Unable to start VM with 5.10-rc3

[Zdenek Kaspar <zkaspar82@gmail.com>]

[-- Attachment #1: Type: text/plain, Size: 766 bytes --]

Hi,

attached file is result from today's linux-master (with fixes
for 5.10-rc4) when I try to start VM on older machine:

model name      : Intel(R) Core(TM)2 CPU          6600  @ 2.40GHz
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ht tm pbe syscall nx lm constant_tsc arch_perfmon pebs bts rep_good nopl cpuid aperfmperf pni dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm lahf_lm pti tpr_shadow dtherm
vmx flags       : tsc_offset vtpr

I did quick check with 5.9 (distro kernel) and it works,
but VM performance seems extremely impacted. 5.8 works fine.

Back to 5.10 issue: it's problematic since 5.10-rc1 and I have no luck
with bisecting (machine doesn't boot).

TIA, Z.

[-- Attachment #2: kvm-5.10-rc3-oops --]
[-- Type: application/octet-stream, Size: 4791 bytes --]

[  287.307287] BUG: kernel NULL pointer dereference, address: 00000000000000a4
[  287.307342] #PF: supervisor read access in kernel mode
[  287.307370] #PF: error_code(0x0000) - not-present page
[  287.307398] PGD 0 P4D 0 
[  287.307415] Oops: 0000 [#1] PREEMPT SMP PTI
[  287.307443] CPU: 1 PID: 608 Comm: qemu-build Not tainted 5.10.0-rc3-1-amd64 #1
[  287.307483] Hardware name:  /DG35EC, BIOS ECG3510M.86A.0118.2010.0113.1426 01/13/2010
[  287.307549] RIP: 0010:is_tdp_mmu_root+0x13/0x30 [kvm]
[  287.307578] Code: 48 8b 87 88 92 00 00 48 81 c7 88 92 00 00 48 39 f8 75 01 c3 0f 0b c3 48 c1 ee 0c 48 c1 e6 06 48 03 35 41 91 29 c9 48 8b 56 28 <0f> b6 82 a4 00 00 00 84 c0 74 08 8b 42 50 85 c0 0f 95 c0 c3 66 0f
[  287.307687] RSP: 0018:ffffb019c06c7c70 EFLAGS: 00010282
[  287.307717] RAX: ffff9bdeb0a44388 RBX: 0000000000000000 RCX: 0000000000000000
[  287.307756] RDX: 0000000000000000 RSI: ffffe3bd806b0780 RDI: ffffb019c0985000
[  287.307795] RBP: 00000000000fe000 R08: 0000000000000002 R09: 0000000000000000
[  287.307834] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000014
[  287.307873] R13: ffff9bdeb0a44000 R14: 0000000000000000 R15: 0000000000000001
[  287.307913] FS:  00007f7f93684640(0000) GS:ffff9bdeff280000(0000) knlGS:0000000000000000
[  287.307957] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  287.307988] CR2: 00000000000000a4 CR3: 00000000482ee000 CR4: 00000000000026e0
[  287.308027] Call Trace:
[  287.308055]  direct_page_fault+0x66/0x900 [kvm]
[  287.308094]  ? writeback_registers+0x18/0x60 [kvm]
[  287.308133]  ? x86_emulate_insn+0x5ee/0xe10 [kvm]
[  287.308169]  kvm_mmu_page_fault+0x344/0x4f0 [kvm]
[  287.308201]  ? vmx_vcpu_enter_exit+0x5c/0x90 [kvm_intel]
[  287.308243]  kvm_arch_vcpu_ioctl_run+0xcaa/0x1c60 [kvm]
[  287.308284]  kvm_vcpu_ioctl+0x203/0x520 [kvm]
[  287.308313]  __x64_sys_ioctl+0x338/0x720
[  287.308338]  ? __x64_sys_futex+0x120/0x190
[  287.308362]  ? restore_altstack+0x14/0xc0
[  287.308388]  do_syscall_64+0x33/0x40
[  287.308409]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[  287.308438] RIP: 0033:0x7f7f94bd1f6b
[  287.308457] Code: 89 d8 49 8d 3c 1c 48 f7 d8 49 39 c4 72 b5 e8 1c ff ff ff 85 c0 78 ba 4c 89 e0 5b 5d 41 5c c3 f3 0f 1e fa b8 10 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d d5 ae 0c 00 f7 d8 64 89 01 48
[  287.308563] RSP: 002b:00007f7f93683628 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
[  287.310506] RAX: ffffffffffffffda RBX: 000000000000ae80 RCX: 00007f7f94bd1f6b
[  287.312451] RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000012
[  287.314336] RBP: 00005570b8032af0 R08: 00005570b60e6850 R09: 00005570b66f9620
[  287.316212] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
[  287.318080] R13: 00005570b66db800 R14: 0000000000000000 R15: 00007f7f93684640
[  287.319927] Modules linked in: vhost_net vhost vhost_iotlb tun nft_reject_ipv4 nf_reject_ipv4 nft_reject nf_tables nfnetlink veth nfsd xxhash_generic nhpoly1305_sse2 nhpoly1305 chacha_generic chacha_x86_64 libchacha adiantum libpoly1305 algif_skcipher af_alg auth_rpcgss nfsv4 dns_resolver nfs lockd grace sunrpc nfs_ssc lzo zram zsmalloc cpufreq_powersave kvm_intel i915 kvm iTCO_wdt lpc_ich bridge video intel_gtt mfd_core 8250 iosf_mbi 8250_base irqbypass i2c_algo_bit evdev e1000e stp llc drm_kms_helper serial_core acpi_cpufreq processor syscopyarea sysfillrect sysimgblt fb_sys_fops button drm sch_fq_codel i2c_core backlight ip_tables x_tables ipv6 autofs4 btrfs blake2b_generic libcrc32c crc32c_generic xor zstd_decompress zstd_compress lzo_compress lzo_decompress raid6_pq ecb xts dm_crypt dm_mod sd_mod t10_pi hid_generic usbhid hid uhci_hcd ehci_pci ehci_hcd ahci sata_sil24 pata_jmicron libahci usbcore usb_common
[  287.332454] CR2: 00000000000000a4
[  287.334683] ---[ end trace abb75000bdcae706 ]---
[  287.336922] RIP: 0010:is_tdp_mmu_root+0x13/0x30 [kvm]
[  287.339211] Code: 48 8b 87 88 92 00 00 48 81 c7 88 92 00 00 48 39 f8 75 01 c3 0f 0b c3 48 c1 ee 0c 48 c1 e6 06 48 03 35 41 91 29 c9 48 8b 56 28 <0f> b6 82 a4 00 00 00 84 c0 74 08 8b 42 50 85 c0 0f 95 c0 c3 66 0f
[  287.343891] RSP: 0018:ffffb019c06c7c70 EFLAGS: 00010282
[  287.346272] RAX: ffff9bdeb0a44388 RBX: 0000000000000000 RCX: 0000000000000000
[  287.348665] RDX: 0000000000000000 RSI: ffffe3bd806b0780 RDI: ffffb019c0985000
[  287.351085] RBP: 00000000000fe000 R08: 0000000000000002 R09: 0000000000000000
[  287.353499] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000014
[  287.355912] R13: ffff9bdeb0a44000 R14: 0000000000000000 R15: 0000000000000001
[  287.358336] FS:  00007f7f93684640(0000) GS:ffff9bdeff280000(0000) knlGS:0000000000000000
[  287.360768] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  287.363207] CR2: 00000000000000a4 CR3: 00000000482ee000 CR4: 00000000000026e0