From: Greg Kurz <groug@kaod.org>
Date: Thu, 14 Sep 2017 10:48:04 +0000 (+0200)
Subject: ppc/kvm: use kvm_vm_check_extension() in kvmppc_is_pr()
X-Git-Tag: qemu-xen-4.11.0-rc1~174^2
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=70a0c19e83aa4c71c879d51e426e89e4b3d4e014;p=qemu-xen.git

ppc/kvm: use kvm_vm_check_extension() in kvmppc_is_pr()

If the host has both KVM PR and KVM HV loaded and we pass:

	-machine pseries,accel=kvm,kvm-type=PR

the kvmppc_is_pr() returns false instead of true. Since the helper
is mostly used as fallback, it doesn't have any real impact with
recent kernels. A notable exception is the workaround to allow
migration between compatible hosts with different PVRs (eg, POWER8
and POWER8E), since KVM still doesn't provide a way to check if a
specific PVR is supported (see commit c363a37a450f for details).

According to the official KVM API documentation [1], KVM_PPC_GET_PVINFO
is "vm ioctl", but we check it as a global ioctl. The following function
in KVM is hence called with kvm == NULL and considers we're in HV mode.

int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
{
	int r;
	/* Assume we're using HV mode when the HV module is loaded */
	int hv_enabled = kvmppc_hv_ops ? 1 : 0;

	if (kvm) {
		/*
		 * Hooray - we know which VM type we're running on. Depend on
		 * that rather than the guess above.
		 */
		hv_enabled = is_kvmppc_hv_enabled(kvm);
	}

Let's use kvm_vm_check_extension() to fix the issue.

[1] https://www.kernel.org/doc/Documentation/virtual/kvm/api.txt

Signed-off-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---

diff --git a/target/ppc/kvm.c b/target/ppc/kvm.c
index 6442dfcb95..1deaf106d2 100644
--- a/target/ppc/kvm.c
+++ b/target/ppc/kvm.c
@@ -120,7 +120,7 @@ static void kvm_kick_cpu(void *opaque)
 static bool kvmppc_is_pr(KVMState *ks)
 {
     /* Assume KVM-PR if the GET_PVINFO capability is available */
-    return kvm_check_extension(ks, KVM_CAP_PPC_GET_PVINFO) != 0;
+    return kvm_vm_check_extension(ks, KVM_CAP_PPC_GET_PVINFO) != 0;
 }
 
 static int kvm_ppc_register_host_cpu_type(void);