Re: git: c0f35dbf19c3 - main - vmm: Use a cpuset_t for vCPUs waiting for STARTUP IPIs.

From: Corvin_Köhne <corvink_at_FreeBSD.org>
Date: Mon, 21 Nov 2022 14:18:37 UTC
On 11/21/2022 2:15 PM, Kristof Provost wrote:
>
> On 18 Nov 2022, at 19:26, John Baldwin wrote:
>
>     The branch main has been updated by jhb:
>
>     URL:
>     https://cgit.FreeBSD.org/src/commit/?id=c0f35dbf19c3c8825bd2b321d8efd582807d1940
>     <https://cgit.FreeBSD.org/src/commit/?id=c0f35dbf19c3c8825bd2b321d8efd582807d1940>
>
>     commit c0f35dbf19c3c8825bd2b321d8efd582807d1940
>     Author: John Baldwin <jhb@FreeBSD.org>
>     AuthorDate: 2022-11-18 18:05:10 +0000
>     Commit: John Baldwin <jhb@FreeBSD.org>
>     CommitDate: 2022-11-18 18:25:38 +0000
>
>     vmm: Use a cpuset_t for vCPUs waiting for STARTUP IPIs.
>
>     Retire the boot_state member of struct vlapic and instead use a
>     cpuset
>     in the VM to track vCPUs waiting for STARTUP IPIs. INIT IPIs add
>     vCPUs to this set, and STARTUP IPIs remove vCPUs from the set.
>     STARTUP IPIs are only reported to userland for vCPUs that were
>     removed
>     from the set.
>
>     In particular, this permits a subsequent change to allocate vCPUs on
>     demand when the vCPU may not be allocated until after a STARTUP
>     IPI is
>     reported to userland.
>
>     Reviewed by: corvink, markj
>     Differential Revision: https://reviews.freebsd.org/D37173
>     ---
>     sys/amd64/include/vmm.h | 3 +++
>     sys/amd64/vmm/io/vlapic.c | 46
>     ++++++++++--------------------------------
>     sys/amd64/vmm/io/vlapic_priv.h | 7 -------
>     sys/amd64/vmm/vmm.c | 27 +++++++++++++++++++++++++
>     4 files changed, 41 insertions(+), 42 deletions(-)
>
>
> I’m seeing a panic starting a bhyve guest, and I think this commit 
> might be the responsible one:
>
> |login: panic: acquiring blockable sleep lock with spinlock or 
> critical section held (sleep mutex) vm rendezvous lock @ 
> /usr/src/sys/amd64/vmm/vmm.c:2508 cpuid = 14 time = 1669035212 KDB: 
> stack backtrace: db_trace_self_wrapper() at 
> db_trace_self_wrapper+0x2b/frame 0xfffffe015f2dd530 vpanic() at 
> vpanic+0x151/frame 0xfffffe015f2dd580 panic() at panic+0x43/frame 
> 0xfffffe015f2dd5e0 witness_checkorder() at 
> witness_checkorder+0xd3e/frame 0xfffffe015f2dd7a0 __mtx_lock_flags() 
> at __mtx_lock_flags+0x94/frame 0xfffffe015f2dd7f0 vm_start_cpus() at 
> vm_start_cpus+0x31/frame 0xfffffe015f2dd820 
> vlapic_icrlo_write_handler() at vlapic_icrlo_write_handler+0x30c/frame 
> 0xfffffe015f2dd8a0 vmx_run() at vmx_run+0x20ed/frame 
> 0xfffffe015f2dd9c0 vm_run() at vm_run+0x1d2/frame 0xfffffe015f2ddaa0 
> vmmdev_ioctl() at vmmdev_ioctl+0x644/frame 0xfffffe015f2ddb40 
