[PATCH v3] x86: add etc/phys-bits fw_cfg file

[Gerd Hoffmann <kraxel@xxxxxxxxxx>]

In case phys bits are functional and can be used by the guest (aka
host-phys-bits=on) add a fw_cfg file carrying the value.  This can
be used by the guest firmware for address space configuration.

This is only enabled for 7.2+ machine types for live migration
compatibility reasons.

Signed-off-by: Gerd Hoffmann <kraxel@xxxxxxxxxx>
---
 hw/i386/fw_cfg.h     |  1 +
 include/hw/i386/pc.h |  1 +
 hw/i386/fw_cfg.c     | 12 ++++++++++++
 hw/i386/pc.c         |  5 +++++
 hw/i386/pc_piix.c    |  2 ++
 hw/i386/pc_q35.c     |  2 ++
 6 files changed, 23 insertions(+)

diff --git a/hw/i386/fw_cfg.h b/hw/i386/fw_cfg.h
index 275f15c1c5e8..6ff198a6cb85 100644
--- a/hw/i386/fw_cfg.h
+++ b/hw/i386/fw_cfg.h
@@ -26,5 +26,6 @@ FWCfgState *fw_cfg_arch_create(MachineState *ms,
 void fw_cfg_build_smbios(MachineState *ms, FWCfgState *fw_cfg);
 void fw_cfg_build_feature_control(MachineState *ms, FWCfgState *fw_cfg);
 void fw_cfg_add_acpi_dsdt(Aml *scope, FWCfgState *fw_cfg);
+void fw_cfg_phys_bits(FWCfgState *fw_cfg);
 
 #endif
diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
index c95333514ed3..bedef1ee13c1 100644
--- a/include/hw/i386/pc.h
+++ b/include/hw/i386/pc.h
@@ -119,6 +119,7 @@ struct PCMachineClass {
     bool enforce_aligned_dimm;
     bool broken_reserved_end;
     bool enforce_amd_1tb_hole;
+    bool phys_bits_in_fw_cfg;
 
     /* generate legacy CPU hotplug AML */
     bool legacy_cpu_hotplug;
diff --git a/hw/i386/fw_cfg.c b/hw/i386/fw_cfg.c
index a283785a8de4..6a1f18925725 100644
--- a/hw/i386/fw_cfg.c
+++ b/hw/i386/fw_cfg.c
@@ -219,3 +219,15 @@ void fw_cfg_add_acpi_dsdt(Aml *scope, FWCfgState *fw_cfg)
     aml_append(dev, aml_name_decl("_CRS", crs));
     aml_append(scope, dev);
 }
+
+void fw_cfg_phys_bits(FWCfgState *fw_cfg)
+{
+    X86CPU *cpu = X86_CPU(first_cpu);
+    uint64_t phys_bits = cpu->phys_bits;
+
+    if (cpu->host_phys_bits) {
+        fw_cfg_add_file(fw_cfg, "etc/phys-bits",
+                        g_memdup2(&phys_bits, sizeof(phys_bits)),
+                        sizeof(phys_bits));
+    }
+}
diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 566accf7e60a..17ecc7fe4331 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -744,6 +744,7 @@ void pc_machine_done(Notifier *notifier, void *data)
 {
     PCMachineState *pcms = container_of(notifier,
                                         PCMachineState, machine_done);
+    PCMachineClass *pcmc = PC_MACHINE_GET_CLASS(pcms);
     X86MachineState *x86ms = X86_MACHINE(pcms);
 
     cxl_hook_up_pxb_registers(pcms->bus, &pcms->cxl_devices_state,
@@ -764,6 +765,9 @@ void pc_machine_done(Notifier *notifier, void *data)
         fw_cfg_build_feature_control(MACHINE(pcms), x86ms->fw_cfg);
         /* update FW_CFG_NB_CPUS to account for -device added CPUs */
         fw_cfg_modify_i16(x86ms->fw_cfg, FW_CFG_NB_CPUS, x86ms->boot_cpus);
+        if (pcmc->phys_bits_in_fw_cfg) {
+            fw_cfg_phys_bits(x86ms->fw_cfg);
+        }
     }
 }
 
@@ -1907,6 +1911,7 @@ static void pc_machine_class_init(ObjectClass *oc, void *data)
     pcmc->kvmclock_enabled = true;
     pcmc->enforce_aligned_dimm = true;
     pcmc->enforce_amd_1tb_hole = true;
+    pcmc->phys_bits_in_fw_cfg = true;
     /* BIOS ACPI tables: 128K. Other BIOS datastructures: less than 4K reported
      * to be used at the moment, 32K should be enough for a while.  */
     pcmc->acpi_data_size = 0x20000 + 0x8000;
diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
index 8043a250adf3..c6a4dbd5c0b0 100644
--- a/hw/i386/pc_piix.c
+++ b/hw/i386/pc_piix.c
@@ -447,9 +447,11 @@ DEFINE_I440FX_MACHINE(v7_2, "pc-i440fx-7.2", NULL,
 
 static void pc_i440fx_7_1_machine_options(MachineClass *m)
 {
+    PCMachineClass *pcmc = PC_MACHINE_CLASS(m);
     pc_i440fx_7_2_machine_options(m);
     m->alias = NULL;
     m->is_default = false;
+    pcmc->phys_bits_in_fw_cfg = false;
     compat_props_add(m->compat_props, hw_compat_7_1, hw_compat_7_1_len);
     compat_props_add(m->compat_props, pc_compat_7_1, pc_compat_7_1_len);
 }
diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
index 53eda50e818c..c2b56daa1550 100644
--- a/hw/i386/pc_q35.c
+++ b/hw/i386/pc_q35.c
@@ -384,8 +384,10 @@ DEFINE_Q35_MACHINE(v7_2, "pc-q35-7.2", NULL,
 
 static void pc_q35_7_1_machine_options(MachineClass *m)
 {
+    PCMachineClass *pcmc = PC_MACHINE_CLASS(m);
     pc_q35_7_2_machine_options(m);
     m->alias = NULL;
+    pcmc->phys_bits_in_fw_cfg = false;
     compat_props_add(m->compat_props, hw_compat_7_1, hw_compat_7_1_len);
     compat_props_add(m->compat_props, pc_compat_7_1, pc_compat_7_1_len);
 }
-- 
2.37.3