[PATCH v10 25/32] ARM: vITS: handle MAPTI/MAPI command

[Andre Przywara <andre.przywara@arm.com>]

The MAPTI commands associates a DeviceID/EventID pair with a LPI/CPU
pair and actually instantiates LPI interrupts. MAPI is just a variant
of this comment, where the LPI ID is the same as the event ID.
We connect the already allocated host LPI to this virtual LPI, so that
any triggering LPI on the host can be quickly forwarded to a guest.
Beside entering the domain and the virtual LPI number in the respective
host LPI entry, we also initialize and add the already allocated
struct pending_irq to our radix tree, so that we can now easily find it
by its virtual LPI number.
We also read the property table to update the enabled bit and the
priority for our new LPI, as we might have missed this during an earlier
INVALL call (which only checks mapped LPIs). But we make sure that the
property table is actually valid, as all redistributors might still
be disabled at this point.
Since write_itte_locked() now sees its first usage, we change the
declaration to static.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
---
 xen/arch/arm/gic-v3-its.c        |  27 ++++++++
 xen/arch/arm/vgic-v3-its.c       | 138 ++++++++++++++++++++++++++++++++++++++-
 xen/include/asm-arm/gic_v3_its.h |   3 +
 3 files changed, 165 insertions(+), 3 deletions(-)

diff --git a/xen/arch/arm/gic-v3-its.c b/xen/arch/arm/gic-v3-its.c
index 8864e0b..41fff64 100644
--- a/xen/arch/arm/gic-v3-its.c
+++ b/xen/arch/arm/gic-v3-its.c
@@ -876,6 +876,33 @@ int gicv3_remove_guest_event(struct domain *d, paddr_t vdoorbell_address,
     return 0;
 }
 
+/*
+ * Connects the event ID for an already assigned device to the given VCPU/vLPI
+ * pair. The corresponding physical LPI is already mapped on the host side
+ * (when assigning the physical device to the guest), so we just connect the
+ * target VCPU/vLPI pair to that interrupt to inject it properly if it fires.
+ * Returns a pointer to the already allocated struct pending_irq that is
+ * meant to be used by that event.
+ */
+struct pending_irq *gicv3_assign_guest_event(struct domain *d,
+                                             paddr_t vdoorbell_address,
+                                             uint32_t vdevid, uint32_t eventid,
+                                             uint32_t virt_lpi)
+{
+    struct pending_irq *pirq;
+    uint32_t host_lpi = 0;
+
+    pirq = get_event_pending_irq(d, vdoorbell_address, vdevid, eventid,
+                                 &host_lpi);
+
+    if ( !pirq )
+        return NULL;
+
+    gicv3_lpi_update_host_entry(host_lpi, d->domain_id, virt_lpi);
+
+    return pirq;
+}
+
 /* Scan the DT for any ITS nodes and create a list of host ITSes out of it. */
 void gicv3_its_dt_init(const struct dt_device_node *node)
 {
diff --git a/xen/arch/arm/vgic-v3-its.c b/xen/arch/arm/vgic-v3-its.c
index e9b1cb4..c350fa5 100644
--- a/xen/arch/arm/vgic-v3-its.c
+++ b/xen/arch/arm/vgic-v3-its.c
@@ -270,9 +270,9 @@ static bool read_itte(struct virt_its *its, uint32_t devid, uint32_t evid,
  * If vcpu_ptr is provided, returns the VCPU belonging to that collection.
  * Must be called with the ITS lock held.
  */
-bool write_itte_locked(struct virt_its *its, uint32_t devid,
-                       uint32_t evid, uint32_t collid, uint32_t vlpi,
-                       struct vcpu **vcpu_ptr)
+static bool write_itte_locked(struct virt_its *its, uint32_t devid,
+                              uint32_t evid, uint32_t collid, uint32_t vlpi,
+                              struct vcpu **vcpu_ptr)
 {
     paddr_t addr;
     struct vits_itte itte;
@@ -413,6 +413,42 @@ out_unlock:
     return ret;
 }
 
+/*
+ * For a given virtual LPI read the enabled bit and priority from the virtual
+ * property table and update the virtual IRQ's state in the given pending_irq.
+ * Must be called with the respective VGIC VCPU lock held.
+ */
+static int update_lpi_property(struct domain *d, struct pending_irq *p)
+{
+    paddr_t addr;
+    uint8_t property;
+    int ret;
+
+    /*
+     * If no redistributor has its LPIs enabled yet, we can't access the
+     * property table. In this case we just can't update the properties,
+     * but this should not be an error from an ITS point of view.
+     */
+    if ( !read_atomic(&d->arch.vgic.rdists_enabled) )
+        return 0;
+
+    addr = d->arch.vgic.rdist_propbase & GENMASK(51, 12);
+
+    ret = vgic_access_guest_memory(d, addr + p->irq - LPI_OFFSET,
+                                   &property, sizeof(property), false);
+    if ( ret )
+        return ret;
+
+    write_atomic(&p->lpi_priority, property & LPI_PROP_PRIO_MASK);
+
+    if ( property & LPI_PROP_ENABLED )
+        set_bit(GIC_IRQ_GUEST_ENABLED, &p->status);
+    else
+        clear_bit(GIC_IRQ_GUEST_ENABLED, &p->status);
+
+    return 0;
+}
+
 /* Must be called with the ITS lock held. */
 static int its_discard_event(struct virt_its *its,
                              uint32_t vdevid, uint32_t vevid)
@@ -538,6 +574,98 @@ static int its_handle_mapd(struct virt_its *its, uint64_t *cmdptr)
     return ret;
 }
 
