powerpc fixes for 4.18 #2

- A fix for hugetlb with 4K pages, broken by our recent changes for split PMD PTL.
 
  - Set the correct assembler machine type on e500mc, needed since binutils 2.26
    introduced two forms for the "wait" instruction.
 
  - A fix for potential missed TLB flushes with MADV_[FREE|DONTNEED] etc. and THP
    on Power9 Radix.
 
  - Three fixes to try and make our panic handling more robust by hard disabling
    interrupts, and not marking stopped CPUs as offline because they haven't been
    properly offlined.
 
  - Three other minor fixes.
 
 Thanks to:
   Aneesh Kumar K.V, Michael Jeanson, Nicholas Piggin.
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Merge tag 'powerpc-4.18-2' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux

Pull powerpc fixes from Michael Ellerman:

 - a fix for hugetlb with 4K pages, broken by our recent changes for
   split PMD PTL.

 - set the correct assembler machine type on e500mc, needed since
   binutils 2.26 introduced two forms for the "wait" instruction.

 - a fix for potential missed TLB flushes with MADV_[FREE|DONTNEED] etc.
   and THP on Power9 Radix.

 - three fixes to try and make our panic handling more robust by hard
   disabling interrupts, and not marking stopped CPUs as offline because
   they haven't been properly offlined.

 - three other minor fixes.

Thanks to: Aneesh Kumar K.V, Michael Jeanson, Nicholas Piggin.

* tag 'powerpc-4.18-2' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/mm/hash/4k: Free hugetlb page table caches correctly.
  powerpc/64s/radix: Fix radix_kvm_prefetch_workaround paca access of not possible CPU
  powerpc/64s: Fix build failures with CONFIG_NMI_IPI=n
  powerpc/64: hard disable irqs on the panic()ing CPU
  powerpc: smp_send_stop do not offline stopped CPUs
  powerpc/64: hard disable irqs in panic_smp_self_stop
  powerpc/64s: Fix DT CPU features Power9 DD2.1 logic
  powerpc/64s/radix: Fix MADV_[FREE|DONTNEED] TLB flush miss problem with THP
  powerpc/e500mc: Set assembler machine type to e500mc

arch/powerpc/Makefile

@@ -244,6 +244,7 @@ cpu-as-$(CONFIG_4xx)		+= -Wa,-m405
 cpu-as-$(CONFIG_ALTIVEC)	+= $(call as-option,-Wa$(comma)-maltivec)
 cpu-as-$(CONFIG_E200)		+= -Wa,-me200
 cpu-as-$(CONFIG_PPC_BOOK3S_64)	+= -Wa,-mpower4
+cpu-as-$(CONFIG_PPC_E500MC)	+= $(call as-option,-Wa$(comma)-me500mc)
 
 KBUILD_AFLAGS += $(cpu-as-y)
 KBUILD_CFLAGS += $(cpu-as-y)

arch/powerpc/include/asm/book3s/32/pgalloc.h

@@ -108,6 +108,7 @@ static inline void pgtable_free(void *table, unsigned index_size)
 }
 
 #define check_pgt_cache()	do { } while (0)
+#define get_hugepd_cache_index(x)  (x)
 
 #ifdef CONFIG_SMP
 static inline void pgtable_free_tlb(struct mmu_gather *tlb,

arch/powerpc/include/asm/book3s/64/pgtable-4k.h

@@ -49,6 +49,27 @@ static inline int hugepd_ok(hugepd_t hpd)
 }
 #define is_hugepd(hpd)		(hugepd_ok(hpd))
 
