[Qemu-devel] [PATCH v2 5/5] pc: pci-info add compat support

["Michael S. Tsirkin" <mst@redhat.com>]

We can't change fw cfg entries or add new ones
without breaking cross version migration.
Add a flag to skip adding new entry when
running with 1.5 compat machine type.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 hw/i386/pc.c         |  7 ++++++-
 hw/i386/pc_piix.c    | 12 ++++++++++--
 include/hw/i386/pc.h |  1 +
 3 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 64101cb..8b548d0 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -988,7 +988,12 @@ typedef struct PcRomPciInfo {
 
 static void pc_fw_cfg_guest_info(PcGuestInfo *guest_info)
 {
-    PcRomPciInfo *info = g_malloc(sizeof *info);
+    PcRomPciInfo *info;
+    if (guest_info->compat_v1_5) {
+        return;
+    }
+
+    info = g_malloc(sizeof *info);
     info->w32_min = cpu_to_le64(guest_info->pci_info.w32.begin);
     info->w32_max = cpu_to_le64(guest_info->pci_info.w32.end);
     info->w64_min = cpu_to_le64(guest_info->pci_info.w64.begin);
diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
index 2717d83..5b281d1 100644
--- a/hw/i386/pc_piix.c
+++ b/hw/i386/pc_piix.c
@@ -57,7 +57,7 @@ static const int ide_iobase2[MAX_IDE_BUS] = { 0x3f6, 0x376 };
 static const int ide_irq[MAX_IDE_BUS] = { 14, 15 };
 
 static bool has_pvpanic = true;
-static bool has_pci_info = true;
+static bool guest_info_compat_v1_5 = false;
 
 /* PC hardware initialisation */
 static void pc_init1(MemoryRegion *system_memory,
@@ -122,6 +122,7 @@ static void pc_init1(MemoryRegion *system_memory,
     }
 
     guest_info = pc_guest_info_init(below_4g_mem_size, above_4g_mem_size);
+    guest_info->compat_v1_5 = guest_info_compat_v1_5;
 
     /* Set PCI window size the way seabios has always done it. */
     /* TODO: consider just starting at below_4g_mem_size */
@@ -259,6 +260,12 @@ static void pc_init_pci(QEMUMachineInitArgs *args)
              initrd_filename, cpu_model, 1, 1);
 }
 
+static void pc_init_pci_1_5(QEMUMachineInitArgs *args)
+{
+    guest_info_compat_v1_5 = true;
+    pc_init_pci(args);
+}
+
 static void pc_init_pci_1_4(QEMUMachineInitArgs *args)
 {
     has_pvpanic = false;
@@ -355,7 +362,7 @@ static QEMUMachine pc_i440fx_machine_v1_6 = {
 static QEMUMachine pc_i440fx_machine_v1_5 = {
     .name = "pc-i440fx-1.5",
     .desc = "Standard PC (i440FX + PIIX, 1996)",
-    .init = pc_init_pci,
+    .init = pc_init_pci_1_5,
     .hot_add_cpu = pc_hot_add_cpu,
     .max_cpus = 255,
     .is_default = 1,
@@ -759,6 +766,7 @@ static QEMUMachine xenfv_machine = {
 
 static void pc_machine_init(void)
 {
+    qemu_register_machine(&pc_i440fx_machine_v1_6);
     qemu_register_machine(&pc_i440fx_machine_v1_5);
     qemu_register_machine(&pc_i440fx_machine_v1_4);
     qemu_register_machine(&pc_machine_v1_3);
diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
index 1bf5219..6419da8 100644
--- a/include/hw/i386/pc.h
+++ b/include/hw/i386/pc.h
@@ -20,6 +20,7 @@ typedef struct PcPciInfo {
 
 struct PcGuestInfo {
     PcPciInfo pci_info;
+    bool compat_v1_5;
     FWCfgState *fw_cfg;
 };
 
-- 
MST