[Qemu-devel] [PULL 3/6] target-i386/machine: fix migrate faile because of Hyper-V HV_X64_MSR_VP_RUNTIME

[Paolo Bonzini]

From: ZhuangYanying <address@hidden>

Hyper-V HV_X64_MSR_VP_RUNTIME was introduced in linux-4.4 + qemu-2.5.

As long as the KVM module supports, qemu will save / load the
vmstate_msr_hyperv_runtime register during the migration.

Regardless of whether the hyperv_runtime configuration of x86_cpu_properties is
enabled.

The qemu-2.3 does not support this feature, of course, failed to migrate.

    linux-BGSfqC:/home/qemu # ./x86_64-softmmu/qemu-system-x86_64 --enable-kvm \
        -nodefaults -machine pc-i440fx-2.3,accel=kvm,usb=off -smp 4 -m 4096 
-drive \
        
file=/work/suse/sles11sp3.img.bak,format=raw,if=none,id=drive-virtio-disk0,cache=none
 \
        -device 
virtio-blk-pci,scsi=off,bus=pci.0,addr=0x5,drive=drive-virtio-disk0,id=virtio-disk0
 \
        -vnc :99 -device cirrus-vga,id=video0,vgamem_mb=8,bus=pci.0,addr=0x2 
-monitor vc

    
save_section_header:se->section_id=3,se->idstr:ram,se->instance_id=0,se->version_id=4
    
save_section_header:se->section_id=0,se->idstr:timer,se->instance_id=0,se->version_id=2
    
save_section_header:se->section_id=4,se->idstr:cpu_common,se->instance_id=0,se->version_id=1
    
save_section_header:se->section_id=5,se->idstr:cpu,se->instance_id=0,se->version_id=12
    vmstate_subsection_save:vmsd->name:cpu/async_pf_msr
    hyperv_runtime_enable_needed:env->msr_hv_runtime=128902811
    vmstate_subsection_save:vmsd->name:cpu/msr_hyperv_runtime

Since hyperv_runtime is false, vm will not use hv->runtime_offset, then
vmstate_msr_hyperv_runtime is no need to transfer while migrating.

Signed-off-by: address@hidden
Message-Id: <address@hidden>
Signed-off-by: Paolo Bonzini <address@hidden>
---
 target-i386/machine.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/target-i386/machine.c b/target-i386/machine.c
index 48037f1..760f82b 100644
--- a/target-i386/machine.c
+++ b/target-i386/machine.c
@@ -709,6 +709,10 @@ static bool hyperv_runtime_enable_needed(void *opaque)
     X86CPU *cpu = opaque;
     CPUX86State *env = &cpu->env;
 
+    if (!cpu->hyperv_runtime) {
+        return false;
+    }
+
     return env->msr_hv_runtime != 0;
 }
 
-- 
1.8.3.1