Re: [PATCH v3 1/1] KVM: s390: pv: make use of ultravisor AIV support

Michael Mueller
2022-02-22T17:27:39Z

On 22.02.22 09:13, Christian Borntraeger wrote:
> Am 09.02.22 um 16:22 schrieb Michael Mueller:
>> This patch enables the ultravisor adapter interruption vitualization
>> support indicated by UV feature BIT_UV_FEAT_AIV. This allows ISC
>> interruption injection directly into the GISA IPM for PV kvm guests.
>>
>> Hardware that does not support this feature will continue to use the
>> UV interruption interception method to deliver ISC interruptions to
>> PV kvm guests. For this purpose, the ECA_AIV bit for all guest cpus
>> will be cleared and the GISA will be disabled during PV CPU setup.
>>
>> In addition a check in __inject_io() has been removed. That reduces the
>> required instructions for interruption handling for PV and traditional
>> kvm guests.
>>
>> Signed-off-by: Michael Mueller <mimu@linux.ibm.com>
>
> The CI said the following with gisa_disable in the calltrace.
> Will drop from next for now.

The issue is reproducible with the GISA switched of:

echo > 0 /sys/modules/kvm/parameters/use_gisa

In that case the code for gisa_disable() is not touched.

The lock is taken in front of kvm_s390_pv_create_cpu()
in this case.

kvm_for_each_vcpu(i, vcpu, kvm) {
mutex_lock(&vcpu->mutex);
r = kvm_s390_pv_create_cpu(vcpu, rc, rrc);
mutex_unlock(&vcpu->mutex);
if (r)
break;
}

I have an idea how to prevent this and will send a patch for both
situations.

[ 319.799638] ======================================================
[ 319.799639] WARNING: possible circular locking dependency detected
[ 319.799641] 5.17.0-rc5-08427-gfd14b6309198 #4661 Not tainted
[ 319.799643] ------------------------------------------------------
[ 319.799644] qemu-system-s39/14220 is trying to acquire lock:
[ 319.799646] 00000000b30c0b50 (&kvm->lock){+.+.}-{3:3}, at:
kvm_s390_set_tod_clock+0x36/0x250
[ 319.799659]
but task is already holding lock:
[ 319.799660] 00000000b5beda60 (&vcpu->mutex){+.+.}-{3:3}, at:
kvm_vcpu_ioctl+0x9a/0x958
[ 319.799665]
which lock already depends on the new lock.

[ 319.799667]
the existing dependency chain (in reverse order) is:
[ 319.799668]
-> #1 (&vcpu->mutex){+.+.}-{3:3}:
[ 319.799671] __mutex_lock+0x8a/0x798
[ 319.799677] mutex_lock_nested+0x32/0x40
[ 319.799679] kvm_arch_vm_ioctl+0x1902/0x2c58
[ 319.799682] kvm_vm_ioctl+0x5b0/0xa80
[ 319.799685] __s390x_sys_ioctl+0xbe/0x100
[ 319.799688] __do_syscall+0x1da/0x208
[ 319.799689] system_call+0x82/0xb0
[ 319.799692]
-> #0 (&kvm->lock){+.+.}-{3:3}:
[ 319.799694] __lock_acquire+0x1916/0x2e70
[ 319.799699] lock_acquire+0x164/0x388
[ 319.799702] __mutex_lock+0x8a/0x798
[ 319.799757] mutex_lock_nested+0x32/0x40
[ 319.799759] kvm_s390_set_tod_clock+0x36/0x250
[ 319.799761] kvm_s390_handle_b2+0x6cc/0x26f0
[ 319.799764] kvm_handle_sie_intercept+0x1fe/0xe98
[ 319.799765] kvm_arch_vcpu_ioctl_run+0xec8/0x1880
[ 319.799768] kvm_vcpu_ioctl+0x29e/0x958
[ 319.799769] __s390x_sys_ioctl+0xbe/0x100
[ 319.799771] __do_syscall+0x1da/0x208
[ 319.799773] system_call+0x82/0xb0
[ 319.799774]
other info that might help us debug this:

[ 319.799776] Possible unsafe locking scenario:

[ 319.799777] CPU0 CPU1
[ 319.799778] ---- ----
[ 319.799779] lock(&vcpu->mutex);
[ 319.799780] lock(&kvm->lock);
[ 319.799782] lock(&vcpu->mutex);
[ 319.799783] lock(&kvm->lock);
[ 319.799784]
*** DEADLOCK ***

