6.12-stable review patch. If anyone has any objections, please let me know.
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From: Tushar Dave tdave@nvidia.com
[ Upstream commit 9cf8a952d57b422d3ff8a9a0163f8adf694f4b2b ]
Commit 47c8846a49ba ("PCI: Extend ACS configurability") introduced bugs that fail to configure ACS ctrl to the value specified by the kernel parameter. Essentially there are two bugs:
1) When ACS is configured for multiple PCI devices using 'config_acs' kernel parameter, it results into error "PCI: Can't parse ACS command line parameter". This is due to a bug that doesn't preserve the ACS mask, but instead overwrites the mask with value 0.
For example, using 'config_acs' to configure ACS ctrl for multiple BDFs fails:
Kernel command line: pci=config_acs=1111011@0020:02:00.0;101xxxx@0039:00:00.0 "dyndbg=file drivers/pci/pci.c +p" PCI: Can't parse ACS command line parameter pci 0020:02:00.0: ACS mask = 0x007f pci 0020:02:00.0: ACS flags = 0x007b pci 0020:02:00.0: Configured ACS to 0x007b
After this fix:
Kernel command line: pci=config_acs=1111011@0020:02:00.0;101xxxx@0039:00:00.0 "dyndbg=file drivers/pci/pci.c +p" pci 0020:02:00.0: ACS mask = 0x007f pci 0020:02:00.0: ACS flags = 0x007b pci 0020:02:00.0: ACS control = 0x005f pci 0020:02:00.0: ACS fw_ctrl = 0x0053 pci 0020:02:00.0: Configured ACS to 0x007b pci 0039:00:00.0: ACS mask = 0x0070 pci 0039:00:00.0: ACS flags = 0x0050 pci 0039:00:00.0: ACS control = 0x001d pci 0039:00:00.0: ACS fw_ctrl = 0x0000 pci 0039:00:00.0: Configured ACS to 0x0050
2) In the bit manipulation logic, we copy the bit from the firmware settings when mask bit 0.
For example, 'disable_acs_redir' fails to clear all three ACS P2P redir bits due to the wrong bit fiddling:
Kernel command line: pci=disable_acs_redir=0020:02:00.0;0030:02:00.0;0039:00:00.0 "dyndbg=file drivers/pci/pci.c +p" pci 0020:02:00.0: ACS mask = 0x002c pci 0020:02:00.0: ACS flags = 0xffd3 pci 0020:02:00.0: Configured ACS to 0xfffb pci 0030:02:00.0: ACS mask = 0x002c pci 0030:02:00.0: ACS flags = 0xffd3 pci 0030:02:00.0: Configured ACS to 0xffdf pci 0039:00:00.0: ACS mask = 0x002c pci 0039:00:00.0: ACS flags = 0xffd3 pci 0039:00:00.0: Configured ACS to 0xffd3
After this fix:
Kernel command line: pci=disable_acs_redir=0020:02:00.0;0030:02:00.0;0039:00:00.0 "dyndbg=file drivers/pci/pci.c +p" pci 0020:02:00.0: ACS mask = 0x002c pci 0020:02:00.0: ACS flags = 0xffd3 pci 0020:02:00.0: ACS control = 0x007f pci 0020:02:00.0: ACS fw_ctrl = 0x007b pci 0020:02:00.0: Configured ACS to 0x0053 pci 0030:02:00.0: ACS mask = 0x002c pci 0030:02:00.0: ACS flags = 0xffd3 pci 0030:02:00.0: ACS control = 0x005f pci 0030:02:00.0: ACS fw_ctrl = 0x005f pci 0030:02:00.0: Configured ACS to 0x0053 pci 0039:00:00.0: ACS mask = 0x002c pci 0039:00:00.0: ACS flags = 0xffd3 pci 0039:00:00.0: ACS control = 0x001d pci 0039:00:00.0: ACS fw_ctrl = 0x0000 pci 0039:00:00.0: Configured ACS to 0x0000
Link: https://lore.kernel.org/r/20250207030338.456887-1-tdave@nvidia.com Fixes: 47c8846a49ba ("PCI: Extend ACS configurability") Signed-off-by: Tushar Dave tdave@nvidia.com Signed-off-by: Bjorn Helgaas bhelgaas@google.com Reviewed-by: Jason Gunthorpe jgg@nvidia.com Reviewed-by: Kuppuswamy Sathyanarayanan sathyanarayanan.kuppuswamy@linux.intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/pci/pci.c | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-)
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 1aa5d6f98ebda..25211d1219227 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -955,8 +955,10 @@ struct pci_acs { };
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 +966,7 @@ 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 +974,8 @@ 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') { @@ -1028,10 +1032,14 @@ 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); + pci_dbg(dev, "ACS fw_ctrl = %#06x\n", caps->fw_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; + /* + * For mask bits that are 0, copy them from the firmware setting + * and apply flags for all the mask bits that are 1. + */ + caps->ctrl = (caps->fw_ctrl & ~mask) | (flags & mask);
pci_info(dev, "Configured ACS to %#06x\n", caps->ctrl); }