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SubjectRe: [PATCH v2 38/52] KVM: arm/arm64: GICv4: Wire init/teardown of per-VM support
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Hi Marc,

On 06/28/2017 10:03 AM, Marc Zyngier wrote:
> Should the HW support GICv4 and an ITS being associated with this
> VM, let's init the its_vm and its_vpe structures.
>
> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
> ---
> virt/kvm/arm/vgic/vgic-init.c | 11 ++++++++++-
> 1 file changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/virt/kvm/arm/vgic/vgic-init.c b/virt/kvm/arm/vgic/vgic-init.c
> index 3a0b8999f011..0de1f0d986d4 100644
> --- a/virt/kvm/arm/vgic/vgic-init.c
> +++ b/virt/kvm/arm/vgic/vgic-init.c
> @@ -285,8 +285,14 @@ int vgic_init(struct kvm *kvm)
> if (ret)
> goto out;
>
> - if (vgic_has_its(kvm))
> + if (vgic_has_its(kvm)) {
> dist->msis_require_devid = true;
> + if (kvm_vgic_global_state.has_gicv4) {
> + ret = vgic_v4_init(kvm);
> + if (ret)
> + goto out;
> + }

This is not quite right, ITS virtual device may not be initialized at the time of
calling vgic-init(). This change breaks the existing KVM functionality with QEMU
hypervisor tool. In later patches, code assumes vgic_v4_init(kvm) was called when
vgic_has_its(kvm) returns a true value.

The right change would be move this logic to inside vgic_its_create() something like this.

--- a/virt/kvm/arm/vgic/vgic-init.c
+++ b/virt/kvm/arm/vgic/vgic-init.c
@@ -285,14 +285,8 @@ int vgic_init(struct kvm *kvm)
if (ret)
goto out;

- if (vgic_has_its(kvm)) {
+ if (vgic_has_its(kvm))
dist->msis_require_devid = true;
- if (kvm_vgic_global_state.has_gicv4) {
- ret = vgic_v4_init(kvm);
- if (ret)
- goto out;
- }
- }

kvm_for_each_vcpu(i, vcpu, kvm)
kvm_vgic_vcpu_enable(vcpu);
--- a/virt/kvm/arm/vgic/vgic-its.c
+++ b/virt/kvm/arm/vgic/vgic-its.c
@@ -1637,6 +1637,7 @@ static int vgic_register_its_iodev(struct kvm *kvm, struct
static int vgic_its_create(struct kvm_device *dev, u32 type)
{
struct vgic_its *its;
+ int ret;

if (type != KVM_DEV_TYPE_ARM_VGIC_ITS)
return -ENODEV;
@@ -1657,6 +1658,12 @@ static int vgic_its_create(struct kvm_device *dev, u32 ty
its->enabled = false;
its->dev = dev;

+ if (kvm_vgic_global_state.has_gicv4) {
+ ret = vgic_v4_init(dev->kvm);
+ if (ret)
+ return -ENOMEM;
+ }
+

> + }
>
> kvm_for_each_vcpu(i, vcpu, kvm)
> kvm_vgic_vcpu_enable(vcpu);
> @@ -323,6 +329,9 @@ static void kvm_vgic_dist_destroy(struct kvm *kvm)
>
> kfree(dist->spis);
> dist->nr_spis = 0;
> +
> + if (kvm_vgic_global_state.has_gicv4 && vgic_has_its(kvm))
> + vgic_v4_teardown(kvm);
> }
>
> void kvm_vgic_vcpu_destroy(struct kvm_vcpu *vcpu)
>

--
Shanker Donthineni
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.

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