KVM: arm64: nv: Handle TLB invalidation targeting L2 stage-1

While dealing with TLB invalidation targeting the guest hypervisor's
own stage-1 was easy, doing the same thing for its own guests is
a bit more involved.

Since such an invalidation is scoped by VMID, it needs to apply to
all s2_mmu contexts that have been tagged by that VMID, irrespective
of the value of VTTBR_EL2.BADDR.

So for each s2_mmu context matching that VMID, we invalidate the
corresponding TLBs, each context having its own "physical" VMID.

Co-developed-by: Jintack Lim <[email protected]>
Co-developed-by: Christoffer Dall <[email protected]>
Signed-off-by: Jintack Lim <[email protected]>
Signed-off-by: Christoffer Dall <[email protected]>
Signed-off-by: Marc Zyngier <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Oliver Upton <[email protected]>

1 files changed, 35 insertions, 0 deletions

diff --git a/arch/arm64/kvm/nested.c b/arch/arm64/kvm/nested.c
index 114a3f59c28b..a2734d135211 100644
--- a/arch/arm64/kvm/nested.c
+++ b/arch/arm64/kvm/nested.c
@@ -364,6 +364,41 @@ int kvm_walk_nested_s2(struct kvm_vcpu *vcpu, phys_addr_t gipa,
 	return ret;
 }
 
+/*
+ * We can have multiple *different* MMU contexts with the same VMID:
+ *
+ * - S2 being enabled or not, hence differing by the HCR_EL2.VM bit
+ *
+ * - Multiple vcpus using private S2s (huh huh...), hence differing by the
+ *   VBBTR_EL2.BADDR address
+ *
+ * - A combination of the above...
+ *
+ * We can always identify which MMU context to pick at run-time.  However,
+ * TLB invalidation involving a VMID must take action on all the TLBs using
+ * this particular VMID. This translates into applying the same invalidation
+ * operation to all the contexts that are using this VMID. Moar phun!
+ */
+void kvm_s2_mmu_iterate_by_vmid(struct kvm *kvm, u16 vmid,
+				const union tlbi_info *info,
+				void (*tlbi_callback)(struct kvm_s2_mmu *,
+						      const union tlbi_info *))
+{
+	write_lock(&kvm->mmu_lock);
+
+	for (int i = 0; i < kvm->arch.nested_mmus_size; i++) {
+		struct kvm_s2_mmu *mmu = &kvm->arch.nested_mmus[i];
+
+		if (!kvm_s2_mmu_valid(mmu))
+			continue;
+
+		if (vmid == get_vmid(mmu->tlb_vttbr))
+			tlbi_callback(mmu, info);
+	}
+
+	write_unlock(&kvm->mmu_lock);
+}
+
 struct kvm_s2_mmu *lookup_s2_mmu(struct kvm_vcpu *vcpu)
 {
 	struct kvm *kvm = vcpu->kvm;