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SubjectRe: [PATCH] x86_64: restore mask_bits in msi shutdown
On Tue, Apr 15, 2008 at 1:12 AM, Andrew Morton
<akpm@linux-foundation.org> wrote:
>
> On Fri, 11 Apr 2008 16:26:11 -0700 Yinghai Lu <yhlu.kernel.send@gmail.com> wrote:
>
> > I can not kexec RHEL 5.1 from 2.6.25-rc3 later
> >
> > caused by:
> > commit 89d694b9dbe769ca1004e01db0ca43964806a611
> > Author: Thomas Gleixner <tglx@linutronix.de>
> > Date: Mon Feb 18 18:25:17 2008 +0100
> >
> > genirq: do not leave interupts enabled on free_irq
> >
> > The default_disable() function was changed in commit:
> >
> > 76d2160147f43f982dfe881404cfde9fd0a9da21
> > genirq: do not mask interrupts by default
> >
> > It removed the mask function in favour of the default delayed
> > interrupt disabling. Unfortunately this also broke the shutdown in
> > free_irq() when the last handler is removed from the interrupt for
> > those architectures which rely on the default implementations. Now we
> > can end up with a enabled interrupt line after the last handler was
> > removed, which can result in spurious interrupts.
> >
> > Fix this by adding a default_shutdown function, which is only
> > installed, when the irqchip implementation does provide neither a
> > shutdown nor a disable function.
> >
> > [@stable: affected versions: .21 - .24 ]
> >
> >
> >
> > for MSI, default_shutdown will call mask_bit for msi device. so all mask bits will
> > left disabled after free_irq.
> > then if kexec next kernel that only can use msi_enable bit.
> > all device's MSI can not be used.
> >
> > So try to restore MSI mask bits that is saved before using msi in first kernel.
> >
> > Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
> >
> > Index: linux-2.6/arch/x86/kernel/io_apic_64.c
> > ===================================================================
> > --- linux-2.6.orig/arch/x86/kernel/io_apic_64.c
> > +++ linux-2.6/arch/x86/kernel/io_apic_64.c
> > @@ -2003,6 +2003,14 @@ static void set_msi_irq_affinity(unsigne
> > }
> > #endif /* CONFIG_SMP */
> >
> > +static void msi_shutdown(unsigned int irq)
> > +{
> > + struct irq_desc *desc = irq_desc + irq;
> > +
> > + msi_restore_mask_bits(irq);
> > + desc->status |= IRQ_MASKED;
> > +}
>
> I wonder if only x86_64 needs this treatment.
>
>
> > Index: linux-2.6/drivers/pci/msi.c
> > ===================================================================
> > --- linux-2.6.orig/drivers/pci/msi.c
> > +++ linux-2.6/drivers/pci/msi.c
> > @@ -123,6 +123,31 @@ static void msix_flush_writes(unsigned i
> > }
> > }
> >
> > +void msi_restore_mask_bits(unsigned int irq)
> > +{
> > + struct msi_desc *entry;
> > +
> > + entry = get_irq_msi(irq);
> > + BUG_ON(!entry || !entry->dev);
> > + switch (entry->msi_attrib.type) {
> > + case PCI_CAP_ID_MSI:
> > + if (entry->msi_attrib.maskbit) {
> > + int pos;
> > + u32 mask_bits;
> > +
> > + pos = (long)entry->mask_base;
> > + mask_bits = entry->orig_mask_bits;
> > + pci_write_config_dword(entry->dev, pos, mask_bits);
> > + }
> > + break;
> > + case PCI_CAP_ID_MSIX:
> > + break;
> > + default:
> > + BUG();
> > + break;
> > + }
> > +}
>
> If no other architectures will ever need this, perhaps it is in the wrong
> file.

need someone has powerpc (64?) etc platform with RHEL 5.1 with PCIe
NIC that is using MSI
to test if they have the same problem with kexec.

YH


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