Re: [PATCH 2/3] KVM: Emulate MSI-X table in kernel

[Sheng Yang <sheng@linux.intel.com>]

On Thursday 03 February 2011 09:05:55 Marcelo Tosatti wrote:
> On Sun, Jan 30, 2011 at 01:11:15PM +0800, Sheng Yang wrote:
> > Then we can support mask bit operation of assigned devices now.
> > 
> > Signed-off-by: Sheng Yang <sheng@linux.intel.com>
> > 
> > +int kvm_vm_ioctl_register_msix_mmio(struct kvm *kvm,
> > +				    struct kvm_msix_mmio_user *mmio_user)
> > +{
> > +	struct kvm_msix_mmio_dev *mmio_dev = &kvm->msix_mmio_dev;
> > +	struct kvm_msix_mmio *mmio = NULL;
> > +	int r = 0, i;
> > +
> > +	mutex_lock(&mmio_dev->lock);
> > +	for (i = 0; i < mmio_dev->mmio_nr; i++) {
> > +		if (mmio_dev->mmio[i].dev_id == mmio_user->dev_id &&
> > +		    (mmio_dev->mmio[i].type & KVM_MSIX_MMIO_TYPE_DEV_MASK) ==
> > +		    (mmio_user->type & KVM_MSIX_MMIO_TYPE_DEV_MASK)) {
> > +			mmio = &mmio_dev->mmio[i];
> > +			if (mmio->max_entries_nr != mmio_user->max_entries_nr) {
> > +				r = -EINVAL;
> > +				goto out;
> > +			}
> > +			break;
> > +		}
> 
> Why allow this ioctl to succeed if there's an entry already present?
> This case is broken as mmio_dev->mmio_nr is increased below.

Oh, It's a bug to let mmio_nr increase even with MMIO found. I've fixed it.

The reason we allow multiply callings is userspace can register different types of 
address here(table address and PBA address).

> PCI bits must be reviewed...

Pardon? PCI related things are already in 2.6.38-rc.

--
regards
Yang, Sheng