Eric Lee / smarc-ti-linux-kernel

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Commit 0d997491f814c87310a6ad7be30a9049c7150489

Authored by Christoffer Dall
1 parent 544c572e03
Exists in smarct4x-processor-sdk-linux-03.00.00.04 and in 4 other branches dlt-processor-sdk-linux-03.00.00.04, smarct3x-processor-sdk-04.01.00.06, smarct3x-processor-sdk-linux-03.00.00.04, smarct4x-processor-sdk-04.01.00.06

arm/arm64: KVM: Fix disabled distributor operation 

We currently do a single update of the vgic state when the distributor
enable/disable control register is accessed and then bypass updating the
state for as long as the distributor remains disabled.

This is incorrect, because updating the state does not consider the
distributor enable bit, and this you can end up in a situation where an
interrupt is marked as pending on the CPU interface, but not pending on
the distributor, which is an impossible state to be in, and triggers a
warning.  Consider for example the following sequence of events:

1. An interrupt is marked as pending on the distributor
   - the interrupt is also forwarded to the CPU interface
2. The guest turns off the distributor (it's about to do a reboot)
   - we stop updating the CPU interface state from now on
3. The guest disables the pending interrupt
   - we remove the pending state from the distributor, but don't touch
     the CPU interface, see point 2.

Since the distributor disable bit really means that no interrupts should
be forwarded to the CPU interface, we modify the code to keep updating
the internal VGIC state, but always set the CPU interface pending bits
to zero when the distributor is disabled.

Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>

Showing 1 changed file with 6 additions and 5 deletions Side-by-side Diff

... ... @@ -1012,6 +1012,12 @@
1012 1012 pend_percpu = vcpu->arch.vgic_cpu.pending_percpu;
1013 1013 pend_shared = vcpu->arch.vgic_cpu.pending_shared;
1014 1014  
  1015 + if (!dist->enabled) {
  1016 + bitmap_zero(pend_percpu, VGIC_NR_PRIVATE_IRQS);
  1017 + bitmap_zero(pend_shared, nr_shared);
  1018 + return 0;
  1019 + }
  1020 +
1015 1021 pending = vgic_bitmap_get_cpu_map(&dist->irq_pending, vcpu_id);
1016 1022 enabled = vgic_bitmap_get_cpu_map(&dist->irq_enabled, vcpu_id);
1017 1023 bitmap_and(pend_percpu, pending, enabled, VGIC_NR_PRIVATE_IRQS);
... ... @@ -1038,11 +1044,6 @@
1038 1044 struct vgic_dist *dist = &kvm->arch.vgic;
1039 1045 struct kvm_vcpu *vcpu;
1040 1046 int c;
1041   -
1042   - if (!dist->enabled) {
1043   - set_bit(0, dist->irq_pending_on_cpu);
1044   - return;
1045   - }
1046 1047  
1047 1048 kvm_for_each_vcpu(c, vcpu, kvm) {
1048 1049 if (compute_pending_for_cpu(vcpu))