From: Vitaly Kuznetsov <vkuznets@redhat.com>
To: kvm@vger.kernel.org, Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>,
"Dr . David Alan Gilbert" <dgilbert@redhat.com>,
Wei Huang <whuang2@amd.com>,
linux-kernel@vger.kernel.org
Subject: [PATCH RFC 0/2] KVM: x86: allow for more CPUID entries
Date: Tue, 15 Sep 2020 17:43:04 +0200 [thread overview]
Message-ID: <20200915154306.724953-1-vkuznets@redhat.com> (raw)
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@redhat.com>
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
next reply other threads:[~2020-09-15 15:51 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-15 15:43 Vitaly Kuznetsov [this message]
2020-09-15 15:43 ` [PATCH RFC 1/2] KVM: x86: allocate vcpu->arch.cpuid_entries dynamically Vitaly Kuznetsov
2020-09-18 2:41 ` Sean Christopherson
2020-10-01 10:04 ` Vitaly Kuznetsov
2020-09-15 15:43 ` [PATCH RFC 2/2] KVM: x86: bump KVM_MAX_CPUID_ENTRIES Vitaly Kuznetsov
2020-09-15 16:51 ` [PATCH RFC 0/2] KVM: x86: allow for more CPUID entries Dr. David Alan Gilbert
2020-09-16 3:49 ` Wei Huang
2020-09-16 7:44 ` Vitaly Kuznetsov
2020-09-16 8:33 ` Dr. David Alan Gilbert
2020-09-16 19:22 ` Wei Huang
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