Re: [PATCH] pv-ops: register xen pci notifier

[Jeremy Fitzhardinge <jeremy@goop.org>]

On 07/26/09 18:56, Weidong Han wrote:
> Register the notifier to handle hot-plug devices and SR-IOV devices
> for Xen hypervisor. When a device is hot added or removed, it adds
> or removes it to Xen via hypercalls.
>   

Looks pretty good.  A few small comments below.

    J

> Signed-off-by: Weidong Han <weidong.han@intel.com>
> ---
>  drivers/xen/Makefile            |    5 +-
>  drivers/xen/pci.c               |  105 +++++++++++++++++++++++++++++++++++++++
>  include/xen/interface/physdev.h |   21 ++++++++
>  3 files changed, 129 insertions(+), 2 deletions(-)
>  create mode 100644 drivers/xen/pci.c
>
> diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile
> index 007aa99..fd5c88c 100644
> --- a/drivers/xen/Makefile
> +++ b/drivers/xen/Makefile
> @@ -1,12 +1,13 @@
>  obj-y	+= grant-table.o features.o events.o manage.o biomerge.o
>  obj-y	+= xenbus/
>  
> +obj-$(CONFIG_PCI)			+= pci.o
>  obj-$(CONFIG_HOTPLUG_CPU)		+= cpu_hotplug.o
>  obj-$(CONFIG_XEN_XENCOMM)		+= xencomm.o
>  obj-$(CONFIG_XEN_BALLOON)		+= balloon.o
>  obj-$(CONFIG_XEN_DEV_EVTCHN)		+= evtchn.o
> -obj-$(CONFIG_XEN_GNTDEV)	+= gntdev.o
> +obj-$(CONFIG_XEN_GNTDEV)		+= gntdev.o
>  obj-$(CONFIG_XEN_BLKDEV_BACKEND)	+= blkback/
>  obj-$(CONFIG_XEN_NETDEV_BACKEND)	+= netback/
>  obj-$(CONFIG_XENFS)			+= xenfs/
> -obj-$(CONFIG_XEN_SYS_HYPERVISOR)	+= sys-hypervisor.o
> \ No newline at end of file
> +obj-$(CONFIG_XEN_SYS_HYPERVISOR)	+= sys-hypervisor.o
> diff --git a/drivers/xen/pci.c b/drivers/xen/pci.c
> new file mode 100644
> index 0000000..b1261d4
> --- /dev/null
> +++ b/drivers/xen/pci.c
> @@ -0,0 +1,105 @@
> +/*
> + * Copyright (c) 2009, Intel Corporation.
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
> + * more details.
> + *
> + * You should have received a copy of the GNU General Public License along with
> + * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
> + * Place - Suite 330, Boston, MA 02111-1307 USA.
> + *
> + * Author: Weidong Han <weidong.han@intel.com>
> + */
> +
> +#include <linux/pci.h>
> +#include <xen/interface/physdev.h>
> +#include <asm/xen/hypercall.h>
> +#include "../pci/pci.h"
> +
> +static int xen_add_device(struct device *dev)
> +{
> +	int r;
> +	struct pci_dev *pci_dev = to_pci_dev(dev);
> +	struct physdev_manage_pci manage_pci;
> +	struct physdev_manage_pci_ext manage_pci_ext;
> +
> +#ifdef CONFIG_PCI_IOV
> +	if (pci_dev->is_virtfn) {
>   

Perhaps something like:

(earlier in the file)

#ifdef CONFIG_PCI_IOV
#define HANDLE_PCI_IOV	1
#else
#define HANDLE_PCI_IOV	0
#endif

(or is there already something we can use as a compile-time constant for this?)

and then:

	if (HANDLE_PCI_IOV && pci_dev->is_virtfn) {
		...
	} else if (pci_ari_enabled( ... )) {
		...
	} else {
		...
	}

That removes the inline #ifdef and the awkward dangling else/#endif
construction.


> +		memset(&manage_pci_ext, 0, sizeof(manage_pci_ext));
>   
Rather than doing this, move the variable decl into this scope and use
an initializer to assign the elements:

		struct physdev_manage_pci_ext manage_pci_ext = {
			.bus = pci_dev->bus->number,
			.devfn = pci_dev->devfn,
			...
		};

(ditto for the others)

> +		manage_pci_ext.bus = pci_dev->bus->number;
> +		manage_pci_ext.devfn = pci_dev->devfn;
> +		manage_pci_ext.is_virtfn = 1;
> +		manage_pci_ext.physfn.bus = pci_dev->physfn->bus->number;
> +		manage_pci_ext.physfn.devfn = pci_dev->physfn->devfn;
> +		r = HYPERVISOR_physdev_op(PHYSDEVOP_manage_pci_add_ext,
> +					  &manage_pci_ext);
> +	} else
> +#endif
>   


> +	if (pci_ari_enabled(pci_dev->bus) && PCI_SLOT(pci_dev->devfn)) {
> +		memset(&manage_pci_ext, 0, sizeof(manage_pci_ext));
> +		manage_pci_ext.bus = pci_dev->bus->number;
> +		manage_pci_ext.devfn = pci_dev->devfn;
> +		manage_pci_ext.is_extfn = 1;
> +		r = HYPERVISOR_physdev_op(PHYSDEVOP_manage_pci_add_ext,
> +					  &manage_pci_ext);
> +	} else {
> +		manage_pci.bus = pci_dev->bus->number;
> +		manage_pci.devfn = pci_dev->devfn;
> +		r = HYPERVISOR_physdev_op(PHYSDEVOP_manage_pci_add,
> +					  &manage_pci);
> +	}
> +
>   
> +	return r;
> +}
> +
> +static int xen_remove_device(struct device *dev)
> +{
> +	int r;
> +	struct pci_dev *pci_dev = to_pci_dev(dev);
> +	struct physdev_manage_pci manage_pci;
> +
> +	manage_pci.bus = pci_dev->bus->number;
> +	manage_pci.devfn = pci_dev->devfn;
> +
> +	r = HYPERVISOR_physdev_op(PHYSDEVOP_manage_pci_remove,
> +				  &manage_pci);
> +
> +	return r;
> +}
> +
> +static int xen_pci_notifier(struct notifier_block *nb,
> +			    unsigned long action, void *data)
> +{
> +	struct device *dev = data;
> +	int r = 0;
> +
> +	switch (action) {
> +	case BUS_NOTIFY_ADD_DEVICE:
> +		r = xen_add_device(dev);
> +		break;
> +	case BUS_NOTIFY_DEL_DEVICE:
> +		r = xen_remove_device(dev);
> +		break;
> +	default:
> +		break;
> +	}
> +
> +	return r;
> +}
> +
> +struct notifier_block device_nb = {
> +	.notifier_call = xen_pci_notifier,
> +};
> +
> +void __init register_xen_pci_notifier(void)
> +{
> +	bus_register_notifier(&pci_bus_type, &device_nb);
> +}
> +
> +fs_initcall(register_xen_pci_notifier);
>   

Why fs_initcall?  Is that the conventional initcall for registering
these kinds of notifiers?

Thanks,
    J