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>

hw/intc/spapr_xive_kvm.c

@@ -742,7 +742,7 @@ int kvmppc_xive_connect(SpaprInterruptController *intc, uint32_t nr_servers,
     SpaprXive *xive = SPAPR_XIVE(intc);
     XiveSource *xsrc = &xive->source;
     Error *local_err = NULL;
-    size_t esb_len = (1ull << xsrc->esb_shift) * xsrc->nr_irqs;
+    size_t esb_len = xive_source_esb_len(xsrc);
     size_t tima_len = 4ull << TM_SHIFT;
     CPUState *cs;
     int fd;
@@ -788,7 +788,7 @@ int kvmppc_xive_connect(SpaprInterruptController *intc, uint32_t nr_servers,
     }
 
     memory_region_init_ram_device_ptr(&xsrc->esb_mmio_kvm, OBJECT(xsrc),
-                                      "xive.esb", esb_len, xsrc->esb_mmap);
+                                      "xive.esb-kvm", esb_len, xsrc->esb_mmap);
     memory_region_add_subregion_overlap(&xsrc->esb_mmio, 0,
                                         &xsrc->esb_mmio_kvm, 1);
 

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);
 }

include/hw/ppc/xive.h

@@ -191,6 +191,7 @@ typedef struct XiveSource {
     uint64_t        esb_flags;
     uint32_t        esb_shift;
     MemoryRegion    esb_mmio;
+    MemoryRegion    esb_mmio_emulated;
 
     /* KVM support */
     void            *esb_mmap;
@@ -215,6 +216,11 @@ static inline bool xive_source_esb_has_2page(XiveSource *xsrc)
         xsrc->esb_shift == XIVE_ESB_4K_2PAGE;
 }
 
+static inline size_t xive_source_esb_len(XiveSource *xsrc)
+{
+    return (1ull << xsrc->esb_shift) * xsrc->nr_irqs;
+}
+
 /* The trigger page is always the first/even page */
 static inline hwaddr xive_source_esb_page(XiveSource *xsrc, uint32_t srcno)
 {