[Qemu-devel] [PATCH 2/2] pseries: Switch VGA endian on H_SET_MODE

[David Gibson <david@gibson.dropbear.id.au>]

When the guest switches the interrupt endian mode, which essentially
means a global machine endian switch, we want to change the VGA
framebuffer endian mode as well in order to be backward compatible
with existing guests who don't know about the new endian control
register.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 hw/ppc/spapr_hcall.c   |  2 ++
 hw/ppc/spapr_pci.c     | 28 ++++++++++++++++++++++++++++
 include/hw/ppc/spapr.h |  1 +
 3 files changed, 31 insertions(+)

diff --git a/hw/ppc/spapr_hcall.c b/hw/ppc/spapr_hcall.c
index 8651447..4f76f1c 100644
--- a/hw/ppc/spapr_hcall.c
+++ b/hw/ppc/spapr_hcall.c
@@ -731,12 +731,14 @@ static target_ulong h_set_mode_resource_le(PowerPCCPU *cpu,
         CPU_FOREACH(cs) {
             set_spr(cs, SPR_LPCR, 0, LPCR_ILE);
         }
+        spapr_pci_switch_vga(true);
         return H_SUCCESS;
 
     case H_SET_MODE_ENDIAN_LITTLE:
         CPU_FOREACH(cs) {
             set_spr(cs, SPR_LPCR, LPCR_ILE, LPCR_ILE);
         }
+        spapr_pci_switch_vga(false);
         return H_SUCCESS;
     }
 
diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
index 21b95b3..acf9e82 100644
--- a/hw/ppc/spapr_pci.c
+++ b/hw/ppc/spapr_pci.c
@@ -966,3 +966,31 @@ static void spapr_pci_register_types(void)
 }
 
 type_init(spapr_pci_register_types)
+
+static int spapr_switch_one_vga(DeviceState *dev, void *opaque)
+{
+    bool be = *(bool *)opaque;
+
+    if (object_dynamic_cast(OBJECT(dev), "VGA")
+        || object_dynamic_cast(OBJECT(dev), "secondary-vga")) {
+        object_property_set_bool(OBJECT(dev), be, "big-endian-framebuffer",
+                                 &error_abort);
+    }
+    return 0;
+}
+
+void spapr_pci_switch_vga(bool big_endian)
+{
+    sPAPRPHBState *sphb;
+
+    /*
+     * For backward compatibility with existing guests, we switch
+     * the endianness of the VGA controller when changing the guest
+     * interrupt mode
+     */
+    QLIST_FOREACH(sphb, &spapr->phbs, list) {
+        BusState *bus = &PCI_HOST_BRIDGE(sphb)->bus->qbus;
+        qbus_walk_children(bus, spapr_switch_one_vga, NULL, NULL, NULL,
+                           &big_endian);
+    }
+}
diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
index 716bff4..6aadc94 100644
--- a/include/hw/ppc/spapr.h
+++ b/include/hw/ppc/spapr.h
@@ -480,5 +480,6 @@ int spapr_dma_dt(void *fdt, int node_off, const char *propname,
                  uint32_t liobn, uint64_t window, uint32_t size);
 int spapr_tcet_dma_dt(void *fdt, int node_off, const char *propname,
                       sPAPRTCETable *tcet);
+void spapr_pci_switch_vga(bool big_endian);
 
 #endif /* !defined (__HW_SPAPR_H__) */
-- 
2.1.0