Re: Windows fails to boot after rebase to QEMU master

[Claudio Fontana]

On 5/27/21 11:48 AM, Claudio Fontana wrote:
> On 5/27/21 11:15 AM, Dr. David Alan Gilbert wrote:
>> * Philippe Mathieu-Daudé (philmd@redhat.com) wrote:
>>> On 5/27/21 10:31 AM, Dr. David Alan Gilbert wrote:
>>>> * Claudio Fontana (cfontana@suse.de) wrote:
>>>>> On 5/26/21 9:30 PM, Dr. David Alan Gilbert wrote:
>>>>>> * Michael S. Tsirkin (mst@redhat.com) wrote:
>>>>>>> On Fri, May 21, 2021 at 11:17:19AM +0200, Siddharth Chandrasekaran 
>>>>>>> wrote:
>>>>>>>> After a rebase to QEMU master, I am having trouble booting windows VMs.
>>>>>>>> Git bisect indicates commit f5cc5a5c1686 ("i386: split cpu accelerators
>>>>>>>> from cpu.c, using AccelCPUClass") to have introduced the issue. I spent
>>>>>>>> some time looking at into it yesterday without much luck.
>>>>>>>>
>>>>>>>> Steps to reproduce:
>>>>>>>>
>>>>>>>>     $ ./configure --enable-kvm --disable-xen 
>>>>>>>> --target-list=x86_64-softmmu --enable-debug
>>>>>>>>     $ make -j `nproc`
>>>>>>>>     $ ./build/x86_64-softmmu/qemu-system-x86_64 \
>>>>>>>>         -cpu 
>>>>>>>> host,hv_synic,hv_vpindex,hv_time,hv_runtime,hv_stimer,hv_crash \
>>>>>>>>         -enable-kvm \
>>>>>>>>         -name test,debug-threads=on \
>>>>>>>>         -smp 1,threads=1,cores=1,sockets=1 \
>>>>>>>>         -m 4G \
>>>>>>>>         -net nic -net user \
>>>>>>>>         -boot d,menu=on \
>>>>>>>>         -usbdevice tablet \
>>>>>>>>         -vnc :3 \
>>>>>>>>         -machine q35,smm=on \
>>>>>>>>         -drive 
>>>>>>>> if=pflash,format=raw,readonly=on,unit=0,file="../OVMF_CODE.secboot.fd" 
>>>>>>>> \
>>>>>>>>         -drive 
>>>>>>>> if=pflash,format=raw,unit=1,file="../OVMF_VARS.secboot.fd" \
>>>>>>>>         -global ICH9-LPC.disable_s3=1 \
>>>>>>>>         -global driver=cfi.pflash01,property=secure,value=on \
>>>>>>>>         -cdrom "../Windows_Server_2016_14393.ISO" \
>>>>>>>>         -drive 
>>>>>>>> file="../win_server_2016.qcow2",format=qcow2,if=none,id=rootfs_drive \
>>>>>>>>         -device ahci,id=ahci \
>>>>>>>>         -device ide-hd,drive=rootfs_drive,bus=ahci.0
>>>>>>>>
>>>>>>>> If the issue is not obvious, I'd like some pointers on how to go about
>>>>>>>> fixing this issue.
>>>>>>>>
>>>>>>>> ~ Sid.
>>>>>>>>
>>>>>>>
>>>>>>> At a guess this commit inadvertently changed something in the CPU ID.
>>>>>>> I'd start by using a linux guest to dump cpuid before and after the
>>>>>>> change.
