ppc/xive: Rework setup of XiveSource::esb_mmio

Depending on whether XIVE is emultated or backed with a KVM XIVE device,
the ESB MMIOs of a XIVE source point to an I/O memory region or a mapped
memory region.

This is currently handled by checking kvm_irqchip_in_kernel() returns
false in xive_source_realize(). This is a bit awkward as we usually
need to do extra things when we're using the in-kernel backend, not
less. But most important, we can do better: turn the existing "xive.esb"
memory region into a plain container, introduce an "xive.esb-emulated"
I/O subregion and rename the existing "xive.esb" subregion in the KVM
code to "xive.esb-kvm". Since "xive.esb-kvm" is added with overlap
and a higher priority, it prevails over "xive.esb-emulated" (ie.
a guest using KVM XIVE will interact with "xive.esb-kvm" instead of
the default "xive.esb-emulated" region.

While here, consolidate the computation of the MMIO region size in
a common helper.

Suggested-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Greg Kurz <groug@kaod.org>
Message-Id: <159679992680.876294.7520540158586170894.stgit@bahia.lan>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

1 files changed, 6 insertions, 5 deletions

diff --git a/hw/intc/xive.c b/hw/intc/xive.c
index 9b55e03..561d746 100644
--- a/hw/intc/xive.c
+++ b/hw/intc/xive.c
@@ -1128,6 +1128,7 @@ static void xive_source_reset(void *dev)
 static void xive_source_realize(DeviceState *dev, Error **errp)
 {
     XiveSource *xsrc = XIVE_SOURCE(dev);
+    size_t esb_len = xive_source_esb_len(xsrc);
 
     assert(xsrc->xive);
 
@@ -1147,11 +1148,11 @@ static void xive_source_realize(DeviceState *dev, Error **errp)
     xsrc->status = g_malloc0(xsrc->nr_irqs);
     xsrc->lsi_map = bitmap_new(xsrc->nr_irqs);
 
-    if (!kvm_irqchip_in_kernel()) {
-        memory_region_init_io(&xsrc->esb_mmio, OBJECT(xsrc),
-                              &xive_source_esb_ops, xsrc, "xive.esb",
-                              (1ull << xsrc->esb_shift) * xsrc->nr_irqs);
-    }
+    memory_region_init(&xsrc->esb_mmio, OBJECT(xsrc), "xive.esb", esb_len);
+    memory_region_init_io(&xsrc->esb_mmio_emulated, OBJECT(xsrc),
+                          &xive_source_esb_ops, xsrc, "xive.esb-emulated",
+                          esb_len);
+    memory_region_add_subregion(&xsrc->esb_mmio, 0, &xsrc->esb_mmio_emulated);
 
     qemu_register_reset(xive_source_reset, dev);
 }