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...] >> Specify one or more PCI devices (in the format >> - specified above) optionally prepended with flags >> - and separated by semicolons. The respective >> - capabilities will be enabled, disabled or >> - unchanged based on what is specified in >> - flags. >> + specified above) prepended with flags and separated >> + by semicolons. The respective capabilities will be >> + enabled, disabled or unchanged based on what is >> + specified in flags. >> >> ACS Flags is defined as follows: >> bit-0 : ACS Source Validation >> @@ -4673,7 +4672,7 @@ >> '1' – force enabled >> 'x' – unchanged >> For example, >> - pci=config_acs=10x >> + pci=config_acs=10x@pci:0:0 >> would configure all devices that support >> ACS to enable P2P Request Redirect, disable >> Translation Blocking, and leave Source > > Is this an unrelated change? The format of the command line shouldn't > be changed to fix the described bug, why is the documentation changed? The documentation as it is (i.e. without my patch), is not correct. IOW, config_acs parameter does require flags and it is not optional. Without flags it results into "ACS Flags missing". Therefore I remove word "optionally" from the documentation text. Secondly, the syntax in the example 'pci=config_acs=10x' is incorrect. The correct syntax should be 'pci=config_acs=10x@pci:0:0' that would configure all devices that support ACS to enable P2P Request Redirect, disable Translation Blocking, and leave Source Validation unchanged from whatever power-up or firmware set it to. > >> static void __pci_config_acs(struct pci_dev *dev, struct pci_acs *caps, >> - const char *p, u16 mask, u16 flags) >> + const char *p, const u16 acs_mask, const u16 acs_flags) >> { >> + u16 flags = acs_flags; >> + u16 mask = acs_mask; >> char *delimit; >> int ret = 0; >> >> @@ -964,7 +965,7 @@ static void __pci_config_acs(struct pci_dev *dev, struct pci_acs *caps, >> return; >> >> while (*p) { >> - if (!mask) { >> + if (!acs_mask) { >> /* Check for ACS flags */ >> delimit = strstr(p, "@"); >> if (delimit) { >> @@ -972,6 +973,8 @@ static void __pci_config_acs(struct pci_dev *dev, struct pci_acs *caps, >> u32 shift = 0; >> >> end = delimit - p - 1; >> + mask = 0; >> + flags = 0; >> >> while (end > -1) { >> if (*(p + end) == '0') { > > This function the entire fix, right? Because the routine was > clobbering acs_mask as it processed the earlier devices? yes, that is correct. > >> @@ -1028,10 +1031,10 @@ static void __pci_config_acs(struct pci_dev *dev, struct pci_acs *caps, >> >> pci_dbg(dev, "ACS mask = %#06x\n", mask); >> pci_dbg(dev, "ACS flags = %#06x\n", flags); >> + pci_dbg(dev, "ACS control = %#06x\n", caps->ctrl); >> >> - /* If mask is 0 then we copy the bit from the firmware setting. */ >> - caps->ctrl = (caps->ctrl & ~mask) | (caps->fw_ctrl & mask); >> - caps->ctrl |= flags; >> + caps->ctrl &= ~mask; >> + caps->ctrl |= (flags & mask); > > And why delete fw_ctrl? Doesn't that break the unchanged > functionality? No, it does not break the unchanged functionality. I removed it because it is not needed after my fix. If it helps, using 'config_acs' the code only allows to configures the lower 7 bits of ACS ctrl for the specified PCI device(s). The bits other than the lower 7 bits of ACS ctrl remain unchanged. The bits specified with 'x' or 'X' that are within the 7 lower bits remain unchanged. Trying to configure bits other than lower 7 bits generates an error message "Invalid ACS flags specified" -Tushar > > Jason