+/*
+ * 16M and 16G huge page directory tables are allocated from slab cache
+ *
+ */
+#define H_16M_CACHE_INDEX (PAGE_SHIFT + H_PTE_INDEX_SIZE + H_PMD_INDEX_SIZE - 24)
+#define H_16G_CACHE_INDEX                                                      \
+	(PAGE_SHIFT + H_PTE_INDEX_SIZE + H_PMD_INDEX_SIZE + H_PUD_INDEX_SIZE - 34)
+
+static inline int get_hugepd_cache_index(int index)
+{
+	switch (index) {
+	case H_16M_CACHE_INDEX:
+		return HTLB_16M_INDEX;
+	case H_16G_CACHE_INDEX:
+		return HTLB_16G_INDEX;
+	default:
+		BUG();
+	}
+	/* should not reach */
+}
+
 #else /* !CONFIG_HUGETLB_PAGE */
 static inline int pmd_huge(pmd_t pmd) { return 0; }
 static inline int pud_huge(pud_t pud) { return 0; }

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

@@ -45,8 +45,17 @@ static inline int hugepd_ok(hugepd_t hpd)
 {
 	return 0;
 }
+
 #define is_hugepd(pdep)			0
 
+/*
+ * This should never get called
+ */
+static inline int get_hugepd_cache_index(int index)
+{
+	BUG();
+}
+
 #else /* !CONFIG_HUGETLB_PAGE */
 static inline int pmd_huge(pmd_t pmd) { return 0; }
 static inline int pud_huge(pud_t pud) { return 0; }

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

@@ -287,6 +287,11 @@ enum pgtable_index {
 	PMD_INDEX,
 	PUD_INDEX,
 	PGD_INDEX,
+	/*
+	 * Below are used with 4k page size and hugetlb
+	 */
+	HTLB_16M_INDEX,
+	HTLB_16G_INDEX,
 };
 
 extern unsigned long __vmalloc_start;

arch/powerpc/include/asm/nmi.h

@@ -8,7 +8,7 @@ extern void arch_touch_nmi_watchdog(void);
 static inline void arch_touch_nmi_watchdog(void) {}
 #endif
 
-#if defined(CONFIG_PPC_BOOK3S_64) && defined(CONFIG_STACKTRACE)
+#if defined(CONFIG_NMI_IPI) && defined(CONFIG_STACKTRACE)
 extern void arch_trigger_cpumask_backtrace(const cpumask_t *mask,
 					   bool exclude_self);
 #define arch_trigger_cpumask_backtrace arch_trigger_cpumask_backtrace

arch/powerpc/include/asm/nohash/32/pgalloc.h

@@ -109,6 +109,7 @@ static inline void pgtable_free(void *table, unsigned index_size)
 }
 
 #define check_pgt_cache()	do { } while (0)
+#define get_hugepd_cache_index(x)	(x)
 
 #ifdef CONFIG_SMP
 static inline void pgtable_free_tlb(struct mmu_gather *tlb,

arch/powerpc/include/asm/nohash/64/pgalloc.h

@@ -141,6 +141,7 @@ static inline void pgtable_free(void *table, int shift)
 	}
 }
 
+#define get_hugepd_cache_index(x)	(x)
 #ifdef CONFIG_SMP
 static inline void pgtable_free_tlb(struct mmu_gather *tlb, void *table, int shift)
 {

arch/powerpc/kernel/dt_cpu_ftrs.c

@@ -711,7 +711,8 @@ static __init void cpufeatures_cpu_quirks(void)
 		cur_cpu_spec->cpu_features |= CPU_FTR_P9_TM_HV_ASSIST;
 		cur_cpu_spec->cpu_features |= CPU_FTR_P9_TM_XER_SO_BUG;
 		cur_cpu_spec->cpu_features |= CPU_FTR_POWER9_DD2_1;
-	} else /* DD2.1 and up have DD2_1 */
+	} else if ((version & 0xffff0000) == 0x004e0000)
+		/* DD2.1 and up have DD2_1 */
 		cur_cpu_spec->cpu_features |= CPU_FTR_POWER9_DD2_1;
 
 	if ((version & 0xffff0000) == 0x004e0000) {

arch/powerpc/kernel/setup-common.c

@@ -700,12 +700,19 @@ EXPORT_SYMBOL(check_legacy_ioport);
 static int ppc_panic_event(struct notifier_block *this,
                              unsigned long event, void *ptr)
 {
+	/*
+	 * panic does a local_irq_disable, but we really
+	 * want interrupts to be hard disabled.
+	 */
+	hard_irq_disable();
+
 	/*
 	 * If firmware-assisted dump has been registered then trigger
 	 * firmware-assisted dump and let firmware handle everything else.
 	 */
 	crash_fadump(NULL, ptr);
-	ppc_md.panic(ptr);  /* May not return */
+	if (ppc_md.panic)
+		ppc_md.panic(ptr);  /* May not return */
 	return NOTIFY_DONE;
 }
 
