When erratum 1319367 is being worked around, special care must
be taken not to allow the page table walker to populate TLBs
while we have the stage-2 translation enabled (which would otherwise
result in a bizare mix of the host S1 and the guest S2).
We enforce this by setting TCR_EL1.EPD{0,1} before restoring the S2
configuration, and clear the same bits after having disabled S2.
Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
---
arch/arm64/kvm/hyp/tlb.c | 23 +++++++++++++++++++++++
1 file changed, 23 insertions(+)
diff --git a/arch/arm64/kvm/hyp/tlb.c b/arch/arm64/kvm/hyp/tlb.c
index eb0efc5557f3..4ef0bf0d76a6 100644
--- a/arch/arm64/kvm/hyp/tlb.c
+++ b/arch/arm64/kvm/hyp/tlb.c
@@ -63,6 +63,22 @@ static void __hyp_text __tlb_switch_to_guest_vhe(struct kvm *kvm,
static void __hyp_text __tlb_switch_to_guest_nvhe(struct kvm *kvm,
struct tlb_inv_context *cxt)
{
+ if (cpus_have_const_cap(ARM64_WORKAROUND_1319367)) {
+ u64 val;
+
+ /*
+ * For CPUs that are affected by ARM 1319367, we need to
+ * avoid a host Stage-1 walk while we have the guest's
+ * Stage-2 set in the VTTBR in order to invalidate TLBs.
+ * We're guaranteed that the S1 MMU is enabled, so we can
+ * simply set the EPD bits to avoid any further TLB fill.
+ */
+ val = cxt->tcr = read_sysreg_el1(SYS_TCR);
+ val |= TCR_EPD1_MASK | TCR_EPD0_MASK;
+ write_sysreg_el1(val, SYS_TCR);
+ isb();
+ }
+
__load_guest_stage2(kvm);
isb();
}
@@ -100,6 +116,13 @@ static void __hyp_text __tlb_switch_to_host_nvhe(struct kvm *kvm,
struct tlb_inv_context *cxt)
{
write_sysreg(0, vttbr_el2);
+
+ if (cpus_have_const_cap(ARM64_WORKAROUND_1319367)) {
+ /* Ensure stage-2 is actually disabled */
+ isb();
+ /* Restore the host's TCR_EL1 */
+ write_sysreg_el1(cxt->tcr, SYS_TCR);
+ }
}
static void __hyp_text __tlb_switch_to_host(struct kvm *kvm,
--
2.20.1
