KVM: PPC: Check privilege level on SPRs

We have 3 privilege levels: problem state, supervisor state and hypervisor
state. Each of them can access different SPRs, so we need to check on every
SPR if it's accessible in the respective mode.

Signed-off-by: Alexander Graf <agraf@suse.de>

1 files changed, 25 insertions, 0 deletions

diff --git a/arch/powerpc/kvm/book3s_emulate.c b/arch/powerpc/kvm/book3s_emulate.c
index 466846557089..bf0ddcd98bcc 100644
--- a/arch/powerpc/kvm/book3s_emulate.c
+++ b/arch/powerpc/kvm/book3s_emulate.c
@@ -63,6 +63,25 @@
  * function pointers, so let's just disable the define. */
 #undef mfsrin
 
+enum priv_level {
+        PRIV_PROBLEM = 0,
+        PRIV_SUPER = 1,
+        PRIV_HYPER = 2,
+};
+
+static bool spr_allowed(struct kvm_vcpu *vcpu, enum priv_level level)
+{
+        /* PAPR VMs only access supervisor SPRs */
+        if (vcpu->arch.papr_enabled && (level > PRIV_SUPER))
+                return false;
+
+        /* Limit user space to its own small SPR set */
+        if ((vcpu->arch.shared->msr & MSR_PR) && level > PRIV_PROBLEM)
+                return false;
+
+        return true;
+}
+
 int kvmppc_core_emulate_op(struct kvm_run *run, struct kvm_vcpu *vcpu,
                            unsigned int inst, int *advance)
 {
@@ -296,6 +315,8 @@ int kvmppc_core_emulate_mtspr(struct kvm_vcpu *vcpu, int sprn, int rs)
 
         switch (sprn) {
         case SPRN_SDR1:
+                if (!spr_allowed(vcpu, PRIV_HYPER))
+                        goto unprivileged;
                 to_book3s(vcpu)->sdr1 = spr_val;
                 break;
         case SPRN_DSISR:
@@ -390,6 +411,7 @@ int kvmppc_core_emulate_mtspr(struct kvm_vcpu *vcpu, int sprn, int rs)
         case SPRN_PMC4_GEKKO:
         case SPRN_WPAR_GEKKO:
                 break;
+unprivileged:
         default:
                 printk(KERN_INFO "KVM: invalid SPR write: %d\n", sprn);
 #ifndef DEBUG_SPR
@@ -421,6 +443,8 @@ int kvmppc_core_emulate_mfspr(struct kvm_vcpu *vcpu, int sprn, int rt)
                 break;
         }
         case SPRN_SDR1:
+                if (!spr_allowed(vcpu, PRIV_HYPER))
+                        goto unprivileged;
                 kvmppc_set_gpr(vcpu, rt, to_book3s(vcpu)->sdr1);
                 break;
         case SPRN_DSISR:
@@ -476,6 +500,7 @@ int kvmppc_core_emulate_mfspr(struct kvm_vcpu *vcpu, int sprn, int rt)
                 kvmppc_set_gpr(vcpu, rt, 0);
                 break;
         default:
+unprivileged:
                 printk(KERN_INFO "KVM: invalid SPR read: %d\n", sprn);
 #ifndef DEBUG_SPR
                 emulated = EMULATE_FAIL;