Re: KVM: Warn if mark_page_dirty() is called without an active vCPU

[Christian Borntraeger]

From: Christian Borntraeger <borntraeger@xxxxxxxxxx>

Quick heads-up.
The new warnon triggers on s390. Here we write to the guest from an
irqfd worker. Since we do not use dirty_ring yet this might be an over-indication.
Still have to look into that.

[ 1801.980777] WARNING: CPU: 12 PID: 117600 at arch/s390/kvm/../../../virt/kvm/kvm_main.c:3166 mark_page_dirty_in_slot+0xa0/0xb0 [kvm]
[ 1801.980839] Modules linked in: xt_CHECKSUM(E) xt_MASQUERADE(E) xt_conntrack(E) ipt_REJECT(E) xt_tcpudp(E) nft_compat(E) nf_nat_tftp(E) nft_objref(E) vhost_vsock(E) vmw_vsock_virtio_transport_common(E) vsock(E) vhost(E) vhost_iotlb(E) nf_conntrack_tftp(E) crc32_generic(E) algif_hash(E) af_alg(E) paes_s390(E) dm_crypt(E) encrypted_keys(E) loop(E) lcs(E) ctcm(E) fsm(E) kvm(E) nft_fib_inet(E) nft_fib_ipv4(E) nft_fib_ipv6(E) nft_fib(E) nft_reject_inet(E) nf_reject_ipv4(E) nf_reject_ipv6(E) nft_reject(E) nft_ct(E) nft_chain_nat(E) nf_nat(E) nf_conntrack(E) nf_defrag_ipv6(E) nf_defrag_ipv4(E) ip_set(E) nf_tables(E) nfnetlink(E) sunrpc(E) dm_service_time(E) dm_multipath(E) scsi_dh_rdac(E) scsi_dh_emc(E) scsi_dh_alua(E) zfcp(E) scsi_transport_fc(E) ism(E) smc(E) ib_core(E) eadm_sch(E) vfio_ccw(E) mdev(E) vfio_iommu_type1(E) vfio(E) sch_fq_codel(E) configfs(E) ip_tables(E) x_tables(E) ghash_s39 [...truncated...]
[ 1801.980915]  sha1_s390(E) sha_common(E) pkey(E) zcrypt(E) rng_core(E) autofs4(E) [last unloaded: vfio_ap]
[ 1801.980931] CPU: 12 PID: 117600 Comm: kworker/12:0 Tainted: G            E     5.17.0-20220113.rc0.git0.32ce2abb03cf.300.fc35.s390x+next #1
[ 1801.980935] Hardware name: IBM 2964 NC9 712 (LPAR)
[ 1801.980938] Workqueue: events irqfd_inject [kvm]
[ 1801.980959] Krnl PSW : 0704e00180000000 000003ff805f0f5c (mark_page_dirty_in_slot+0xa4/0xb0 [kvm])
[ 1801.980981]            R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:2 PM:0 RI:0 EA:3
[ 1801.980985] Krnl GPRS: 000003ff298e9040 000000017754a660 0000000000000000 0000000000000000
[ 1801.980988]            000000003fefcc36 ffffffffffffff68 0000000000000000 0000000177871500
[ 1801.980990]            00000001d1918000 000000003fefcc36 00000001d1918000 0000000000000000
[ 1801.980993]            00000001375b0000 00000001d191a838 000003ff805f0ee6 0000038000babb48
[ 1801.981003] Krnl Code: 000003ff805f0f4c: eb9ff0a00004	lmg	%r9,%r15,160(%r15)
                          000003ff805f0f52: c0f400018c61	brcl	15,000003ff80622814
                         #000003ff805f0f58: af000000		mc	0,0
                         >000003ff805f0f5c: eb9ff0a00004	lmg	%r9,%r15,160(%r15)
                          000003ff805f0f62: c0f400018c59	brcl	15,000003ff80622814
                          000003ff805f0f68: c004ffe37b10	brcl	0,000003ff80260588
                          000003ff805f0f6e: ec360033007c	cgij	%r3,0,6,000003ff805f0fd4
                          000003ff805f0f74: e31020100012	lt	%r1,16(%r2)
[ 1801.981057] Call Trace:
[ 1801.981060]  [<000003ff805f0f5c>] mark_page_dirty_in_slot+0xa4/0xb0 [kvm]
[ 1801.981083]  [<000003ff8060e9fe>] adapter_indicators_set+0xde/0x268 [kvm]
[ 1801.981104]  [<000003ff80613c24>] set_adapter_int+0x64/0xd8 [kvm]
[ 1801.981124]  [<000003ff805fb9aa>] kvm_set_irq+0xc2/0x130 [kvm]
[ 1801.981144]  [<000003ff805f8d86>] irqfd_inject+0x76/0xa0 [kvm]
[ 1801.981164]  [<0000000175e56906>] process_one_work+0x1fe/0x470
[ 1801.981173]  [<0000000175e570a4>] worker_thread+0x64/0x498
[ 1801.981176]  [<0000000175e5ef2c>] kthread+0x10c/0x110
[ 1801.981180]  [<0000000175de73c8>] __ret_from_fork+0x40/0x58
[ 1801.981185]  [<000000017698440a>] ret_from_fork+0xa/0x40