On Fri, Mar 15, 2019 at 03:51:57PM +0000, Singh, Brijesh wrote: > Hi Daniel, > > > On 3/15/19 7:18 AM, Daniel P. Berrangé wrote: > > On Fri, Jan 18, 2019 at 12:51:50PM +0000, Singh, Brijesh wrote: > >> > >> On 1/18/19 3:39 AM, Erik Skultety wrote: > >>> I proceeded with cloning [1] to systemd and creating an udev rule that I planned > >>> on submitting to systemd upstream - the initial idea was to mimic /dev/kvm and > >>> make it world accessible to which Brijesh from AMD expressed a concern that > >>> regular users might deplete the resources (limit on the number of guests > >>> allowed by the platform). > > > > [snip] > > > >>> But since the limit is claimed to be around 4, Dan > >> > >> > >> FYI, the limit on EPYC is 15. > > > > Do any cRyzen CPUs support SEV, and if so is their limit also 15 ? > > > > SEV support is *not* available on any of Ryzen's yet! Ok, thanks for clarifying. > > Regardless, I'm assuming this limit is liable to change at any time > > in future CPU generations, so from the the mgmt app perspective I > > think is is important that QEMU / libvirt can both report what this > > limit is. > > > > Yes, the limit may change on future CPU generations. We can query the > limit through the CPUID Fn0x8000_001f[ECX]. That's nice! > > For QEMU I think query-sev-capabilities probably should report the > > guest limit. I guess QEMU would in turn want to ask the kernel, > > rather than hardcode info itself. So if this info isn't already > > exposed by the kernel we might need work there too. > > > > > I don't think we need to add a kernel interface for querying this > information, it can be obtained using the cpuid instruction or > access its via /dev/cpuid/<cpu>. Agreed, using CPUID direct from QEMU ought to be sufficient. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :| -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list
