[SRU,Zesty,2/2] PCI: Disable VF decoding before pcibios_sriov_disable() updates resources

From: Gavin Shan <gwshan@linux.vnet.ibm.com>

A struct resource represents the address space consumed by a device.  We
should not modify that resource while the device is actively using the
address space.  For VFs, pci_iov_update_resource() enforces this by
printing a warning and doing nothing if the VFE (VF Enable) and MSE (VF
Memory Space Enable) bits are set.

Previously, both sriov_enable() and sriov_disable() called the
pcibios_sriov_disable() arch hook, which may update the struct resource,
while VFE and MSE were enabled.  This effectively dropped the resource
update pcibios_sriov_disable() intended to do.

Disable VF memory decoding before calling pcibios_sriov_disable().

Reported-by: Carol L Soto <clsoto@us.ibm.com>
Tested-by: Carol L Soto <clsoto@us.ibm.com>
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
[bhelgaas: changelog]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: shan.gavin@gmail.com
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
(cherry picked from linux-next commit 0fc690a7c3f7053613dcbab6a7613bb6586d8ee2)
Signed-off-by: Joseph Salisbury <joseph.salisbury@canonical.com>
---
 drivers/pci/iov.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

On 09/08/2017 09:38 AM, Joseph Salisbury wrote:
> From: Gavin Shan <gwshan@linux.vnet.ibm.com>
>
> A struct resource represents the address space consumed by a device.  We
> should not modify that resource while the device is actively using the
> address space.  For VFs, pci_iov_update_resource() enforces this by
> printing a warning and doing nothing if the VFE (VF Enable) and MSE (VF
> Memory Space Enable) bits are set.
>
> Previously, both sriov_enable() and sriov_disable() called the
> pcibios_sriov_disable() arch hook, which may update the struct resource,
> while VFE and MSE were enabled.  This effectively dropped the resource
> update pcibios_sriov_disable() intended to do.
>
> Disable VF memory decoding before calling pcibios_sriov_disable().
>
> Reported-by: Carol L Soto <clsoto@us.ibm.com>
> Tested-by: Carol L Soto <clsoto@us.ibm.com>
> Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
> [bhelgaas: changelog]
> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
> Cc: shan.gavin@gmail.com
> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Cc: Paul Mackerras <paulus@samba.org>
> (cherry picked from linux-next commit 0fc690a7c3f7053613dcbab6a7613bb6586d8ee2)
> Signed-off-by: Joseph Salisbury <joseph.salisbury@canonical.com>
> ---
>  drivers/pci/iov.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
> index 2479ae8..138830f 100644
> --- a/drivers/pci/iov.c
> +++ b/drivers/pci/iov.c
> @@ -331,7 +331,6 @@ static int sriov_enable(struct pci_dev *dev, int nr_virtfn)
>  	while (i--)
>  		pci_iov_remove_virtfn(dev, i, 0);
>  
> -	pcibios_sriov_disable(dev);
>  err_pcibios:
>  	iov->ctrl &= ~(PCI_SRIOV_CTRL_VFE | PCI_SRIOV_CTRL_MSE);
>  	pci_cfg_access_lock(dev);
> @@ -339,6 +338,8 @@ static int sriov_enable(struct pci_dev *dev, int nr_virtfn)
>  	ssleep(1);
>  	pci_cfg_access_unlock(dev);
>  
> +	pcibios_sriov_disable(dev);
> +
>  	if (iov->link != dev->devfn)
>  		sysfs_remove_link(&dev->dev.kobj, "dep_link");
>  
> @@ -357,14 +358,14 @@ static void sriov_disable(struct pci_dev *dev)
>  	for (i = 0; i < iov->num_VFs; i++)
>  		pci_iov_remove_virtfn(dev, i, 0);
>  
> -	pcibios_sriov_disable(dev);
> -
>  	iov->ctrl &= ~(PCI_SRIOV_CTRL_VFE | PCI_SRIOV_CTRL_MSE);
>  	pci_cfg_access_lock(dev);
>  	pci_write_config_word(dev, iov->pos + PCI_SRIOV_CTRL, iov->ctrl);
>  	ssleep(1);
>  	pci_cfg_access_unlock(dev);
>  
> +	pcibios_sriov_disable(dev);
> +
>  	if (iov->link != dev->devfn)
>  		sysfs_remove_link(&dev->dev.kobj, "dep_link");
>  

I forgot to add the buglink in this patch.  Just let me know if I should
send a v2:

BugLink: http://bugs.launchpad.net/bugs/1715073