Re: [PATCH] virtio-pci: alloc only resources actually used.

From: Gerd Hoffmann
Date: Thu Jun 18 2015 - 04:15:50 EST


Hi,

> > +static struct resource *request_capability(struct pci_dev *dev, int off,
> > + const char *name)
> > +{
> > + u8 bar;
> > + u32 offset, length;
> > +
> > + pci_read_config_byte(dev, off + offsetof(struct virtio_pci_cap,
> > + bar),
> > + &bar);
> > + pci_read_config_dword(dev, off + offsetof(struct virtio_pci_cap, offset),
> > + &offset);
> > + pci_read_config_dword(dev, off + offsetof(struct virtio_pci_cap, length),
> > + &length);
> > +
> > + return request_mem_region(pci_resource_start(dev, bar) + offset,
> > + length, name);
> > +}
> > +
>
> For device config, this might request too much. The spec says:
> The drivers SHOULD only map part of configuration structure large enough
> for device operation.

We don't map it here though. We just reserve what belongs to virtio
according to the capabilities.

> I think you should limit this to PAGE_SIZE like we do for map_capability.

notify is much larger than PAGE_SIZE.

> > err = -EINVAL;
> > vp_dev->common = map_capability(pci_dev, common,
> > sizeof(struct virtio_pci_common_cfg), 4,
>
> map_capability has a bunch of checks in place to validate the capability
> structure. With request_capability called earlier, they are now done too
> late.

Hmm, lets move the checks to find_capability then?

cheers,
Gerd


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