kernel/linux.git/virt/kvm/arm/arch_timer.c, branch v4.7.4

KVM: arm/arm64: Move timer IRQ map to latest possible time

2016-05-20T13:39:41+00:00

We are about to modify the VGIC to allocate all data structures dynamically and store mapped IRQ information on a per-IRQ struct, which is indeed allocated dynamically at init time. Therefore, we cannot record the mapped IRQ info from the timer at timer reset time like it's done now, because VCPU reset happens before timer init. A possible later time to do this is on the first run of a per VCPU, it just requires us to move the enable state to be a per-VCPU state and do the lookup of the physical IRQ number when we are about to run the VCPU. Signed-off-by: Christoffer Dall Signed-off-by: Andre Przywara

KVM: arm/arm64: vgic: Remove irq_phys_map from interface

2016-05-20T13:39:40+00:00

Now that the virtual arch timer does not care about the irq_phys_map anymore, let's rework kvm_vgic_map_phys_irq() to return an error value instead. Any reference to that mapping can later be done by passing the correct combination of VCPU and virtual IRQ number. This makes the irq_phys_map handling completely private to the VGIC code. Signed-off-by: Andre Przywara Reviewed-by: Eric Auger Reviewed-by: Christoffer Dall

KVM: arm/arm64: arch_timer: Remove irq_phys_map

2016-05-20T13:39:39+00:00

Now that the interface between the arch timer and the VGIC does not require passing the irq_phys_map entry pointer anymore, let's remove it from the virtual arch timer and use the virtual IRQ number instead directly. The remaining pointer returned by kvm_vgic_map_phys_irq() will be removed in the following patch. Signed-off-by: Andre Przywara Reviewed-by: Eric Auger Reviewed-by: Christoffer Dall

KVM: arm/arm64: Remove the IRQ field from struct irq_phys_map

2016-05-20T13:39:39+00:00

The communication of a Linux IRQ number from outside the VGIC to the vgic was a leftover from the day when the vgic code cared about how a particular device injects virtual interrupts mapped to a physical interrupt. We can safely remove this notion, leaving all physical IRQ handling to be done in the device driver (the arch timer in this case), which makes room for a saner API for the new VGIC. Signed-off-by: Christoffer Dall Signed-off-by: Andre Przywara Reviewed-by: Eric Auger

KVM: arm/arm64: vgic: avoid map in kvm_vgic_unmap_phys_irq()

2016-05-20T13:39:38+00:00

kvm_vgic_unmap_phys_irq() only needs the virtual IRQ number, so let's just pass that between the arch timer and the VGIC to get rid of the irq_phys_map pointer. Signed-off-by: Andre Przywara Reviewed-by: Eric Auger Reviewed-by: Christoffer Dall

KVM: arm/arm64: vgic: avoid map in kvm_vgic_map_is_active()

2016-05-20T13:39:38+00:00

For getting the active state of a mapped IRQ, we actually only need the virtual IRQ number, not the pointer to the mapping entry. Pass the virtual IRQ number from the arch timer to the VGIC directly. Signed-off-by: Andre Przywara Reviewed-by: Eric Auger Reviewed-by: Christoffer Dall

KVM: arm/arm64: vgic: avoid map in kvm_vgic_inject_mapped_irq()

2016-05-20T13:39:37+00:00

When we want to inject a hardware mapped IRQ into a guest, we actually only need the virtual IRQ number from the irq_phys_map. So let's pass this number directly from the arch timer to the VGIC to avoid using the map as a parameter. Signed-off-by: Andre Przywara Reviewed-by: Eric Auger Reviewed-by: Christoffer Dall

KVM: arm/arm64: arch_timer: Rely on the arch timer to parse the firmware tables

2016-05-03T10:54:21+00:00

The firmware table is currently parsed by the virtual timer code in order to retrieve the virtual timer interrupt. However, this is already done by the arch timer driver. To avoid code duplication, use the newly function arch_timer_get_kvm_info() which return all the information required by the virtual timer code. Signed-off-by: Julien Grall Acked-by: Christoffer Dall Signed-off-by: Christoffer Dall

KVM: arm/arm64: Handle forward time correction gracefully

2016-04-06T11:17:54+00:00

On a host that runs NTP, corrections can have a direct impact on the background timer that we program on the behalf of a vcpu. In particular, NTP performing a forward correction will result in a timer expiring sooner than expected from a guest point of view. Not a big deal, we kick the vcpu anyway. But on wake-up, the vcpu thread is going to perform a check to find out whether or not it should block. And at that point, the timer check is going to say "timer has not expired yet, go back to sleep". This results in the timer event being lost forever. There are multiple ways to handle this. One would be record that the timer has expired and let kvm_cpu_has_pending_timer return true in that case, but that would be fairly invasive. Another is to check for the "short sleep" condition in the hrtimer callback, and restart the timer for the remaining time when the condition is detected. This patch implements the latter, with a bit of refactoring in order to avoid too much code duplication. Cc: Reported-by: Alexander Graf Reviewed-by: Alexander Graf Signed-off-by: Marc Zyngier Signed-off-by: Christoffer Dall

KVM: arm/arm64: timer: Add active state caching

2016-02-29T18:34:22+00:00

Programming the active state in the (re)distributor can be an expensive operation so it makes some sense to try and reduce the number of accesses as much as possible. So far, we program the active state on each VM entry, but there is some opportunity to do less. An obvious solution is to cache the active state in memory, and only program it in the HW when conditions change. But because the HW can also change things under our feet (the active state can transition from 1 to 0 when the guest does an EOI), some precautions have to be taken, which amount to only caching an "inactive" state, and always programing it otherwise. With this in place, we observe a reduction of around 700 cycles on a 2GHz GICv2 platform for a NULL hypercall. Reviewed-by: Christoffer Dall Signed-off-by: Marc Zyngier