xen: Introduce the Xen mapcache

On IA32 host or IA32 PAE host, at present, generally, we can't create
an HVM guest with more than 2G memory, because generally it's almost
impossible for Qemu to find a large enough and consecutive virtual
address space to map an HVM guest's whole physical address space.
The attached patch fixes this issue using dynamic mapping based on
little blocks of memory.

Each call to qemu_get_ram_ptr makes a call to qemu_map_cache with the
lock option, so mapcache will not unmap these ram_ptr.

Blocks that do not belong to the RAM, but usually to a device ROM or to
a framebuffer, are handled in a separate function. So the whole RAMBlock
can be map.

Signed-off-by: Jun Nakajima <jun.nakajima@intel.com>
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: Alexander Graf <agraf@suse.de>

1 files changed, 4 insertions, 0 deletions

diff --git a/xen-stub.c b/xen-stub.c
index 3a8449c148..8d2fa54b4b 100644
--- a/xen-stub.c
+++ b/xen-stub.c
@@ -22,6 +22,10 @@ void xen_piix_pci_write_config_client(uint32_t address, uint32_t val, int len)
 {
 }
 
+void xen_ram_alloc(ram_addr_t ram_addr, ram_addr_t size)
+{
+}
+
 qemu_irq *xen_interrupt_controller_init(void)
 {
     return NULL;