>>>>>>
>>>>>> I've not had a chance to do that yet, however I did just end up with a
>>>>>> bisect of a linux guest failure bisecting to the same patch:
>>>>>>
>>>>>> [dgilbert@dgilbert-t580 qemu]$ git bisect bad
>>>>>> f5cc5a5c168674f84bf061cdb307c2d25fba5448 is the first bad commit
>>>>>> commit f5cc5a5c168674f84bf061cdb307c2d25fba5448
>>>>>> Author: Claudio Fontana <cfontana@suse.de>
>>>>>> Date:   Mon Mar 22 14:27:40 2021 +0100
>>>>>>
>>>>>>     i386: split cpu accelerators from cpu.c, using AccelCPUClass
>>>>>>     
>>>>>>     i386 is the first user of AccelCPUClass, allowing to split
>>>>>>     cpu.c into:
>>>>>>     
>>>>>>     cpu.c            cpuid and common x86 cpu functionality
>>>>>>     host-cpu.c       host x86 cpu functions and "host" cpu type
>>>>>>     kvm/kvm-cpu.c    KVM x86 AccelCPUClass
>>>>>>     hvf/hvf-cpu.c    HVF x86 AccelCPUClass
>>>>>>     tcg/tcg-cpu.c    TCG x86 AccelCPUClass
>>>
>>> Well this is a big commit... I'm not custom to x86 target, and am
>>> having hard time following the cpu host/max change.
>>>
>>> Is it working when you use '-cpu max,...' instead of '-cpu host,'?
>>
>> No; and in fact the cpuid's are almost entirely different with and
>> without this patch! (both with -cpu host).  It looks like with this
>> patch we're getting the cpuid for the TCG cpuid rather than the host:
>>
>> Prior to this patch:
>> :/# cat /proc/cpuinfo
>> processor       : 0
>> vendor_id       : GenuineIntel
>> cpu family      : 6
>> model           : 142
>> model name      : Intel(R) Core(TM) i7-8650U CPU @ 1.90GHz
>> stepping        : 10
>> microcode       : 0xe0
>> cpu MHz         : 2111.998
>> cache size      : 16384 KB
>> physical id     : 0
>> siblings        : 1
>> core id         : 0
>> cpu cores       : 1
>> apicid          : 0
>> initial apicid  : 0
>> fpu             : yes
>> fpu_exception   : yes
>> cpuid level     : 22
>> wp              : yes
>> flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca 
>> cmov pat pse36 clflush mmx fxsr sse sse2 ss syscall nx pdpe1gb rdtscp lm 
>> constant
>> _tsc arch_perfmon rep_good nopl xtopology cpuid tsc_known_freq pni pclmulqdq 
>> vmx ssse3 fma cx16 pdcm pcid sse4_1 sse4_2 x2apic movbe popcnt 
>> tsc_deadline_tim
>> er aes xsave avx f16c rdrand hypervisor lahf_lm abm 3dnowprefetch 
>> cpuid_fault invpcid_single pti ssbd ibrs ibpb stibp tpr_shadow vnmi 
>> flexpriority ept vpid
>> ept_ad fsgsbase tsc_adjust bmi1 hle avx2 smep bmi2 erms invpcid rtm mpx 
>> rdseed adx smap clflushopt xsaveopt xsavec xgetbv1 xsaves arat umip md_clear 
>> arch_ca
>> pabilities
>> vmx flags       : vnmi preemption_timer invvpid ept_x_only ept_ad ept_1gb 
>> flexpriority tsc_offset vtpr mtf vapic ept vpid unrestricted_guest 
>> shadow_vmcs pml
>> bugs            : cpu_meltdown spectre_v1 spectre_v2 spec_store_bypass l1tf 
>> mds swapgs taa srbds
>> bogomips        : 4223.99
