KVM: MIPS/T&E: Use lockless GVA helpers for dyntrans

Use the lockless GVA helpers to implement the dynamic translation of
guest instructions. This will allow it to handle asynchronous TLB
flushes when they are implemented.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org

arch/mips/kvm/dyntrans.c

@@ -33,10 +33,32 @@ static int kvm_mips_trans_replace(struct kvm_vcpu *vcpu, u32 *opc,
 	unsigned long vaddr = (unsigned long)opc;
 	int err;
 
+retry:
+	/* The GVA page table is still active so use the Linux TLB handlers */
+	kvm_trap_emul_gva_lockless_begin(vcpu);
 	err = put_user(replace.word, opc);
+	kvm_trap_emul_gva_lockless_end(vcpu);
+
 	if (unlikely(err)) {
-		kvm_err("%s: Invalid address: %p\n", __func__, opc);
-		return err;
+		/*
+		 * We write protect clean pages in GVA page table so normal
+		 * Linux TLB mod handler doesn't silently dirty the page.
+		 * Its also possible we raced with a GVA invalidation.
+		 * Try to force the page to become dirty.
+		 */
+		err = kvm_trap_emul_gva_fault(vcpu, vaddr, true);
+		if (unlikely(err)) {
+			kvm_info("%s: Address unwriteable: %p\n",
+				 __func__, opc);
+			return -EFAULT;
+		}
+
+		/*
+		 * Try again. This will likely trigger a TLB refill, which will
+		 * fetch the new dirty entry from the GVA page table, which
+		 * should then succeed.
+		 */
+		goto retry;
 	}
 	__local_flush_icache_user_range(vaddr, vaddr + 4);