@@ -716,7 +723,8 @@ static struct notifier_block ppc_panic_block = {
 
 void __init setup_panic(void)
 {
-	if (!ppc_md.panic)
+	/* PPC64 always does a hard irq disable in its panic handler */
+	if (!IS_ENABLED(CONFIG_PPC64) && !ppc_md.panic)
 		return;
 	atomic_notifier_chain_register(&panic_notifier_list, &ppc_panic_block);
 }

arch/powerpc/kernel/setup_64.c

@@ -387,6 +387,14 @@ void early_setup_secondary(void)
 
 #endif /* CONFIG_SMP */
 
+void panic_smp_self_stop(void)
+{
+	hard_irq_disable();
+	spin_begin();
+	while (1)
+		spin_cpu_relax();
+}
+
 #if defined(CONFIG_SMP) || defined(CONFIG_KEXEC_CORE)
 static bool use_spinloop(void)
 {

arch/powerpc/kernel/smp.c

@@ -600,9 +600,6 @@ static void nmi_stop_this_cpu(struct pt_regs *regs)
 	nmi_ipi_busy_count--;
 	nmi_ipi_unlock();
 
-	/* Remove this CPU */
-	set_cpu_online(smp_processor_id(), false);
-
 	spin_begin();
 	while (1)
 		spin_cpu_relax();
@@ -617,9 +614,6 @@ void smp_send_stop(void)
 
 static void stop_this_cpu(void *dummy)
 {
-	/* Remove this CPU */
-	set_cpu_online(smp_processor_id(), false);
-
 	hard_irq_disable();
 	spin_begin();
 	while (1)

arch/powerpc/kernel/stacktrace.c

@@ -196,7 +196,7 @@ save_stack_trace_tsk_reliable(struct task_struct *tsk,
 EXPORT_SYMBOL_GPL(save_stack_trace_tsk_reliable);
 #endif /* CONFIG_HAVE_RELIABLE_STACKTRACE */
 
-#ifdef CONFIG_PPC_BOOK3S_64
+#if defined(CONFIG_PPC_BOOK3S_64) && defined(CONFIG_NMI_IPI)
 static void handle_backtrace_ipi(struct pt_regs *regs)
 {
 	nmi_cpu_backtrace(regs);
@@ -242,4 +242,4 @@ void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
 {
 	nmi_trigger_cpumask_backtrace(mask, exclude_self, raise_backtrace_ipi);
 }
-#endif /* CONFIG_PPC64 */
+#endif /* defined(CONFIG_PPC_BOOK3S_64) && defined(CONFIG_NMI_IPI) */

arch/powerpc/mm/hugetlbpage.c

@@ -337,7 +337,8 @@ static void free_hugepd_range(struct mmu_gather *tlb, hugepd_t *hpdp, int pdshif
 	if (shift >= pdshift)
 		hugepd_free(tlb, hugepte);
 	else
-		pgtable_free_tlb(tlb, hugepte, pdshift - shift);
+		pgtable_free_tlb(tlb, hugepte,
+				 get_hugepd_cache_index(pdshift - shift));
 }
 
