arm/arm64: KVM: Detect vGIC presence at runtime
Before commit 662d9715840aef44dcb573b0f9fab9e8319c868a
("arm/arm64: KVM: Kill CONFIG_KVM_ARM_{VGIC,TIMER}") is was possible to
compile the kernel without vGIC and vTimer support. Commit message says
about possibility to detect vGIC support in runtime, but this has never
been implemented.
This patch introduces runtime check, restoring the lost functionality.
It again allows to use KVM on hardware without vGIC. Interrupt
controller has to be emulated in userspace in this case.
-ENODEV return code from probe function means there's no GIC at all.
-ENXIO happens when, for example, there is GIC node in the device tree,
but it does not specify vGIC resources. Any other error code is still
treated as full stop because it might mean some really serious problems.
Signed-off-by: Pavel Fedin <p.fedin@samsung.com>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
(cherry picked from commit c7da6fa43cb1c5e649da0f478a491feb9208cae7)
Signed-off-by: Alex Shi <alex.shi@linaro.org>
diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index 0178376..b936475 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -63,6 +63,8 @@
static unsigned int kvm_vmid_bits __read_mostly;
static DEFINE_SPINLOCK(kvm_vmid_lock);
+static bool vgic_present;
+
static void kvm_arm_set_running_vcpu(struct kvm_vcpu *vcpu)
{
BUG_ON(preemptible());
@@ -134,7 +136,8 @@
kvm->arch.vmid_gen = 0;
/* The maximum number of VCPUs is limited by the host's GIC model */
- kvm->arch.max_vcpus = kvm_vgic_get_max_vcpus();
+ kvm->arch.max_vcpus = vgic_present ?
+ kvm_vgic_get_max_vcpus() : KVM_MAX_VCPUS;
return ret;
out_free_stage2_pgd:
@@ -172,6 +175,8 @@
int r;
switch (ext) {
case KVM_CAP_IRQCHIP:
+ r = vgic_present;
+ break;
case KVM_CAP_IOEVENTFD:
case KVM_CAP_DEVICE_CTRL:
case KVM_CAP_USER_MEMORY:
@@ -914,6 +919,8 @@
switch (dev_id) {
case KVM_ARM_DEVICE_VGIC_V2:
+ if (!vgic_present)
+ return -ENXIO;
return kvm_vgic_addr(kvm, type, &dev_addr->addr, true);
default:
return -ENODEV;
@@ -928,6 +935,8 @@
switch (ioctl) {
case KVM_CREATE_IRQCHIP: {
+ if (!vgic_present)
+ return -ENXIO;
return kvm_vgic_create(kvm, KVM_DEV_TYPE_ARM_VGIC_V2);
}
case KVM_ARM_SET_DEVICE_ADDR: {
@@ -1118,8 +1127,17 @@
* Init HYP view of VGIC
*/
err = kvm_vgic_hyp_init();
- if (err)
+ switch (err) {
+ case 0:
+ vgic_present = true;
+ break;
+ case -ENODEV:
+ case -ENXIO:
+ vgic_present = false;
+ break;
+ default:
goto out_free_context;
+ }
/*
* Init HYP architected timer support