+static int its_handle_mapti(struct virt_its *its, uint64_t *cmdptr)
+{
+    uint32_t devid = its_cmd_get_deviceid(cmdptr);
+    uint32_t eventid = its_cmd_get_id(cmdptr);
+    uint32_t intid = its_cmd_get_physical_id(cmdptr), _intid;
+    uint16_t collid = its_cmd_get_collection(cmdptr);
+    struct pending_irq *pirq;
+    struct vcpu *vcpu = NULL;
+    int ret = -1;
+
+    if ( its_cmd_get_command(cmdptr) == GITS_CMD_MAPI )
+        intid = eventid;
+
+    spin_lock(&its->its_lock);
+    /*
+     * Check whether there is a valid existing mapping. If yes, behavior is
+     * unpredictable, we choose to ignore this command here.
+     * This makes sure we start with a pristine pending_irq below.
+     */
+    if ( read_itte_locked(its, devid, eventid, &vcpu, &_intid) &&
+         _intid != INVALID_LPI )
+    {
+        spin_unlock(&its->its_lock);
+        return -1;
+    }
+
+    /* Enter the mapping in our virtual ITS tables. */
+    if ( !write_itte_locked(its, devid, eventid, collid, intid, &vcpu) )
+    {
+        spin_unlock(&its->its_lock);
+        return -1;
+    }
+
+    spin_unlock(&its->its_lock);
+
+    /*
+     * Connect this virtual LPI to the corresponding host LPI, which is
+     * determined by the same device ID and event ID on the host side.
+     * This returns us the corresponding, still unused pending_irq.
+     */
+    pirq = gicv3_assign_guest_event(its->d, its->doorbell_address,
+                                    devid, eventid, intid);
+    if ( !pirq )
+        goto out_remove_mapping;
+
+    vgic_init_pending_irq(pirq, intid);
+
+    /*
+     * Now read the guest's property table to initialize our cached state.
+     * We don't need the VGIC VCPU lock here, because the pending_irq isn't
+     * in the radix tree yet.
+     */
+    ret = update_lpi_property(its->d, pirq);
+    if ( ret )
+        goto out_remove_host_entry;
+
+    pirq->lpi_vcpu_id = vcpu->vcpu_id;
+    /*
+     * Mark this LPI as new, so any older (now unmapped) LPI in any LR
+     * can be easily recognised as such.
+     */
+    set_bit(GIC_IRQ_GUEST_PRISTINE_LPI, &pirq->status);
+
+    /*
+     * Now insert the pending_irq into the domain's LPI tree, so that
+     * it becomes live.
+     */
+    write_lock(&its->d->arch.vgic.pend_lpi_tree_lock);
+    ret = radix_tree_insert(&its->d->arch.vgic.pend_lpi_tree, intid, pirq);
+    write_unlock(&its->d->arch.vgic.pend_lpi_tree_lock);
+
+    if ( !ret )
+        return 0;
+
+    /*
+     * radix_tree_insert() returns an error either due to an internal
+     * condition (like memory allocation failure) or because the LPI already
+     * existed in the tree. We don't support the latter case, so we always
+     * cleanup and return an error here in any case.
+     */
+out_remove_host_entry:
+    gicv3_remove_guest_event(its->d, its->doorbell_address, devid, eventid);
+
+out_remove_mapping:
+    spin_lock(&its->its_lock);
+    write_itte_locked(its, devid, eventid,
+                      UNMAPPED_COLLECTION, INVALID_LPI, NULL);
+    spin_unlock(&its->its_lock);
+
+    return ret;
+}
+
 #define ITS_CMD_BUFFER_SIZE(baser)      ((((baser) & 0xff) + 1) << 12)
 #define ITS_CMD_OFFSET(reg)             ((reg) & GENMASK(19, 5))
 
@@ -579,6 +707,10 @@ static int vgic_its_handle_cmds(struct domain *d, struct virt_its *its)
         case GITS_CMD_MAPD:
             ret = its_handle_mapd(its, command);
             break;
+        case GITS_CMD_MAPI:
+        case GITS_CMD_MAPTI:
+            ret = its_handle_mapti(its, command);
+            break;
         case GITS_CMD_SYNC:
             /* We handle ITS commands synchronously, so we ignore SYNC. */
             break;
diff --git a/xen/include/asm-arm/gic_v3_its.h b/xen/include/asm-arm/gic_v3_its.h
index e78dadf..c6404ea 100644
--- a/xen/include/asm-arm/gic_v3_its.h
+++ b/xen/include/asm-arm/gic_v3_its.h
@@ -175,6 +175,9 @@ struct pending_irq *gicv3_its_get_event_pending_irq(struct domain *d,
                                                     uint32_t veventid);
 int gicv3_remove_guest_event(struct domain *d, paddr_t vdoorbell_address,
                                      uint32_t vdevid, uint32_t veventid);
+struct pending_irq *gicv3_assign_guest_event(struct domain *d, paddr_t doorbell,
+                                             uint32_t devid, uint32_t eventid,
+                                             uint32_t virt_lpi);
 void gicv3_lpi_update_host_entry(uint32_t host_lpi, int domain_id,
                                  uint32_t virt_lpi);
 
-- 
2.9.0


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