[Qemu-devel] [PATCHv3] pc: reduce duplication, fix PIIX descriptions

[Michael S. Tsirkin]

We have a lot of code duplication between machine types,
this increases with each new machine type
and each new field.

This has already introduced a minor bug: description
for pc-1.3 says "Standard PC" while description for
pc-1.4 is "Standard PC (i440FX + PIIX, 1996)"
which makes you think 1.3 is somehow more standard,
or newer, while in fact it's a revision of the same PC.

This patch addresses this issue by using macros, along
the lines used by PC_COMPAT_X_X - only for
non-property options.

The approach can in the future extend to non-PC machine types.

Cc: Paolo Bonzini <address@hidden>
Signed-off-by: Michael S. Tsirkin <address@hidden>

---

Eduardo suggested adding a comment for the desc field
documenting that it is not exposed to guest.
However, Markus sent a patch that actually will expose
desc to guests starting from 1.7, so this doesn't look
like a fundamental restriction.
Further, we have many fields not exposed to guests -
it seems arbitrary to document that for this specific
one only.  It would make more sense to audit code and document fields
exposed to guests.

For this reason I didn't include Eduardo's suggestion.

Please review, if there are no objections, I'll apply this on top of
Markus's patch on my tree.

Changes from v2:
    rebase on top of Markus' patch
Changes from v1:
    add missing desc for Q35 to address Paolo's comment


---
 hw/i386/pc_piix.c    | 86 +++++++++++++++++++++-------------------------------
 hw/i386/pc_q35.c     | 25 ++++++++-------
 include/hw/i386/pc.h |  8 +++++
 3 files changed, 56 insertions(+), 63 deletions(-)

diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
index aa0a39a..275e395 100644
--- a/hw/i386/pc_piix.c
+++ b/hw/i386/pc_piix.c
@@ -334,36 +334,39 @@ static void pc_xen_hvm_init(QEMUMachineInitArgs *args)
 }
 #endif
 
+#define PC_I440FX_MACHINE_OPTIONS \
+    PC_DEFAULT_MACHINE_OPTIONS, \
+    .desc = "Standard PC (i440FX + PIIX, 1996)", \
+    .hot_add_cpu = pc_hot_add_cpu
+
+#define PC_I440FX_1_6_MACHINE_OPTIONS PC_I440FX_MACHINE_OPTIONS
+
 static QEMUMachine pc_i440fx_machine_v1_6 = {
+    PC_I440FX_1_6_MACHINE_OPTIONS,
     .name = "pc-i440fx-1.6",
     .alias = "pc",
-    .desc = "Standard PC (i440FX + PIIX, 1996)",
     .init = pc_init_pci_1_6,
-    .hot_add_cpu = pc_hot_add_cpu,
-    .max_cpus = 255,
     .is_default = 1,
-    .default_boot_order = "cad",
 };
 
 static QEMUMachine pc_i440fx_machine_v1_5 = {
+    PC_I440FX_1_6_MACHINE_OPTIONS,
     .name = "pc-i440fx-1.5",
-    .desc = "Standard PC (i440FX + PIIX, 1996)",
     .init = pc_init_pci_1_5,
-    .hot_add_cpu = pc_hot_add_cpu,
-    .max_cpus = 255,
     .compat_props = (GlobalProperty[]) {
         PC_COMPAT_1_5,
         { /* end of list */ }
     },
-    .default_boot_order = "cad",
 };
 
+#define PC_I440FX_1_4_MACHINE_OPTIONS \
+    PC_I440FX_1_6_MACHINE_OPTIONS, \
+    .hot_add_cpu = NULL
+
 static QEMUMachine pc_i440fx_machine_v1_4 = {
+    PC_I440FX_1_4_MACHINE_OPTIONS,
     .name = "pc-i440fx-1.4",
-    .desc = "Standard PC (i440FX + PIIX, 1996)",
     .init = pc_init_pci_1_4,
-    .max_cpus = 255,
-    .default_boot_order = "cad",
     .compat_props = (GlobalProperty[]) {
         PC_COMPAT_1_4,
         { /* end of list */ }
@@ -391,11 +394,9 @@ static QEMUMachine pc_i440fx_machine_v1_4 = {
         }
 
 static QEMUMachine pc_machine_v1_3 = {
+    PC_I440FX_1_4_MACHINE_OPTIONS,
     .name = "pc-1.3",
-    .desc = "Standard PC",
     .init = pc_init_pci_1_3,
-    .max_cpus = 255,
-    .default_boot_order = "cad",
     .compat_props = (GlobalProperty[]) {
         PC_COMPAT_1_3,
         { /* end of list */ }
@@ -430,12 +431,13 @@ static QEMUMachine pc_machine_v1_3 = {
             .value    = "off",\
         }
 
