Il 29/11/2013 15:50, Liu, Jinsong ha scritto: > > There is no reason to get the size and offset from the host. Peter > > Anvin confirmed that the sizes and offsets will never change (as > > should be the case for migration to work across different CPU > > versions). In fact, the size and offset is documented for every > > XSAVE feature except MPX in the copy I have of the Intel > > documentation. > > If the sizes and offsets will never change, what's the bad effect of getting them from host? In case TCG gets AVX/MPX support later, you will not be able to get CPUID values from the host. The leaf 0xd code was written so that it would work for both KVM and TCG. When QEMU got AVX support, we decided not to treat XSAVE data as opaque blobs, and instead "unmarshal" data out of it into the CPUX86State struct and back. This is again useful for TCG, but it also makes for easier interpretation of migration state. You will have to rely on precise sizes and offsets in the marshaling/unmarshaling code of kvm_get_xsave/kvm_put_xsave, so it is not a big problem to have them here as well. Paolo -- 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
