Description of problem: Boot guest with EPYC cpu model, and set dies in QEMU cli, QEMU quit and print error message. Version-Release number of selected component (if applicable): qemu-kvm-4.1.0-1.module+el8.1.0+3966+4a23dca1 kernel-4.18.0-131.el8.x86_64 How reproducible: always Steps to Reproduce: 1. # /usr/libexec/qemu-kvm -smp 1,dies=2,maxcpus=2 -cpu EPYC 2. 3. Actual results: # /usr/libexec/qemu-kvm -smp 1,dies=2,maxcpus=2 -cpu EPYC qemu-kvm: kvm_init_vcpu failed: Argument list too long Expected results: No error. Additional info:
libvirt doesn't support the "dies" option yet (see bug 1702444). Lowering severity and priority and moving to 8.2.0.
QEMU has been recently split into sub-components and as a one-time operation to avoid breakage of tools, we are setting the QEMU sub-component of this BZ to "General". Please review and change the sub-component if necessary the next time you review this BZ. Thanks
Fixed by the 4.2.0 rebase, upstream commit: commit af95cafb877f563ed39ce8a5b2abe227dd5312fa Author: Eduardo Habkost <ehabkost> Date: Thu Aug 22 19:52:10 2019 -0300 i386: Omit all-zeroes entries from KVM CPUID table KVM has a 80-entry limit at KVM_SET_CPUID2. With the introduction of CPUID[0x1F], it is now possible to hit this limit with unusual CPU configurations, e.g.: $ ./x86_64-softmmu/qemu-system-x86_64 \ -smp 1,dies=2,maxcpus=2 \ -cpu EPYC,check=off,enforce=off \ -machine accel=kvm qemu-system-x86_64: kvm_init_vcpu failed: Argument list too long This happens because QEMU adds a lot of all-zeroes CPUID entries for unused CPUID leaves. In the example above, we end up creating 48 all-zeroes CPUID entries. KVM already returns all-zeroes when emulating the CPUID instruction if an entry is missing, so the all-zeroes entries are redundant. Skip those entries. This reduces the CPUID table size by half while keeping CPUID output unchanged. Reported-by: Yumei Huang <yuhuang> Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1741508 Signed-off-by: Eduardo Habkost <ehabkost> Message-Id: <20190822225210.32541-1-ehabkost> Acked-by: Paolo Bonzini <pbonzini> Signed-off-by: Eduardo Habkost <ehabkost>
Updating Fixed In Version to exact build tag. Danilo, should this be manually added to 8.2 errata?
Test with qemu-kvm-4.2.0-13.module+el8.2.0+5898+fb4bceae, the issue is gone.
BZ was added to errata, so clearing needinfo request from comment 8.
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory, and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. https://access.redhat.com/errata/RHBA-2020:2017