Re: [PATCH RFC 0/2] KVM: x86: allow for more CPUID entries

2020-09-16 Thread Wei Huang
On 09/16 09:33, Dr. David Alan Gilbert wrote: > * Wei Huang (wei.hua...@amd.com) wrote: > > On 09/15 05:51, Dr. David Alan Gilbert wrote: > > > * Vitaly Kuznetsov (vkuzn...@redhat.com) wrote: > > > > With QEMU and newer AMD CPUs (namely: Epyc 'Rome') the current limit for > > > > Could you elabora

Re: [PATCH RFC 0/2] KVM: x86: allow for more CPUID entries

2020-09-16 Thread Dr. David Alan Gilbert
* Wei Huang (wei.hua...@amd.com) wrote: > On 09/15 05:51, Dr. David Alan Gilbert wrote: > > * Vitaly Kuznetsov (vkuzn...@redhat.com) wrote: > > > With QEMU and newer AMD CPUs (namely: Epyc 'Rome') the current limit for > > Could you elaborate on this limit? On Rome, I counted ~35 CPUID functions

Re: [PATCH RFC 0/2] KVM: x86: allow for more CPUID entries

2020-09-16 Thread Vitaly Kuznetsov
Wei Huang writes: > On 09/15 05:51, Dr. David Alan Gilbert wrote: >> * Vitaly Kuznetsov (vkuzn...@redhat.com) wrote: >> > With QEMU and newer AMD CPUs (namely: Epyc 'Rome') the current limit for > > Could you elaborate on this limit? On Rome, I counted ~35 CPUID functions > which > include Fn000

Re: [PATCH RFC 0/2] KVM: x86: allow for more CPUID entries

2020-09-15 Thread Wei Huang
On 09/15 05:51, Dr. David Alan Gilbert wrote: > * Vitaly Kuznetsov (vkuzn...@redhat.com) wrote: > > With QEMU and newer AMD CPUs (namely: Epyc 'Rome') the current limit for Could you elaborate on this limit? On Rome, I counted ~35 CPUID functions which include Fn_, Fn4000_ and Fn8000_x

Re: [PATCH RFC 0/2] KVM: x86: allow for more CPUID entries

2020-09-15 Thread Dr. David Alan Gilbert
* Vitaly Kuznetsov (vkuzn...@redhat.com) wrote: > With QEMU and newer AMD CPUs (namely: Epyc 'Rome') the current limit for > KVM_MAX_CPUID_ENTRIES(80) is reported to be hit. Last time it was raised > from '40' in 2010. We can, of course, just bump it a little bit to fix > the immediate issue but th

[PATCH RFC 0/2] KVM: x86: allow for more CPUID entries

2020-09-15 Thread Vitaly Kuznetsov
With QEMU and newer AMD CPUs (namely: Epyc 'Rome') the current limit for KVM_MAX_CPUID_ENTRIES(80) is reported to be hit. Last time it was raised from '40' in 2010. We can, of course, just bump it a little bit to fix the immediate issue but the report made me wonder why we need to pre- allocate vcp