[Qemu-devel] [PATCH 2.1 v7 3/3] xen-hvm: Handle machine opt max-ram-below-4g

[Don Slutz <dslutz@verizon.com>]

This is the xen part of "pc & q35: Add new machine opt max-ram-below-4g"

Note: this machine option cannot be used to increase the amount
of ram below 4G.

Signed-off-by: Don Slutz <dslutz@verizon.com>
---
v7:
     Rename from "xen-hvm: Pass is_default to xen_hvm_init"
     Drop is_default.
     Use object_property_get_int() to get max-ram-below-4g.
     Do min(xen limit, user limit).
v6:
    Changed to work with the changes in #2:
      Added max_ram_below_4g_changed in order to know if it is a default value
      or a user specified one.
    Added "assert(pc_machine->max_ram_below_4g_changed > 0)" so that
      "make check" will abort on default not set for any of the pc or
      q35 machine types.
    Dropped "Acked-by: Stefano Stabellin" do to bigger change.

 xen-hvm.c | 35 +++++++++++++++++++++++------------
 1 file changed, 23 insertions(+), 12 deletions(-)

diff --git a/xen-hvm.c b/xen-hvm.c
index a0b6b5d..2745a7a 100644
--- a/xen-hvm.c
+++ b/xen-hvm.c
@@ -161,25 +161,36 @@ static void xen_ram_init(ram_addr_t *below_4g_mem_size,
 {
     MemoryRegion *sysmem = get_system_memory();
     ram_addr_t block_len;
+    uint64_t user_lowmem = object_property_get_int(qdev_get_machine(),
+                                                   PC_MACHINE_MAX_RAM_BELOW_4G,
+                                                   &error_abort);
 
-    block_len = ram_size;
-    if (ram_size >= HVM_BELOW_4G_RAM_END) {
-        /* Xen does not allocate the memory continuously, and keep a hole at
-         * HVM_BELOW_4G_MMIO_START of HVM_BELOW_4G_MMIO_LENGTH
-         */
-        block_len += HVM_BELOW_4G_MMIO_LENGTH;
+    /* Handle the machine opt max-ram-below-4g.  It is basicly doing
+     * min(xen limit, user limit).
+     */
+    if (HVM_BELOW_4G_RAM_END <= user_lowmem) {
+        user_lowmem = HVM_BELOW_4G_RAM_END;
     }
-    memory_region_init_ram(&ram_memory, NULL, "xen.ram", block_len);
-    *ram_memory_p = &ram_memory;
-    vmstate_register_ram_global(&ram_memory);
 
-    if (ram_size >= HVM_BELOW_4G_RAM_END) {
-        *above_4g_mem_size = ram_size - HVM_BELOW_4G_RAM_END;
-        *below_4g_mem_size = HVM_BELOW_4G_RAM_END;
+    if (ram_size >= user_lowmem) {
+        *above_4g_mem_size = ram_size - user_lowmem;
+        *below_4g_mem_size = user_lowmem;
     } else {
         *above_4g_mem_size = 0;
         *below_4g_mem_size = ram_size;
     }
+    if (!*above_4g_mem_size) {
+        block_len = ram_size;
+    } else {
+        /*
+         * Xen does not allocate the memory continuously, it keeps a
+         * hole of the size computed above or passed in.
+         */
+        block_len = (1ULL << 32) + *above_4g_mem_size;
+    }
+    memory_region_init_ram(&ram_memory, NULL, "xen.ram", block_len);
+    *ram_memory_p = &ram_memory;
+    vmstate_register_ram_global(&ram_memory);
 
     memory_region_init_alias(&ram_640k, NULL, "xen.ram.640k",
                              &ram_memory, 0, 0xa0000);
-- 
1.8.4