[PATCH v2 1/2] arm: vgic: Add the ability to trigger MSIs from the Hypervisor

[Mykyta Poturai <Mykyta_Poturai@xxxxxxxx>]

From: Mykyta Poturai <Mykyta_Poturai@xxxxxxxx>

Add the vgic_its_trigger_msi() function to the vgic interface. This
function allows to inject MSIs from the Hypervisor to the guest.
Which is useful for userspace PCI backend drivers.

Signed-off-by: Mykyta Poturai <mykyta_poturai@xxxxxxxx>
---
v1->v2:
* replace -1 with -ENOENT
* reduce guest memory access in vgic_its_trigger_msi
---
 xen/arch/arm/include/asm/vgic.h | 11 +++++++++++
 xen/arch/arm/vgic-v3-its.c      | 19 +++++++++++++++++++
 2 files changed, 30 insertions(+)

diff --git a/xen/arch/arm/include/asm/vgic.h b/xen/arch/arm/include/asm/vgic.h
index e309dca1ad..3d8e3a8343 100644
--- a/xen/arch/arm/include/asm/vgic.h
+++ b/xen/arch/arm/include/asm/vgic.h
@@ -318,6 +318,17 @@ extern bool vgic_migrate_irq(struct vcpu *old, struct vcpu 
*new, unsigned int ir
 extern void vgic_check_inflight_irqs_pending(struct vcpu *v,
                                              unsigned int rank, uint32_t r);
 
+#ifdef CONFIG_HAS_ITS
+int vgic_its_trigger_msi(struct domain *d, paddr_t doorbell_address,
+                                u32 devid, u32 eventid);
+#else
+static inline int vgic_its_trigger_msi(struct domain *d, paddr_t 
doorbell_address,
+                                u32 devid, u32 eventid)
+{
+    return -EOPNOTSUPP;
+}
+#endif /* CONFIG_HAS_ITS */
+
 #endif /* !CONFIG_NEW_VGIC */
 
 /*** Common VGIC functions used by Xen arch code ****/
diff --git a/xen/arch/arm/vgic-v3-its.c b/xen/arch/arm/vgic-v3-its.c
index c65c1dbf52..be5bfe0d21 100644
--- a/xen/arch/arm/vgic-v3-its.c
+++ b/xen/arch/arm/vgic-v3-its.c
@@ -1484,6 +1484,25 @@ static int vgic_v3_its_init_virtual(struct domain *d, 
paddr_t guest_addr,
     return 0;
 }
 
+int vgic_its_trigger_msi(struct domain *d, paddr_t doorbell_address,
+                                u32 devid, u32 eventid)
+{
+    struct pending_irq *pend;
+    unsigned int vcpu_id;
+
+    pend = gicv3_its_get_event_pending_irq(d,doorbell_address, devid, eventid);
+    if ( !pend )
+        return -ENOENT;
+    
+    vcpu_id = ACCESS_ONCE(pend->lpi_vcpu_id);
+    if ( vcpu_id >= d->max_vcpus )
+          return -ENOENT;
+
+    vgic_inject_irq(d, d->vcpu[vcpu_id], pend->irq, true);
+
+    return 0;
+}
+
 unsigned int vgic_v3_its_count(const struct domain *d)
 {
     struct host_its *hw_its;
-- 
2.34.1