KVM: PPC: Book3S HV: Add a capability for enabling secure guests

At present, on Power systems with Protected Execution Facility
hardware and an ultravisor, a KVM guest can transition to being a
secure guest at will.  Userspace (QEMU) has no way of knowing
whether a host system is capable of running secure guests.  This
will present a problem in future when the ultravisor is capable of
migrating secure guests from one host to another, because
virtualization management software will have no way to ensure that
secure guests only run in domains where all of the hosts can
support secure guests.

This adds a VM capability which has two functions: (a) userspace
can query it to find out whether the host can support secure guests,
and (b) userspace can enable it for a guest, which allows that
guest to become a secure guest.  If userspace does not enable it,
KVM will return an error when the ultravisor does the hypercall
that indicates that the guest is starting to transition to a
secure guest.  The ultravisor will then abort the transition and
the guest will terminate.

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Ram Pai <linuxram@us.ibm.com>

1 files changed, 16 insertions, 0 deletions

diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index a308de610cdf..fa6e4fc7d0e4 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -5429,6 +5429,21 @@ static void unpin_vpa_reset(struct kvm *kvm, struct kvmppc_vpa *vpa)
 }
 
 /*
+ * Enable a guest to become a secure VM, or test whether
+ * that could be enabled.
+ * Called when the KVM_CAP_PPC_SECURE_GUEST capability is
+ * tested (kvm == NULL) or enabled (kvm != NULL).
+ */
+static int kvmhv_enable_svm(struct kvm *kvm)
+{
+	if (!kvmppc_uvmem_available())
+		return -EINVAL;
+	if (kvm)
+		kvm->arch.svm_enabled = 1;
+	return 0;
+}
+
+/*
  *  IOCTL handler to turn off secure mode of guest
  *
  * - Release all device pages
@@ -5548,6 +5563,7 @@ static struct kvmppc_ops kvm_ops_hv = {
 	.enable_nested = kvmhv_enable_nested,
 	.load_from_eaddr = kvmhv_load_from_eaddr,
 	.store_to_eaddr = kvmhv_store_to_eaddr,
+	.enable_svm = kvmhv_enable_svm,
 	.svm_off = kvmhv_svm_off,
 };