d47c4c454a
The diag 0x44 handler, which handles a directed yield, goes into a a codepath that does a kvm_for_each_vcpu() and ultimately deliverable_irqs(). The new check for kvm_s390_pv_cpu_is_protected() contains an assertion that the vcpu->mutex is held, which isn't going to be the case in this scenario. The result is a plethora of these messages if the lock debugging is enabled, and thus an implication that we have a problem. WARNING: CPU: 9 PID: 16167 at arch/s390/kvm/kvm-s390.h:239 deliverable_irqs+0x1c6/0x1d0 [kvm] ...snip... Call Trace: [<000003ff80429bf2>] deliverable_irqs+0x1ca/0x1d0 [kvm] ([<000003ff80429b34>] deliverable_irqs+0x10c/0x1d0 [kvm]) [<000003ff8042ba82>] kvm_s390_vcpu_has_irq+0x2a/0xa8 [kvm] [<000003ff804101e2>] kvm_arch_dy_runnable+0x22/0x38 [kvm] [<000003ff80410284>] kvm_vcpu_on_spin+0x8c/0x1d0 [kvm] [<000003ff80436888>] kvm_s390_handle_diag+0x3b0/0x768 [kvm] [<000003ff80425af4>] kvm_handle_sie_intercept+0x1cc/0xcd0 [kvm] [<000003ff80422bb0>] __vcpu_run+0x7b8/0xfd0 [kvm] [<000003ff80423de6>] kvm_arch_vcpu_ioctl_run+0xee/0x3e0 [kvm] [<000003ff8040ccd8>] kvm_vcpu_ioctl+0x2c8/0x8d0 [kvm] [<00000001504ced06>] ksys_ioctl+0xae/0xe8 [<00000001504cedaa>] __s390x_sys_ioctl+0x2a/0x38 [<0000000150cb9034>] system_call+0xd8/0x2d8 2 locks held by CPU 2/KVM/16167: #0: 00000001951980c0 (&vcpu->mutex){+.+.}, at: kvm_vcpu_ioctl+0x90/0x8d0 [kvm] #1: 000000019599c0f0 (&kvm->srcu){....}, at: __vcpu_run+0x4bc/0xfd0 [kvm] Last Breaking-Event-Address: [<000003ff80429b34>] deliverable_irqs+0x10c/0x1d0 [kvm] irq event stamp: 11967 hardirqs last enabled at (11975): [<00000001502992f2>] console_unlock+0x4ca/0x650 hardirqs last disabled at (11982): [<0000000150298ee8>] console_unlock+0xc0/0x650 softirqs last enabled at (7940): [<0000000150cba6ca>] __do_softirq+0x422/0x4d8 softirqs last disabled at (7929): [<00000001501cd688>] do_softirq_own_stack+0x70/0x80 Considering what's being done here, let's fix this by removing the mutex assertion rather than acquiring the mutex for every other vcpu. Fixes: 201ae986ead7 ("KVM: s390: protvirt: Implement interrupt injection") Signed-off-by: Eric Farman <farman@linux.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com> Reviewed-by: Cornelia Huck <cohuck@redhat.com> Link: https://lore.kernel.org/r/20200415190353.63625-1-farman@linux.ibm.com Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.