linux-kernel - Re: [PATCH v10 5/7] PCI: handle SR-IOV Virtual Function Migration

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Date:	Fri, 6 Mar 2009 14:13:41 -0700
From:	Matthew Wilcox <matthew@....cx>
To:	Yu Zhao <yu.zhao@...el.com>
Cc:	jbarnes@...tuousgeek.org, linux-pci@...r.kernel.org,
	kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v10 5/7] PCI: handle SR-IOV Virtual Function Migration

On Fri, Feb 20, 2009 at 02:54:46PM +0800, Yu Zhao wrote:
> +static int sriov_migration(struct pci_dev *dev)
> +{
> +	u16 status;
> +	struct pci_sriov *iov = dev->sriov;
> +
> +	if (!iov->nr_virtfn)
> +		return 0;
> +
> +	if (!(iov->cap & PCI_SRIOV_CAP_VFM))
> +		return 0;
> +
> +	pci_read_config_word(iov->self, iov->pos + PCI_SRIOV_STATUS, &status);

You passed in dev here, you don't need to use iov->self, right?

> +	if (!(status & PCI_SRIOV_STATUS_VFM))
> +		return 0;
> +
> +	schedule_work(&iov->mtask);
> +
> +	return 1;
> +}

> +/**
> + * pci_sriov_migration - notify SR-IOV core of Virtual Function Migration
> + * @dev: the PCI device
> + *
> + * Returns IRQ_HANDLED if the IRQ is handled, or IRQ_NONE if not.
> + *
> + * Physical Function driver is responsible to register IRQ handler using
> + * VF Migration Interrupt Message Number, and call this function when the
> + * interrupt is generated by the hardware.
> + */
> +irqreturn_t pci_sriov_migration(struct pci_dev *dev)
> +{
> +	if (!dev->sriov)
> +		return IRQ_NONE;
> +
> +	return sriov_migration(dev) ? IRQ_HANDLED : IRQ_NONE;
> +}
> +EXPORT_SYMBOL_GPL(pci_sriov_migration);

OK, I think I get it -- you've basically written an interrupt handler
for the driver to call from its interrupt handler.  Am I right in
thinking that the reason the driver needs to do the interrupt handler
here is because we don't currently have an interface that looks like:

int pci_get_msix_interrupt(struct pci_dev *dev, unsigned vector);

?  If so, we should probably add it; I want it for my MSI-X rewrite
anyway.

-- 
Matthew Wilcox				Intel Open Source Technology Centre
"Bill, look, we understand that you're interested in selling us this
operating system, but compare it to ours.  We can't possibly take such
a retrograde step."
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