Hi,

On 05/05/2017 14:50, Marc Zyngier wrote:

On 05/05/17 10:57, Christoffer Dall wrote:

quoted

On Thu, May 04, 2017 at 01:44:35PM +0200, Eric Auger wrote:

quoted

When creating the lpi we now ask the redistributor what is the state
of the LPI (priority, enabled, pending).

Signed-off-by: Eric Auger <eric.auger@redhat.com>

---

v6: creation
---
 virt/kvm/arm/vgic/vgic-its.c | 35 ++++++++++++++++++++++++-----------
 1 file changed, 24 insertions(+), 11 deletions(-)

diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
index f43ea30c..3ad615a 100644
--- a/virt/kvm/arm/vgic/vgic-its.c
+++ b/virt/kvm/arm/vgic/vgic-its.c

@@ -38,6 +38,8 @@
 
 static int vgic_its_set_abi(struct vgic_its *its, int rev);
 static const struct vgic_its_abi *vgic_its_get_abi(struct vgic_its *its);
+static int update_lpi_config(struct kvm *kvm, struct vgic_irq *irq,
+			     struct kvm_vcpu *filter_vcpu);
 
 /*
  * Creates a new (reference to a) struct vgic_irq for a given LPI.

@@ -46,10 +48,12 @@ static const struct vgic_its_abi *vgic_its_get_abi(struct vgic_its *its);
  * If this is a "new" LPI, we allocate and initialize a new struct vgic_irq.
  * This function returns a pointer to the _unlocked_ structure.
  */
-static struct vgic_irq *vgic_add_lpi(struct kvm *kvm, u32 intid)
+static struct vgic_irq *vgic_add_lpi(struct kvm *kvm, u32 intid,
+				     struct kvm_vcpu *vcpu)
 {
 	struct vgic_dist *dist = &kvm->arch.vgic;
 	struct vgic_irq *irq = vgic_get_irq(kvm, NULL, intid), *oldirq;
+	int ret;
 
 	/* In this case there is no put, since we keep the reference. */
 	if (irq)

@@ -66,6 +70,7 @@ static struct vgic_irq *vgic_add_lpi(struct kvm *kvm, u32 intid)
 	irq->config = VGIC_CONFIG_EDGE;
 	kref_init(&irq->refcount);
 	irq->intid = intid;
+	irq->target_vcpu = vcpu;
 
 	spin_lock(&dist->lpi_list_lock);
 

@@ -97,6 +102,19 @@ static struct vgic_irq *vgic_add_lpi(struct kvm *kvm, u32 intid)
 out_unlock:
 	spin_unlock(&dist->lpi_list_lock);
 
+	/*
+	 * We "cache" the configuration table entries in out struct vgic_irq's.

s/out/our/ ?

quoted

+	 * However we only have those structs for mapped IRQs, so we read in
+	 * the respective config data from memory here upon mapping the LPI.
+	 */
+	ret = update_lpi_config(kvm, irq, NULL);
+	if (ret)
+		return ERR_PTR(ret);
+
+	ret = vgic_v3_lpi_sync_pending_status(kvm, irq);
+	if (ret)
+		return ERR_PTR(ret);
+
 	return irq;
 }
 

@@ -769,6 +787,7 @@ static int vgic_its_cmd_handle_mapi(struct kvm *kvm, struct vgic_its *its,
 	u32 event_id = its_cmd_get_id(its_cmd);
 	u32 coll_id = its_cmd_get_collection(its_cmd);
 	struct its_ite *ite;
+	struct kvm_vcpu *vcpu = NULL;
 	struct its_device *device;
 	struct its_collection *collection, *new_coll = NULL;
 	int lpi_nr;

@@ -814,7 +833,10 @@ static int vgic_its_cmd_handle_mapi(struct kvm *kvm, struct vgic_its *its,
 	ite->collection = collection;
 	ite->lpi = lpi_nr;
 
-	irq = vgic_add_lpi(kvm, lpi_nr);
+	if (its_is_collection_mapped(collection))
+		vcpu = kvm_get_vcpu(kvm, collection->target_addr);
+
+	irq = vgic_add_lpi(kvm, lpi_nr, vcpu);

So, if we don't have the collection and therefore end up with irq->vcpu
== NULL, how do we ever read the pending bit from memory as the affinity
may later change?

Is this a problem with our idea of only looking at the pending bit on
vgic_add_lpi, or does it just mean that we should sample the pending bit
whenever we move LPIs around to VCPUs and if the bit is set, then also
set the pennding_latch (if not already set), or what should happen here?

It means that we would need to sample that bit on MOVI and maybe MOVALL
as well, but this feels a bit odd. How did that bit land there the first
place?

Without talking about save/restore, before this series the pending table
was sync'ed on RDIST LPI enable only and that's all. This is kept.

Now talking about save/restore, if we restore an LPI whose collection is
not attached to any RDIST, we can't sync at that time. The problem
exists if we check the pending bit on vgic_add_lpi or later, ie. at the
end of the ITS table restore process (as I did before). I don't see in
the spec we are supposed to read the pending table on MAPTI or MAPC.

Thanks

Eric

Thanks,

	M.