Re: [GIT PULL] First batch of KVM changes for Linux 5.9

From: Ingo Molnar
Date: Tue Sep 08 2020 - 14:11:18 EST


* Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote:

> Paolo Bonzini (11):
> Merge branch 'kvm-async-pf-int' into HEAD

kvmtool broke in this merge window, hanging during bootup right after CPU bringup:

[ 1.289404] #63
[ 0.012468] kvm-clock: cpu 63, msr 6ff69fc1, secondary cpu clock
[ 0.012468] [Firmware Bug]: CPU63: APIC id mismatch. Firmware: 3f APIC: 14
[ 1.302320] kvm-guest: KVM setup async PF for cpu 63
[ 1.302320] kvm-guest: stealtime: cpu 63, msr 1379d7600

Eventually trigger an RCU stall warning:

[ 22.302392] rcu: INFO: rcu_sched detected stalls on CPUs/tasks:
[ 22.302392] rcu: 1-...!: (68 GPs behind) idle=00c/0/0x0 softirq=0/0 fqs=0 (false positive?)

I've bisected this down to the above merge commit. The individual commit:

b1d405751cd5: ("KVM: x86: Switch KVM guest to using interrupts for page ready APF delivery")

appears to be working fine standalone.

I'm using x86-64 defconfig+kvmconfig on SVM. Can send more info on request.

The kvmtool.git commit I've tested is 90b2d3adadf2.