 100644 --- a/drivers/pci/quirks.c +++ b/drivers/pci/quirks.c @@ -5145,10 +5145,14 @@ static int pci_quirk_intel_spt_pch_acs(struct pci_dev *dev, u16 acs_flags) return -ENOTTY; /* see pci_acs_flags_enabled() */ - pci_read_config_dword(dev, pos + PCI_ACS_CAP, &cap); + if (pci_read_config_dword(dev, pos + PCI_ACS_CAP, &cap) || + PCI_POSSIBLE_ERROR(cap)) + return 0; acs_flags &= (cap | PCI_ACS_EC); - pci_read_config_dword(dev, pos + INTEL_SPT_ACS_CTRL, &ctrl); + if (pci_read_config_dword(dev, pos + INTEL_SPT_ACS_CTRL, &ctrl) || + PCI_POSSIBLE_ERROR(ctrl)) + return 0; return pci_acs_ctrl_enabled(acs_flags, ctrl); } -- 2.56.0