+#define PC_I440FX_1_2_MACHINE_OPTIONS \
+    PC_I440FX_1_4_MACHINE_OPTIONS, \
+    .init = pc_init_pci_1_2
+
 static QEMUMachine pc_machine_v1_2 = {
+    PC_I440FX_1_2_MACHINE_OPTIONS,
     .name = "pc-1.2",
-    .desc = "Standard PC",
-    .init = pc_init_pci_1_2,
-    .max_cpus = 255,
-    .default_boot_order = "cad",
     .compat_props = (GlobalProperty[]) {
         PC_COMPAT_1_2,
         { /* end of list */ }
@@ -475,11 +477,8 @@ static QEMUMachine pc_machine_v1_2 = {
         }
 
 static QEMUMachine pc_machine_v1_1 = {
+    PC_I440FX_1_2_MACHINE_OPTIONS,
     .name = "pc-1.1",
-    .desc = "Standard PC",
-    .init = pc_init_pci_1_2,
-    .max_cpus = 255,
-    .default_boot_order = "cad",
     .compat_props = (GlobalProperty[]) {
         PC_COMPAT_1_1,
         { /* end of list */ }
@@ -507,11 +506,8 @@ static QEMUMachine pc_machine_v1_1 = {
         }
 
 static QEMUMachine pc_machine_v1_0 = {
+    PC_I440FX_1_2_MACHINE_OPTIONS,
     .name = "pc-1.0",
-    .desc = "Standard PC",
-    .init = pc_init_pci_1_2,
-    .max_cpus = 255,
-    .default_boot_order = "cad",
     .compat_props = (GlobalProperty[]) {
         PC_COMPAT_1_0,
         { /* end of list */ }
@@ -523,11 +519,8 @@ static QEMUMachine pc_machine_v1_0 = {
         PC_COMPAT_1_0
 
 static QEMUMachine pc_machine_v0_15 = {
+    PC_I440FX_1_2_MACHINE_OPTIONS,
     .name = "pc-0.15",
-    .desc = "Standard PC",
-    .init = pc_init_pci_1_2,
-    .max_cpus = 255,
-    .default_boot_order = "cad",
     .compat_props = (GlobalProperty[]) {
         PC_COMPAT_0_15,
         { /* end of list */ }
@@ -556,11 +549,8 @@ static QEMUMachine pc_machine_v0_15 = {
         }
 
 static QEMUMachine pc_machine_v0_14 = {
+    PC_I440FX_1_2_MACHINE_OPTIONS,
     .name = "pc-0.14",
-    .desc = "Standard PC",
-    .init = pc_init_pci_1_2,
-    .max_cpus = 255,
-    .default_boot_order = "cad",
     .compat_props = (GlobalProperty[]) {
         PC_COMPAT_0_14, 
         {
@@ -589,12 +579,13 @@ static QEMUMachine pc_machine_v0_14 = {
             .value    = stringify(1),\
         }
 
+#define PC_I440FX_0_13_MACHINE_OPTIONS \
+    PC_I440FX_1_2_MACHINE_OPTIONS, \
+    .init = pc_init_pci_no_kvmclock
+
 static QEMUMachine pc_machine_v0_13 = {
+    PC_I440FX_0_13_MACHINE_OPTIONS,
     .name = "pc-0.13",
-    .desc = "Standard PC",
-    .init = pc_init_pci_no_kvmclock,
-    .max_cpus = 255,
-    .default_boot_order = "cad",
     .compat_props = (GlobalProperty[]) {
         PC_COMPAT_0_13,
         {
@@ -640,11 +631,8 @@ static QEMUMachine pc_machine_v0_13 = {
         }
 
 static QEMUMachine pc_machine_v0_12 = {
+    PC_I440FX_0_13_MACHINE_OPTIONS,
     .name = "pc-0.12",
-    .desc = "Standard PC",
-    .init = pc_init_pci_no_kvmclock,
-    .max_cpus = 255,
-    .default_boot_order = "cad",
     .compat_props = (GlobalProperty[]) {
         PC_COMPAT_0_12,
         {
@@ -674,11 +662,8 @@ static QEMUMachine pc_machine_v0_12 = {
         }
 
 static QEMUMachine pc_machine_v0_11 = {
+    PC_I440FX_0_13_MACHINE_OPTIONS,
     .name = "pc-0.11",
-    .desc = "Standard PC, qemu 0.11",
-    .init = pc_init_pci_no_kvmclock,
-    .max_cpus = 255,
-    .default_boot_order = "cad",
     .compat_props = (GlobalProperty[]) {
         PC_COMPAT_0_11,
         {
@@ -696,11 +681,8 @@ static QEMUMachine pc_machine_v0_11 = {
 };
 