>> clflush size    : 64
>> cache_alignment : 64
>> address sizes   : 39 bits physical, 48 bits virtual
>> power management:
>>
>> With this patch:
>> processor       : 0
>> vendor_id       : AuthenticAMD
>> cpu family      : 6
>> model           : 6
>> model name      : QEMU TCG CPU version 2.5+
>> stepping        : 3
>> cpu MHz         : 2111.998
>> cache size      : 512 KB
>> physical id     : 0
>> siblings        : 1
>> core id         : 0
>> cpu cores       : 1
>> apicid          : 0
>> initial apicid  : 0
>> fpu             : yes
>> fpu_exception   : yes
>> cpuid level     : 13
>> wp              : yes
>> flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca 
>> cmov pat pse36 clflush mmx fxsr sse sse2 ss syscall nx pdpe1gb rdtscp lm 
>> nopl cpu
>> id tsc_known_freq pni pclmulqdq vmx ssse3 fma cx16 pdcm pcid sse4_1 sse4_2 
>> x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand hypervisor 
>> lahf_
>> lm abm 3dnowprefetch invpcid_single ssbd ibrs ibpb stibp vmmcall fsgsbase 
>> tsc_adjust bmi1 hle avx2 smep bmi2 erms invpcid rtm mpx rdseed adx smap 
>> clflushopt
>>  xsaveopt xsavec xgetbv1 xsaves arat umip md_clear arch_capabilities
>> bugs            : fxsave_leak sysret_ss_attrs spectre_v1 spectre_v2 
>> spec_store_bypass taa
>> bogomips        : 4223.99
>> TLB size        : 1024 4K pages
>> clflush size    : 64
>> cache_alignment : 64
>> address sizes   : 40 bits physical, 48 bits virtual
>> power management:
>>
>> cpuid.f5cc5a5c16
>>
>> CPU 0:
>>    0x00000000 0x00: eax=0x0000000d ebx=0x68747541 ecx=0x444d4163 
>> edx=0x69746e65
>>    0x00000001 0x00: eax=0x00000663 ebx=0x00000800 ecx=0xfffab223 
>> edx=0x0f8bfbff
>>    0x00000002 0x00: eax=0x00000001 ebx=0x00000000 ecx=0x0000004d 
>> edx=0x002c307d
>>    0x00000003 0x00: eax=0x00000000 ebx=0x00000000 ecx=0x00000000 
>> edx=0x00000000
>>    0x00000004 0x00: eax=0x00000121 ebx=0x01c0003f ecx=0x0000003f 
>> edx=0x00000001
>>    0x00000004 0x01: eax=0x00000122 ebx=0x01c0003f ecx=0x0000003f 
>> edx=0x00000001
>>    0x00000004 0x02: eax=0x00000143 ebx=0x03c0003f ecx=0x00000fff 
>> edx=0x00000001
>>    0x00000004 0x03: eax=0x00000163 ebx=0x03c0003f ecx=0x00003fff 
>> edx=0x00000006
>>    0x00000005 0x00: eax=0x00000000 ebx=0x00000000 ecx=0x00000003 
>> edx=0x00000000
>>    0x00000006 0x00: eax=0x00000004 ebx=0x00000000 ecx=0x00000000 
>> edx=0x00000000
>>    0x00000007 0x00: eax=0x00000000 ebx=0x009c4fbb ecx=0x00000004 
>> edx=0xac000400
>>    0x00000008 0x00: eax=0x00000000 ebx=0x00000000 ecx=0x00000000 
>> edx=0x00000000
>>    0x00000009 0x00: eax=0x00000000 ebx=0x00000000 ecx=0x00000000 
>> edx=0x00000000
>>    0x0000000a 0x00: eax=0x07300402 ebx=0x00000000 ecx=0x00000000 
>> edx=0x00008603
>>    0x0000000b 0x00: eax=0x00000000 ebx=0x00000001 ecx=0x00000100 
>> edx=0x00000000
>>    0x0000000b 0x01: eax=0x00000000 ebx=0x00000001 ecx=0x00000201 
