[Qemu-devel] [PATCH v5 10/18] hw/arm/virt: Bump the 255GB initial RAM limit

[Eric Auger <eric.auger@redhat.com>]

Now we have the extended memory map (high IO regions beyond the
scalable RAM) and dynamic IPA range support at KVM/ARM level
we can bump the legacy 255GB initial RAM limit. The actual maximum
RAM size now depends on the physical CPU and host kernel.

Signed-off-by: Eric Auger <eric.auger@redhat.com>
---
 hw/arm/virt.c | 26 +++++++-------------------
 1 file changed, 7 insertions(+), 19 deletions(-)

diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index a89ffbf4d7..61c3bb1cef 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -93,22 +93,9 @@
 
 #define PLATFORM_BUS_NUM_IRQS 64
 
-/* RAM limit in GB. Since VIRT_MEM starts at the 1GB mark, this means
- * RAM can go up to the 256GB mark, leaving 256GB of the physical
- * address space unallocated and free for future use between 256G and 512G.
- * If we need to provide more RAM to VMs in the future then we need to:
- *  * allocate a second bank of RAM starting at 2TB and working up
- *  * fix the DT and ACPI table generation code in QEMU to correctly
- *    report two split lumps of RAM to the guest
- *  * fix KVM in the host kernel to allow guests with >40 bit address spaces
- * (We don't want to fill all the way up to 512GB with RAM because
- * we might want it for non-RAM purposes later. Conversely it seems
- * reasonable to assume that anybody configuring a VM with a quarter
- * of a terabyte of RAM will be doing it on a host with more than a
- * terabyte of physical address space.)
- */
-#define RAMLIMIT_GB 255
-#define RAMLIMIT_BYTES (RAMLIMIT_GB * 1024ULL * 1024 * 1024)
+/* Legacy RAM limit in GB (< version 4.0) */
+#define LEGACY_RAMLIMIT_GB 255
+#define LEGACY_RAMLIMIT_BYTES (LEGACY_RAMLIMIT_GB * GiB)
 
 /* Addresses and sizes of our components.
  * 0..128MB is space for a flash device so we can run bootrom code such as UEFI.
@@ -149,7 +136,7 @@ static const MemMapEntry a15memmap[] = {
     [VIRT_PCIE_MMIO] =          { 0x10000000, 0x2eff0000 },
     [VIRT_PCIE_PIO] =           { 0x3eff0000, 0x00010000 },
     [VIRT_PCIE_ECAM] =          { 0x3f000000, 0x01000000 },
-    [VIRT_MEM] =                { 0x40000000, RAMLIMIT_BYTES },
+    [VIRT_MEM] =                { 0x40000000, LEGACY_RAMLIMIT_BYTES },
 };
 
 /* Memory map beyond the RAM */
@@ -1456,8 +1443,9 @@ static void machvirt_init(MachineState *machine)
 
     vms->smp_cpus = smp_cpus;
 
-    if (machine->ram_size > vms->memmap[VIRT_MEM].size) {
-        error_report("mach-virt: cannot model more than %dGB RAM", RAMLIMIT_GB);
+    if (!vms->extended_memmap && machine->ram_size > LEGACY_RAMLIMIT_GB) {
+        error_report("mach-virt: cannot model more than %dGB RAM",
+                     LEGACY_RAMLIMIT_GB);
         exit(1);
     }
 
-- 
2.20.1