[SeaBIOS] [RFC PATCH v3 19/19] alternative: Introduce paravirt interface QEMU_CFG_PCI_WINDOW

[Vasilis Liaskovitis]

Qemu already calculates the 32-bit and 64-bit PCI starting offsets based on
initial memory and hotplug-able dimms. This info needs to be passed to Seabios
for PCI initialization.

Signed-off-by: Vasilis Liaskovitis 
---
 docs/specs/fwcfg.txt |    9 +++++++++
 hw/fw_cfg.h          |    1 +
 hw/pc_piix.c         |   10 ++++++++++
 3 files changed, 20 insertions(+), 0 deletions(-)

diff --git a/docs/specs/fwcfg.txt b/docs/specs/fwcfg.txt
index 55f96d9..d9fa215 100644
--- a/docs/specs/fwcfg.txt
+++ b/docs/specs/fwcfg.txt
@@ -26,3 +26,12 @@ Entry max_cpus+nb_numa_nodes+1 contains the number of memory dimms (nb_hp_dimms)
 The last 3 * nb_hp_dimms entries are organized in triplets: Each triplet contains
 the physical address offset, size (in bytes), and node proximity for the
 respective dimm.
+
+FW_CFG_PCI_WINDOW paravirt info
+--------------------
+QEMU passes the starting address for the 32-bit and 64-bit PCI windows to BIOS.
+The following layouts are followed:
+
+--------------------------------
+pcimem32_start | pcimem64_start | 
+--------------------------------
diff --git a/hw/fw_cfg.h b/hw/fw_cfg.h
index 856bf91..6c8c151 100644
--- a/hw/fw_cfg.h
+++ b/hw/fw_cfg.h
@@ -27,6 +27,7 @@
 #define FW_CFG_SETUP_SIZE       0x17
 #define FW_CFG_SETUP_DATA       0x18
 #define FW_CFG_FILE_DIR         0x19
+#define FW_CFG_PCI_WINDOW       0x1a

#define FW_CFG_FILE_FIRST       0x20
 #define FW_CFG_FILE_SLOTS       0x10
diff --git a/hw/pc_piix.c b/hw/pc_piix.c
index d1fd276..034761f 100644
--- a/hw/pc_piix.c
+++ b/hw/pc_piix.c
@@ -44,6 +44,7 @@
 #include "memory.h"
 #include "exec-memory.h"
 #include "dimm.h"
+#include "fw_cfg.h"
 #ifdef CONFIG_XEN
 #  include <xen/hvm/hvm_info_table.h>
 #endif
@@ -149,6 +150,7 @@ static void pc_init1(MemoryRegion *system_memory,
     MemoryRegion *pci_memory;
     MemoryRegion *rom_memory;
     void *fw_cfg = NULL;
+    uint64_t *pci_window_fw_cfg;

pc_cpus_init(cpu_model);

@@ -205,6 +207,14 @@ static void pc_init1(MemoryRegion *system_memory,
                                ? 0
                                : ((uint64_t)1 << 62)),
                               pci_memory, ram_memory);
+
+        pci_window_fw_cfg = g_malloc0(2 * 8);
+        pci_window_fw_cfg[0] = cpu_to_le64(below_4g_mem_size +
+                                below_4g_hp_mem_size);
+        pci_window_fw_cfg[1] = cpu_to_le64(0x100000000ULL + above_4g_mem_size
+                                + above_4g_hp_mem_size);
+        fw_cfg_add_bytes(fw_cfg, FW_CFG_PCI_WINDOW, 
+                            (uint8_t *)pci_window_fw_cfg, 2 * 8);
     } else {
         pci_bus = NULL;
         i440fx_state = NULL;