 static void hugetlb_free_pmd_range(struct mmu_gather *tlb, pud_t *pud,

arch/powerpc/mm/pgtable-book3s64.c

@@ -409,6 +409,18 @@ static inline void pgtable_free(void *table, int index)
 	case PUD_INDEX:
 		kmem_cache_free(PGT_CACHE(PUD_CACHE_INDEX), table);
 		break;
+#if defined(CONFIG_PPC_4K_PAGES) && defined(CONFIG_HUGETLB_PAGE)
+		/* 16M hugepd directory at pud level */
+	case HTLB_16M_INDEX:
+		BUILD_BUG_ON(H_16M_CACHE_INDEX <= 0);
+		kmem_cache_free(PGT_CACHE(H_16M_CACHE_INDEX), table);
+		break;
+		/* 16G hugepd directory at the pgd level */
+	case HTLB_16G_INDEX:
+		BUILD_BUG_ON(H_16G_CACHE_INDEX <= 0);
+		kmem_cache_free(PGT_CACHE(H_16G_CACHE_INDEX), table);
+		break;
+#endif
 		/* We don't free pgd table via RCU callback */
 	default:
 		BUG();

arch/powerpc/mm/tlb-radix.c

@@ -689,22 +689,17 @@ EXPORT_SYMBOL(radix__flush_tlb_kernel_range);
 static unsigned long tlb_single_page_flush_ceiling __read_mostly = 33;
 static unsigned long tlb_local_single_page_flush_ceiling __read_mostly = POWER9_TLB_SETS_RADIX * 2;
 
-void radix__flush_tlb_range(struct vm_area_struct *vma, unsigned long start,
-		     unsigned long end)
+static inline void __radix__flush_tlb_range(struct mm_struct *mm,
+					unsigned long start, unsigned long end,
+					bool flush_all_sizes)
 
 {
-	struct mm_struct *mm = vma->vm_mm;
 	unsigned long pid;
 	unsigned int page_shift = mmu_psize_defs[mmu_virtual_psize].shift;
 	unsigned long page_size = 1UL << page_shift;
 	unsigned long nr_pages = (end - start) >> page_shift;
 	bool local, full;
 
-#ifdef CONFIG_HUGETLB_PAGE
-	if (is_vm_hugetlb_page(vma))
-		return radix__flush_hugetlb_tlb_range(vma, start, end);
-#endif
-
 	pid = mm->context.id;
 	if (unlikely(pid == MMU_NO_CONTEXT))
 		return;
@@ -738,37 +733,64 @@ is_local:
 				_tlbie_pid(pid, RIC_FLUSH_TLB);
 		}
 	} else {
-		bool hflush = false;
+		bool hflush = flush_all_sizes;
+		bool gflush = flush_all_sizes;
 		unsigned long hstart, hend;
+		unsigned long gstart, gend;
 
-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
-		hstart = (start + HPAGE_PMD_SIZE - 1) >> HPAGE_PMD_SHIFT;
-		hend = end >> HPAGE_PMD_SHIFT;
-		if (hstart < hend) {
-			hstart <<= HPAGE_PMD_SHIFT;
-			hend <<= HPAGE_PMD_SHIFT;
+		if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
 			hflush = true;
+
+		if (hflush) {
+			hstart = (start + PMD_SIZE - 1) & PMD_MASK;
+			hend = end & PMD_MASK;
+			if (hstart == hend)
+				hflush = false;
+		}
+
+		if (gflush) {
+			gstart = (start + PUD_SIZE - 1) & PUD_MASK;
+			gend = end & PUD_MASK;
+			if (gstart == gend)
+				gflush = false;
 		}
-#endif
 