 static QEMUMachine pc_machine_v0_10 = {
+    PC_I440FX_0_13_MACHINE_OPTIONS,
     .name = "pc-0.10",
-    .desc = "Standard PC, qemu 0.10",
-    .init = pc_init_pci_no_kvmclock,
-    .max_cpus = 255,
-    .default_boot_order = "cad",
     .compat_props = (GlobalProperty[]) {
         PC_COMPAT_0_11,
         {
@@ -730,11 +712,11 @@ static QEMUMachine pc_machine_v0_10 = {
 };
 
 static QEMUMachine isapc_machine = {
+    PC_COMMON_MACHINE_OPTIONS,
     .name = "isapc",
     .desc = "ISA-only PC",
     .init = pc_init_isa,
     .max_cpus = 1,
-    .default_boot_order = "cad",
     .compat_props = (GlobalProperty[]) {
         { /* end of list */ }
     },
@@ -742,12 +724,12 @@ static QEMUMachine isapc_machine = {
 
 #ifdef CONFIG_XEN
 static QEMUMachine xenfv_machine = {
+    PC_COMMON_MACHINE_OPTIONS,
     .name = "xenfv",
     .desc = "Xen Fully-virtualized PC",
     .init = pc_xen_hvm_init,
     .max_cpus = HVM_MAX_VCPUS,
     .default_machine_opts = "accel=xen",
-    .default_boot_order = "cad",
 };
 #endif
 
diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
index 291ad97..d7b7c3b 100644
--- a/hw/i386/pc_q35.c
+++ b/hw/i386/pc_q35.c
@@ -253,35 +253,38 @@ static void pc_q35_init_1_4(QEMUMachineInitArgs *args)
     pc_q35_init(args);
 }
 
+#define PC_Q35_MACHINE_OPTIONS \
+    PC_DEFAULT_MACHINE_OPTIONS, \
+    .desc = "Standard PC (Q35 + ICH9, 2009)", \
+    .hot_add_cpu = pc_hot_add_cpu
+
+#define PC_Q35_1_6_MACHINE_OPTIONS PC_Q35_MACHINE_OPTIONS
+
 static QEMUMachine pc_q35_machine_v1_6 = {
+    PC_Q35_1_6_MACHINE_OPTIONS,
     .name = "pc-q35-1.6",
     .alias = "q35",
-    .desc = "Standard PC (Q35 + ICH9, 2009)",
     .init = pc_q35_init_1_6,
-    .hot_add_cpu = pc_hot_add_cpu,
-    .max_cpus = 255,
-    .default_boot_order = "cad",
 };
 
 static QEMUMachine pc_q35_machine_v1_5 = {
+    PC_Q35_1_6_MACHINE_OPTIONS,
     .name = "pc-q35-1.5",
-    .desc = "Standard PC (Q35 + ICH9, 2009)",
     .init = pc_q35_init_1_5,
-    .hot_add_cpu = pc_hot_add_cpu,
-    .max_cpus = 255,
-    .default_boot_order = "cad",
     .compat_props = (GlobalProperty[]) {
         PC_COMPAT_1_5,
         { /* end of list */ }
     },
 };
 
+#define PC_Q35_1_4_MACHINE_OPTIONS \
+    PC_Q35_1_6_MACHINE_OPTIONS, \
+    .hot_add_cpu = NULL
+
 static QEMUMachine pc_q35_machine_v1_4 = {
+    PC_Q35_1_4_MACHINE_OPTIONS,
     .name = "pc-q35-1.4",
-    .desc = "Standard PC (Q35 + ICH9, 2009)",
     .init = pc_q35_init_1_4,
-    .max_cpus = 255,
-    .default_boot_order = "cad",
     .compat_props = (GlobalProperty[]) {
         PC_COMPAT_1_4,
         { /* end of list */ }
diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
index 475ba9e..7fb04d8 100644
--- a/include/hw/i386/pc.h
+++ b/include/hw/i386/pc.h
@@ -325,4 +325,12 @@ int e820_add_entry(uint64_t, uint64_t, uint32_t);
             .value    = stringify(0),\
         }
 
+#define PC_COMMON_MACHINE_OPTIONS \
+    .default_boot_order = "cad"
+
+#define PC_DEFAULT_MACHINE_OPTIONS \
+    PC_COMMON_MACHINE_OPTIONS, \
+    .hot_add_cpu = pc_hot_add_cpu, \
+    .max_cpus = 255
+
 #endif
-- 
MST