[ 319.799785] 2 locks held by qemu-system-s39/14220:
[ 319.799787] #0: 00000000b5beda60 (&vcpu->mutex){+.+.}-{3:3}, at:
kvm_vcpu_ioctl+0x9a/0x958
[ 319.799791] #1: 00000000b30c4588 (&kvm->srcu){....}-{0:0}, at:
kvm_arch_vcpu_ioctl_run+0x6f2/0x1880
[ 319.799796]
stack backtrace:
[ 319.799798] CPU: 5 PID: 14220 Comm: qemu-system-s39 Not tainted
5.17.0-rc5-08427-gfd14b6309198 #4661
[ 319.799801] Hardware name: IBM 8561 T01 701 (LPAR)
[ 319.799802] Call Trace:
[ 319.799803] [<000000020d7410de>] dump_stack_lvl+0x76/0x98
[ 319.799808] [<000000020cbbd268>] check_noncircular+0x140/0x160
[ 319.799811] [<000000020cbc0efe>] __lock_acquire+0x1916/0x2e70
[ 319.799813] [<000000020cbc2dbc>] lock_acquire+0x164/0x388
[ 319.799816] [<000000020d75013a>] __mutex_lock+0x8a/0x798
[ 319.799818] [<000000020d75087a>] mutex_lock_nested+0x32/0x40
[ 319.799820] [<000000020cb029a6>] kvm_s390_set_tod_clock+0x36/0x250
[ 319.799823] [<000000020cb14d14>] kvm_s390_handle_b2+0x6cc/0x26f0
[ 319.799825] [<000000020cb09b6e>] kvm_handle_sie_intercept+0x1fe/0xe98
[ 319.799827] [<000000020cb06c28>] kvm_arch_vcpu_ioctl_run+0xec8/0x1880
[ 319.799829] [<000000020caeddc6>] kvm_vcpu_ioctl+0x29e/0x958
[ 319.799831] [<000000020ce4e82e>] __s390x_sys_ioctl+0xbe/0x100
[ 319.799833] [<000000020d744a72>] __do_syscall+0x1da/0x208
[ 319.799835] [<000000020d757322>] system_call+0x82/0xb0
[ 319.799836] INFO: lockdep is turned off.

