KVM: PPC: Book3S HV: Clear the key field of HPTE when the page is paged out

Currently we mark a HPTE for emulated MMIO with HPTE_V_ABSENT bit
set as well as key 0x1f. However, those HPTEs may be conflicted with
the HPTE for real guest RAM page HPTE with key 0x1f when the page
get paged out.

This patch clears the key field of HPTE when the page is paged out,
then recover it when HPTE is re-established.
Signed-off-by: Yongji Xie <xyjxie@linux.vnet.ibm.com>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>

arch/powerpc/kvm/book3s_64_mmu_hv.c

@@ -575,7 +575,8 @@ int kvmppc_book3s_hv_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu,
 	 */
 	if (psize < PAGE_SIZE)
 		psize = PAGE_SIZE;
-	r = (r & ~(HPTE_R_PP0 - psize)) | ((pfn << PAGE_SHIFT) & ~(psize - 1));
+	r = (r & HPTE_R_KEY_HI) | (r & ~(HPTE_R_PP0 - psize)) |
+					((pfn << PAGE_SHIFT) & ~(psize - 1));
 	if (hpte_is_writable(r) && !write_ok)
 		r = hpte_make_readonly(r);
 	ret = RESUME_GUEST;
@@ -758,6 +759,7 @@ static int kvm_unmap_rmapp(struct kvm *kvm, unsigned long *rmapp,
 		    hpte_rpn(ptel, psize) == gfn) {
 			hptep[0] |= cpu_to_be64(HPTE_V_ABSENT);
 			kvmppc_invalidate_hpte(kvm, hptep, i);
+			hptep[1] &= ~cpu_to_be64(HPTE_R_KEY_HI | HPTE_R_KEY_LO);
 			/* Harvest R and C */
 			rcbits = be64_to_cpu(hptep[1]) & (HPTE_R_R | HPTE_R_C);
 			*rmapp |= rcbits << KVMPPC_RMAP_RC_SHIFT;

arch/powerpc/kvm/book3s_hv_rm_mmu.c

@@ -265,8 +265,10 @@ long kvmppc_do_h_enter(struct kvm *kvm, unsigned long flags,
 
 	if (pa)
 		pteh |= HPTE_V_VALID;
-	else
+	else {
 		pteh |= HPTE_V_ABSENT;
+		ptel &= ~(HPTE_R_KEY_HI | HPTE_R_KEY_LO);
+	}
 
 	/*If we had host pte mapping then  Check WIMG */
 	if (ptep && !hpte_cache_flags_ok(ptel, is_ci)) {
@@ -352,6 +354,7 @@ long kvmppc_do_h_enter(struct kvm *kvm, unsigned long flags,
 			/* inval in progress, write a non-present HPTE */
 			pteh |= HPTE_V_ABSENT;
 			pteh &= ~HPTE_V_VALID;
+			ptel &= ~(HPTE_R_KEY_HI | HPTE_R_KEY_LO);
 			unlock_rmap(rmap);
 		} else {
 			kvmppc_add_revmap_chain(kvm, rev, rmap, pte_index,