i386/cpu/hyperv: support over 64 vcpus for windows guests

Starting with Windows Server 2012 and Windows 8, if
CPUID.40000005.EAX contains a value of -1, Windows assumes specific
limit to the number of VPs. In this case, Windows Server 2012
guest VMs may use more than 64 VPs, up to the maximum supported
number of processors applicable to the specific Windows
version being used.

https://docs.microsoft.com/en-us/virtualization/hyper-v-on-windows/reference/tlfs

For compatibility, Let's introduce a new property for X86CPU,
named "x-hv-max-vps" as Eduardo's suggestion, and set it
to 0x40 before machine 2.10.

(The "x-" prefix indicates that the property is not supposed to
be a stable user interface.)

Signed-off-by: Gonglei <arei.gonglei@huawei.com>
Message-Id: <1505143227-14324-1-git-send-email-arei.gonglei@huawei.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
index 82269045247c00f81aeebc87014816266a059ac0..087d184ef50c0574a0bd6048b71bfb9d18525df3 100644 (file)
--- a/include/hw/i386/pc.h
+++ b/include/hw/i386/pc.h
@@ -371,6 +371,11 @@ bool e820_get_entry(int, uint32_t, uint64_t *, uint64_t *);
 
 #define PC_COMPAT_2_10 \
     HW_COMPAT_2_10 \
+    {\
+        .driver   = TYPE_X86_CPU,\
+        .property = "x-hv-max-vps",\
+        .value    = "0x40",\
+    },
 
 #define PC_COMPAT_2_9 \
     HW_COMPAT_2_9 \

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index 7644f6dc2c0cce9903bd911a3f9cb6feaa19a035..40c3091edf2fcb63f93208551b7f47a4d814e5ba 100644 (file)
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -4145,6 +4145,20 @@ static Property x86_cpu_properties[] = {
                      false),
     DEFINE_PROP_BOOL("vmware-cpuid-freq", X86CPU, vmware_cpuid_freq, true),
     DEFINE_PROP_BOOL("tcg-cpuid", X86CPU, expose_tcg, true),
+
+    /*
+     * From "Requirements for Implementing the Microsoft
+     * Hypervisor Interface":
+     * https://docs.microsoft.com/en-us/virtualization/hyper-v-on-windows/reference/tlfs
+     *
+     * "Starting with Windows Server 2012 and Windows 8, if
+     * CPUID.40000005.EAX contains a value of -1, Windows assumes that
+     * the hypervisor imposes no specific limit to the number of VPs.
+     * In this case, Windows Server 2012 guest VMs may use more than
+     * 64 VPs, up to the maximum supported number of processors applicable
+     * to the specific Windows version being used."
+     */
+    DEFINE_PROP_INT32("x-hv-max-vps", X86CPU, hv_max_vps, -1),
     DEFINE_PROP_END_OF_LIST()
 };
 

diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index 525d35d836c9313312d7cd1ab33fdb59595c8837..5c726f3e4be8d49ed2598b0581b649a1255d2a53 100644 (file)
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -1282,6 +1282,8 @@ struct X86CPU {
     int32_t socket_id;
     int32_t core_id;
     int32_t thread_id;
+
+    int32_t hv_max_vps;
 };
 
 static inline X86CPU *x86_env_get_cpu(CPUX86State *env)

diff --git a/target/i386/kvm.c b/target/i386/kvm.c
index 739334a5a6f3cd2987afb922c4c7d412758f6498..ee4e91fa6432f69ce925a893ea0eb1731c735897 100644 (file)
--- a/target/i386/kvm.c
+++ b/target/i386/kvm.c
@@ -786,7 +786,8 @@ int kvm_arch_init_vcpu(CPUState *cs)
 
         c = &cpuid_data.entries[cpuid_i++];
         c->function = HYPERV_CPUID_IMPLEMENT_LIMITS;
-        c->eax = 0x40;
+
+        c->eax = cpu->hv_max_vps;
         c->ebx = 0x40;
 
         kvm_base = KVM_CPUID_SIGNATURE_NEXT;