[PATCH] pci-hyperv: Use device serial number as PCI domain

[PATCH] pci-hyperv: Use device serial number as PCI domain

[Haiyang Zhang]

This allows PCI domain numbers starts with 1, and also unique
on the same VM. So names, such as VF NIC names, that include
domain number as part of the name, can be shorter than that
based on part of bus UUID previously. The new names will also
stay same for VMs created with copied VHD and same number of
devices.

Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Reviewed-by: K. Y. Srinivasan <kys@microsoft.com>

---
 drivers/pci/host/pci-hyperv.c |   10 ++++++++++
 1 files changed, 10 insertions(+), 0 deletions(-)

diff --git a/drivers/pci/host/pci-hyperv.c b/drivers/pci/host/pci-hyperv.c
index 3efcc7b..b92b565 100644
--- a/drivers/pci/host/pci-hyperv.c
+++ b/drivers/pci/host/pci-hyperv.c
@@ -1315,6 +1315,16 @@ static void put_pcichild(struct hv_pci_dev *hpdev,
 	get_pcichild(hpdev, hv_pcidev_ref_initial);
 	get_pcichild(hpdev, hv_pcidev_ref_childlist);
 	spin_lock_irqsave(&hbus->device_list_lock, flags);
+	/* When a device is being added into the bus, we set the PCI domain
+	 * number to be the device serial number, which is non zero and
+	 * unique on the same VM. The serial numbers start with 1, and
+	 * increase by 1 for each device. So device names including this
+	 * can have shorter names than based on the bus instance UUID.
+	 * Only the first device serial number is used for domain, so the
+	 * domain number will not change after the first device is added.
+	 */
+	if (list_empty(&hbus->children))
+		hbus->sysdata.domain = desc->ser;
 	list_add_tail(&hpdev->list_entry, &hbus->children);
 	spin_unlock_irqrestore(&hbus->device_list_lock, flags);
 	return hpdev;
-- 
1.7.1

Re: [PATCH] pci-hyperv: Use device serial number as PCI domain

[Stephen Hemminger]

On Mon, 13 Feb 2017 18:10:11 +0000
Haiyang Zhang <haiyangz@microsoft.com> wrote:

> This allows PCI domain numbers starts with 1, and also unique
> on the same VM. So names, such as VF NIC names, that include
> domain number as part of the name, can be shorter than that
> based on part of bus UUID previously. The new names will also
> stay same for VMs created with copied VHD and same number of
> devices.
> 
> Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
> Reviewed-by: K. Y. Srinivasan <kys@microsoft.com>

Looks like a good solution to persistent names.

Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>

Re: [PATCH] pci-hyperv: Use device serial number as PCI domain

[Bjorn Helgaas]

On Mon, Feb 13, 2017 at 06:10:11PM +0000, Haiyang Zhang wrote:
> 
> This allows PCI domain numbers starts with 1, and also unique
> on the same VM. So names, such as VF NIC names, that include
> domain number as part of the name, can be shorter than that
> based on part of bus UUID previously. The new names will also
> stay same for VMs created with copied VHD and same number of
> devices.
> 
> Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
> Reviewed-by: K. Y. Srinivasan <kys@microsoft.com>

Applied to pci/host-hv for v4.11, thanks!

I assume Stephen meant a "Reviewed-by", not a "Signed-off-by", so that's
what I added.

> ---
>  drivers/pci/host/pci-hyperv.c |   10 ++++++++++
>  1 files changed, 10 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/pci/host/pci-hyperv.c b/drivers/pci/host/pci-hyperv.c
> index 3efcc7b..b92b565 100644
> --- a/drivers/pci/host/pci-hyperv.c
> +++ b/drivers/pci/host/pci-hyperv.c
> @@ -1315,6 +1315,16 @@ static void put_pcichild(struct hv_pci_dev *hpdev,
>  	get_pcichild(hpdev, hv_pcidev_ref_initial);
>  	get_pcichild(hpdev, hv_pcidev_ref_childlist);
>  	spin_lock_irqsave(&hbus->device_list_lock, flags);
> +	/* When a device is being added into the bus, we set the PCI domain
> +	 * number to be the device serial number, which is non zero and
> +	 * unique on the same VM. The serial numbers start with 1, and
> +	 * increase by 1 for each device. So device names including this
> +	 * can have shorter names than based on the bus instance UUID.
> +	 * Only the first device serial number is used for domain, so the
> +	 * domain number will not change after the first device is added.
> +	 */
> +	if (list_empty(&hbus->children))
> +		hbus->sysdata.domain = desc->ser;
>  	list_add_tail(&hpdev->list_entry, &hbus->children);
>  	spin_unlock_irqrestore(&hbus->device_list_lock, flags);
>  	return hpdev;
> -- 
> 1.7.1
>