KVM: PPC: Introduce shared page

For transparent variable sharing between the hypervisor and guest, I introduce
a shared page. This shared page will contain all the registers the guest can
read and write safely without exiting guest context.

This patch only implements the stubs required for the basic structure of the
shared page. The actual register moving follows.

Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/arch/powerpc/kvm/e500.c b/arch/powerpc/kvm/e500.c
index e8a00b0c4449..71750f2dd5d3 100644
--- a/arch/powerpc/kvm/e500.c
+++ b/arch/powerpc/kvm/e500.c
@@ -117,8 +117,14 @@ struct kvm_vcpu *kvmppc_core_vcpu_create(struct kvm *kvm, unsigned int id)
         if (err)
                 goto uninit_vcpu;
 
+        vcpu->arch.shared = (void*)__get_free_page(GFP_KERNEL|__GFP_ZERO);
+        if (!vcpu->arch.shared)
+                goto uninit_tlb;
+
         return vcpu;
 
+uninit_tlb:
+        kvmppc_e500_tlb_uninit(vcpu_e500);
 uninit_vcpu:
         kvm_vcpu_uninit(vcpu);
 free_vcpu:
@@ -131,6 +137,7 @@ void kvmppc_core_vcpu_free(struct kvm_vcpu *vcpu)
 {
         struct kvmppc_vcpu_e500 *vcpu_e500 = to_e500(vcpu);
 
+        free_page((unsigned long)vcpu->arch.shared);
         kvmppc_e500_tlb_uninit(vcpu_e500);
         kvm_vcpu_uninit(vcpu);
         kmem_cache_free(kvm_vcpu_cache, vcpu_e500);