Merge tag 'powerpc-5.0-4' of git://git.kernel.org/pub/scm/linux/kerne…

…l/git/powerpc/linux

Pull powerpc fixes from Michael Ellerman:
 "Just two fixes, both going to stable.

   - Our support for split pmd page table lock had a bug which could
     lead to a crash on mremap() when using the Radix MMU (Power9 only).

   - A fix for the PAPR SCM driver (nvdimm) we added last release, which
     had a bug where we might mis-handle a hypervisor response leading
     to us failing to attach the memory region.

  Thanks to: Aneesh Kumar K.V, Oliver O'Halloran"

* tag 'powerpc-5.0-4' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/papr_scm: Use the correct bind address
  powerpc/radix: Fix kernel crash with mremap()

arch/powerpc/include/asm/book3s/64/pgtable.h

@@ -1258,21 +1258,13 @@ extern pmd_t pmdp_invalidate(struct vm_area_struct *vma, unsigned long address,
 
 #define pmd_move_must_withdraw pmd_move_must_withdraw
 struct spinlock;
-static inline int pmd_move_must_withdraw(struct spinlock *new_pmd_ptl,
-					 struct spinlock *old_pmd_ptl,
-					 struct vm_area_struct *vma)
-{
-	if (radix_enabled())
-		return false;
-	/*
-	 * Archs like ppc64 use pgtable to store per pmd
-	 * specific information. So when we switch the pmd,
-	 * we should also withdraw and deposit the pgtable
-	 */
-	return true;
-}
-
-
+extern int pmd_move_must_withdraw(struct spinlock *new_pmd_ptl,
+				  struct spinlock *old_pmd_ptl,
+				  struct vm_area_struct *vma);
+/*
+ * Hash translation mode use the deposited table to store hash pte
+ * slot information.
+ */
 #define arch_needs_pgtable_deposit arch_needs_pgtable_deposit
 static inline bool arch_needs_pgtable_deposit(void)
 {

arch/powerpc/mm/pgtable-book3s64.c

@@ -400,3 +400,25 @@ void arch_report_meminfo(struct seq_file *m)
 		   atomic_long_read(&direct_pages_count[MMU_PAGE_1G]) << 20);
 }
 #endif /* CONFIG_PROC_FS */
+
+/*
+ * For hash translation mode, we use the deposited table to store hash slot
+ * information and they are stored at PTRS_PER_PMD offset from related pmd
+ * location. Hence a pmd move requires deposit and withdraw.
+ *
+ * For radix translation with split pmd ptl, we store the deposited table in the
+ * pmd page. Hence if we have different pmd page we need to withdraw during pmd
+ * move.
+ *
+ * With hash we use deposited table always irrespective of anon or not.
+ * With radix we use deposited table only for anonymous mapping.
+ */
+int pmd_move_must_withdraw(struct spinlock *new_pmd_ptl,
+			   struct spinlock *old_pmd_ptl,
+			   struct vm_area_struct *vma)
+{
+	if (radix_enabled())
+		return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma);
+
+	return true;
+}

arch/powerpc/platforms/pseries/papr_scm.c

@@ -43,6 +43,7 @@ static int drc_pmem_bind(struct papr_scm_priv *p)
 {
 	unsigned long ret[PLPAR_HCALL_BUFSIZE];
 	uint64_t rc, token;
+	uint64_t saved = 0;
 
 	/*
 	 * When the hypervisor cannot map all the requested memory in a single
@@ -56,6 +57,8 @@ static int drc_pmem_bind(struct papr_scm_priv *p)
 		rc = plpar_hcall(H_SCM_BIND_MEM, ret, p->drc_index, 0,
 				p->blocks, BIND_ANY_ADDR, token);
 		token = ret[0];
+		if (!saved)
+			saved = ret[1];
 		cond_resched();
 	} while (rc == H_BUSY);
 
@@ -64,7 +67,7 @@ static int drc_pmem_bind(struct papr_scm_priv *p)
 		return -ENXIO;
 	}
 
-	p->bound_addr = ret[1];
+	p->bound_addr = saved;
 
 	dev_dbg(&p->pdev->dev, "bound drc %x to %pR\n", p->drc_index, &p->res);