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KVM: arm64: vgic: Don't check for vgic_ready() when setting NR_IRQS

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KVM commits to a particular sizing of SPIs when the vgic is initialized,
which is before the point a vgic becomes ready. On top of that, KVM
supplies a default amount of SPIs should userspace not explicitly
configure this.

As such, the check for vgic_ready() in the handling of
KVM_DEV_ARM_VGIC_GRP_NR_IRQS is completely wrong, and testing if nr_spis
is nonzero is sufficient for preventing userspace from playing games
with us.

Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20241017001947.2707312-2-oliver.upton@linux.dev
Signed-off-by: Marc Zyngier <maz@kernel.org>
This commit is contained in:
Oliver Upton 2024-10-17 00:19:46 +00:00 committed by Marc Zyngier
parent c6c167afa0
commit 5978d4ec7e
1 changed files with 6 additions and 1 deletions
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7
arch/arm64/kvm/vgic/vgic-kvm-device.c
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@ -236,7 +236,12 @@ static int vgic_set_common_attr(struct kvm_device *dev,
mutex_lock(&dev->kvm->arch.config_lock); mutex_lock(&dev->kvm->arch.config_lock);
if (vgic_ready(dev->kvm) || dev->kvm->arch.vgic.nr_spis) /*
* Either userspace has already configured NR_IRQS or
* the vgic has already been initialized and vgic_init()
* supplied a default amount of SPIs.
*/
if (dev->kvm->arch.vgic.nr_spis)
ret = -EBUSY; ret = -EBUSY;
else else
dev->kvm->arch.vgic.nr_spis = dev->kvm->arch.vgic.nr_spis =