440fx: fix PAM, PCI holes

The current implementation of PAM and the PCI holes is broken in several
ways:

  - PCI BARs are not restricted to the PCI hole (a BAR may hide memory)
  - PCI devices do not respect PAM (if a PCI device maps a region while
    PAM maps the region to RAM, the request will be honored)

This patch fixes things by introducing a pci address space, and using
memory region aliases to represent PAM regions, SMRAM, and PCI holes.

The memory hierarchy looks something like

system_memory
 |
 +--- low memory alias (0-0xe0000000)
 |      |
 |      +-- ram@0
 |
 +--- high memory alias (0x100000000-EOM)
 |      |
 |      +-- ram@0xe0000000
 |
 +--- pci hole alias (end of low memory-0x100000000)
 |      |
 |      +-- pci@end-of-low-memory
 |
 |
 +--- pam[n] (0xc0000-0xc3fff etc) (when set to pci, priority 1)
 |      |
 |      +-- pci@0xc4000 etc
 |
 +--- smram (0xa0000-0xbffff) (when set to pci/vga, priority 1)
        |
        +-- pci@0xa0000 etc

ram (simple ram region)

pci
 |
 +--- BARn
 |
 +--- VGA 0xa0000-0xbffff
 |
 +--- ROMs

Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

1 files changed, 7 insertions, 4 deletions

diff --git a/hw/pc.c b/hw/pc.c
index a29a29f956..263fb1a773 100644
--- a/hw/pc.c
+++ b/hw/pc.c
@@ -964,7 +964,9 @@ void pc_memory_init(MemoryRegion *system_memory,
                     const char *kernel_cmdline,
                     const char *initrd_filename,
                     ram_addr_t below_4g_mem_size,
-                    ram_addr_t above_4g_mem_size)
+                    ram_addr_t above_4g_mem_size,
+                    MemoryRegion *pci_memory,
+                    MemoryRegion **ram_memory)
 {
     char *filename;
     int ret, linux_boot, i;
@@ -982,6 +984,7 @@ void pc_memory_init(MemoryRegion *system_memory,
     ram = g_malloc(sizeof(*ram));
     memory_region_init_ram(ram, NULL, "pc.ram",
                            below_4g_mem_size + above_4g_mem_size);
+    *ram_memory = ram;
     ram_below_4g = g_malloc(sizeof(*ram_below_4g));
     memory_region_init_alias(ram_below_4g, "ram-below-4g", ram,
                              0, below_4g_mem_size);
@@ -1026,7 +1029,7 @@ void pc_memory_init(MemoryRegion *system_memory,
     isa_bios = g_malloc(sizeof(*isa_bios));
     memory_region_init_alias(isa_bios, "isa-bios", bios,
                              bios_size - isa_bios_size, isa_bios_size);
-    memory_region_add_subregion_overlap(system_memory,
+    memory_region_add_subregion_overlap(pci_memory,
                                         0x100000 - isa_bios_size,
                                         isa_bios,
                                         1);
@@ -1034,13 +1037,13 @@ void pc_memory_init(MemoryRegion *system_memory,
 
     option_rom_mr = g_malloc(sizeof(*option_rom_mr));
     memory_region_init_ram(option_rom_mr, NULL, "pc.rom", PC_ROM_SIZE);
-    memory_region_add_subregion_overlap(system_memory,
+    memory_region_add_subregion_overlap(pci_memory,
                                         PC_ROM_MIN_VGA,
                                         option_rom_mr,
                                         1);
 
     /* map all the bios at the top of memory */
-    memory_region_add_subregion(system_memory,
+    memory_region_add_subregion(pci_memory,
                                 (uint32_t)(-bios_size),
                                 bios);