On Thu, Jun 01, 2023 at 11:17:30AM +0100, Daniel P. Berrangé wrote: > On Thu, Jun 01, 2023 at 11:09:45AM +0100, Joao Martins wrote: > > > > > > On 31/05/2023 23:51, Suravee Suthikulpanit wrote: > > > Since KVM_MAX_VCPUS is currently defined to 1024 for x86 as shown in > > > arch/x86/include/asm/kvm_host.h, update QEMU limits to the same number. > > > > > > In case KVM could not support the specified number of vcpus, QEMU would > > > return the following error message: > > > > > > qemu-system-x86_64: kvm_init_vcpu: kvm_get_vcpu failed (xxx): Invalid > > > argument > > > > > > Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpa...@amd.com> > > > --- > > > > > > Changes from V1: > > > (https://lore.kernel.org/all/ynkdgsii1vfvx...@redhat.com/T/) > > > * Bump from 512 to KVM_MAX_VCPUS (per Igor's suggestion) > > > > > > Note: > > > From the last discussion, Daniel mentioned that SMBIO 2.1 tables might > > > cause overflow at approx 720 CPUs, and it might require using the > > > SMBIO 3.0 entry point. Also, we might need to change the default for > > > the x86 machine type to SMBIO 3.0. However, I do not know the status > > > of this. > > > > > I suspect smbios 3.0 (64-bit entry point) is already supported. > > > > With current qemu and all the smbios fixes in the last cycle, perhaps this > > is > > mainly just setting smbios_entry_point_type to SMBIOS_ENTRY_POINT_TYPE_64 if > > MachineState::smp::max_cpus is bigger than 720 (e.g. in pc_q35_init()?) > > The need for the 64-bit entry point depends on a combination of RAM config > and CPU count. IMHO we need to unconditionally switch the latest machine > types to use the 64-bit entry point by default, rather than trying to infer > some special condition to dynamically change on the fly.
Yes, makes sense. > Before doing that we need confirmation that our firmware builds in qemu.git > (SeaBIOS and EDK2) will be happy with the 64-bit EP. I suspect they should > be fine by now, but I've CC'd Gerd to confirm. > > With regards, > Daniel
