powerpc/kvm/book3s: Add helper to walk partition scoped linux page table.

The locking rules for walking partition scoped table is different from process
scoped table. Hence add a helper for secondary linux page table walk and also
add check whether we are holding the right locks.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200505071729.54912-10-aneesh.kumar@linux.ibm.com

arch/powerpc/include/asm/kvm_book3s_64.h

@@ -14,6 +14,7 @@
 #include <asm/book3s/64/mmu-hash.h>
 #include <asm/cpu_has_feature.h>
 #include <asm/ppc-opcode.h>
+#include <asm/pte-walk.h>
 
 #ifdef CONFIG_PPC_PSERIES
 static inline bool kvmhv_on_pseries(void)
@@ -634,6 +635,18 @@ extern void kvmhv_remove_nest_rmap_range(struct kvm *kvm,
 				unsigned long gpa, unsigned long hpa,
 				unsigned long nbytes);
 
+static inline pte_t *find_kvm_secondary_pte(struct kvm *kvm, unsigned long ea,
+					    unsigned *hshift)
+{
+	pte_t *pte;
+
+	VM_WARN(!spin_is_locked(&kvm->mmu_lock),
+		"%s called with kvm mmu_lock not held \n", __func__);
+	pte = __find_linux_pte(kvm->arch.pgtable, ea, NULL, hshift);
+
+	return pte;
+}
+
 #endif /* CONFIG_KVM_BOOK3S_HV_POSSIBLE */
 
 #endif /* __ASM_KVM_BOOK3S_64_H__ */

arch/powerpc/kvm/book3s_64_mmu_radix.c

@@ -981,7 +981,7 @@ int kvm_unmap_radix(struct kvm *kvm, struct kvm_memory_slot *memslot,
 		return 0;
 	}
 
-	ptep = __find_linux_pte(kvm->arch.pgtable, gpa, NULL, &shift);
+	ptep = find_kvm_secondary_pte(kvm, gpa, &shift);
 	if (ptep && pte_present(*ptep))
 		kvmppc_unmap_pte(kvm, ptep, gpa, shift, memslot,
 				 kvm->arch.lpid);
@@ -1001,7 +1001,7 @@ int kvm_age_radix(struct kvm *kvm, struct kvm_memory_slot *memslot,
 	if (kvm->arch.secure_guest & KVMPPC_SECURE_INIT_DONE)
 		return ref;
 
-	ptep = __find_linux_pte(kvm->arch.pgtable, gpa, NULL, &shift);
+	ptep = find_kvm_secondary_pte(kvm, gpa, &shift);
 	if (ptep && pte_present(*ptep) && pte_young(*ptep)) {
 		old = kvmppc_radix_update_pte(kvm, ptep, _PAGE_ACCESSED, 0,
 					      gpa, shift);
@@ -1028,7 +1028,7 @@ int kvm_test_age_radix(struct kvm *kvm, struct kvm_memory_slot *memslot,
 	if (kvm->arch.secure_guest & KVMPPC_SECURE_INIT_DONE)
 		return ref;
 
-	ptep = __find_linux_pte(kvm->arch.pgtable, gpa, NULL, &shift);
+	ptep = find_kvm_secondary_pte(kvm, gpa, &shift);
 	if (ptep && pte_present(*ptep) && pte_young(*ptep))
 		ref = 1;
 	return ref;
@@ -1048,7 +1048,7 @@ static int kvm_radix_test_clear_dirty(struct kvm *kvm,
 	if (kvm->arch.secure_guest & KVMPPC_SECURE_INIT_DONE)
 		return ret;
 
-	ptep = __find_linux_pte(kvm->arch.pgtable, gpa, NULL, &shift);
+	ptep = find_kvm_secondary_pte(kvm, gpa, &shift);
 	if (ptep && pte_present(*ptep) && pte_dirty(*ptep)) {
 		ret = 1;
 		if (shift)
@@ -1109,7 +1109,7 @@ void kvmppc_radix_flush_memslot(struct kvm *kvm,
 	gpa = memslot->base_gfn << PAGE_SHIFT;
 	spin_lock(&kvm->mmu_lock);
 	for (n = memslot->npages; n; --n) {
-		ptep = __find_linux_pte(kvm->arch.pgtable, gpa, NULL, &shift);
+		ptep = find_kvm_secondary_pte(kvm, gpa, &shift);
 		if (ptep && pte_present(*ptep))
 			kvmppc_unmap_pte(kvm, ptep, gpa, shift, memslot,
 					 kvm->arch.lpid);

arch/powerpc/kvm/book3s_hv_nested.c

@@ -1362,7 +1362,7 @@ static long int __kvmhv_nested_page_fault(struct kvm_run *run,
 	/* See if can find translation in our partition scoped tables for L1 */
 	pte = __pte(0);
 	spin_lock(&kvm->mmu_lock);
-	pte_p = __find_linux_pte(kvm->arch.pgtable, gpa, NULL, &shift);
+	pte_p = find_kvm_secondary_pte(kvm, gpa, &shift);
 	if (!shift)
 		shift = PAGE_SHIFT;
 	if (pte_p)