linux-kernel - Re: [PATCH 2/3] Refactor msi/msix restore code Part2

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Date:	Wed, 31 Jul 2013 16:41:32 -0600
From:	Bjorn Helgaas <bhelgaas@...gle.com>
To:	zhenzhong.duan@...cle.com
Cc:	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	xen-devel <xen-devel@...ts.xen.org>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	Feng Jin <joe.jin@...cle.com>,
	Sucheta Chakraborty <sucheta.chakraborty@...gic.com>
Subject: Re: [PATCH 2/3] Refactor msi/msix restore code Part2

On Tue, Jul 23, 2013 at 9:08 PM, Zhenzhong Duan
<zhenzhong.duan@...cle.com> wrote:
> xen_initdom_restore_msi_irqs trigger a hypercall to restore addr/data/mask
> in dom0. It's better to do the same for default_restore_msi_irqs in baremetal.
>
> Move restore of mask in default_restore_msi_irqs, this could avoid mask
> restored twice in dom0, once in hypercall, the other in kernel.
>
> Without that, qlcnic driver calling pci_reset_function will lost interrupt
> in dom0.
>
> Tested-by: Sucheta Chakraborty <sucheta.chakraborty@...gic.com>
> Signed-off-by: Zhenzhong Duan <zhenzhong.duan@...cle.com>
> ---
>  drivers/pci/msi.c |   17 ++++++++++++++---
>  1 files changed, 14 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
> index 87223ae..922fb49 100644
> --- a/drivers/pci/msi.c
> +++ b/drivers/pci/msi.c
> @@ -216,6 +216,8 @@ void unmask_msi_irq(struct irq_data *data)
>  #ifdef HAVE_DEFAULT_MSI_RESTORE_IRQS
>  void default_restore_msi_irqs(struct pci_dev *dev, int irq)
>  {
> +       int pos;
> +       u16 control;
>         struct msi_desc *entry;
>
>         entry = NULL;
> @@ -228,8 +230,19 @@ void default_restore_msi_irqs(struct pci_dev *dev, int irq)
>                 entry = irq_get_msi_desc(irq);
>         }
>
> -       if (entry)
> +       if (entry) {
>                 write_msi_msg(irq, &entry->msg);
> +               if (dev->msix_enabled) {
> +                       msix_mask_irq(entry, entry->masked);
> +                       readl(entry->mask_base);
> +               } else {
> +                       pos = entry->msi_attrib.pos;
> +                       pci_read_config_word(dev, pos + PCI_MSI_FLAGS,
> +                                            &control);
> +                       msi_mask_irq(entry, msi_capable_mask(control),
> +                                    entry->masked);
> +               }
> +       }
>  }
>  #endif
>
> @@ -406,7 +419,6 @@ static void __pci_restore_msi_state(struct pci_dev *dev)
>         arch_restore_msi_irqs(dev, dev->irq);
>
>         pci_read_config_word(dev, dev->msi_cap + PCI_MSI_FLAGS, &control);
> -       msi_mask_irq(entry, msi_capable_mask(control), entry->masked);
>         control &= ~PCI_MSI_FLAGS_QSIZE;
>         control |= (entry->msi_attrib.multiple << 4) | PCI_MSI_FLAGS_ENABLE;
>         pci_write_config_word(dev, dev->msi_cap + PCI_MSI_FLAGS, control);
> @@ -430,7 +442,6 @@ static void __pci_restore_msix_state(struct pci_dev *dev)
>
>         list_for_each_entry(entry, &dev->msi_list, list) {
>                 arch_restore_msi_irqs(dev, entry->irq);
> -               msix_mask_irq(entry, entry->masked);
>         }
>
>         control &= ~PCI_MSIX_FLAGS_MASKALL;

Konrad, are you OK with this patch now?

If so, can you (Zhenzhong) update the changelog with some of the info
from the conversation with Konrad?  It seems like a few more details
are needed to make it clear why we need this change.

Bjorn
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