 		asm volatile("ptesync": : :"memory");
 		if (local) {
 			__tlbiel_va_range(start, end, pid, page_size, mmu_virtual_psize);
 			if (hflush)
 				__tlbiel_va_range(hstart, hend, pid,
-						HPAGE_PMD_SIZE, MMU_PAGE_2M);
+						PMD_SIZE, MMU_PAGE_2M);
+			if (gflush)
+				__tlbiel_va_range(gstart, gend, pid,
+						PUD_SIZE, MMU_PAGE_1G);
 			asm volatile("ptesync": : :"memory");
 		} else {
 			__tlbie_va_range(start, end, pid, page_size, mmu_virtual_psize);
 			if (hflush)
 				__tlbie_va_range(hstart, hend, pid,
-						HPAGE_PMD_SIZE, MMU_PAGE_2M);
+						PMD_SIZE, MMU_PAGE_2M);
+			if (gflush)
+				__tlbie_va_range(gstart, gend, pid,
+						PUD_SIZE, MMU_PAGE_1G);
 			fixup_tlbie();
 			asm volatile("eieio; tlbsync; ptesync": : :"memory");
 		}
 	}
 	preempt_enable();
 }
+
+void radix__flush_tlb_range(struct vm_area_struct *vma, unsigned long start,
+		     unsigned long end)
+
+{
+#ifdef CONFIG_HUGETLB_PAGE
+	if (is_vm_hugetlb_page(vma))
+		return radix__flush_hugetlb_tlb_range(vma, start, end);
+#endif
+
+	__radix__flush_tlb_range(vma->vm_mm, start, end, false);
+}
 EXPORT_SYMBOL(radix__flush_tlb_range);
 
 static int radix_get_mmu_psize(int page_size)
@@ -837,6 +859,8 @@ void radix__tlb_flush(struct mmu_gather *tlb)
 	int psize = 0;
 	struct mm_struct *mm = tlb->mm;
 	int page_size = tlb->page_size;
+	unsigned long start = tlb->start;
+	unsigned long end = tlb->end;
 
 	/*
 	 * if page size is not something we understand, do a full mm flush
@@ -847,15 +871,45 @@ void radix__tlb_flush(struct mmu_gather *tlb)
 	 */
 	if (tlb->fullmm) {
 		__flush_all_mm(mm, true);
+#if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLB_PAGE)
+	} else if (mm_tlb_flush_nested(mm)) {
+		/*
+		 * If there is a concurrent invalidation that is clearing ptes,
+		 * then it's possible this invalidation will miss one of those
+		 * cleared ptes and miss flushing the TLB. If this invalidate
+		 * returns before the other one flushes TLBs, that can result
+		 * in it returning while there are still valid TLBs inside the
+		 * range to be invalidated.
+		 *
+		 * See mm/memory.c:tlb_finish_mmu() for more details.
+		 *
+		 * The solution to this is ensure the entire range is always
+		 * flushed here. The problem for powerpc is that the flushes
+		 * are page size specific, so this "forced flush" would not
+		 * do the right thing if there are a mix of page sizes in
+		 * the range to be invalidated. So use __flush_tlb_range
+		 * which invalidates all possible page sizes in the range.
+		 *
+		 * PWC flush probably is not be required because the core code
+		 * shouldn't free page tables in this path, but accounting
+		 * for the possibility makes us a bit more robust.
+		 *
+		 * need_flush_all is an uncommon case because page table
+		 * teardown should be done with exclusive locks held (but
+		 * after locks are dropped another invalidate could come
+		 * in), it could be optimized further if necessary.
+		 */
+		if (!tlb->need_flush_all)
+			__radix__flush_tlb_range(mm, start, end, true);
+		else
+			radix__flush_all_mm(mm);
+#endif
 	} else if ( (psize = radix_get_mmu_psize(page_size)) == -1) {
 		if (!tlb->need_flush_all)
 			radix__flush_tlb_mm(mm);
 		else
 			radix__flush_all_mm(mm);
 	} else {
-		unsigned long start = tlb->start;
-		unsigned long end = tlb->end;
-
 		if (!tlb->need_flush_all)
 			radix__flush_tlb_range_psize(mm, start, end, psize);
 		else
@@ -1043,6 +1097,8 @@ extern void radix_kvm_prefetch_workaround(struct mm_struct *mm)
 		for (; sib <= cpu_last_thread_sibling(cpu) && !flush; sib++) {
 			if (sib == cpu)
 				continue;
+			if (!cpu_possible(sib))
+				continue;
 			if (paca_ptrs[sib]->kvm_hstate.kvm_vcpu)
 				flush = true;
 		}