KVM: powerpc: Map guest userspace with TID=0 mappings
When we use TID=N userspace mappings, we must ensure that kernel mappings have
been destroyed when entering userspace. Using TID=1/TID=0 for kernel/user
mappings and running userspace with PID=0 means that userspace can't access the
kernel mappings, but the kernel can directly access userspace.
The net is that we don't need to flush the TLB on privilege switches, but we do
on guest context switches (which are far more infrequent). Guest boot time
performance improvement: about 30%.
Signed-off-by: Hollis Blanchard <hollisb@us.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
diff --git a/arch/powerpc/include/asm/kvm_ppc.h b/arch/powerpc/include/asm/kvm_ppc.h
index 8e7e429..8931ba7 100644
--- a/arch/powerpc/include/asm/kvm_ppc.h
+++ b/arch/powerpc/include/asm/kvm_ppc.h
@@ -64,6 +64,7 @@
extern void kvmppc_mmu_invalidate(struct kvm_vcpu *vcpu, gva_t eaddr,
gva_t eend, u32 asid);
extern void kvmppc_mmu_priv_switch(struct kvm_vcpu *vcpu, int usermode);
+extern void kvmppc_mmu_switch_pid(struct kvm_vcpu *vcpu, u32 pid);
/* XXX Book E specific */
extern void kvmppc_tlbe_set_modified(struct kvm_vcpu *vcpu, unsigned int i);
@@ -95,4 +96,12 @@
kvm_vcpu_block(vcpu);
}
+static inline void kvmppc_set_pid(struct kvm_vcpu *vcpu, u32 new_pid)
+{
+ if (vcpu->arch.pid != new_pid) {
+ vcpu->arch.pid = new_pid;
+ vcpu->arch.swap_pid = 1;
+ }
+}
+
#endif /* __POWERPC_KVM_PPC_H__ */