>
>    LOCKDEP_CIRCULAR (suite: kvm-unit-tests-kvm, case: -)
>                 WARNING: possible circular locking dependency detected
>
> 5.17.0-20220221.rc5.git1.b8f0356a093a.300.fc35.s390x+debug #1 Not tainted
>                 ------------------------------------------------------
>                 qemu-system-s39/161139 is trying to acquire lock:
>                 0000000280dc0b98 (&kvm->lock){+.+.}-{3:3}, at:
> kvm_s390_set_tod_clock+0x36/0x220 [kvm]
>                 but task is already holding lock:
>                 0000000280f4e4b8 (&vcpu->mutex){+.+.}-{3:3}, at:
> kvm_vcpu_ioctl+0x9a/0xa40 [kvm]
>                 which lock already depends on the new lock.
>                 the existing dependency chain (in reverse order) is:
>                 -> #1 (&vcpu->mutex){+.+.}-{3:3}:
>                        __lock_acquire+0x604/0xbd8
>                        lock_acquire.part.0+0xe2/0x250
>                        lock_acquire+0xb0/0x200
>                        __mutex_lock+0x9e/0x8a0
>                        mutex_lock_nested+0x32/0x40
>                        kvm_s390_gisa_disable+0xa4/0x130 [kvm]
>                        kvm_s390_handle_pv+0x718/0x778 [kvm]
>                        kvm_arch_vm_ioctl+0x4ac/0x5f8 [kvm]
>                        kvm_vm_ioctl+0x336/0x530 [kvm]
>                        __s390x_sys_ioctl+0xbe/0x100
>                        __do_syscall+0x1da/0x208
>                        system_call+0x82/0xb0
>                 -> #0 (&kvm->lock){+.+.}-{3:3}:
>                        check_prev_add+0xe0/0xed8
>                        validate_chain+0x736/0xb20
>                        __lock_acquire+0x604/0xbd8
>                        lock_acquire.part.0+0xe2/0x250
>                        lock_acquire+0xb0/0x200
>                        __mutex_lock+0x9e/0x8a0
>                        mutex_lock_nested+0x32/0x40
>                        kvm_s390_set_tod_clock+0x36/0x220 [kvm]
>                        kvm_s390_handle_b2+0x378/0x728 [kvm]
>                        kvm_handle_sie_intercept+0x13a/0x448 [kvm]
>                        vcpu_post_run+0x28e/0x560 [kvm]
>                        __vcpu_run+0x266/0x388 [kvm]
>                        kvm_arch_vcpu_ioctl_run+0x10a/0x270 [kvm]
>                        kvm_vcpu_ioctl+0x27c/0xa40 [kvm]
>                        __s390x_sys_ioctl+0xbe/0x100
>                        __do_syscall+0x1da/0x208
>                        system_call+0x82/0xb0
>                 other info that might help us debug this:
>                  Possible unsafe locking scenario:
>                        CPU0                    CPU1
>                        ----                    ----
>                   lock(&vcpu->mutex);
>                                                lock(&kvm->lock);
>                                                lock(&vcpu->mutex);
>                   lock(&kvm->lock);
>                  *** DEADLOCK ***
>                 2 locks held by qemu-system-s39/161139:
>                  #0: 0000000280f4e4b8 (&vcpu->mutex){+.+.}-{3:3}, at:
> kvm_vcpu_ioctl+0x9a/0xa40 [kvm]
>                  #1: 0000000280dc47c8 (&kvm->srcu){....}-{0:0}, at:
> __vcpu_run+0x1d4/0x388 [kvm]
>                 stack backtrace:
>                 CPU: 10 PID: 161139 Comm: qemu-system-s39 Not tainted
> 5.17.0-20220221.rc5.git1.b8f0356a093a.300.fc35.s390x+debug #1
>                 Hardware name: IBM 8561 T01 701 (LPAR)
>                 Call Trace:
>                  [<00000001da4e89de>] dump_stack_lvl+0x8e/0xc8
>                  [<00000001d9876c56>] check_noncircular+0x136/0x158
>                  [<00000001d9877c70>] check_prev_add+0xe0/0xed8
>                  [<00000001d987919e>] validate_chain+0x736/0xb20
>                  [<00000001d987b23c>] __lock_acquire+0x604/0xbd8
>                  [<00000001d987c432>] lock_acquire.part.0+0xe2/0x250
>                  [<00000001d987c650>] lock_acquire+0xb0/0x200
>                  [<00000001da4f72ae>] __mutex_lock+0x9e/0x8a0
>                  [<00000001da4f7ae2>] mutex_lock_nested+0x32/0x40
>                  [<000003ff8070cd6e>] kvm_s390_set_tod_clock+0x36/0x220
> [kvm]
>                  [<000003ff8071dd68>] kvm_s390_handle_b2+0x378/0x728 [kvm]
>                  [<000003ff8071146a>]
> kvm_handle_sie_intercept+0x13a/0x448 [kvm]
>                  [<000003ff8070dd46>] vcpu_post_run+0x28e/0x560 [kvm]
>                  [<000003ff8070e27e>] __vcpu_run+0x266/0x388 [kvm]
>                  [<000003ff8070eba2>]
> kvm_arch_vcpu_ioctl_run+0x10a/0x270 [kvm]
>                  [<000003ff806f4044>] kvm_vcpu_ioctl+0x27c/0xa40 [kvm]
>                  [<00000001d9b47ac6>] __s390x_sys_ioctl+0xbe/0x100
>                  [<00000001da4ec152>] __do_syscall+0x1da/0x208
>                  [<00000001da4fec42>] system_call+0x82/0xb0
>                 INFO: lockdep is turned off.

[ 319.799638] ======================================================
[ 319.799639] WARNING: possible circular locking dependency detected
[ 319.799641] 5.17.0-rc5-08427-gfd14b6309198 #4661 Not tainted
[ 319.799643] ------------------------------------------------------
[ 319.799644] qemu-system-s39/14220 is trying to acquire lock:
[ 319.799646] 00000000b30c0b50 (&kvm->lock){+.+.}-{3:3}, at:
kvm_s390_set_tod_clock+0x36/0x250
[ 319.799659]
but task is already holding lock:
[ 319.799660] 00000000b5beda60 (&vcpu->mutex){+.+.}-{3:3}, at:
kvm_vcpu_ioctl+0x9a/0x958
[ 319.799665]
which lock already depends on the new lock.

