[PATCH 2/4] arm64: KVM: add missing dsb before invalidating Stage-2 TLBs

[Marc Zyngier]

When performing a Stage-2 TLB invalidation, it is necessary to
make sure the write to the page tables is observable by all CPUs.

For this purpose, add a dsb instruction to __kvm_tlb_flush_vmid_ipa
before doing the TLB invalidation itself.

Signed-off-by: Marc Zyngier <marc.zyngier at arm.com>
---
 arch/arm64/kvm/hyp.S | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/arm64/kvm/hyp.S b/arch/arm64/kvm/hyp.S
index 218802f..e1ccfcc 100644
--- a/arch/arm64/kvm/hyp.S
+++ b/arch/arm64/kvm/hyp.S
@@ -604,6 +604,8 @@ END(__kvm_vcpu_run)
 
 // void __kvm_tlb_flush_vmid_ipa(struct kvm *kvm, phys_addr_t ipa);
 ENTRY(__kvm_tlb_flush_vmid_ipa)
+	dsb	ishst	// Make sure previous writes are observable
+
 	kern_hyp_va	x0
 	ldr	x2, [x0, #KVM_VTTBR]
 	msr	vttbr_el2, x2
-- 
1.8.2.3