[Qemu-devel] [PATCH 15/35] pc: add 'etc/reserved-memory-end' fw_cfg interface for SeaBIOS

[Igor Mammedov]

'etc/reserved-memory-end' will allow QEMU to tell BIOS where PCI
BARs mapping could safely start in high memory.

Allowing BIOS to start mapping 64-bit PCI BARs at address where it
wouldn't conflict with other mappings QEMU might place before it.

That permits QEMU to reserve extra address space before
64-bit PCI hole for memory hotplug.

Signed-off-by: Igor Mammedov <address@hidden>
---
 hw/i386/pc.c         | 9 ++++++++-
 hw/i386/pc_piix.c    | 3 +++
 hw/i386/pc_q35.c     | 3 +++
 include/hw/i386/pc.h | 1 +
 4 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 6fe1803..b164e37 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -1200,7 +1200,8 @@ FWCfgState *pc_memory_init(MemoryRegion *system_memory,
     }
 
     /* initialize hotplug memory address space */
-    if (ram_size < machine->init_args.maxram_size) {
+    if (guest_info->has_reserved_memory &&
+        (ram_size < machine->init_args.maxram_size)) {
         ram_addr_t hotplug_mem_size =
             machine->init_args.maxram_size - ram_size;
 
@@ -1233,6 +1234,12 @@ FWCfgState *pc_memory_init(MemoryRegion *system_memory,
     fw_cfg = bochs_bios_init();
     rom_set_fw(fw_cfg);
 
+    if (guest_info->has_reserved_memory && pcms->hotplug_memory_base) {
+        uint64_t *val = g_malloc(sizeof(*val));
+        *val = cpu_to_le64(ROUND_UP(pcms->hotplug_memory_base, 0x1ULL << 30));
+        fw_cfg_add_file(fw_cfg, "etc/reserved-memory-end", val, sizeof(*val));
+    }
+
     if (linux_boot) {
         load_linux(fw_cfg, kernel_filename, initrd_filename, kernel_cmdline, 
below_4g_mem_size);
     }
diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
index 62f750d..098fbfc 100644
--- a/hw/i386/pc_piix.c
+++ b/hw/i386/pc_piix.c
@@ -66,6 +66,7 @@ static bool smbios_type1_defaults = true;
  * pages in the host.
  */
 static bool gigabyte_align = true;
+static bool has_reserved_memory = true;
 
 /* PC hardware initialisation */
 static void pc_init1(QEMUMachineInitArgs *args,
@@ -142,6 +143,7 @@ static void pc_init1(QEMUMachineInitArgs *args,
 
     guest_info->has_pci_info = has_pci_info;
     guest_info->isapc_ram_fw = !pci_enabled;
+    guest_info->has_reserved_memory = has_reserved_memory;
 
     if (smbios_type1_defaults) {
         /* These values are guest ABI, do not change */
@@ -264,6 +266,7 @@ static void pc_init_pci(QEMUMachineInitArgs *args)
 
 static void pc_compat_2_0(QEMUMachineInitArgs *args)
 {
+    has_reserved_memory = false;
 }
 
 static void pc_compat_1_7(QEMUMachineInitArgs *args)
diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
index ee68de7..89fd4b4 100644
--- a/hw/i386/pc_q35.c
+++ b/hw/i386/pc_q35.c
@@ -56,6 +56,7 @@ static bool smbios_type1_defaults = true;
  * pages in the host.
  */
 static bool gigabyte_align = true;
+static bool has_reserved_memory = true;
 
 /* PC hardware initialisation */
 static void pc_q35_init(QEMUMachineInitArgs *args)
@@ -129,6 +130,7 @@ static void pc_q35_init(QEMUMachineInitArgs *args)
     guest_info->has_pci_info = has_pci_info;
     guest_info->isapc_ram_fw = false;
     guest_info->has_acpi_build = has_acpi_build;
+    guest_info->has_reserved_memory = has_reserved_memory;
 
     if (smbios_type1_defaults) {
         /* These values are guest ABI, do not change */
@@ -242,6 +244,7 @@ static void pc_q35_init(QEMUMachineInitArgs *args)
 
 static void pc_compat_2_0(QEMUMachineInitArgs *args)
 {
+    has_reserved_memory = false;
 }
 
 static void pc_compat_1_7(QEMUMachineInitArgs *args)
diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
index a1f21ba..36f2f52 100644
--- a/include/hw/i386/pc.h
+++ b/include/hw/i386/pc.h
@@ -77,6 +77,7 @@ struct PcGuestInfo {
     uint64_t *node_cpu;
     FWCfgState *fw_cfg;
     bool has_acpi_build;
+    bool has_reserved_memory;
 };
 
 /* parallel.c */
-- 
1.9.0