> devfs_ioctl() at devfs_ioctl+0xcd/frame 0xfffffe015f2ddb90 vn_ioctl() 
> at vn_ioctl+0x131/frame 0xfffffe015f2ddca0 devfs_ioctl_f() at 
> devfs_ioctl_f+0x1e/frame 0xfffffe015f2ddcc0 kern_ioctl() at 
> kern_ioctl+0x202/frame 0xfffffe015f2ddd30 sys_ioctl() at 
> sys_ioctl+0x12a/frame 0xfffffe015f2dde00 amd64_syscall() at 
> amd64_syscall+0x12e/frame 0xfffffe015f2ddf30 fast_syscall_common() at 
> fast_syscall_common+0xf8/frame 0xfffffe015f2ddf30 --- syscall (54, 
> FreeBSD ELF64, ioctl), rip = 0x3dd9cbd7f94a, rsp = 0x3ddc1d44ae58, rbp 
> = 0x3ddc1d44af10 --- |
>
> And kgdb’s backtrace:
>
> |(kgdb) bt #0 __curthread () at 
> /usr/src/sys/amd64/include/pcpu_aux.h:59 #1 dump_savectx () at 
> /usr/src/sys/kern/kern_shutdown.c:405 #2 0xffffffff80bec678 in dumpsys 
> (di=0x0) at /usr/src/sys/x86/include/dump.h:87 #3 doadump 
> (textdump=textdump@entry=0) at /usr/src/sys/kern/kern_shutdown.c:434 
> #4 0xffffffff804b403a in db_dump (dummy=<optimized out>, 
> dummy2=<unavailable>, dummy3=<unavailable>, dummy4=<unavailable>) at 
> /usr/src/sys/ddb/db_command.c:593 #5 0xffffffff804b3e40 in db_command 
> (last_cmdp=<optimized out>, cmd_table=<optimized out>, dopager=true) 
> at /usr/src/sys/ddb/db_command.c:506 #6 0xffffffff804b3b0d in 
> db_command_loop () at /usr/src/sys/ddb/db_command.c:553 #7 
> 0xffffffff804b71a6 in db_trap (type=<optimized out>, code=<optimized 
> out>) at /usr/src/sys/ddb/db_main.c:270 #8 0xffffffff80c3b89e in 
> kdb_trap (type=type@entry=3, code=<unavailable>, code@entry=0, 
> tf=tf@entry=0xfffffe015f2dd470) at /usr/src/sys/kern/subr_kdb.c:745 #9 
> 0xffffffff810ce577 in trap (frame=0xfffffe015f2dd470) at 
> /usr/src/sys/amd64/amd64/trap.c:611 #10 <signal handler called> #11 
> kdb_enter (why=<optimized out>, msg=<optimized out>) at 
> /usr/src/sys/kern/subr_kdb.c:509 #12 0xffffffff80bec822 in vpanic 
> (fmt=<optimized out>, ap=ap@entry=0xfffffe015f2dd5c0) at 
> /usr/src/sys/kern/kern_shutdown.c:967 #13 0xffffffff80bec5c3 in panic 
> (fmt=0xffffffff81e8ce70 <cnputs_mtx> "\314:)\201\377\377\377\377") at 
> /usr/src/sys/kern/kern_shutdown.c:903 #14 0xffffffff80c5ea4e in 
> witness_checkorder (lock=0xfffff804d585d138, flags=<optimized out>, 
> file=<optimized out>, line=2508, interlock=<optimized out>) at 
> /usr/src/sys/kern/subr_witness.c:1202 #15 0xffffffff80bc6d04 in 
> __mtx_lock_flags (c=0xfffff804d585d150, opts=0, 
> file=0xffffffff8322542d "/usr/src/sys/amd64/vmm/vmm.c", line=2508) at 
> /usr/src/sys/kern/kern_mutex.c:278 #16 0xffffffff83204101 in 
> vm_start_cpus (vm=0xfffff804d585d000, 
> tostart=tostart@entry=0xfffffe015f2dd858) at 
> /usr/src/sys/amd64/vmm/vmm.c:2508 #17 0xffffffff83211b5c in 
> vlapic_icrlo_write_handler (vlapic=vlapic@entry=0xfffff8048dc14a80, 
> retu=retu@entry=0xfffffe015f2dd950) at 
