* Unable to start VM with 5.10-rc3
@ 2020-11-10 15:23 Zdenek Kaspar
2020-11-11 1:13 ` Ben Gardon
0 siblings, 1 reply; 5+ messages in thread
From: Zdenek Kaspar @ 2020-11-10 15:23 UTC (permalink / raw)
To: kvm
[-- 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
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: Unable to start VM with 5.10-rc3
2020-11-10 15:23 Unable to start VM with 5.10-rc3 Zdenek Kaspar
@ 2020-11-11 1:13 ` Ben Gardon
2020-11-11 11:09 ` Zdenek Kaspar
0 siblings, 1 reply; 5+ messages in thread
From: Ben Gardon @ 2020-11-11 1:13 UTC (permalink / raw)
To: Zdenek Kaspar; +Cc: kvm, Jim Mattson
Hi Zdenek,
That crash is most likely the result of a missing check for an invalid
root HPA or NULL shadow page in is_tdp_mmu_root, which could have
prevented the NULL pointer dereference.
However, I'm not sure how a vCPU got to that point in the page fault
handler with a bad EPT root page.
I see VMX in your list of flags, is your machine 64 bit with EPT or
some other configuration?
I'm surprised you are finding your machine unable to boot for
bisecting. Do you know if it's crashing in the same spot or somewhere
else? I wouldn't expect the KVM page fault handler to run as part of
boot.
I will send out a patch first thing tomorrow morning (PST) to WARN
instead of crashing with a NULL pointer dereference. Are you able to
reproduce the issue with any KVM selftest?
Ben
On Tue, Nov 10, 2020 at 7:24 AM Zdenek Kaspar <zkaspar82@gmail.com> wrote:
>
> 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.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: Unable to start VM with 5.10-rc3
2020-11-11 1:13 ` Ben Gardon
@ 2020-11-11 11:09 ` Zdenek Kaspar
2020-11-11 18:37 ` Ben Gardon
0 siblings, 1 reply; 5+ messages in thread
From: Zdenek Kaspar @ 2020-11-11 11:09 UTC (permalink / raw)
To: Ben Gardon; +Cc: kvm, Jim Mattson
[-- Attachment #1: Type: text/plain, Size: 2176 bytes --]
Hi, I'm sure my bisect has nothing to do with KVM,
because it was quick shot between -rc1 and previous release.
This old CPU doesn't have EPT (see attached file)
./run_tests.sh
FAIL apic-split (timeout; duration=90s)
FAIL ioapic-split (timeout; duration=90s)
FAIL apic (timeout; duration=30)
... ^C
few RIP is_tdp_mmu_root observed in dmesg
Z.
On Tue, 10 Nov 2020 17:13:21 -0800
Ben Gardon <bgardon@google.com> wrote:
> Hi Zdenek,
>
> That crash is most likely the result of a missing check for an invalid
> root HPA or NULL shadow page in is_tdp_mmu_root, which could have
> prevented the NULL pointer dereference.
> However, I'm not sure how a vCPU got to that point in the page fault
> handler with a bad EPT root page.
>
> I see VMX in your list of flags, is your machine 64 bit with EPT or
> some other configuration?
>
> I'm surprised you are finding your machine unable to boot for
> bisecting. Do you know if it's crashing in the same spot or somewhere
> else? I wouldn't expect the KVM page fault handler to run as part of
> boot.
>
> I will send out a patch first thing tomorrow morning (PST) to WARN
> instead of crashing with a NULL pointer dereference. Are you able to
> reproduce the issue with any KVM selftest?
