While most accesses to the i8259 are with the kvm mutex taken, the call
to kvm_pic_read_irq() is not. We can't easily take the kvm mutex there
since the function is called with interrupts disabled.
Fix by adding a spinlock to the virtual interrupt controller. Since we
can't send an IPI under the spinlock (we also take the same spinlock in
an irq disabled context), we defer the IPI until the spinlock is released.
Similarly, we defer irq ack notifications until after spinlock release to
avoid lock recursion.
Signed-off-by: Avi Kivity <avi@redhat.com>
This patch refactors the NMI watchdog delivery patch, consolidating
tests and providing a proper API for delivering watchdog events.
An included micro-optimization is to check only for apic_hw_enabled in
kvm_apic_local_deliver (the test for LVT mask is covering the
soft-disabled case already).
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Acked-by: Sheng Yang <sheng@linux.intel.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
LINT0 of the LAPIC can be used to route PIT events as NMI watchdog ticks
into the guest. This patch aligns the in-kernel irqchip emulation with
the user space irqchip with already supports this feature. The trick is
to route PIT interrupts to all LAPIC's LVT0 lines.
Rebased and slightly polished patch originally posted by Sheng Yang.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Sheng Yang <sheng.yang@intel.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Moving irq ack notification logic as common, and make
it shared with ia64 side.
Signed-off-by: Xiantao Zhang <xiantao.zhang@intel.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
The PIC code makes little effort to avoid kvm_vcpu_kick(), resulting in
unnecessary guest exits in some conditions.
For example, if the timer interrupt is routed through the IOAPIC, IRR
for IRQ 0 will get set but not cleared, since the APIC is handling the
acks.
This means that everytime an interrupt < 16 is triggered, the priority
logic will find IRQ0 pending and send an IPI to vcpu0 (in case IRQ0 is
not masked, which is Linux's case).
Introduce a new variable isr_ack to represent the IRQ's for which the
guest has been signalled / cleared the ISR. Use it to avoid more than
one IPI per trigger-ack cycle, in addition to the avoidance when ISR is
set in get_priority().
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Based on a patch from: Ben-Ami Yassour <benami@il.ibm.com>
which was based on a patch from: Amit Shah <amit.shah@qumranet.com>
Notify IRQ acking on PIC/APIC emulation. The previous patch missed two things:
- Edge triggered interrupts on IOAPIC
- PIC reset with IRR/ISR set should be equivalent to ack (LAPIC probably
needs something similar).
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
CC: Amit Shah <amit.shah@qumranet.com>
CC: Ben-Ami Yassour <benami@il.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
This can be used by kvm subsystems that are interested in when
interrupts are acked, for example time drift compensation.
Signed-off-by: Avi Kivity <avi@qumranet.com>
This function injects an interrupt into the guest given the kvm struct,
the (guest) irq number and the interrupt level.
Signed-off-by: Amit Shah <amit.shah@qumranet.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
Migrate the PIT timer to the physical CPU which vcpu0 is scheduled on,
similarly to what is done for the LAPIC timers, otherwise PIT interrupts
will be delayed until an unrelated event causes an exit.
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.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>
Migrating the apic timer in the critical section is not very nice, and is
absolutely horrible with the real-time port. Move migration to the regular
vcpu execution path, triggered by a new bitflag.
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Avi Kivity <avi@qumranet.com>
Moving kvm_vcpu_kick() to x86.c. Since it should be
common for all archs, put its declarations in <linux/kvm_host.h>
Signed-off-by: Zhang Xiantao <xiantao.zhang@intel.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
This paves the way for multiple architecture support. Note that while
ioapic.c could potentially be shared with ia64, it is also moved.
Signed-off-by: Avi Kivity <avi@qumranet.com>
Avi Kivity
Jan Kiszka
Xiantao Zhang
Marcelo Tosatti
Amit Shah
Ben-Ami Yassour