[Qemu-devel] [PULL v2 5/5] target-i386: Disable SVM by default in KVM mode

["Andreas Färber" <afaerber@suse.de>]

From: Eduardo Habkost <ehabkost@redhat.com>

Make SVM be disabled by default on all CPU models when in KVM mode.
Nested SVM is enabled by default in the KVM kernel module, but it is
probably less stable than nested VMX (which is already disabled by
default).

Add a new compat function, x86_cpu_compat_kvm_no_autodisable(), to keep
compatibility on previous machine-types.

Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>
---
 hw/i386/pc_piix.c | 1 +
 hw/i386/pc_q35.c  | 1 +
 target-i386/cpu.c | 6 ++++++
 target-i386/cpu.h | 1 +
 4 files changed, 9 insertions(+)

diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
index 8de85c3..b559181 100644
--- a/hw/i386/pc_piix.c
+++ b/hw/i386/pc_piix.c
@@ -308,6 +308,7 @@ static void pc_compat_2_1(MachineState *machine)
     smbios_uuid_encoded = false;
     x86_cpu_compat_set_features("coreduo", FEAT_1_ECX, CPUID_EXT_VMX, 0);
     x86_cpu_compat_set_features("core2duo", FEAT_1_ECX, CPUID_EXT_VMX, 0);
+    x86_cpu_compat_kvm_no_autodisable(FEAT_8000_0001_ECX, CPUID_EXT3_SVM);
 }
 
 static void pc_compat_2_0(MachineState *machine)
diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
index fd8593b..598e679 100644
--- a/hw/i386/pc_q35.c
+++ b/hw/i386/pc_q35.c
@@ -287,6 +287,7 @@ static void pc_compat_2_1(MachineState *machine)
     smbios_uuid_encoded = false;
     x86_cpu_compat_set_features("coreduo", FEAT_1_ECX, CPUID_EXT_VMX, 0);
     x86_cpu_compat_set_features("core2duo", FEAT_1_ECX, CPUID_EXT_VMX, 0);
+    x86_cpu_compat_kvm_no_autodisable(FEAT_8000_0001_ECX, CPUID_EXT3_SVM);
 }
 
 static void pc_compat_2_0(MachineState *machine)
diff --git a/target-i386/cpu.c b/target-i386/cpu.c
index b731832..fa860de 100644
--- a/target-i386/cpu.c
+++ b/target-i386/cpu.c
@@ -461,6 +461,7 @@ static uint32_t kvm_default_features[FEATURE_WORDS] = {
 static uint32_t kvm_default_unset_features[FEATURE_WORDS] = {
     [FEAT_1_EDX] = CPUID_ACPI,
     [FEAT_1_ECX] = CPUID_EXT_MONITOR,
+    [FEAT_8000_0001_ECX] = CPUID_EXT3_SVM,
 };
 
 void x86_cpu_compat_kvm_no_autoenable(FeatureWord w, uint32_t features)
@@ -468,6 +469,11 @@ void x86_cpu_compat_kvm_no_autoenable(FeatureWord w, uint32_t features)
     kvm_default_features[w] &= ~features;
 }
 
+void x86_cpu_compat_kvm_no_autodisable(FeatureWord w, uint32_t features)
+{
+    kvm_default_unset_features[w] &= ~features;
+}
+
 /*
  * Returns the set of feature flags that are supported and migratable by
  * QEMU, for a given FeatureWord.
diff --git a/target-i386/cpu.h b/target-i386/cpu.h
index a3fc6d8..1b2c12a 100644
--- a/target-i386/cpu.h
+++ b/target-i386/cpu.h
@@ -1366,6 +1366,7 @@ void x86_cpu_compat_set_features(const char *cpu_model, FeatureWord w,
                                  uint32_t feat_add, uint32_t feat_remove);
 
 void x86_cpu_compat_kvm_no_autoenable(FeatureWord w, uint32_t features);
+void x86_cpu_compat_kvm_no_autodisable(FeatureWord w, uint32_t features);
 
 
 /* Return name of 32-bit register, from a R_* constant */
-- 
1.8.4.5