[ 319.799667]
the existing dependency chain (in reverse order) is:
[ 319.799668]
-> #1 (&vcpu->mutex){+.+.}-{3:3}:
[ 319.799671] __mutex_lock+0x8a/0x798
[ 319.799677] mutex_lock_nested+0x32/0x40
[ 319.799679] kvm_arch_vm_ioctl+0x1902/0x2c58
[ 319.799682] kvm_vm_ioctl+0x5b0/0xa80
[ 319.799685] __s390x_sys_ioctl+0xbe/0x100
[ 319.799688] __do_syscall+0x1da/0x208
[ 319.799689] system_call+0x82/0xb0
[ 319.799692]
-> #0 (&kvm->lock){+.+.}-{3:3}:
[ 319.799694] __lock_acquire+0x1916/0x2e70
[ 319.799699] lock_acquire+0x164/0x388
[ 319.799702] __mutex_lock+0x8a/0x798
[ 319.799757] mutex_lock_nested+0x32/0x40
[ 319.799759] kvm_s390_set_tod_clock+0x36/0x250
[ 319.799761] kvm_s390_handle_b2+0x6cc/0x26f0
[ 319.799764] kvm_handle_sie_intercept+0x1fe/0xe98
[ 319.799765] kvm_arch_vcpu_ioctl_run+0xec8/0x1880
[ 319.799768] kvm_vcpu_ioctl+0x29e/0x958
[ 319.799769] __s390x_sys_ioctl+0xbe/0x100
[ 319.799771] __do_syscall+0x1da/0x208
[ 319.799773] system_call+0x82/0xb0
[ 319.799774]
other info that might help us debug this:

[ 319.799776] Possible unsafe locking scenario:

[ 319.799777] CPU0 CPU1
[ 319.799778] ---- ----
[ 319.799779] lock(&vcpu->mutex);
[ 319.799780] lock(&kvm->lock);
[ 319.799782] lock(&vcpu->mutex);
[ 319.799783] lock(&kvm->lock);
[ 319.799784]
*** DEADLOCK ***

[ 319.799785] 2 locks held by qemu-system-s39/14220:
[ 319.799787] #0: 00000000b5beda60 (&vcpu->mutex){+.+.}-{3:3}, at:
kvm_vcpu_ioctl+0x9a/0x958
[ 319.799791] #1: 00000000b30c4588 (&kvm->srcu){....}-{0:0}, at:
kvm_arch_vcpu_ioctl_run+0x6f2/0x1880
[ 319.799796]
stack backtrace:
[ 319.799798] CPU: 5 PID: 14220 Comm: qemu-system-s39 Not tainted
5.17.0-rc5-08427-gfd14b6309198 #4661
[ 319.799801] Hardware name: IBM 8561 T01 701 (LPAR)
[ 319.799802] Call Trace:
[ 319.799803] [<000000020d7410de>] dump_stack_lvl+0x76/0x98
[ 319.799808] [<000000020cbbd268>] check_noncircular+0x140/0x160
[ 319.799811] [<000000020cbc0efe>] __lock_acquire+0x1916/0x2e70
[ 319.799813] [<000000020cbc2dbc>] lock_acquire+0x164/0x388
[ 319.799816] [<000000020d75013a>] __mutex_lock+0x8a/0x798
[ 319.799818] [<000000020d75087a>] mutex_lock_nested+0x32/0x40
[ 319.799820] [<000000020cb029a6>] kvm_s390_set_tod_clock+0x36/0x250
[ 319.799823] [<000000020cb14d14>] kvm_s390_handle_b2+0x6cc/0x26f0
[ 319.799825] [<000000020cb09b6e>] kvm_handle_sie_intercept+0x1fe/0xe98
[ 319.799827] [<000000020cb06c28>] kvm_arch_vcpu_ioctl_run+0xec8/0x1880
[ 319.799829] [<000000020caeddc6>] kvm_vcpu_ioctl+0x29e/0x958
[ 319.799831] [<000000020ce4e82e>] __s390x_sys_ioctl+0xbe/0x100
[ 319.799833] [<000000020d744a72>] __do_syscall+0x1da/0x208
[ 319.799835] [<000000020d757322>] system_call+0x82/0xb0
[ 319.799836] INFO: lockdep is turned off.