[Qemu-devel] [PATCH 1/9] Export function for VA defined ram allocation

[Alexander Graf <agraf@suse.de>]

S390 requires vmas for guests to be < 256 GB. So we need to directly export
mmaps "try to use this vma as start address" feature to not accidently get
over that limit.

Signed-off-by: Alexander Graf <agraf@suse.de>
---
 cpu-common.h |    1 +
 exec.c       |   15 +++++++++++++--
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/cpu-common.h b/cpu-common.h
index 6302372..ecaf9e3 100644
--- a/cpu-common.h
+++ b/cpu-common.h
@@ -30,6 +30,7 @@ static inline void cpu_register_physical_memory(target_phys_addr_t start_addr,
 
 ram_addr_t cpu_get_physical_page_desc(target_phys_addr_t addr);
 ram_addr_t qemu_ram_alloc(ram_addr_t);
+ram_addr_t _qemu_ram_alloc(ram_addr_t size, void *map_at);
 void qemu_ram_free(ram_addr_t addr);
 /* This should only be used for ram local to a device.  */
 void *qemu_get_ram_ptr(ram_addr_t addr);
diff --git a/exec.c b/exec.c
index 076d26b..36c26cd 100644
--- a/exec.c
+++ b/exec.c
@@ -2404,14 +2404,20 @@ void qemu_unregister_coalesced_mmio(target_phys_addr_t addr, ram_addr_t size)
         kvm_uncoalesce_mmio_region(addr, size);
 }
 
-ram_addr_t qemu_ram_alloc(ram_addr_t size)
+ram_addr_t _qemu_ram_alloc(ram_addr_t size, void *map_at)
 {
     RAMBlock *new_block;
 
     size = TARGET_PAGE_ALIGN(size);
     new_block = qemu_malloc(sizeof(*new_block));
 
-    new_block->host = qemu_vmalloc(size);
+    if (map_at) {
+        new_block->host = mmap(map_at, size, PROT_EXEC|PROT_READ|PROT_WRITE,
+                               MAP_SHARED | MAP_ANONYMOUS, -1, 0);
+
+    } else {
+        new_block->host = qemu_vmalloc(size);
+    }
 #ifdef MADV_MERGEABLE
     madvise(new_block->host, size, MADV_MERGEABLE);
 #endif
@@ -2434,6 +2440,11 @@ ram_addr_t qemu_ram_alloc(ram_addr_t size)
     return new_block->offset;
 }
 
+ram_addr_t qemu_ram_alloc(ram_addr_t size)
+{
+    return _qemu_ram_alloc(size, NULL);
+}
+
 void qemu_ram_free(ram_addr_t addr)
 {
     /* TODO: implement this.  */
-- 
1.6.0.2