>
> Ben
>
>
> On Tue, Nov 10, 2020 at 7:24 AM Zdenek Kaspar <zkaspar82@gmail.com>
> wrote:
> >
> > 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: vmxcap-out --]
[-- Type: application/octet-stream, Size: 5466 bytes --]
Basic VMX Information
Hex: 0x1a040000000007
Revision 7
VMCS size 1024
VMCS restricted to 32 bit addresses no
Dual-monitor support yes
VMCS memory type 6
INS/OUTS instruction information no
IA32_VMX_TRUE_*_CTLS support no
pin-based controls
External interrupt exiting yes
NMI exiting yes
Virtual NMIs no
Activate VMX-preemption timer no
Process posted interrupts no
primary processor-based controls
Interrupt window exiting yes
Use TSC offsetting yes
HLT exiting yes
INVLPG exiting yes
MWAIT exiting yes
RDPMC exiting yes
RDTSC exiting yes
CR3-load exiting forced
CR3-store exiting forced
CR8-load exiting yes
CR8-store exiting yes
Use TPR shadow yes
NMI-window exiting no
MOV-DR exiting yes
Unconditional I/O exiting yes
Use I/O bitmaps yes
Monitor trap flag no
Use MSR bitmaps yes
MONITOR exiting yes
PAUSE exiting yes
Activate secondary control no
secondary processor-based controls
Virtualize APIC accesses no
Enable EPT no
Descriptor-table exiting no
Enable RDTSCP no
Virtualize x2APIC mode no
Enable VPID no
WBINVD exiting no
Unrestricted guest no
APIC register emulation no
Virtual interrupt delivery no
PAUSE-loop exiting no
RDRAND exiting no
Enable INVPCID no
Enable VM functions no
VMCS shadowing no
Enable ENCLS exiting no
RDSEED exiting no
Enable PML no
EPT-violation #VE no
Conceal non-root operation from PT no
Enable XSAVES/XRSTORS no
Mode-based execute control (XS/XU) no
Sub-page write permissions no
GPA translation for PT no
TSC scaling no
User wait and pause no
ENCLV exiting no
VM-Exit controls
Save debug controls forced
Host address-space size yes
Load IA32_PERF_GLOBAL_CTRL no
Acknowledge interrupt on exit yes
Save IA32_PAT no
Load IA32_PAT no
Save IA32_EFER no
Load IA32_EFER no
Save VMX-preemption timer value no
Clear IA32_BNDCFGS no
Conceal VM exits from PT no
Clear IA32_RTIT_CTL no
VM-Entry controls
Load debug controls forced
IA-32e mode guest yes
Entry to SMM yes
Deactivate dual-monitor treatment yes
Load IA32_PERF_GLOBAL_CTRL no
Load IA32_PAT no
Load IA32_EFER no
Load IA32_BNDCFGS no
Conceal VM entries from PT no
Load IA32_RTIT_CTL no
Miscellaneous data
Hex: 0x403c0
VMX-preemption timer scale (log2) 0
Store EFER.LMA into IA-32e mode guest control no
HLT activity state yes
Shutdown activity state yes
Wait-for-SIPI activity state yes
PT in VMX operation no
IA32_SMBASE support no
Number of CR3-target values 4
MSR-load/store count recommendation 0
IA32_SMM_MONITOR_CTL[2] can be set to 1 no
VMWRITE to VM-exit information fields no
Inject event with insn length=0 no
MSEG revision identifier 0
VPID and EPT capabilities
Hex: 0x0
Execute-only EPT translations no
Page-walk length 4 no
Paging-structure memory type UC no
Paging-structure memory type WB no
2MB EPT pages no
1GB EPT pages no
INVEPT supported no
EPT accessed and dirty flags no
Advanced VM-exit information for EPT violations no
Single-context INVEPT no
All-context INVEPT no
INVVPID supported no
Individual-address INVVPID no
Single-context INVVPID no
All-context INVVPID no
Single-context-retaining-globals INVVPID no
VM Functions
Hex: 0x0
EPTP Switching no
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: Unable to start VM with 5.10-rc3
2020-11-11 11:09 ` Zdenek Kaspar
@ 2020-11-11 18:37 ` Ben Gardon
2020-11-11 22:16 ` Zdenek Kaspar
0 siblings, 1 reply; 5+ messages in thread
From: Ben Gardon @ 2020-11-11 18:37 UTC (permalink / raw)
To: Zdenek Kaspar; +Cc: kvm, Jim Mattson
Hi Zdenek,
I'm working on reproducing the issue. I don't have access to a CPU
without EPT, but I tried turning off EPT on a Skylake and I think I
reproduced the issue, but wasn't able to confirm in the logs.
If you were operating without EPT I assume the guest was in non-paging
mode to get into direct_page_fault in the first place. I would still
have expected the root HPA to be valid unless...
Ah, if you're operating with PAE, then the root hpa will be valid but
not have a shadow page associated with it, as it is set to
__pa(vcpu->arch.mmu->pae_root) in mmu_alloc_direct_roots.
In that case, I can see why we get a NULL pointer dereference in
is_tdp_mmu_root.
I will send out a patch that should fix this if the issue is as
described above. I don't have hardware to test this on, but if you
don't mind applying the patch and checking it, that would be awesome.
Ben
On Wed, Nov 11, 2020 at 3:09 AM Zdenek Kaspar <zkaspar82@gmail.com> wrote:
>
> Hi, I'm sure my bisect has nothing to do with KVM,
> because it was quick shot between -rc1 and previous release.
>
> This old CPU doesn't have EPT (see attached file)
>
> ./run_tests.sh
> FAIL apic-split (timeout; duration=90s)
> FAIL ioapic-split (timeout; duration=90s)
> FAIL apic (timeout; duration=30)
> ... ^C
> few RIP is_tdp_mmu_root observed in dmesg
>
> Z.
>
> On Tue, 10 Nov 2020 17:13:21 -0800
> Ben Gardon <bgardon@google.com> wrote:
>
> > Hi Zdenek,
> >
> > That crash is most likely the result of a missing check for an invalid
> > root HPA or NULL shadow page in is_tdp_mmu_root, which could have
> > prevented the NULL pointer dereference.
