i386: prefer system KVM_GET_SUPPORTED_HV_CPUID ioctl over vCPU's one

KVM_GET_SUPPORTED_HV_CPUID was made a system wide ioctl which can be called
prior to creating vCPUs and we are going to use that to expand Hyper-V cpu
features early. Use it when it is supported by KVM.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
Message-Id: <20210422161130.652779-14-vkuznets@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>

diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
index 9005a4233f09ec926eeb38216725efa31bea0af0..6bcb74b1d84649cbb10d007f057626ac686601d3 100644 (file)
--- a/target/i386/kvm/kvm.c
+++ b/target/i386/kvm/kvm.c
@@ -929,7 +929,8 @@ static struct {
     },
 };
 
-static struct kvm_cpuid2 *try_get_hv_cpuid(CPUState *cs, int max)
+static struct kvm_cpuid2 *try_get_hv_cpuid(CPUState *cs, int max,
+                                           bool do_sys_ioctl)
 {
     struct kvm_cpuid2 *cpuid;
     int r, size;
@@ -938,7 +939,11 @@ static struct kvm_cpuid2 *try_get_hv_cpuid(CPUState *cs, int max)
     cpuid = g_malloc0(size);
     cpuid->nent = max;
 
-    r = kvm_vcpu_ioctl(cs, KVM_GET_SUPPORTED_HV_CPUID, cpuid);
+    if (do_sys_ioctl) {
+        r = kvm_ioctl(kvm_state, KVM_GET_SUPPORTED_HV_CPUID, cpuid);
+    } else {
+        r = kvm_vcpu_ioctl(cs, KVM_GET_SUPPORTED_HV_CPUID, cpuid);
+    }
     if (r == 0 && cpuid->nent >= max) {
         r = -E2BIG;
     }
@@ -965,13 +970,17 @@ static struct kvm_cpuid2 *get_supported_hv_cpuid(CPUState *cs)
     /* 0x40000000..0x40000005, 0x4000000A, 0x40000080..0x40000080 leaves */
     int max = 10;
     int i;
+    bool do_sys_ioctl;
+
+    do_sys_ioctl =
+        kvm_check_extension(kvm_state, KVM_CAP_SYS_HYPERV_CPUID) > 0;
 
     /*
      * When the buffer is too small, KVM_GET_SUPPORTED_HV_CPUID fails with
      * -E2BIG, however, it doesn't report back the right size. Keep increasing
      * it and re-trying until we succeed.
      */
-    while ((cpuid = try_get_hv_cpuid(cs, max)) == NULL) {
+    while ((cpuid = try_get_hv_cpuid(cs, max, do_sys_ioctl)) == NULL) {
         max++;
     }
 
@@ -981,7 +990,7 @@ static struct kvm_cpuid2 *get_supported_hv_cpuid(CPUState *cs)
      * information early, just check for the capability and set the bit
      * manually.
      */
-    if (kvm_check_extension(cs->kvm_state,
+    if (!do_sys_ioctl && kvm_check_extension(cs->kvm_state,
                             KVM_CAP_HYPERV_ENLIGHTENED_VMCS) > 0) {
         for (i = 0; i < cpuid->nent; i++) {
             if (cpuid->entries[i].function == HV_CPUID_ENLIGHTMENT_INFO) {