On Sun, Aug 25, 2013 at 09:26:47PM -0400, Chris Metcalf wrote: > On 8/25/2013 7:39 AM, Gleb Natapov wrote: > > On Mon, Aug 12, 2013 at 04:24:11PM -0400, Chris Metcalf wrote: > >> This change provides the initial framework support for KVM on tilegx. > >> Basic virtual disk and networking is supported. > >> > > This needs to be broken down to more reviewable patches. > > I already broke out one pre-requisite patch that wasn't strictly KVM-related: > > https://lkml.org/lkml/2013/8/12/339 > > In addition, we've separately arranged to support booting our kernels in a way that is compatible with the Tilera booter running at the highest privilege level, which enables multiple kernel privilege levels: > > https://lkml.org/lkml/2013/5/2/468 > > How would you recommend further breaking down this patch? It's pretty much just the basic support for minimal KVM. I suppose I could break out all the I/O related stuff into a separate patch, though it wouldn't amount to much; perhaps the console could also be broken out separately. Any other suggestions? > First of all please break out host and guest bits. Also I/O related stuff, like you suggest (so that guest PV bits will be in separate patch) and change to a common code (not much as far as I see) with explanation why it is needed. (Why kvm_vcpu_kick() is not needed for instance?) > > Also can you > > describe the implementation a little bit? Does tile arch has vitalization > > extension this implementation uses, or is it trap and emulate approach? > > If later does it run unmodified guest kernels? What userspace are you > > using with this implementation? > > We could do full virtualization via trap and emulate, but we've elected to do a para-virtualized approach. Userspace runs at PL (privilege level) 0, the guest kernel runs at PL1, and the host runs at PL2. We have available per-PL resources for various things, and take advantage of having two on-chip timers (for example) to handle timing for the host and guest kernels. We run the same userspace with either the host or the guest. > OK, thanks for explanation. Why have you decided to do PV over trap and emulate? -- Gleb. -- 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
