Merge tag 'kvm-ppc-fixes-4.19-2' of git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc into HEAD

Second set of PPC KVM fixes for 4.19

Two fixes for KVM on POWER machines.  Both of these relate to memory
corruption and host crashes seen when transparent huge pages are
enabled.  The first fixes a host crash that can occur when a DMA
mapping is removed by the guest and the page mapped was part of a
transparent huge page; the second fixes corruption that could occur
when a hypervisor page fault for a radix guest is being serviced at
the same time that the backing page is being collapsed or split.

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

@@ -1051,7 +1051,6 @@ static inline void vmemmap_remove_mapping(unsigned long start,
 	return hash__vmemmap_remove_mapping(start, page_size);
 }
 #endif
-struct page *realmode_pfn_to_page(unsigned long pfn);
 
 static inline pte_t pmd_pte(pmd_t pmd)
 {

arch/powerpc/include/asm/iommu.h

@@ -220,8 +220,6 @@ extern void iommu_del_device(struct device *dev);
 extern int __init tce_iommu_bus_notifier_init(void);
 extern long iommu_tce_xchg(struct iommu_table *tbl, unsigned long entry,
 		unsigned long *hpa, enum dma_data_direction *direction);
-extern long iommu_tce_xchg_rm(struct iommu_table *tbl, unsigned long entry,
-		unsigned long *hpa, enum dma_data_direction *direction);
 #else
 static inline void iommu_register_group(struct iommu_table_group *table_group,
 					int pci_domain_number,

arch/powerpc/include/asm/mmu_context.h

@@ -38,6 +38,7 @@ extern long mm_iommu_ua_to_hpa(struct mm_iommu_table_group_mem_t *mem,
 		unsigned long ua, unsigned int pageshift, unsigned long *hpa);
 extern long mm_iommu_ua_to_hpa_rm(struct mm_iommu_table_group_mem_t *mem,
 		unsigned long ua, unsigned int pageshift, unsigned long *hpa);
+extern void mm_iommu_ua_mark_dirty_rm(struct mm_struct *mm, unsigned long ua);
 extern long mm_iommu_mapped_inc(struct mm_iommu_table_group_mem_t *mem);
 extern void mm_iommu_mapped_dec(struct mm_iommu_table_group_mem_t *mem);
 #endif

arch/powerpc/kernel/iommu.c

@@ -1013,31 +1013,6 @@ long iommu_tce_xchg(struct iommu_table *tbl, unsigned long entry,
 }
 EXPORT_SYMBOL_GPL(iommu_tce_xchg);
 
-#ifdef CONFIG_PPC_BOOK3S_64
-long iommu_tce_xchg_rm(struct iommu_table *tbl, unsigned long entry,
-		unsigned long *hpa, enum dma_data_direction *direction)
-{
-	long ret;
-
-	ret = tbl->it_ops->exchange_rm(tbl, entry, hpa, direction);
-
-	if (!ret && ((*direction == DMA_FROM_DEVICE) ||
-			(*direction == DMA_BIDIRECTIONAL))) {
-		struct page *pg = realmode_pfn_to_page(*hpa >> PAGE_SHIFT);
-
-		if (likely(pg)) {
-			SetPageDirty(pg);
-		} else {
-			tbl->it_ops->exchange_rm(tbl, entry, hpa, direction);
-			ret = -EFAULT;
-		}
-	}
-
-	return ret;
-}
-EXPORT_SYMBOL_GPL(iommu_tce_xchg_rm);
-#endif
-
 int iommu_take_ownership(struct iommu_table *tbl)
 {
 	unsigned long flags, i, sz = (tbl->it_size + 7) >> 3;

arch/powerpc/kvm/book3s_64_mmu_radix.c

@@ -525,8 +525,8 @@ int kvmppc_book3s_radix_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu,
 				   unsigned long ea, unsigned long dsisr)
 {
 	struct kvm *kvm = vcpu->kvm;
-	unsigned long mmu_seq, pte_size;
-	unsigned long gpa, gfn, hva, pfn;
+	unsigned long mmu_seq;
+	unsigned long gpa, gfn, hva;
 	struct kvm_memory_slot *memslot;
 	struct page *page = NULL;
 	long ret;
@@ -623,9 +623,10 @@ int kvmppc_book3s_radix_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu,
 	 */
 	hva = gfn_to_hva_memslot(memslot, gfn);
 	if (upgrade_p && __get_user_pages_fast(hva, 1, 1, &page) == 1) {
-		pfn = page_to_pfn(page);
 		upgrade_write = true;
 	} else {
+		unsigned long pfn;
+
 		/* Call KVM generic code to do the slow-path check */
 		pfn = __gfn_to_pfn_memslot(memslot, gfn, false, NULL,
 					   writing, upgrade_p);
@@ -639,63 +640,45 @@ int kvmppc_book3s_radix_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu,
 		}
 	}
 