>> edx=0x00000000
>>    0x0000000c 0x00: eax=0x00000000 ebx=0x00000000 ecx=0x00000000 
>> edx=0x00000000
>>    0x0000000d 0x00: eax=0x0000001f ebx=0x00000440 ecx=0x00000440 
>> edx=0x00000000
>>    0x0000000d 0x01: eax=0x0000000f ebx=0x000003c0 ecx=0x00000000 
>> edx=0x00000000
>>    0x0000000d 0x02: eax=0x00000100 ebx=0x00000240 ecx=0x00000000 
>> edx=0x00000000
>>    0x0000000d 0x03: eax=0x00000040 ebx=0x000003c0 ecx=0x00000000 
>> edx=0x00000000
>>    0x0000000d 0x04: eax=0x00000040 ebx=0x00000400 ecx=0x00000000 
>> edx=0x00000000
>>    0x40000000 0x00: eax=0x40000001 ebx=0x4b4d564b ecx=0x564b4d56 
>> edx=0x0000004d
>>    0x40000001 0x00: eax=0x01007afb ebx=0x00000000 ecx=0x00000000 
>> edx=0x00000000
>>    0x80000000 0x00: eax=0x80000008 ebx=0x68747541 ecx=0x444d4163 
>> edx=0x69746e65
>>    0x80000001 0x00: eax=0x00000663 ebx=0x00000000 ecx=0x00000121 
>> edx=0x2d93fbff
>>    0x80000002 0x00: eax=0x554d4551 ebx=0x47435420 ecx=0x55504320 
>> edx=0x72657620
>>    0x80000003 0x00: eax=0x6e6f6973 ebx=0x352e3220 ecx=0x0000002b 
>> edx=0x00000000
>>    0x80000004 0x00: eax=0x00000000 ebx=0x00000000 ecx=0x00000000 
>> edx=0x00000000
>>    0x80000005 0x00: eax=0x01ff01ff ebx=0x01ff01ff ecx=0x40020140 
>> edx=0x40020140
>>    0x80000006 0x00: eax=0x00000000 ebx=0x42004200 ecx=0x02008140 
>> edx=0x00808140
>>    0x80000007 0x00: eax=0x00000000 ebx=0x00000000 ecx=0x00000000 
>> edx=0x00000000
>>    0x80000008 0x00: eax=0x00003028 ebx=0x0100d000 ecx=0x00000000 
>> edx=0x00000000
>>    0x80860000 0x00: eax=0x00000000 ebx=0x00000000 ecx=0x00000000 
>> edx=0x00000000
>>    0xc0000000 0x00: eax=0x00000000 ebx=0x00000000 ecx=0x00000000 
>> edx=0x00000000
>>
>>
>> cpuid.0ac2b19743
>>
>> CPU 0:
>>    0x00000000 0x00: eax=0x00000016 ebx=0x756e6547 ecx=0x6c65746e 
>> edx=0x49656e69
>>    0x00000001 0x00: eax=0x000806ea ebx=0x00000800 ecx=0xfffab223 
>> edx=0x0f8bfbff
>>    0x00000002 0x00: eax=0x00000001 ebx=0x00000000 ecx=0x0000004d 
>> edx=0x002c307d
>>    0x00000003 0x00: eax=0x00000000 ebx=0x00000000 ecx=0x00000000 
>> edx=0x00000000
>>    0x00000004 0x00: eax=0x00000121 ebx=0x01c0003f ecx=0x0000003f 
>> edx=0x00000001
>>    0x00000004 0x01: eax=0x00000122 ebx=0x01c0003f ecx=0x0000003f 
>> edx=0x00000001
>>    0x00000004 0x02: eax=0x00000143 ebx=0x03c0003f ecx=0x00000fff 
>> edx=0x00000001
>>    0x00000004 0x03: eax=0x00000163 ebx=0x03c0003f ecx=0x00003fff 
>> edx=0x00000006
>>    0x00000005 0x00: eax=0x00000000 ebx=0x00000000 ecx=0x00000003 
>> edx=0x00000000
>>    0x00000006 0x00: eax=0x00000004 ebx=0x00000000 ecx=0x00000000 
>> edx=0x00000000
>>    0x00000007 0x00: eax=0x00000000 ebx=0x009c4fbb ecx=0x00000004 
>> edx=0xac000400
>>    0x00000008 0x00: eax=0x00000000 ebx=0x00000000 ecx=0x00000000 
>> edx=0x00000000
>>    0x00000009 0x00: eax=0x00000000 ebx=0x00000000 ecx=0x00000000 
>> edx=0x00000000
