This same bug kernel NULL pointer dereference, address: 0000000000000040 appears in my log. It is related to qemu-system-x86. It appears every time after boot on my system. The rest of the system works fine afterwards, only qemu-system-x86 is in state [defunct] and unusable. After removing qemu-system-x86 the bug no longer appears. Hope this helps. K May 3 09:38:24 rytz kernel: [ 21.940379] ccp 0000:0a:00.1: sev command 0x4 timed out, disabling PSP May 3 09:38:24 rytz kernel: [ 21.940387] ccp 0000:0a:00.1: SEV: failed to get status. Error: 0x0 May 3 09:38:24 rytz kernel: [ 21.940413] BUG: kernel NULL pointer dereference, address: 0000000000000040 May 3 09:38:24 rytz kernel: [ 21.940415] #PF: supervisor read access in kernel mode May 3 09:38:24 rytz kernel: [ 21.940416] #PF: error_code(0x0000) - not-present page May 3 09:38:24 rytz kernel: [ 21.940416] PGD 0 P4D 0 May 3 09:38:24 rytz kernel: [ 21.940418] Oops: 0000 [#1] SMP NOPTI May 3 09:38:24 rytz kernel: [ 21.940420] CPU: 2 PID: 1511 Comm: qemu-system-x86 Tainted: P O 5.4.0-28-generic #32-Ubuntu May 3 09:38:24 rytz kernel: [ 21.940422] Hardware name: Gigabyte Technology Co., Ltd. X570 AORUS PRO/X570 AORUS PRO, BIOS F5 09/04/2019 May 3 09:38:24 rytz kernel: [ 21.940427] RIP: 0010:sev_ioctl_do_pdh_export+0x185/0x2f0 [ccp] May 3 09:38:24 rytz kernel: [ 21.940428] Code: 48 01 d0 48 0b 05 7b eb 4d df 49 89 44 24 10 8b 45 cc 41 89 44 24 18 eb 06 45 31 ff 45 31 f6 48 8b 05 67 5d 00 00 48 8d 53 0c <83> 78 40 01 74 1b 48 89 d7 48 89 55 b0 e8 29 f5 ff ff 48 8b 55 b0 May 3 09:38:24 rytz kernel: [ 21.940429] RSP: 0018:ffffaa0b81a7bd98 EFLAGS: 00010246 May 3 09:38:24 rytz kernel: [ 21.940430] RAX: 0000000000000000 RBX: ffffaa0b81a7be00 RCX: 0000000000000000 May 3 09:38:24 rytz kernel: [ 21.940431] RDX: ffffaa0b81a7be0c RSI: ffffffffc0370279 RDI: ffff9df1fb407800 May 3 09:38:24 rytz kernel: [ 21.940432] RBP: ffffaa0b81a7bde8 R08: ffff9df1fe8af080 R09: ffff9df1fb407800 May 3 09:38:24 rytz kernel: [ 21.940432] R10: 000000051e1c2f00 R11: 0000000002a58819 R12: ffff9df1f1cefe20 May 3 09:38:24 rytz kernel: [ 21.940433] R13: ffff9df1e71f46c0 R14: 0000000000000000 R15: 0000000000000000 May 3 09:38:24 rytz kernel: [ 21.940434] FS: 00007f8477c0c5c0(0000) GS:ffff9df1fe880000(0000) knlGS:0000000000000000 May 3 09:38:24 rytz kernel: [ 21.940435] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 May 3 09:38:24 rytz kernel: [ 21.940436] CR2: 0000000000000040 CR3: 00000007eddaa000 CR4: 0000000000340ee0 May 3 09:38:24 rytz kernel: [ 21.940436] Call Trace: May 3 09:38:24 rytz kernel: [ 21.940440] sev_ioctl+0x3f2/0x510 [ccp] May 3 09:38:24 rytz kernel: [ 21.940443] do_vfs_ioctl+0x407/0x670 May 3 09:38:24 rytz kernel: [ 21.940445] ? putname+0x4a/0x50 May 3 09:38:24 rytz kernel: [ 21.940446] ksys_ioctl+0x67/0x90 May 3 09:38:24 rytz kernel: [ 21.940447] __x64_sys_ioctl+0x1a/0x20 May 3 09:38:24 rytz kernel: [ 21.940450] do_syscall_64+0x57/0x190 May 3 09:38:24 rytz kernel: [ 21.940452] entry_SYSCALL_64_after_hwframe+0x44/0xa9 May 3 09:38:24 rytz kernel: [ 21.940453] RIP: 0033:0x7f847901037b May 3 09:38:24 rytz kernel: [ 21.940454] Code: 0f 1e fa 48 8b 05 15 3b 0d 00 64 c7 00 26 00 00 00 48 c7 c0 ff ff ff ff c3 66 0f 1f 44 00 00 f3 0f 1e fa b8 10 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d e5 3a 0d 00 f7 d8 64 89 01 48 May 3 09:38:24 rytz kernel: [ 21.940455] RSP: 002b:00007ffc447d4b38 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 May 3 09:38:24 rytz kernel: [ 