On Wed, Feb 15, 2017 at 02:45:06PM +0800, Yongji Xie wrote:
> Currently we reassign the alignment by extending resources' size in
> pci_reassigndev_resource_alignment(). This could potentially break
> some drivers when the driver uses the size to locate register
> whose length is related to the size. Some examples as below:
I understand the motivation to stop changing the resource size. That
makes good sense.
> - misc\Hpilo.c:
This isn't Windows; please use regular Linux forward slashes here.
> off = pci_resource_len(pdev, bar) - 0x2000;
>
> - net\ethernet\chelsio\cxgb4\cxgb4_uld.h:
> (pci_resource_len((pdev), 2) - roundup_pow_of_two((vres)->ocq.size))
>
> - infiniband\hw\nes\Nes_hw.c:
> num_pds = pci_resource_len(nesdev->pcidev, BAR_1) >> PAGE_SHIFT;
>
> This risk could be easily prevented before because we only had one way
> (kernel parameter resource_alignment) to touch those codes. And even
> some users may be happy to see the extended size.
>
> But now we define a default alignment for all devices which would also
> touch those codes. It would be hard to prevent the risk in this case. So
> this patch tries to use START_ALIGNMENT to identify the resource's
> alignment without extending the size when the alignment reassigning is
> caused by the default alignment.
But I don't understand the new START_ALIGNMENT case.
> Signed-off-by: Yongji Xie <xyjxie@xxxxxxxxxxxxxxxxxx>
> ---
> drivers/pci/pci.c | 34 ++++++++++++++++++++++++----------
> 1 files changed, 24 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 2622e9b..0017e5e 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -4958,7 +4958,8 @@ void pci_ignore_hotplug(struct pci_dev *dev)
> * RETURNS: Resource alignment if it is specified.
> * Zero if it is not specified.
Since there's function doc, please update it to reflect the new
"resize" return parameter.
What does "resize" mean? I can't figure it out from your code.
> */
> -static resource_size_t pci_specified_resource_alignment(struct pci_dev *dev)
> +static resource_size_t pci_specified_resource_alignment(struct pci_dev *dev,
> + bool *resize)
> {
> int seg, bus, slot, func, align_order, count;
> unsigned short vendor, device, subsystem_vendor, subsystem_device;
> @@ -5002,6 +5003,7 @@ static resource_size_t pci_specified_resource_alignment(struct pci_dev *dev)
> (!device || (device == dev->device)) &&
> (!subsystem_vendor || (subsystem_vendor == dev->subsystem_vendor)) &&
> (!subsystem_device || (subsystem_device == dev->subsystem_device))) {
> + *resize = true;
> if (align_order == -1)
> align = PAGE_SIZE;
> else
> @@ -5027,6 +5029,7 @@ static resource_size_t pci_specified_resource_alignment(struct pci_dev *dev)
> bus == dev->bus->number &&
> slot == PCI_SLOT(dev->devfn) &&
> func == PCI_FUNC(dev->devfn)) {
> + *resize = true;
> if (align_order == -1)
> align = PAGE_SIZE;
> else
> @@ -5059,6 +5062,7 @@ void pci_reassigndev_resource_alignment(struct pci_dev *dev)
> struct resource *r;
> resource_size_t align, size;
> u16 command;
> + bool resize = false;
>
> /*
> * VF BARs are read-only zero according to SR-IOV spec r1.1, sec
> @@ -5070,7 +5074,7 @@ void pci_reassigndev_resource_alignment(struct pci_dev *dev)
> return;
>
> /* check if specified PCI is target device to reassign */
> - align = pci_specified_resource_alignment(dev);
> + align = pci_specified_resource_alignment(dev, &resize);
> if (!align)
> return;
>
> @@ -5098,15 +5102,25 @@ void pci_reassigndev_resource_alignment(struct pci_dev *dev)
> }
>
> size = resource_size(r);
> - if (size < align) {
> - size = align;
> - dev_info(&dev->dev,
> - "Rounding up size of resource #%d to %#llx.\n",
> - i, (unsigned long long)size);
> + if (resize) {
> + if (size < align) {
> + size = align;
> + dev_info(&dev->dev,
> + "Rounding up size of resource #%d to %#llx.\n",
> + i, (unsigned long long)size);
> + }
> + r->flags |= IORESOURCE_UNSET;
> + r->end = size - 1;
> + r->start = 0;
> + } else {
> + if (size < align) {
> + r->flags &= ~IORESOURCE_SIZEALIGN;
> + r->flags |= IORESOURCE_STARTALIGN |
> + IORESOURCE_UNSET;
> + r->start = align;
> + r->end = r->start + size - 1;
If you have to have two blocks that fiddle with r->start, etc., they
should at least be as similar as possible. You should have this in
both cases:
r->end = r->start + size - 1;
> + }
> }
> - r->flags |= IORESOURCE_UNSET;
> - r->end = size - 1;
> - r->start = 0;
> }
> /* Need to disable bridge's resource window,
> * to enable the kernel to reassign new resource
> --
> 1.7.1
>
