KVM performs TPR raising asynchronously to QEMU, specifically outside
QEMU's global lock. When an interrupt is injected into the APIC and TPR
is checked to decide if this can be delivered, a stale TPR value may be
used, causing spurious interrupts in the end.
Fix this by deferring apic_update_irq to the context of the target VCPU.
We introduce a new interrupt flag for this, CPU_INTERRUPT_POLL. When it
is set, the VCPU calls apic_poll_irq before checking for further pending
interrupts. To avoid special-casing KVM, we also implement this logic
for TCG mode.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
This enables acceleration for MMIO-based TPR registers accesses of
32-bit Windows guest systems. It is mostly useful with KVM enabled,
either on older Intel CPUs (without flexpriority feature, can also be
manually disabled for testing) or any current AMD processor.
The approach introduced here is derived from the original version of
qemu-kvm. It was refactored, documented, and extended by support for
user space APIC emulation, both with and without KVM acceleration. The
VMState format was kept compatible, so was the ABI to the option ROM
that implements the guest-side para-virtualized driver service. This
enables seamless migration from qemu-kvm to upstream or, one day,
between KVM and TCG mode.
The basic concept goes like this:
- VAPIC PV interface consisting of I/O port 0x7e and (for KVM in-kernel
irqchip) a vmcall hypercall is registered
- VAPIC option ROM is loaded into guest
- option ROM activates TPR MMIO access reporting via port 0x7e
- TPR accesses are trapped and patched in the guest to call into option
ROM instead, VAPIC support is enabled
- option ROM TPR helpers track state in memory and invoke hypercall to
poll for pending IRQs if required
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
This was done in a mostly automated fashion. I did it in three steps and then
rebased it into a single step which avoids repeatedly touching every file in
the tree.
The first step was a sed-based addition of the parent type to the subclass
registration functions.
The second step was another sed-based removal of subclass registration functions
while also adding virtual functions from the base class into a class_init
function as appropriate.
Finally, a python script was used to convert the DeviceInfo structures and
qdev_register_subclass functions to TypeInfo structures, class_init functions,
and type_register_static calls.
We are almost fully converted to QOM after this commit.
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
This converts three devices because apic and ioapic are subclasses of sysbus.
Converting subclasses independently of their base class is prohibitively hard.
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
To enable migration between accelerated and non-accelerated APIC models,
we will need to handle the timer saving and restoring specially and can
no longer rely on the automatics of VMSTATE_TIMER. Specifically,
accelerated model will not start any QEMUTimer.
This patch therefore factors out the generic bits into apic_next_timer
and use a post-load callback to implemented model-specific logic.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
The KVM in-kernel APIC model will reuse parts of the user space model
while providing the same frontend view to guest and most management
interfaces.
Factor out an APIC base class to encapsulate those parts that will be
shared by user space and KVM model. This class offers callback hooks for
init, base/tpr setting, and the external NMI delivery that will be
set via APICCommonInfo structure and implemented specifically in the
subclasses.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