21.940456] RAX: ffffffffffffffda RBX: 00005607b65f5170 RCX: 00007f847901037b May 3 09:38:24 rytz kernel: [ 21.940457] RDX: 00007ffc447d4b50 RSI: 00000000c0105300 RDI: 0000000000000010 May 3 09:38:24 rytz kernel: [ 21.940457] RBP: 0000000000000010 R08: 0000000000000000 R09: 0000000000000005 May 3 09:38:24 rytz kernel: [ 21.940458] R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffc447d4b50 May 3 09:38:24 rytz kernel: [ 21.940459] R13: 00007ffc447d4c70 R14: 00007ffc447d4c68 R15: 00007ffc447d4b60 May 3 09:38:24 rytz kernel: [ 21.940460] Modules linked in: ccm xt_CHECKSUM xt_MASQUERADE xt_conntrack ipt_REJECT nf_reject_ipv4 xt_tcpudp ip6table_mangle ip6table_nat iptable_mangle iptable_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 libcrc32c nf_tables nfnetlink ip6table_filter ip6_tables iptable_filter bpfilter bridge stp llc snd_hda_codec_hdmi nvidia_uvm(O) nvidia_drm(PO) nvidia_modeset(PO) snd_hda_codec_realtek snd_hda_codec_generic ledtrig_audio snd_hda_intel snd_intel_dspcfg snd_hda_codec snd_hda_core nvidia(PO) nls_iso8859_1 snd_hwdep snd_pcm snd_seq_midi mt7601u snd_seq_midi_event snd_rawmidi mac80211 snd_seq drm_kms_helper snd_seq_device cfg80211 snd_timer ipmi_devintf ipmi_msghandler ucsi_ccg fb_sys_fops typec_ucsi snd syscopyarea sysfillrect libarc4 input_leds kvm wmi_bmof typec mxm_wmi k10temp ccp sysimgblt soundcore mac_hid sch_fq_codel parport_pc ppdev lp drm parport ip_tables x_tables autofs4 dm_crypt hid_generic usbhid hid crct10dif_pclmul crc32_pclmul ghash_clmulni_intel aesni_intel May 3 09:38:24 rytz kernel: [ 21.940484] crypto_simd cryptd glue_helper igb i2c_piix4 ahci dca libahci i2c_algo_bit nvme i2c_nvidia_gpu nvme_core wmi May 3 09:38:24 rytz kernel: [ 21.940490] CR2: 0000000000000040 May 3 09:38:24 rytz kernel: [ 21.940491] ---[ end trace dc819f71e9e01b8b ]--- May 3 09:38:24 rytz kernel: [ 21.940493] RIP: 0010:sev_ioctl_do_pdh_export+0x185/0x2f0 [ccp] May 3 09:38:24 rytz kernel: [ 21.940494] Code: 48 01 d0 48 0b 05 7b eb 4d df 49 89 44 24 10 8b 45 cc 41 89 44 24 18 eb 06 45 31 ff 45 31 f6 48 8b 05 67 5d 00 00 48 8d 53 0c <83> 78 40 01 74 1b 48 89 d7 48 89 55 b0 e8 29 f5 ff ff 48 8b 55 b0 May 3 09:38:24 rytz kernel: [ 21.940495] RSP: 0018:ffffaa0b81a7bd98 EFLAGS: 00010246 May 3 09:38:24 rytz kernel: [ 21.940496] RAX: 0000000000000000 RBX: ffffaa0b81a7be00 RCX: 0000000000000000 May 3 09:38:24 rytz kernel: [ 21.940496] RDX: ffffaa0b81a7be0c RSI: ffffffffc0370279 RDI: ffff9df1fb407800 May 3 09:38:24 rytz kernel: [ 21.940497] RBP: ffffaa0b81a7bde8 R08: ffff9df1fe8af080 R09: ffff9df1fb407800 May 3 09:38:24 rytz kernel: [ 21.940497] R10: 000000051e1c2f00 R11: 0000000002a58819 R12: ffff9df1f1cefe20 May 3 09:38:24 rytz kernel: [ 21.940498] R13: ffff9df1e71f46c0 R14: 0000000000000000 R15: 0000000000000000 May 3 09:38:24 rytz kernel: [ 21.940499] FS: 00007f8477c0c5c0(0000) GS:ffff9df1fe880000(0000) knlGS:0000000000000000 May 3 09:38:24 rytz kernel: [ 21.940500] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 May 3 09:38:24 rytz kernel: [ 21.940500] CR2: 0000000000000040 CR3: 00000007eddaa000 CR4: 0000000000340ee0 May 3 09:38:24 rytz kernel: [ 21.945079] kvm: Nested Virtualization enabled May 3 09:38:24 rytz kernel: [ 21.945088] kvm: Nested Paging enabled May 3 09:38:24 rytz kernel: [ 21.945089] SVM: Virtual VMLOAD VMSAVE supported May 3 09:38:24 rytz kernel: [ 21.945089] SVM: Virtual GIF supported May 3 09:38:24 rytz kernel: [ 21.961144] MCE: In-kernel MCE decoding enabled.