• Jiang Liu's avatar
    ACPI, PCI: Penalize legacy IRQ used by ACPI SCI · f4e4aaa5
    Jiang Liu authored
    commit 5d0ddfeb upstream.
    
    Nick Meier reported a regression with HyperV that "
      After rebooting the VM, the following messages are logged in syslog
      when trying to load the tulip driver:
        tulip: Linux Tulip drivers version 1.1.15 (Feb 27, 2007)
        tulip: 0000:00:0a.0: PCI INT A: failed to register GSI
        tulip: Cannot enable tulip board #0, aborting
        tulip: probe of 0000:00:0a.0 failed with error -16
      Errors occur in 3.19.0 kernel
      Works in 3.17 kernel.
    "
    
    According to the ACPI dump file posted by Nick at
    https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1440072
    
    The ACPI MADT table includes an interrupt source overridden entry for
    ACPI SCI:
    [236h 0566  1]                Subtable Type : 02 <Interrupt Source Override>
    [237h 0567  1]                       Length : 0A
    [238h 0568  1]                          Bus : 00
    [239h 0569  1]                       Source : 09
    [23Ah 0570  4]                    Interrupt : 00000009
    [23Eh 0574  2]        Flags (decoded below) : 000D
                                       Polarity : 1
                                   Trigger Mode : 3
    
    And in DSDT table, we have _PRT method to define PCI interrupts, which
    eventually goes to:
            Name (PRSA, ResourceTemplate ()
            {
                IRQ (Level, ActiveLow, Shared, )
                    {3,4,5,7,9,10,11,12,14,15}
            })
            Name (PRSB, ResourceTemplate ()
            {
                IRQ (Level, ActiveLow, Shared, )
                    {3,4,5,7,9,10,11,12,14,15}
            })
            Name (PRSC, ResourceTemplate ()
            {
                IRQ (Level, ActiveLow, Shared, )
                    {3,4,5,7,9,10,11,12,14,15}
            })
            Name (PRSD, ResourceTemplate ()
            {
                IRQ (Level, ActiveLow, Shared, )
                    {3,4,5,7,9,10,11,12,14,15}
            })
    
    According to the MADT and DSDT tables, IRQ 9 may be used for:
     1) ACPI SCI in level, high mode
     2) PCI legacy IRQ in level, low mode
    So there's a conflict in polarity setting for IRQ 9.
    
    Prior to commit cd68f6bd ("x86, irq, acpi: Get rid of special
    handling of GSI for ACPI SCI"), ACPI SCI is handled specially and
    there's no check for conflicts between ACPI SCI and PCI legagy IRQ.
    And it seems that the HyperV hypervisor doesn't make use of the
    polarity configuration in IOAPIC entry, so it just works.
    
    Commit cd68f6bd gets rid of the specially handling of ACPI SCI,
    and then the pin attribute checking code discloses the conflicts
    between ACPI SCI and PCI legacy IRQ on HyperV virtual machine,
    and rejects the request to assign IRQ9 to PCI devices.
    
    So penalize legacy IRQ used by ACPI SCI and mark it unusable if ACPI
    SCI attributes conflict with PCI IRQ attributes.
    
    Please refer to following links for more information:
    https://bugzilla.kernel.org/show_bug.cgi?id=101301
    https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1440072
    
    Fixes: cd68f6bd ("x86, irq, acpi: Get rid of special handling of GSI for ACPI SCI")
    Reported-and-tested-by: default avatarNick Meier <nmeier@microsoft.com>
    Acked-by: default avatarThomas Gleixner <tglx@linutronix.de>
    Signed-off-by: default avatarJiang Liu <jiang.liu@linux.intel.com>
    Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    f4e4aaa5
pci_link.c 23.4 KB