The spec says it is UNPREDICTABLE to enable the ITS
if any of the following conditions are true:

- GITS_CBASER.Valid == 0.
- GITS_BASER<n>.Valid == 0, for any GITS_BASER<n> register
  where the Type field indicates Device.
- GITS_BASER<n>.Valid == 0, for any GITS_BASER<n> register
  where the Type field indicates Interrupt Collection and
  GITS_TYPER.HCC == 0.

In that case, let's keep the ITS disabled.

Signed-off-by: Eric Auger <eric.au...@redhat.com>
Reported-by: Andre Przywara <andre.przyw...@arm.com>

---

v3: creation
---
 virt/kvm/arm/vgic/vgic-its.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
index 51cb836..c5717cf 100644
--- a/virt/kvm/arm/vgic/vgic-its.c
+++ b/virt/kvm/arm/vgic/vgic-its.c
@@ -1488,6 +1488,16 @@ static void vgic_mmio_write_its_ctlr(struct kvm *kvm, 
struct vgic_its *its,
        its->enabled = !!(val & GITS_CTLR_ENABLE);
 
        /*
+        * It is UNPREDICTABLE to enable the ITS if any of the CBASER or
+        * device/collection BASER are invalid
+        */
+       if (its->enabled &&
+               (!(its->baser_device_table & GITS_BASER_VALID) ||
+                !(its->baser_coll_table & GITS_BASER_VALID) ||
+                !(its->cbaser && GITS_CBASER_VALID)))
+               its->enabled = false;
+
+       /*
         * Try to process any pending commands. This function bails out early
         * if the ITS is disabled or no commands have been queued.
         */
-- 
2.5.5

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