[PATCH 20/26] hw/riscv: pfsoc: Correct PolarFire SoC DDR aliases

[Bin Meng <bin.meng@processmission.com>]

The 64-bit cached and non-cached windows alias the complete physical
DDR from offset zero. Treating them as only the portion above 1 GiB
leaves valid Icicle Kit memory nodes unbacked with the board's 2 GiB.

Map both high windows over the full machine RAM.

Signed-off-by: Bin Meng <bin.meng@processmission.com>
---

 hw/riscv/microchip_pfsoc.c | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/hw/riscv/microchip_pfsoc.c b/hw/riscv/microchip_pfsoc.c
index f348de6fd4..a2fbc89222 100644
--- a/hw/riscv/microchip_pfsoc.c
+++ b/hw/riscv/microchip_pfsoc.c
@@ -570,15 +570,27 @@ static void microchip_icicle_kit_machine_init(MachineState *machine)
                             TYPE_MICROCHIP_PFSOC);
     qdev_realize(DEVICE(&s->soc), NULL, &error_fatal);
 
-    /* Split RAM into low and high regions using aliases to machine->ram */
+    /*
+     * The four CPU-visible windows alias the same physical DDR from offset
+     * zero. For the Icicle Kit's 2 GiB of DDR, they map as follows:
+     *
+     * CPU address     Attribute           Visible size   DDR range
+     * 0x0080000000    32-bit cached       1 GiB          [0, 1 GiB)
+     * 0x00c0000000    32-bit non-cached   1 GiB          [0, 1 GiB)
+     * 0x1000000000    64-bit cached       2 GiB          [0, 2 GiB)
+     * 0x1400000000    64-bit non-cached   2 GiB          [0, 2 GiB)
+     *
+     * "Low" and "high" describe the CPU address windows, not the lower and
+     * upper portions of physical DDR.
+     */
     mem_low_size = memmap[MICROCHIP_PFSOC_DRAM_LO].size;
-    mem_high_size = machine->ram_size - mem_low_size;
+    mem_high_size = machine->ram_size;
     memory_region_init_alias(mem_low, NULL,
                              "microchip.icicle.kit.ram_low", machine->ram,
                              0, mem_low_size);
     memory_region_init_alias(mem_high, NULL,
                              "microchip.icicle.kit.ram_high", machine->ram,
-                             mem_low_size, mem_high_size);
+                             0, mem_high_size);
 
     /* Register RAM */
     memory_region_add_subregion(system_memory,
-- 
2.34.1