[RFC PATCH 5/5] hw/arm: Only minimise flash size on older machines

[David Edmondson <david.edmondson@oracle.com>]

Prior to 5.2 the flash images loaded into the bottom 128MB always
filled the region. Ensure that this continues to be the case.

Signed-off-by: David Edmondson <david.edmondson@oracle.com>
---
 hw/arm/virt-acpi-build.c | 11 +++---
 hw/arm/virt.c            | 79 ++++++++++++++++++++++++++--------------
 include/hw/arm/virt.h    |  3 +-
 3 files changed, 60 insertions(+), 33 deletions(-)

diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c
index 2c08d36624..6e3d72a9e9 100644
--- a/hw/arm/virt-acpi-build.c
+++ b/hw/arm/virt-acpi-build.c
@@ -117,16 +117,17 @@ static void acpi_dsdt_add_flash1(Aml *scope, int index,
     aml_append(scope, dev);
 }
 
-static void acpi_dsdt_add_flash(Aml *scope, const MemMapEntry *flash_memmap,
-    PFlashCFI01 *flash[2])
+static void acpi_dsdt_add_flash(Aml *scope, VirtMachineState *vms)
 {
+    MemMapEntry *flash_memmap = &vms->memmap[VIRT_FLASH];
+
     acpi_dsdt_add_flash1(scope, 0,
                          flash_memmap->base,
-                         virt_flash_size(flash[0]));
+                         virt_flash_size(vms, vms->flash[0]));
 
     acpi_dsdt_add_flash1(scope, 1,
                          flash_memmap->base + flash_memmap->size / 2,
-                         virt_flash_size(flash[1]));
+                         virt_flash_size(vms, vms->flash[1]));
 }
 
 static void acpi_dsdt_add_virtio(Aml *scope,
@@ -606,7 +607,7 @@ build_dsdt(GArray *table_data, BIOSLinker *linker, VirtMachineState *vms)
     acpi_dsdt_add_uart(scope, &memmap[VIRT_UART],
                        (irqmap[VIRT_UART] + ARM_SPI_BASE));
     if (vmc->acpi_expose_flash) {
-        acpi_dsdt_add_flash(scope, &memmap[VIRT_FLASH], vms->flash);
+        acpi_dsdt_add_flash(scope, vms);
     }
     acpi_dsdt_add_fw_cfg(scope, &memmap[VIRT_FW_CFG]);
     acpi_dsdt_add_virtio(scope, &memmap[VIRT_MMIO],
diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index 03ec844bf3..e851622cb5 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -933,9 +933,15 @@ static void create_virtio_devices(const VirtMachineState *vms)
 
 #define VIRT_FLASH_SECTOR_SIZE (256 * KiB)
 
-int64_t virt_flash_size(PFlashCFI01 *flash)
+int64_t virt_flash_size(VirtMachineState *vms, PFlashCFI01 *flash)
 {
-    return blk_getlength(pflash_cfi01_get_blk(flash));
+    VirtMachineClass *vmc = VIRT_MACHINE_GET_CLASS(vms);
+
+    if (vmc->maximize_flash_size) {
+        return vms->memmap[VIRT_FLASH].size / 2;
+    } else {
+        return blk_getlength(pflash_cfi01_get_blk(flash));
+    }
 }
 
 static PFlashCFI01 *virt_flash_create1(VirtMachineState *vms,
@@ -1014,47 +1020,65 @@ static void virt_flash_map(VirtMachineState *vms,
     MemMapEntry *m = &vms->memmap[VIRT_FLASH];
 
     virt_flash_map1(vms->flash[0], m->base,
-                    virt_flash_size(vms->flash[0]), secure_sysmem);
+                    virt_flash_size(vms, vms->flash[0]), secure_sysmem);
 
     virt_flash_map1(vms->flash[1], m->base + m->size / 2,
-                    virt_flash_size(vms->flash[1]), sysmem);
+                    virt_flash_size(vms, vms->flash[1]), sysmem);
 }
 
 static void virt_flash_fdt(VirtMachineState *vms,
                            MemoryRegion *sysmem,
                            MemoryRegion *secure_sysmem)
 {
+    VirtMachineClass *vmc = VIRT_MACHINE_GET_CLASS(vms);
     bool secure = sysmem != secure_sysmem;
     MemMapEntry *m = &vms->memmap[VIRT_FLASH];
     hwaddr flashbase0 = m->base;
     hwaddr flashbase1 = m->base + m->size / 2;
-    hwaddr flashsize0 = virt_flash_size(vms->flash[0]);
-    hwaddr flashsize1 = virt_flash_size(vms->flash[1]);
+    hwaddr flashsize0 = virt_flash_size(vms, vms->flash[0]);
+    hwaddr flashsize1 = virt_flash_size(vms, vms->flash[1]);
     char *nodename;
 
