Re: [PATCH] x86_64: restore mask_bits in msi shutdown

On Tue, Apr 15, 2008 at 1:12 AM, Andrew Morton
<akpm@xxxxxxxxxxxxxxxxxxxx> wrote:

On Fri, 11 Apr 2008 16:26:11 -0700 Yinghai Lu <yhlu.kernel.send@xxxxxxxxx> wrote:

> I can not kexec RHEL 5.1 from 2.6.25-rc3 later
>
> caused by:
> commit 89d694b9dbe769ca1004e01db0ca43964806a611
> Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> 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@xxxxxxxxx>
>
> 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
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

Relevant Pages