[PATCH 03/10] KVM: PPC: Check privilege level on SPRs

Alexander Graf
2011-08-09T16:31:41Z

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>
---
arch/powerpc/kvm/book3s_emulate.c | 25 +++++++++++++++++++++++++
1 files changed, 25 insertions(+), 0 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_emulate.c b/arch/powerpc/kvm/book3s_emulate.c
index 4668465..bf0ddcd 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;
--
1.6.0.2