Re: [PATCH v5 2/5] i386/pc: create pci-host qdev prior to pc_memory_init()

[Mark Cave-Ayland]

On 16/06/2022 14:21, Reviewed-by: Igor Mammedov wrote:
On Fri, 20 May 2022 11:45:29 +0100
Joao Martins <joao.m.mart...@oracle.com> wrote:

At the start of pc_memory_init() we usually pass a range of
0..UINT64_MAX as pci_memory, when really its 2G (i440fx) or
32G (q35). To get the real user value, we need to get pci-host
passed property for default pci_hole64_size. Thus to get that,
create the qdev prior to memory init to better make estimations
on max used/phys addr.

This is in preparation to determine that host-phys-bits are
enough and also for pci-hole64-size to be considered to relocate
ram-above-4g to be at 1T (on AMD platforms).

with comments below fixed
Reviewed-by: Igor Mammedov <imamm...@redhat.com>
  
Signed-off-by: Joao Martins <joao.m.mart...@oracle.com>
---
  hw/i386/pc_piix.c            | 5 ++++-
  hw/i386/pc_q35.c             | 6 +++---
  hw/pci-host/i440fx.c         | 3 +--
  include/hw/pci-host/i440fx.h | 2 +-
  4 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
index 578e537b3525..12d4a279c793 100644
--- a/hw/i386/pc_piix.c
+++ b/hw/i386/pc_piix.c
@@ -91,6 +91,7 @@ static void pc_init1(MachineState *machine,
      MemoryRegion *pci_memory;
      MemoryRegion *rom_memory;
      ram_addr_t lowmem;
+    DeviceState *i440fx_dev;
  
      /*
       * Calculate ram split, for memory below and above 4G.  It's a bit
@@ -164,9 +165,11 @@ static void pc_init1(MachineState *machine,
          pci_memory = g_new(MemoryRegion, 1);
          memory_region_init(pci_memory, NULL, "pci", UINT64_MAX);
          rom_memory = pci_memory;
+        i440fx_dev = qdev_new(host_type);
      } else {
          pci_memory = NULL;
          rom_memory = system_memory;
+        i440fx_dev = NULL;
      }
  
      pc_guest_info_init(pcms);
@@ -199,7 +202,7 @@ static void pc_init1(MachineState *machine,
  
          pci_bus = i440fx_init(host_type,
                                pci_type,
-                              &i440fx_state,
+                              i440fx_dev, &i440fx_state,
confusing names, suggest to rename i440fx_state -> pci_i440fx and i440fx_dev -> 
i440fx_host
or something like this

It might be worth considering this series on top of Bernhard's patch here: 
https://lists.gnu.org/archive/html/qemu-devel/2022-06/msg02206.html.

                                system_memory, system_io, machine->ram_size,
                                x86ms->below_4g_mem_size,
                                x86ms->above_4g_mem_size,
diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
index 42eb8b97079a..8d867bdb274a 100644
--- a/hw/i386/pc_q35.c
+++ b/hw/i386/pc_q35.c
@@ -203,12 +203,12 @@ static void pc_q35_init(MachineState *machine)
                              pcms->smbios_entry_point_type);
      }
  
-    /* allocate ram and load rom/bios */
-    pc_memory_init(pcms, get_system_memory(), rom_memory, &ram_memory);
-
      /* create pci host bus */
      q35_host = Q35_HOST_DEVICE(qdev_new(TYPE_Q35_HOST_DEVICE));
  
+    /* allocate ram and load rom/bios */
+    pc_memory_init(pcms, get_system_memory(), rom_memory, &ram_memory);
+
      object_property_add_child(qdev_get_machine(), "q35", OBJECT(q35_host));
      object_property_set_link(OBJECT(q35_host), MCH_HOST_PROP_RAM_MEM,
                               OBJECT(ram_memory), NULL);
diff --git a/hw/pci-host/i440fx.c b/hw/pci-host/i440fx.c
index e08716142b6e..5c1bab5c58ed 100644
--- a/hw/pci-host/i440fx.c
+++ b/hw/pci-host/i440fx.c
@@ -238,6 +238,7 @@ static void i440fx_realize(PCIDevice *dev, Error **errp)
  }
  
  PCIBus *i440fx_init(const char *host_type, const char *pci_type,

does it still need 'host_type'?

+                    DeviceState *dev,
                      PCII440FXState **pi440fx_state,
                      MemoryRegion *address_space_mem,
                      MemoryRegion *address_space_io,
@@ -247,7 +248,6 @@ PCIBus *i440fx_init(const char *host_type, const char 
*pci_type,
                      MemoryRegion *pci_address_space,
                      MemoryRegion *ram_memory)
  {
-    DeviceState *dev;
      PCIBus *b;
      PCIDevice *d;
      PCIHostState *s;
@@ -255,7 +255,6 @@ PCIBus *i440fx_init(const char *host_type, const char 
*pci_type,
      unsigned i;
      I440FXState *i440fx;
  
-    dev = qdev_new(host_type);
      s = PCI_HOST_BRIDGE(dev);
      b = pci_root_bus_new(dev, NULL, pci_address_space,
                           address_space_io, 0, TYPE_PCI_BUS);
diff --git a/include/hw/pci-host/i440fx.h b/include/hw/pci-host/i440fx.h
index f068aaba8fda..c4710445e30a 100644
--- a/include/hw/pci-host/i440fx.h
+++ b/include/hw/pci-host/i440fx.h
@@ -36,7 +36,7 @@ struct PCII440FXState {
  #define TYPE_IGD_PASSTHROUGH_I440FX_PCI_DEVICE "igd-passthrough-i440FX"
  
  PCIBus *i440fx_init(const char *host_type, const char *pci_type,
-                    PCII440FXState **pi440fx_state,
+                    DeviceState *dev, PCII440FXState **pi440fx_state,
                      MemoryRegion *address_space_mem,
                      MemoryRegion *address_space_io,
                      ram_addr_t ram_size,


ATB,

Mark.