>>    0x0000000a 0x00: eax=0x07300402 ebx=0x00000000 ecx=0x00000000 
>> edx=0x00008603
>>    0x0000000b 0x00: eax=0x00000000 ebx=0x00000001 ecx=0x00000100 
>> edx=0x00000000
>>    0x0000000b 0x01: eax=0x00000000 ebx=0x00000001 ecx=0x00000201 
>> edx=0x00000000
>>    0x0000000c 0x00: eax=0x00000000 ebx=0x00000000 ecx=0x00000000 
>> edx=0x00000000
>>    0x0000000d 0x00: eax=0x0000001f ebx=0x00000440 ecx=0x00000440 
>> edx=0x00000000
>>    0x0000000d 0x01: eax=0x0000000f ebx=0x000003c0 ecx=0x00000000 
>> edx=0x00000000
>>    0x0000000d 0x02: eax=0x00000100 ebx=0x00000240 ecx=0x00000000 
>> edx=0x00000000
>>    0x0000000d 0x03: eax=0x00000040 ebx=0x000003c0 ecx=0x00000000 
>> edx=0x00000000
>>    0x0000000d 0x04: eax=0x00000040 ebx=0x00000400 ecx=0x00000000 
>> edx=0x00000000
>>    0x0000000e 0x00: eax=0x00000000 ebx=0x00000000 ecx=0x00000000 
>> edx=0x00000000
>>    0x0000000f 0x00: eax=0x00000000 ebx=0x00000000 ecx=0x00000000 
>> edx=0x00000000
>>    0x00000010 0x00: eax=0x00000000 ebx=0x00000000 ecx=0x00000000 
>> edx=0x00000000
>>    0x00000011 0x00: eax=0x00000000 ebx=0x00000000 ecx=0x00000000 
>> edx=0x00000000
>>    0x00000012 0x00: eax=0x00000000 ebx=0x00000000 ecx=0x00000000 
>> edx=0x00000000
>>    0x00000013 0x00: eax=0x00000000 ebx=0x00000000 ecx=0x00000000 
>> edx=0x00000000
>>    0x00000014 0x00: eax=0x00000000 ebx=0x00000000 ecx=0x00000000 
>> edx=0x00000000
>>    0x00000015 0x00: eax=0x00000000 ebx=0x00000000 ecx=0x00000000 
>> edx=0x00000000
>>    0x00000016 0x00: eax=0x00000000 ebx=0x00000000 ecx=0x00000000 
>> edx=0x00000000
>>    0x40000000 0x00: eax=0x40000001 ebx=0x4b4d564b ecx=0x564b4d56 
>> edx=0x0000004d
>>    0x40000001 0x00: eax=0x01007afb ebx=0x00000000 ecx=0x00000000 
>> edx=0x00000000
>>    0x80000000 0x00: eax=0x80000008 ebx=0x756e6547 ecx=0x6c65746e 
>> edx=0x49656e69
>>    0x80000001 0x00: eax=0x000806ea ebx=0x00000000 ecx=0x00000121 
>> edx=0x2c100800
>>    0x80000002 0x00: eax=0x65746e49 ebx=0x2952286c ecx=0x726f4320 
>> edx=0x4d542865
>>    0x80000003 0x00: eax=0x37692029 ebx=0x3536382d ecx=0x43205530 
>> edx=0x40205550
>>    0x80000004 0x00: eax=0x392e3120 ebx=0x7a484730 ecx=0x00000000 
>> edx=0x00000000
>>    0x80000005 0x00: eax=0x01ff01ff ebx=0x01ff01ff ecx=0x40020140 
>> edx=0x40020140
>>    0x80000006 0x00: eax=0x00000000 ebx=0x42004200 ecx=0x02008140 
>> edx=0x00808140
>>    0x80000007 0x00: eax=0x00000000 ebx=0x00000000 ecx=0x00000000 
>> edx=0x00000000
>>    0x80000008 0x00: eax=0x00003027 ebx=0x0100d000 ecx=0x00000000 
>> edx=0x00000000
>>    0x80860000 0x00: eax=0x00000000 ebx=0x00000000 ecx=0x00000000 
>> edx=0x00000000
>>    0xc0000000 0x00: eax=0x00000000 ebx=0x00000000 ecx=0x00000000 
>> edx=0x00000000
>>
> 
> I started looking at it.
> 
> Claudio
> 

I wonder how I missed this, the initialization functions for max_x86_cpu_initfn 
and kvm_cpu_max_instance_init end up being called in the wrong order.