RHEL-8.4 disabled traditional asynchronous page fault mechanism and added a new one (interrupt based asynchronous page fault) which can be enabled with 'kvm-asyncpf-int' CPU option. The new mechanism is, however, not enabled by default as upstream QEMU supports kernels which don't have it. Downstream, we should be good as RHEL kernels starting with 8.4 have the required bits.
QE bot(pre verify): Set 'Verified:Tested,SanityOnly' as gating/tier1 test pass.
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 (virt:av bug fix and enhancement update), 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-2021:4684
(In reply to Vitaly Kuznetsov from comment #0) > RHEL-8.4 disabled traditional asynchronous page fault mechanism and added a > new one (interrupt based asynchronous page fault) which can be enabled with > 'kvm-asyncpf-int' CPU option. The new mechanism is, however, not enabled by > default as upstream QEMU supports kernels which don't have it. Downstream, > we should be good as RHEL kernels starting with 8.4 have the required bits. Hi Vitaly, From this description, do you mean that this feature needs guest having RHEL8.4 kernel or newer, right? I didn't get the expected results while testing RHEL7.9 guest on RHEL9.2. Test Env: Guest: 3.10.0-1160.el7.x86_64 Host 5.14.0-252.el9.x86_64 qemu-kvm-7.2.0-6.el9.x86_64 Command Line: -machine pc-q35-rhel9.2.0,memory-backend=mem-machine_mem \ -smp 6,maxcpus=6,cores=3,threads=1,dies=1,sockets=2 \ Test results: Inside guest: # dmesg | grep async [ 0.000000] KVM setup async PF for cpu 0 [ 0.991006] KVM setup async PF for cpu 1 [ 1.002968] KVM setup async PF for cpu 2 [ 1.024623] KVM setup async PF for cpu 3 [ 1.035768] KVM setup async PF for cpu 4 [ 1.048057] KVM setup async PF for cpu 5 # grep Hyp /proc/interrupts ------> Nothing output Please help to check this, thanks. BR, Nana
(In reply to liunana from comment #19) > (In reply to Vitaly Kuznetsov from comment #0) > > RHEL-8.4 disabled traditional asynchronous page fault mechanism and added a > > new one (interrupt based asynchronous page fault) which can be enabled with > > 'kvm-asyncpf-int' CPU option. The new mechanism is, however, not enabled by > > default as upstream QEMU supports kernels which don't have it. Downstream, > > we should be good as RHEL kernels starting with 8.4 have the required bits. > > Hi Vitaly, > > > From this description, do you mean that this feature needs guest having > RHEL8.4 kernel or newer, right? > I didn't get the expected results while testing RHEL7.9 guest on RHEL9.2. > > Yea, RHEL7 doesn't support this new mechanism, we backported it to RHEL8.4 so only kernels >= kernel-4.18.0-252.el8 use it. There's no harm done if the guest doesn't support the feature, it just won't get enabled.