[PATCH 0/2] KVM: arm64: vgic-v4: Don't allocate vPEs that a VM can't use

[Fuad Tabba <fuad.tabba@linux.dev>]

Hi folks,

Two fixes for vgic_its_create() allocating vPEs for a VM that never
uses them. Nothing frees them when the VM is destroyed, and each
doorbell handler stays registered with a freed vCPU.

The first is for a GICv2 VM, which KVM can run on a GICv4.0 host whose
CPU interface supports legacy operation. The second is for a GICv3 VM
whose VMM cleared nASSGIcap on a GICv4.1 host with vSGIs.

Tested on AEM FVP, with has-gicv4.1=0 for the GICv2 case and =1 for the
other. With my reproducer (clear nASSGIcap for the second case,
initialise the vgic, create an ITS, destroy the VM), the kernel without
the fix leaves four "vcpu" doorbells in /proc/interrupts in each case,
and the fixed one doesn't leave any.

It doesn't conflict with my vgic init error-path series [1].

Based on Linux 7.3-rc3 (fd73f4a665989; also applies to kvmarm-7.4).

Cheers,
/fuad

[1] https://lore.kernel.org/all/20260921072958.2918477-1-fuad.tabba@linux.dev/

Fuad Tabba (2):
  KVM: arm64: vgic-v4: Don't allocate vPEs for a GICv2 VM
  KVM: arm64: vgic-v4: Don't allocate vPEs when userspace clears
    nASSGIcap

 arch/arm64/kvm/vgic/vgic-v4.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)


base-commit: fd73f4a6659897191fa0d40695fe370925dd3780
-- 
2.47.3