The current interrupt handling on s390 misbehaves on an error case. On s390
each cpu has the prefix area (lowcore) for interrupt delivery. This memory
must always be available. If we fail to access the prefix area for a guest
on interrupt delivery the configuration is completely unusable. There is no
point in sending another program interrupt to an inaccessible lowcore.
Furthermore, we should not bug the host kernel, because this can be triggered
by userspace. I think the guest kernel itself can not trigger the problem, as
SET PREFIX and SIGNAL PROCESSOR SET PREFIX both check that the memory is
available and sane. As this is a userspace bug (e.g. setting the wrong guest
offset, unmapping guest memory) we should kill the userspace process instead
of BUGing the host kernel.
In the long term we probably should notify the userspace process about this
problem.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
While doing some tests with our lcrash implementation I have seen a
naming conflict with prefix_info in kvm_host.h vs. addrconf.h
To avoid future conflicts lets rename private definitions in
asm/kvm_host.h by adding the kvm_s390 prefix.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
The call to add_timer was issued before local_int.lock was taken and before
timer_due was set to 0. If the timer expires before the lock is being taken,
the timer function will set timer_due to 1 and exit before the vcpu falls
asleep. Depending on other external events, the vcpu might sleep forever.
This fix pulls setting timer_due to the beginning of the function before
add_timer, which ensures correct behavior.
Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
Timers that fire between guest hlt and vcpu_block's add_wait_queue() are
ignored, possibly resulting in hangs.
Also make sure that atomic_inc and waitqueue_active tests happen in the
specified order, otherwise the following race is open:
CPU0 CPU1
if (waitqueue_active(wq))
add_wait_queue()
if (!atomic_read(pit_timer->pending))
schedule()
atomic_inc(pit_timer->pending)
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
This patch contains the s390 interrupt subsystem (similar to in kernel apic)
including timer interrupts (similar to in-kernel-pit) and enabled wait
(similar to in kernel hlt).
In order to achieve that, this patch also introduces intercept handling
for instruction intercepts, and it implements load control instructions.
This patch introduces an ioctl KVM_S390_INTERRUPT which is valid for both
the vm file descriptors and the vcpu file descriptors. In case this ioctl is
issued against a vm file descriptor, the interrupt is considered floating.
Floating interrupts may be delivered to any virtual cpu in the configuration.
The following interrupts are supported:
SIGP STOP - interprocessor signal that stops a remote cpu
SIGP SET PREFIX - interprocessor signal that sets the prefix register of a
(stopped) remote cpu
INT EMERGENCY - interprocessor interrupt, usually used to signal need_reshed
and for smp_call_function() in the guest.
PROGRAM INT - exception during program execution such as page fault, illegal
instruction and friends
RESTART - interprocessor signal that starts a stopped cpu
INT VIRTIO - floating interrupt for virtio signalisation
INT SERVICE - floating interrupt for signalisations from the system
service processor
struct kvm_s390_interrupt, which is submitted as ioctl parameter when injecting
an interrupt, also carrys parameter data for interrupts along with the interrupt
type. Interrupts on s390 usually have a state that represents the current
operation, or identifies which device has caused the interruption on s390.
kvm_s390_handle_wait() does handle waitpsw in two flavors: in case of a
disabled wait (that is, disabled for interrupts), we exit to userspace. In case
of an enabled wait we set up a timer that equals the cpu clock comparator value
and sleep on a wait queue.
[christian: change virtio interrupt to 0x2603]
Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
