KVM: arm64: Inject exception on out-of-IPA-range translation fault

When taking a translation fault for an IPA that is outside of
the range defined by the hypervisor (between the HW PARange and
the IPA range), we stupidly treat it as an IO and forward the access
to userspace. Of course, userspace can't do much with it, and things
end badly.

Arguably, the guest is braindead, but we should at least catch the
case and inject an exception.

Check the faulting IPA against:
- the sanitised PARange: inject an address size fault
- the IPA size: inject an abort

Reported-by: Christoffer Dall <christoffer.dall@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>

1 files changed, 28 insertions, 0 deletions

diff --git a/arch/arm64/kvm/inject_fault.c b/arch/arm64/kvm/inject_fault.c
index b47df73e98d7..ba20405d2dc2 100644
--- a/arch/arm64/kvm/inject_fault.c
+++ b/arch/arm64/kvm/inject_fault.c
@@ -145,6 +145,34 @@ void kvm_inject_pabt(struct kvm_vcpu *vcpu, unsigned long addr)
 		inject_abt64(vcpu, true, addr);
 }
 
+void kvm_inject_size_fault(struct kvm_vcpu *vcpu)
+{
+	unsigned long addr, esr;
+
+	addr  = kvm_vcpu_get_fault_ipa(vcpu);
+	addr |= kvm_vcpu_get_hfar(vcpu) & GENMASK(11, 0);
+
+	if (kvm_vcpu_trap_is_iabt(vcpu))
+		kvm_inject_pabt(vcpu, addr);
+	else
+		kvm_inject_dabt(vcpu, addr);
+
+	/*
+	 * If AArch64 or LPAE, set FSC to 0 to indicate an Address
+	 * Size Fault at level 0, as if exceeding PARange.
+	 *
+	 * Non-LPAE guests will only get the external abort, as there
+	 * is no way to to describe the ASF.
+	 */
+	if (vcpu_el1_is_32bit(vcpu) &&
+	    !(vcpu_read_sys_reg(vcpu, TCR_EL1) & TTBCR_EAE))
+		return;
+
+	esr = vcpu_read_sys_reg(vcpu, ESR_EL1);
+	esr &= ~GENMASK_ULL(5, 0);
+	vcpu_write_sys_reg(vcpu, esr, ESR_EL1);
+}
+
 /**
  * kvm_inject_undefined - inject an undefined instruction into the guest
  * @vcpu: The vCPU in which to inject the exception