[Qemu-devel] [RFC 03/12] pc: Reverse pc_init_pci() compatibility logic

[Eduardo Habkost <ehabkost@redhat.com>]

Currently, the pc-1.4 machine init function enables PV EOI and then
calls the pc-1.2 machine init function. The problem with this approach
is that now we can't enable any compatibility code inside the pc-1.2
init function because it would enable the compatibility behavior on
pc-1.3 and pc-1.4 as well.

This reverses the logic so that the pc-1.2 machine init function will
disable PV EOI, and then call the pc-1.4 machine init function. This way
we can change the pc-1.2 init function to enable compatibility behavior,
and the pc-1.4 init function would just use the default behavior.

It would be interesting to eventually change pc_init_pci_no_kvmclock()
and pc_init_isa() to reuse pc_init_pci_1_2() as well (so we don't need
to duplicate compatibility code on those two functions). But this will
be probably much easier to do after we create a PCInitArgs struct for
the PC initialization arguments.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
Cc: kvm@vger.kernel.org
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Gleb Natapov <gleb@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
---
 hw/pc_piix.c      | 22 +++++++++++++---------
 target-i386/cpu.c |  5 +++--
 target-i386/cpu.h |  2 +-
 3 files changed, 17 insertions(+), 12 deletions(-)

diff --git a/hw/pc_piix.c b/hw/pc_piix.c
index 2b3d58b..13d7cc8 100644
--- a/hw/pc_piix.c
+++ b/hw/pc_piix.c
@@ -233,12 +233,14 @@ static void pc_init_pci(QEMUMachineInitArgs *args)
              initrd_filename, cpu_model, 1, 1);
 }
 
-static void pc_init_pci_1_3(QEMUMachineInitArgs *args)
+/* PC machine init function for pc-0.14 to pc-1.2 */
+static void pc_init_pci_1_2(QEMUMachineInitArgs *args)
 {
-    enable_kvm_pv_eoi();
+    disable_kvm_pv_eoi();
     pc_init_pci(args);
 }
 
+/* PC init function for pc-0.10 to pc-0.13, and reused by xenfv */
 static void pc_init_pci_no_kvmclock(QEMUMachineInitArgs *args)
 {
     ram_addr_t ram_size = args->ram_size;
@@ -247,6 +249,7 @@ static void pc_init_pci_no_kvmclock(QEMUMachineInitArgs *args)
     const char *kernel_cmdline = args->kernel_cmdline;
     const char *initrd_filename = args->initrd_filename;
     const char *boot_device = args->boot_device;
+    disable_kvm_pv_eoi();
     pc_init1(get_system_memory(),
              get_system_io(),
              ram_size, boot_device,
@@ -264,6 +267,7 @@ static void pc_init_isa(QEMUMachineInitArgs *args)
     const char *boot_device = args->boot_device;
     if (cpu_model == NULL)
         cpu_model = "486";
+    disable_kvm_pv_eoi();
     pc_init1(get_system_memory(),
              get_system_io(),
              ram_size, boot_device,
@@ -286,7 +290,7 @@ static QEMUMachine pc_machine_v1_4 = {
     .name = "pc-1.4",
     .alias = "pc",
     .desc = "Standard PC",
-    .init = pc_init_pci_1_3,
+    .init = pc_init_pci,
     .max_cpus = 255,
     .is_default = 1,
 };
@@ -301,7 +305,7 @@ static QEMUMachine pc_machine_v1_4 = {
 static QEMUMachine pc_machine_v1_3 = {
     .name = "pc-1.3",
     .desc = "Standard PC",
-    .init = pc_init_pci_1_3,
+    .init = pc_init_pci,
     .max_cpus = 255,
     .compat_props = (GlobalProperty[]) {
         PC_COMPAT_1_3,
@@ -340,7 +344,7 @@ static QEMUMachine pc_machine_v1_3 = {
 static QEMUMachine pc_machine_v1_2 = {
     .name = "pc-1.2",
     .desc = "Standard PC",
-    .init = pc_init_pci,
+    .init = pc_init_pci_1_2,
     .max_cpus = 255,
     .compat_props = (GlobalProperty[]) {
         PC_COMPAT_1_2,
@@ -383,7 +387,7 @@ static QEMUMachine pc_machine_v1_2 = {
 static QEMUMachine pc_machine_v1_1 = {
     .name = "pc-1.1",
     .desc = "Standard PC",
-    .init = pc_init_pci,
+    .init = pc_init_pci_1_2,
     .max_cpus = 255,
     .compat_props = (GlobalProperty[]) {
         PC_COMPAT_1_1,
@@ -418,7 +422,7 @@ static QEMUMachine pc_machine_v1_1 = {
 static QEMUMachine pc_machine_v1_0 = {
     .name = "pc-1.0",
     .desc = "Standard PC",
-    .init = pc_init_pci,
+    .init = pc_init_pci_1_2,
     .max_cpus = 255,
     .compat_props = (GlobalProperty[]) {
         PC_COMPAT_1_0,
@@ -433,7 +437,7 @@ static QEMUMachine pc_machine_v1_0 = {
 static QEMUMachine pc_machine_v0_15 = {
     .name = "pc-0.15",
     .desc = "Standard PC",
-    .init = pc_init_pci,
+    .init = pc_init_pci_1_2,
     .max_cpus = 255,
     .compat_props = (GlobalProperty[]) {
         PC_COMPAT_0_15,
@@ -465,7 +469,7 @@ static QEMUMachine pc_machine_v0_15 = {
 static QEMUMachine pc_machine_v0_14 = {
     .name = "pc-0.14",
     .desc = "Standard PC",
-    .init = pc_init_pci,
+    .init = pc_init_pci_1_2,
     .max_cpus = 255,
     .compat_props = (GlobalProperty[]) {
         PC_COMPAT_0_14, 
diff --git a/target-i386/cpu.c b/target-i386/cpu.c
index 57a22b7..492656c 100644
--- a/target-i386/cpu.c
+++ b/target-i386/cpu.c
@@ -211,11 +211,12 @@ static uint32_t kvm_default_features = (1 << KVM_FEATURE_CLOCKSOURCE) |
         (1 << KVM_FEATURE_CLOCKSOURCE2) |
         (1 << KVM_FEATURE_ASYNC_PF) |
         (1 << KVM_FEATURE_STEAL_TIME) |
+        (1 << KVM_FEATURE_PV_EOI) |
         (1 << KVM_FEATURE_CLOCKSOURCE_STABLE_BIT);
 
-void enable_kvm_pv_eoi(void)
+void disable_kvm_pv_eoi(void)
 {
-    kvm_default_features |= (1UL << KVM_FEATURE_PV_EOI);
+    kvm_default_features &= ~(1UL << KVM_FEATURE_PV_EOI);
 }
 
 void host_cpuid(uint32_t function, uint32_t count,
diff --git a/target-i386/cpu.h b/target-i386/cpu.h
index e4a7c50..f3c9df5 100644
--- a/target-i386/cpu.h
+++ b/target-i386/cpu.h
@@ -1233,7 +1233,7 @@ void do_smm_enter(CPUX86State *env1);
 
 void cpu_report_tpr_access(CPUX86State *env, TPRAccess access);
 
-void enable_kvm_pv_eoi(void);
+void disable_kvm_pv_eoi(void);
 
 /* Return name of 32-bit register, from a R_* constant */
 const char *get_register_name_32(unsigned int reg);
-- 
1.7.11.7