-    if (secure) {
-        nodename = g_strdup_printf("/secflash@%" PRIx64, flashbase0);
-    } else {
+    if (vmc->maximize_flash_size && !secure) {
+        /* Report both flash devices as a single node in the DT */
         nodename = g_strdup_printf("/flash@%" PRIx64, flashbase0);
-    }
-    qemu_fdt_add_subnode(vms->fdt, nodename);
-    qemu_fdt_setprop_string(vms->fdt, nodename, "compatible", "cfi-flash");
-    qemu_fdt_setprop_sized_cells(vms->fdt, nodename, "reg",
-                                 2, flashbase0, 2, flashsize0);
-    qemu_fdt_setprop_cell(vms->fdt, nodename, "bank-width", 4);
-    if (secure) {
-        qemu_fdt_setprop_string(vms->fdt, nodename, "status", "disabled");
-        qemu_fdt_setprop_string(vms->fdt, nodename, "secure-status", "okay");
-    }
-    g_free(nodename);
+        qemu_fdt_add_subnode(vms->fdt, nodename);
+        qemu_fdt_setprop_string(vms->fdt, nodename, "compatible", "cfi-flash");
+        qemu_fdt_setprop_sized_cells(vms->fdt, nodename, "reg",
+                                     2, flashbase0, 2, flashsize0,
+                                     2, flashbase1, 2, flashsize1);
+        qemu_fdt_setprop_cell(vms->fdt, nodename, "bank-width", 4);
+        g_free(nodename);
+    } else {
+        /*
+         * If we are not intending to fill the flash region or one is
+         * device is secure, report two distinct nodes.
+         */
+        if (secure) {
+            nodename = g_strdup_printf("/secflash@%" PRIx64, flashbase0);
+        } else {
+            nodename = g_strdup_printf("/flash@%" PRIx64, flashbase0);
+        }
+        qemu_fdt_add_subnode(vms->fdt, nodename);
+        qemu_fdt_setprop_string(vms->fdt, nodename, "compatible", "cfi-flash");
+        qemu_fdt_setprop_sized_cells(vms->fdt, nodename, "reg",
+                                     2, flashbase0, 2, flashsize0);
+        qemu_fdt_setprop_cell(vms->fdt, nodename, "bank-width", 4);
+        if (secure) {
+            qemu_fdt_setprop_string(vms->fdt, nodename, "status", "disabled");
+            qemu_fdt_setprop_string(vms->fdt, nodename,
+                                    "secure-status", "okay");
+        }
+        g_free(nodename);
 
-    nodename = g_strdup_printf("/flash@%" PRIx64, flashbase1);
-    qemu_fdt_add_subnode(vms->fdt, nodename);
-    qemu_fdt_setprop_string(vms->fdt, nodename, "compatible", "cfi-flash");
-    qemu_fdt_setprop_sized_cells(vms->fdt, nodename, "reg",
-                                 2, flashbase1, 2, flashsize1);
-    qemu_fdt_setprop_cell(vms->fdt, nodename, "bank-width", 4);
-    g_free(nodename);
+        nodename = g_strdup_printf("/flash@%" PRIx64, flashbase1);
+        qemu_fdt_add_subnode(vms->fdt, nodename);
+        qemu_fdt_setprop_string(vms->fdt, nodename, "compatible", "cfi-flash");
+        qemu_fdt_setprop_sized_cells(vms->fdt, nodename, "reg",
+                                     2, flashbase1, 2, flashsize1);
+        qemu_fdt_setprop_cell(vms->fdt, nodename, "bank-width", 4);
+        g_free(nodename);
+    }
 }
 
 static bool virt_firmware_init(VirtMachineState *vms,
@@ -2614,6 +2638,7 @@ static void virt_machine_5_1_options(MachineClass *mc)
     virt_machine_5_2_options(mc);
     compat_props_add(mc->compat_props, hw_compat_5_1, hw_compat_5_1_len);
     vmc->no_kvm_steal_time = true;
+    vmc->maximize_flash_size = true;
 }
 DEFINE_VIRT_MACHINE(5, 1)
 
diff --git a/include/hw/arm/virt.h b/include/hw/arm/virt.h
index ee21d691ea..1135e7e165 100644
--- a/include/hw/arm/virt.h
+++ b/include/hw/arm/virt.h
@@ -127,6 +127,7 @@ struct VirtMachineClass {
     bool kvm_no_adjvtime;
     bool no_kvm_steal_time;
     bool acpi_expose_flash;
+    bool maximize_flash_size;
 };
 
 struct VirtMachineState {
@@ -172,7 +173,7 @@ OBJECT_DECLARE_TYPE(VirtMachineState, VirtMachineClass, VIRT_MACHINE)
 
 void virt_acpi_setup(VirtMachineState *vms);
 bool virt_is_acpi_enabled(VirtMachineState *vms);
-int64_t virt_flash_size(PFlashCFI01 *flash);
+int64_t virt_flash_size(VirtMachineState *vms, PFlashCFI01 *flash);
 
 /* Return the number of used redistributor regions  */
 static inline int virt_gicv3_redist_region_count(VirtMachineState *vms)
-- 
2.28.0