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authorAlexander Graf <agraf@suse.de>2016-09-27 21:08:06 +0200
committerChristoffer Dall <cdall@linaro.org>2017-04-09 07:49:38 -0700
commitd9e1397783765a275c3a7930250dcdb7e9480d7d (patch)
tree378a3533159595a77a117bda8f242e8288295893 /include/kvm/arm_arch_timer.h
parent3fe17e6826162021d5e9274949571b19fc94826b (diff)
downloadlinux-d9e1397783765a275c3a7930250dcdb7e9480d7d.tar.bz2
KVM: arm/arm64: Support arch timers with a userspace gic
If you're running with a userspace gic or other interrupt controller (that is no vgic in the kernel), then you have so far not been able to use the architected timers, because the output of the architected timers, which are driven inside the kernel, was a kernel-only construct between the arch timer code and the vgic. This patch implements the new KVM_CAP_ARM_USER_IRQ feature, where we use a side channel on the kvm_run structure, run->s.regs.device_irq_level, to always notify userspace of the timer output levels when using a userspace irqchip. This works by ensuring that before we enter the guest, if the timer output level has changed compared to what we last told userspace, we don't enter the guest, but instead return to userspace to notify it of the new level. If we are exiting, because of an MMIO for example, and the level changed at the same time, the value is also updated and userspace can sample the line as it needs. This is nicely achieved simply always updating the timer_irq_level field after the main run loop. Note that the kvm_timer_update_irq trace event is changed to show the host IRQ number for the timer instead of the guest IRQ number, because the kernel no longer know which IRQ userspace wires up the timer signal to. Also note that this patch implements all required functionality but does not yet advertise the capability. Reviewed-by: Alexander Graf <agraf@suse.de> Reviewed-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Alexander Graf <agraf@suse.de> Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Diffstat (limited to 'include/kvm/arm_arch_timer.h')
-rw-r--r--include/kvm/arm_arch_timer.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/include/kvm/arm_arch_timer.h b/include/kvm/arm_arch_timer.h
index fe797d6ef89d..295584f31a4e 100644
--- a/include/kvm/arm_arch_timer.h
+++ b/include/kvm/arm_arch_timer.h
@@ -63,6 +63,8 @@ int kvm_timer_vcpu_reset(struct kvm_vcpu *vcpu,
void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu);
void kvm_timer_flush_hwstate(struct kvm_vcpu *vcpu);
void kvm_timer_sync_hwstate(struct kvm_vcpu *vcpu);
+bool kvm_timer_should_notify_user(struct kvm_vcpu *vcpu);
+void kvm_timer_update_run(struct kvm_vcpu *vcpu);
void kvm_timer_vcpu_terminate(struct kvm_vcpu *vcpu);
u64 kvm_arm_timer_get_reg(struct kvm_vcpu *, u64 regid);