sparc32_dma: remove is_ledma hack and replace with memory region alias

This hack originated from before the memory region API was introduced, and
increased the size of the ledma DMA device to capture incorrect accesses
beyond the end of the ledma device. A full analysis can be found on Artyom's
blog at http://tyom.blogspot.co.uk/2010/10/bug-in-all-solaris-versions-after-57.html.

With the memory API we can now simply alias the incorrect access onto its
intended destination allowing us to remove the hack.
Signed-off-by: NMark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Reviewed-by: NArtyom Tarasenko <atar4qemu@gmail.com>
Reviewed-by: NPhilippe Mathieu-Daudé <f4bug@amsat.org>
Tested-by: NPhilippe Mathieu-Daudé <f4bug@amsat.org>

hw/dma/sparc32_dma.c

@@ -160,12 +160,6 @@ static uint64_t dma_mem_read(void *opaque, hwaddr addr,
     DMADeviceState *s = opaque;
     uint32_t saddr;
 
-    if (s->is_ledma && (addr > DMA_MAX_REG_OFFSET)) {
-        /* aliased to espdma, but we can't get there from here */
-        /* buggy driver if using undocumented behavior, just return 0 */
-        trace_sparc32_dma_mem_readl(addr, 0);
-        return 0;
-    }
     saddr = (addr & DMA_MASK) >> 2;
     trace_sparc32_dma_mem_readl(addr, s->dmaregs[saddr]);
     return s->dmaregs[saddr];
@@ -177,11 +171,6 @@ static void dma_mem_write(void *opaque, hwaddr addr,
     DMADeviceState *s = opaque;
     uint32_t saddr;
 
-    if (s->is_ledma && (addr > DMA_MAX_REG_OFFSET)) {
-        /* aliased to espdma, but we can't get there from here */
-        trace_sparc32_dma_mem_writel(addr, 0, val);
-        return;
-    }
     saddr = (addr & DMA_MASK) >> 2;
     trace_sparc32_dma_mem_writel(addr, s->dmaregs[saddr], val);
     switch (saddr) {
@@ -296,7 +285,6 @@ static void sparc32_espdma_device_init(Object *obj)
 
     memory_region_init_io(&s->iomem, OBJECT(s), &dma_mem_ops, s,
                           "espdma-mmio", DMA_SIZE);
-    s->is_ledma = 0;
 }
 
 static void sparc32_espdma_device_realize(DeviceState *dev, Error **errp)
@@ -337,8 +325,7 @@ static void sparc32_ledma_device_init(Object *obj)
     DMADeviceState *s = SPARC32_DMA_DEVICE(obj);
 
     memory_region_init_io(&s->iomem, OBJECT(s), &dma_mem_ops, s,
-                          "ledma-mmio", DMA_ETH_SIZE);
-    s->is_ledma = 1;
+                          "ledma-mmio", DMA_SIZE);
 }
 
 static void sparc32_ledma_device_realize(DeviceState *dev, Error **errp)
@@ -411,6 +398,11 @@ static void sparc32_dma_realize(DeviceState *dev, Error **errp)
     sbd = SYS_BUS_DEVICE(ledma);
     memory_region_add_subregion(&s->dmamem, 0x10,
                                 sysbus_mmio_get_region(sbd, 0));
+
+    /* Add ledma alias to handle SunOS 5.7 - Solaris 9 invalid access bug */
+    memory_region_init_alias(&s->ledma_alias, OBJECT(dev), "ledma-alias",
+                             sysbus_mmio_get_region(sbd, 0), 0x4, 0x4);
+    memory_region_add_subregion(&s->dmamem, 0x20, &s->ledma_alias);
 }
 
 static void sparc32_dma_init(Object *obj)

include/hw/sparc/sparc32_dma.h

@@ -21,7 +21,6 @@ struct DMADeviceState {
     qemu_irq irq;
     void *iommu;
     qemu_irq gpio[2];
-    uint32_t is_ledma;
 };
 
 #define TYPE_SPARC32_ESPDMA_DEVICE "sparc32-espdma"
@@ -52,6 +51,7 @@ typedef struct SPARC32DMAState {
     SysBusDevice parent_obj;
 
     MemoryRegion dmamem;
+    MemoryRegion ledma_alias;
     ESPDMADeviceState *espdma;
     LEDMADeviceState *ledma;
 } SPARC32DMAState;