On Sun, May 30, 2010 at 03:27:05PM +0300, Avi Kivity wrote: > On 05/30/2010 03:19 PM, Michael S. Tsirkin wrote: >> On Fri, May 28, 2010 at 04:07:38PM -0700, Tom Lyon wrote: >> >>> The VFIO "driver" is used to allow privileged AND non-privileged processes to >>> implement user-level device drivers for any well-behaved PCI, PCI-X, and PCIe >>> devices. >>> Signed-off-by: Tom Lyon<pugs@xxxxxxxxx> >>> --- >>> This patch is the evolution of code which was first proposed as a patch to >>> uio/uio_pci_generic, then as a more generic uio patch. Now it is taken entirely >>> out of the uio framework, and things seem much cleaner. Of course, there is >>> a lot of functional overlap with uio, but the previous version just seemed >>> like a giant mode switch in the uio code that did not lead to clarity for >>> either the new or old code. >>> >> IMO this was because this driver does two things: programming iommu and >> handling interrupts. uio does interrupt handling. >> We could have moved iommu / DMA programming to >> a separate driver, and have uio work with it. >> This would solve limitation of the current driver >> that is needs an iommu domain per device. >> > > How do we enforce security then? We need to ensure that unprivileged > users can only use the device with an iommu. Force assigning to iommu before we allow any other operation? >>> [a pony for avi...] >>> The major new functionality in this version is the ability to deal with >>> PCI config space accesses (through read& write calls) - but includes table >>> driven code to determine whats safe to write and what is not. >>> >> I don't really see why this is helpful: a driver written corrrectly >> will not access these addresses, and we need an iommu anyway to protect >> us against a drivers. >> > > Haven't reviewed the code (yet) but things like the BARs, MSI, and > interrupt disable need to be protected from the guest regardless of the > iommu. Yes but userspace can do this. As long as userspace can not crash the kernel, no reason to put this policy into kernel. > > -- > error compiling committee.c: too many arguments to function -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