> > However, I'm not sure how a vCPU got to that point in the page fault
> > handler with a bad EPT root page.
> >
> > I see VMX in your list of flags, is your machine 64 bit with EPT or
> > some other configuration?
> >
> > I'm surprised you are finding your machine unable to boot for
> > bisecting. Do you know if it's crashing in the same spot or somewhere
> > else? I wouldn't expect the KVM page fault handler to run as part of
> > boot.
> >
> > I will send out a patch first thing tomorrow morning (PST) to WARN
> > instead of crashing with a NULL pointer dereference. Are you able to
> > reproduce the issue with any KVM selftest?
> >
> > Ben
> >
> >
> > On Tue, Nov 10, 2020 at 7:24 AM Zdenek Kaspar <zkaspar82@gmail.com>
> > wrote:
> > >
> > > 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.
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: Unable to start VM with 5.10-rc3
2020-11-11 18:37 ` Ben Gardon
@ 2020-11-11 22:16 ` Zdenek Kaspar
0 siblings, 0 replies; 5+ messages in thread
From: Zdenek Kaspar @ 2020-11-11 22:16 UTC (permalink / raw)
To: Ben Gardon; +Cc: kvm, Jim Mattson
Hi Ben,
[PATCH] kvm: x86/mmu: Fix is_tdp_mmu_check when using PAE
fixes is_tdp_mmu_root NULL pointer dereference,
tested on: Intel(R) Core(TM)2 CPU 6600 @ 2.40GHz
Thanks, Z.
On Wed, 11 Nov 2020 10:37:49 -0800
Ben Gardon <bgardon@google.com> wrote:
> Hi Zdenek,
>
> I'm working on reproducing the issue. I don't have access to a CPU
> without EPT, but I tried turning off EPT on a Skylake and I think I
> reproduced the issue, but wasn't able to confirm in the logs.
>
> If you were operating without EPT I assume the guest was in non-paging
> mode to get into direct_page_fault in the first place. I would still
> have expected the root HPA to be valid unless...
>
> Ah, if you're operating with PAE, then the root hpa will be valid but
> not have a shadow page associated with it, as it is set to
> __pa(vcpu->arch.mmu->pae_root) in mmu_alloc_direct_roots.
> In that case, I can see why we get a NULL pointer dereference in
> is_tdp_mmu_root.
>
> I will send out a patch that should fix this if the issue is as
> described above. I don't have hardware to test this on, but if you
> don't mind applying the patch and checking it, that would be awesome.
>
> Ben
>
> On Wed, Nov 11, 2020 at 3:09 AM Zdenek Kaspar <zkaspar82@gmail.com>
> wrote:
> >
> > Hi, I'm sure my bisect has nothing to do with KVM,
> > because it was quick shot between -rc1 and previous release.
> >
> > This old CPU doesn't have EPT (see attached file)
> >
> > ./run_tests.sh
> > FAIL apic-split (timeout; duration=90s)
> > FAIL ioapic-split (timeout; duration=90s)
> > FAIL apic (timeout; duration=30)
> > ... ^C
> > few RIP is_tdp_mmu_root observed in dmesg
> >
> > Z.
> >
> > On Tue, 10 Nov 2020 17:13:21 -0800
> > Ben Gardon <bgardon@google.com> wrote:
> >
> > > Hi Zdenek,
> > >
> > > That crash is most likely the result of a missing check for an
> > > invalid root HPA or NULL shadow page in is_tdp_mmu_root, which
> > > could have prevented the NULL pointer dereference.
> > > However, I'm not sure how a vCPU got to that point in the page
> > > fault handler with a bad EPT root page.
> > >
> > > I see VMX in your list of flags, is your machine 64 bit with EPT
> > > or some other configuration?
> > >
> > > I'm surprised you are finding your machine unable to boot for
> > > bisecting. Do you know if it's crashing in the same spot or
> > > somewhere else? I wouldn't expect the KVM page fault handler to
> > > run as part of boot.
> > >
> > > I will send out a patch first thing tomorrow morning (PST) to WARN
> > > instead of crashing with a NULL pointer dereference. Are you able
> > > to reproduce the issue with any KVM selftest?
> > >
> > > Ben
> > >
> > >
> > > On Tue, Nov 10, 2020 at 7:24 AM Zdenek Kaspar
> > > <zkaspar82@gmail.com> wrote:
> > > >
> > > > 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.
> >
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2020-11-11 22:16 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-11-10 15:23 Unable to start VM with 5.10-rc3 Zdenek Kaspar
2020-11-11 1:13 ` Ben Gardon
2020-11-11 11:09 ` Zdenek Kaspar
2020-11-11 18:37 ` Ben Gardon
2020-11-11 22:16 ` Zdenek Kaspar
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