Public bug reported:
Linux kernel upstream 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
** Affects: linux-nvidia (Ubuntu)
Importance: Undecided
Status: New
** Description changed:
- Linux kernel upstream Commit 47c8846a49ba ("PCI: Extend ACS
configurability") introduced bugs
- that fail to configure ACS ctrl to the value specified by the kernel
parameter.
+ Linux kernel upstream 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
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https://bugs.launchpad.net/bugs/2100340
Title:
PCI/ACS: Fix 'pci=config_acs=' parameter
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