> /usr/src/sys/amd64/vmm/io/vlapic.c:1172 #18 0xffffffff8321977d in 
> vmx_handle_apic_write (vcpu=0xfffff8048db3ac00, 
> vlapic=0xfffff8048dc14a80, qual=768) at 
> /usr/src/sys/amd64/vmm/intel/vmx.c:2184 #19 vmx_exit_process 
> (vmx=0xfffff804d585b000, vcpu=0xfffff8048db3ac00, 
> vmexit=0xfffff804a7c1a688) at /usr/src/sys/amd64/vmm/intel/vmx.c:2767 
> #20 vmx_run (vcpui=0xfffff8048db3ac00, rip=<optimized out>, 
> pmap=0xfffffe003dce1530, evinfo=0xfffffe015f2dd9d8) at 
> /usr/src/sys/amd64/vmm/intel/vmx.c:3174 #21 0xffffffff83202572 in 
> vm_run (vcpu=vcpu@entry=0xfffff804a7c1a600, 
> vme_user=vme_user@entry=0xfffff80032601b08) at 
> /usr/src/sys/amd64/vmm/vmm.c:1873 #22 0xffffffff83205ab4 in 
> vmmdev_ioctl (cdev=<optimized out>, cmd=3230692865, data=<optimized 
> out>, fflag=<optimized out>, td=<optimized out>) at 
> /usr/src/sys/amd64/vmm/vmm_dev.c:565 #23 0xffffffff80a7be7d in 
> devfs_ioctl (ap=0xfffffe015f2ddba8) at 
> /usr/src/sys/fs/devfs/devfs_vnops.c:933 #24 0xffffffff80cf6421 in 
> vn_ioctl (fp=0xfffff8000ce2cb40, com=<optimized out>, 
> data=0xfffff80032601b00, active_cred=0xfffff8000c4d0800, td=0x10) at 
> /usr/src/sys/kern/vfs_vnops.c:1699 #25 0xffffffff80a7c52e in 
> devfs_ioctl_f (fp=0xffffffff81e8ce70 <cnputs_mtx>, com=0, 
> data=0xffffffff812a0000, cred=0x1, td=0x10) at 
> /usr/src/sys/fs/devfs/devfs_vnops.c:864 #26 0xffffffff80c64672 in 
> fo_ioctl (fp=0xfffff8000ce2cb40, com=3230692865, data=0x1d0, 
> active_cred=0x1, td=<optimized out>) at /usr/src/sys/sys/file.h:365 
> #27 kern_ioctl (td=td@entry=0xfffffe0160936000, fd=<optimized out>, 
> com=com@entry=3230692865, data=0x1d0 <error: Cannot access memory at 
> address 0x1d0>, data@entry=0xfffff80032601b00 "") at 
> /usr/src/sys/kern/sys_generic.c:803 #28 0xffffffff80c643ba in 
> sys_ioctl (td=0xfffffe0160936000, uap=0xfffffe01609363f8) at 
> /usr/src/sys/kern/sys_generic.c:711 #29 0xffffffff810cf3be in 
> syscallenter (td=<optimized out>) at 
> /usr/src/sys/amd64/amd64/../../kern/subr_syscall.c:189 #30 
> amd64_syscall (td=0xfffffe0160936000, traced=0) at 
> /usr/src/sys/amd64/amd64/trap.c:1200 #31 <signal handler called> #32 
> 0x00003dd9cbd7f94a in ?? () Backtrace stopped: Cannot access memory at 
> address 0x3ddc1d44ae58 (kgdb) fr 16 #16 0xffffffff83204101 in 
> vm_start_cpus (vm=0xfffff804d585d000, 
> tostart=tostart@entry=0xfffffe015f2dd858) at 
> /usr/src/sys/amd64/vmm/vmm.c:2508 2508 mtx_lock(&vm->rendezvous_mtx); |
>
> I believe WITNESS is upset that we’re going to potentially sleep doing 
> mtx_lock(&vm->rendezvous_mtx); in vm_start_cpus() when we’ve done 
> critical_enter() in vm_run().
>
> Best regards,
> Kristof
>

Can you please test https://reviews.freebsd.org/D37452?


-- 
Best regards,
Corvin