On 11 January 2016 at 16:21, Andrew Jones <drjones@xxxxxxxxxx> wrote: > On Mon, Jan 11, 2016 at 05:09:27PM +0100, Andrew Jones wrote: >> On Mon, Jan 11, 2016 at 04:09:29PM +0100, Christoffer Dall wrote: >> > Are vcpu ids already exposed to userspace (beyond the stupid >> > KVM_IRQ_LINE) ioctl and as such we're bound to whatever upper limit and >> > format they have? >> >> The only other place I found is KVM_CREATE_VCPU. I suppose we could move >> to MPIDR for that, and it would be a nice way to handle the "userspace >> determines MPIDR" work that I plan to do. Both KVM and its userspaces >> would still use some counter-based vcpu identifiers internally, to avoid >> large, sparse structures, but I guess the advantage is that they don't >> have to agree on how they do that. The 'vcpu id' used by KVM_CREATE_VCPU >> is already 32-bits, and is supposed to be an arbitrary identifier. That >> all looks good for converting to MPIDR. >> > > Correction. I understand that vcpu-id is "supposed" to be an arbitrary > identifier now, but it doesn't appear that all the assumptions that it's > a counter are gone yet... virt/kvm/kvm_main.c has > > static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, u32 id) > ... > if (id >= KVM_MAX_VCPUS) > return -EINVAL; I think the last time we talked about supporting "userspace determines MPIDR" the idea was to do it by allowing userspace to write to the MPIDR register with KVM_SET_ONE_REG. So you'd create a bunch of CPUs with vcpu-ids as usual, and then the MPIDRs would be set for them later as appropriate (or not at all, if userspace was an older qemu). thanks -- PMM -- 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
