* Vitaly Kuznetsov (vkuznets@xxxxxxxxxx) 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 the report made me wonder why we need to pre- > allocate vcpu->arch.cpuid_entries array instead of sizing it dynamically. > This RFC is intended to feed my curiosity. > > Very mildly tested with selftests/kvm-unit-tests and nothing seems to > break. I also don't have access to the system where the original issue > was reported but chances we're fixing it are very good IMO as just the > second patch alone was reported to be sufficient. > > Reported-by: Dr. David Alan Gilbert <dgilbert@xxxxxxxxxx> Oh nice, I was just going to bump the magic number :-) Anyway, this seems to work for me, so: Tested-by: Dr. David Alan Gilbert <dgilbert@xxxxxxxxxx> > Vitaly Kuznetsov (2): > KVM: x86: allocate vcpu->arch.cpuid_entries dynamically > KVM: x86: bump KVM_MAX_CPUID_ENTRIES > > arch/x86/include/asm/kvm_host.h | 4 +-- > arch/x86/kvm/cpuid.c | 55 ++++++++++++++++++++++++--------- > arch/x86/kvm/x86.c | 1 + > 3 files changed, 43 insertions(+), 17 deletions(-) > > -- > 2.25.4 > -- Dr. David Alan Gilbert / dgilbert@xxxxxxxxxx / Manchester, UK
