As it turns out, not all the interrupt controllers are able to
expose a vGIC maintenance interrupt as a distrete signal.
And to be fair, it doesn't really matter as all we require is
for *something* to kick us out of guest mode out way or another.
On systems that do not expose a maintenance interrupt as such,
there are two outcomes:
- either the virtual CPUIF does generate an interrupt, and
by the time we are back to the host the interrupt will have long
been disabled (as we set ICH_HCR_EL2.EN to 0 on exit). In this case,
interrupt latency is as good as it gets.
- or some other event (physical timer) will take us out of the guest
anyway, and the only drawback is a bad interrupt latency.
So let's be tolerant to the lack of maintenance interrupt, and just let
the user know that their mileage may vary...
Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
---
arch/arm64/kvm/vgic/vgic-init.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/arch/arm64/kvm/vgic/vgic-init.c b/arch/arm64/kvm/vgic/vgic-init.c
index 9b491263f5f7..00c75495fd0c 100644
--- a/arch/arm64/kvm/vgic/vgic-init.c
+++ b/arch/arm64/kvm/vgic/vgic-init.c
@@ -521,11 +521,6 @@ int kvm_vgic_hyp_init(void)
if (!gic_kvm_info)
return -ENODEV;
- if (!gic_kvm_info->maint_irq) {
- kvm_err("No vgic maintenance irq\n");
- return -ENXIO;
- }
-
switch (gic_kvm_info->type) {
case GIC_V2:
ret = vgic_v2_probe(gic_kvm_info);
@@ -549,6 +544,11 @@ int kvm_vgic_hyp_init(void)
if (ret)
return ret;
+ if (!kvm_vgic_global_state.maint_irq) {
+ kvm_err("No maintenance interrupt available, fingers crossed...\n");
+ return 0;
+ }
+
ret = request_percpu_irq(kvm_vgic_global_state.maint_irq,
vgic_maintenance_handler,
"vgic", kvm_get_running_vcpus());
--
2.29.2
