KVM: ARM: Handle guest faults in KVM

Handles the guest faults in KVM by mapping in corresponding user pages
in the 2nd stage page tables.

We invalidate the instruction cache by MVA whenever we map a page to the
guest (no, we cannot only do it when we have an iabt because the guest
may happily read/write a page before hitting the icache) if the hardware
uses VIPT or PIPT.  In the latter case, we can invalidate only that
physical page.  In the first case, all bets are off and we simply must
invalidate the whole affair.  Not that VIVT icaches are tagged with
vmids, and we are out of the woods on that one.  Alexander Graf was nice
enough to remind us of this massive pain.

Reviewed-by: Will Deacon <will.deacon@arm.com>
Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <c.dall@virtualopensystems.com>

2 files changed, 14 insertions, 0 deletions

diff --git a/arch/arm/include/asm/kvm_asm.h b/arch/arm/include/asm/kvm_asm.h
index f6652f6..5e06e81 100644
--- a/arch/arm/include/asm/kvm_asm.h
+++ b/arch/arm/include/asm/kvm_asm.h
@@ -71,6 +71,8 @@ extern char __kvm_hyp_vector[];
 extern char __kvm_hyp_code_start[];
 extern char __kvm_hyp_code_end[];
 
+extern void __kvm_tlb_flush_vmid(struct kvm *kvm);
+
 extern void __kvm_flush_vm_context(void);
 extern void __kvm_tlb_flush_vmid(struct kvm *kvm);
 
diff --git a/arch/arm/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h
index 499e7b0..421a20b 100644
--- a/arch/arm/include/asm/kvm_mmu.h
+++ b/arch/arm/include/asm/kvm_mmu.h
@@ -35,4 +35,16 @@ void kvm_mmu_free_memory_caches(struct kvm_vcpu *vcpu);
 phys_addr_t kvm_mmu_get_httbr(void);
 int kvm_mmu_init(void);
 void kvm_clear_hyp_idmap(void);
+
+static inline bool kvm_is_write_fault(unsigned long hsr)
+{
+	unsigned long hsr_ec = hsr >> HSR_EC_SHIFT;
+	if (hsr_ec == HSR_EC_IABT)
+		return false;
+	else if ((hsr & HSR_ISV) && !(hsr & HSR_WNR))
+		return false;
+	else
+		return true;
+}
+
 #endif /* __ARM_KVM_MMU_H__ */