On Wed, Mar 04, 2015 at 06:03:11PM +0100, Paolo Bonzini wrote: > > > On 04/03/2015 15:29, Catalin Marinas wrote: > > I disagree it is 100% a host-side issue. It is a host-side issue _if_ > > the host tells the guest that the (virtual) device is non-coherent (or, > > more precisely, it does not explicitly tell the guest that the device is > > coherent). If the guest thinks the (virtual) device is non-coherent > > because of information passed by the host, I fully agree that the host > > needs to manage the cache coherency. > > > > However, the host could also pass a "dma-coherent" property in the DT > > given to the guest and avoid any form of cache maintenance. If the guest > > does not honour such coherency property, it's a guest problem and it > > needs fixing in the guest. This isn't any different from a real physical > > device behaviour. > > Can you add that property to the device tree for PCI devices too? Yes but not with mainline yet: http://thread.gmane.org/gmane.linux.kernel.iommu/8935 We can add the property at the PCI host bridge level (with the drawback that it covers all the PCI devices), like here: Documentation/devicetree/bindings/pci/xgene-pci.txt -- Catalin -- 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
