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[PATCH v4 17/21] i386: support 'hv-passthrough, hv-feature=off' on the c


From: Vitaly Kuznetsov
Subject: [PATCH v4 17/21] i386: support 'hv-passthrough, hv-feature=off' on the command line
Date: Wed, 10 Feb 2021 17:40:29 +0100

Currently, we support 'hv-passthrough,hv-feature=on' enablement, this
is supposed to mean "hv-feature is mandatory, don't start without it". Add
support for 'hv-passthrough,hv-feature=off' meaning "enable everything
supported by the host except for hv-feature".

While on it, make 'hv-passthrough' parse semantics in-line with other
options in qemu: when specified, it overrides what was previously set with
what's supported by the host. This can later be modified with 'hv-feature=on'/
'hv-feature=off'.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
 target/i386/cpu.c     | 28 +++++++++++++++++++++++++++-
 target/i386/kvm/kvm.c |  4 ++++
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index e8a004c39d04..f8df2caed779 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -4725,6 +4725,29 @@ static void x86_hv_stimer_direct_set(Object *obj, bool 
value, Error **errp)
     x86_hv_feature_set(obj, value, HYPERV_FEAT_STIMER_DIRECT);
 }
 
+static bool x86_hv_passthrough_get(Object *obj, Error **errp)
+{
+    X86CPU *cpu = X86_CPU(obj);
+
+    return cpu->hyperv_passthrough;
+}
+
+static void x86_hv_passthrough_set(Object *obj, bool value, Error **errp)
+{
+    X86CPU *cpu = X86_CPU(obj);
+
+    cpu->hyperv_passthrough = value;
+
+    /* hv-passthrough overrides everything with what's supported by the host */
+    if (value) {
+        cpu->hyperv_features = 0;
+        cpu->hyperv_features_on = 0;
+        cpu->hyperv_features_off = 0;
+    }
+
+    return;
+}
+
 /* Generic getter for "feature-words" and "filtered-features" properties */
 static void x86_cpu_get_feature_words(Object *obj, Visitor *v,
                                       const char *name, void *opaque,
@@ -7281,7 +7304,6 @@ static Property x86_cpu_properties[] = {
                        HYPERV_SPINLOCK_NEVER_NOTIFY),
     DEFINE_PROP_ON_OFF_AUTO("hv-no-nonarch-coresharing", X86CPU,
                             hyperv_no_nonarch_cs, ON_OFF_AUTO_OFF),
-    DEFINE_PROP_BOOL("hv-passthrough", X86CPU, hyperv_passthrough, false),
 
     DEFINE_PROP_BOOL("check", X86CPU, check_cpuid, true),
     DEFINE_PROP_BOOL("enforce", X86CPU, enforce_cpuid, false),
@@ -7460,6 +7482,10 @@ static void x86_cpu_common_class_init(ObjectClass *oc, 
void *data)
                                    x86_hv_stimer_direct_get,
                                    x86_hv_stimer_direct_set);
 
+    object_class_property_add_bool(oc, "hv-passthrough",
+                                   x86_hv_passthrough_get,
+                                   x86_hv_passthrough_set);
+
     for (w = 0; w < FEATURE_WORDS; w++) {
         int bitnr;
         for (bitnr = 0; bitnr < 64; bitnr++) {
diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
index 30013f0d7cee..fca088d4d3b5 100644
--- a/target/i386/kvm/kvm.c
+++ b/target/i386/kvm/kvm.c
@@ -1153,6 +1153,10 @@ static int hv_cpuid_check_and_set(CPUState *cs, int 
feature, Error **errp)
         return 0;
     }
 
+    if (cpu->hyperv_passthrough && (cpu->hyperv_features_off & BIT(feature))) {
+        return 0;
+    }
+
     deps = kvm_hyperv_properties[feature].dependencies;
     while (deps) {
         dep_feat = ctz64(deps);
-- 
2.29.2




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