xen/pvh: Piggyback on PVHVM for event channels (v2)

PVH is a PV guest with a twist - there are certain things
that work in it like HVM and some like PV. There is
a similar mode - PVHVM where we run in HVM mode with
PV code enabled - and this patch explores that.

The most notable PV interfaces are the XenBus and event channels.

We will piggyback on how the event channel mechanism is
used in PVHVM - that is we want the normal native IRQ mechanism
and we will install a vector (hvm callback) for which we
will call the event channel mechanism.

This means that from a pvops perspective, we can use
native_irq_ops instead of the Xen PV specific. Albeit in the
future we could support pirq_eoi_map. But that is
a feature request that can be shared with PVHVM.

Signed-off-by: Mukesh Rathor <mukesh.rathor@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>

1 files changed, 9 insertions, 5 deletions

diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c
index 1d16185e82b2..4672e003c0ad 100644
--- a/drivers/xen/events/events_base.c
+++ b/drivers/xen/events/events_base.c
@@ -1685,8 +1685,15 @@ void __init xen_init_IRQ(void)
         pirq_needs_eoi = pirq_needs_eoi_flag;
 
 #ifdef CONFIG_X86
-        if (xen_hvm_domain()) {
+        if (xen_pv_domain()) {
+                irq_ctx_init(smp_processor_id());
+                if (xen_initial_domain())
+                        pci_xen_initial_domain();
+        }
+        if (xen_feature(XENFEAT_hvm_callback_vector))
                 xen_callback_vector();
+
+        if (xen_hvm_domain()) {
                 native_init_IRQ();
                 /* pci_xen_hvm_init must be called after native_init_IRQ so that
                  * __acpi_register_gsi can point at the right function */
@@ -1695,13 +1702,10 @@ void __init xen_init_IRQ(void)
                 int rc;
                 struct physdev_pirq_eoi_gmfn eoi_gmfn;
 
-                irq_ctx_init(smp_processor_id());
-                if (xen_initial_domain())
-                        pci_xen_initial_domain();
-
                 pirq_eoi_map = (void *)__get_free_page(GFP_KERNEL|__GFP_ZERO);
                 eoi_gmfn.gmfn = virt_to_mfn(pirq_eoi_map);
                 rc = HYPERVISOR_physdev_op(PHYSDEVOP_pirq_eoi_gmfn_v2, &eoi_gmfn);
+                /* TODO: No PVH support for PIRQ EOI */
                 if (rc != 0) {
                         free_page((unsigned long) pirq_eoi_map);
                         pirq_eoi_map = NULL;