Anthony Liguori wrote: > Rusty Russell wrote: >> On Mon, 2007-05-28 at 20:54 -0500, Anthony Liguori wrote: >> >>> Howdy, >>> >>> Does anyone know what the state of a pv_ops backend for KVM is? I >>> know Ingo has an implementation that implements CR3 caching but I >>> don't see any branches in Avi's git tree. >>> >>> Perhaps we should try for a simple pv_ops backend for 2.6.23 seeing >>> as how the host infrastructure is there? I'd be willing to do some >>> leg work here... >>> >> >> "Me too". It's at least worth toying with the mmu batching stuff to see >> if that can shave some cycles there: it seems that cr3 caching is the >> main win for context switch so batching there won't help. >> > > I'm working on a simple patch that just adds the infrastructure. > >> IIRC Ingo used a magic MSR to detect kvm, and there was a question mark >> over that. > > I am not too worried about using an MSR. There's really no fool proof > method here. The only thing to do IMHO is move the kvm pv_ops backend > into a separate file and add appropriate Kconfig stuff. > >> VMI uses a different technique, which is probably worth >> considering... >> > > VMI can determine that it's under VMware since VMware has to publish > an option ROM. It's quite neat, but overkill for what we're doing > (since we're not going to be using a ROM anyway).
The near to being blessed way to do this is to use a CPUID leaf (I believe it is 0x40000000) to identify the hypervisor. I don't have the exact details, but making CPUID 0x40000000 return 'KVMKVMKVMKVM' sounds like a pretty safe detection technique. We're probably dropping the ROM probing in favor of this for 64-bit. Zach ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