-	/* See if we can insert a 1GB or 2MB large PTE here */
-	level = 0;
-	if (page && PageCompound(page)) {
-		pte_size = PAGE_SIZE << compound_order(compound_head(page));
-		if (pte_size >= PUD_SIZE &&
-		    (gpa & (PUD_SIZE - PAGE_SIZE)) ==
-		    (hva & (PUD_SIZE - PAGE_SIZE))) {
-			level = 2;
-			pfn &= ~((PUD_SIZE >> PAGE_SHIFT) - 1);
-		} else if (pte_size >= PMD_SIZE &&
-			   (gpa & (PMD_SIZE - PAGE_SIZE)) ==
-			   (hva & (PMD_SIZE - PAGE_SIZE))) {
-			level = 1;
-			pfn &= ~((PMD_SIZE >> PAGE_SHIFT) - 1);
-		}
-	}
-
 	/*
-	 * Compute the PTE value that we need to insert.
+	 * Read the PTE from the process' radix tree and use that
+	 * so we get the shift and attribute bits.
 	 */
-	if (page) {
-		pgflags = _PAGE_READ | _PAGE_EXEC | _PAGE_PRESENT | _PAGE_PTE |
-			_PAGE_ACCESSED;
-		if (writing || upgrade_write)
-			pgflags |= _PAGE_WRITE | _PAGE_DIRTY;
-		pte = pfn_pte(pfn, __pgprot(pgflags));
+	local_irq_disable();
+	ptep = __find_linux_pte(vcpu->arch.pgdir, hva, NULL, &shift);
+	pte = *ptep;
+	local_irq_enable();
+
+	/* Get pte level from shift/size */
+	if (shift == PUD_SHIFT &&
+	    (gpa & (PUD_SIZE - PAGE_SIZE)) ==
+	    (hva & (PUD_SIZE - PAGE_SIZE))) {
+		level = 2;
+	} else if (shift == PMD_SHIFT &&
+		   (gpa & (PMD_SIZE - PAGE_SIZE)) ==
+		   (hva & (PMD_SIZE - PAGE_SIZE))) {
+		level = 1;
 	} else {
-		/*
-		 * Read the PTE from the process' radix tree and use that
-		 * so we get the attribute bits.
-		 */
-		local_irq_disable();
-		ptep = __find_linux_pte(vcpu->arch.pgdir, hva, NULL, &shift);
-		pte = *ptep;
-		local_irq_enable();
-		if (shift == PUD_SHIFT &&
-		    (gpa & (PUD_SIZE - PAGE_SIZE)) ==
-		    (hva & (PUD_SIZE - PAGE_SIZE))) {
-			level = 2;
-		} else if (shift == PMD_SHIFT &&
-			   (gpa & (PMD_SIZE - PAGE_SIZE)) ==
-			   (hva & (PMD_SIZE - PAGE_SIZE))) {
-			level = 1;
-		} else if (shift && shift != PAGE_SHIFT) {
-			/* Adjust PFN */
-			unsigned long mask = (1ul << shift) - PAGE_SIZE;
-			pte = __pte(pte_val(pte) | (hva & mask));
-		}
-		pte = __pte(pte_val(pte) | _PAGE_EXEC | _PAGE_ACCESSED);
-		if (writing || upgrade_write) {
-			if (pte_val(pte) & _PAGE_WRITE)
-				pte = __pte(pte_val(pte) | _PAGE_DIRTY);
-		} else {
-			pte = __pte(pte_val(pte) & ~(_PAGE_WRITE | _PAGE_DIRTY));
+		level = 0;
+		if (shift > PAGE_SHIFT) {
+			/*
+			 * If the pte maps more than one page, bring over
+			 * bits from the virtual address to get the real
+			 * address of the specific single page we want.
+			 */
+			unsigned long rpnmask = (1ul << shift) - PAGE_SIZE;
+			pte = __pte(pte_val(pte) | (hva & rpnmask));
 		}
 	}
 
+	pte = __pte(pte_val(pte) | _PAGE_EXEC | _PAGE_ACCESSED);
+	if (writing || upgrade_write) {
+		if (pte_val(pte) & _PAGE_WRITE)
+			pte = __pte(pte_val(pte) | _PAGE_DIRTY);
+	} else {
+		pte = __pte(pte_val(pte) & ~(_PAGE_WRITE | _PAGE_DIRTY));
+	}
+
 	/* Allocate space in the tree and write the PTE */
 	ret = kvmppc_create_pte(kvm, pte, gpa, level, mmu_seq);
 

arch/powerpc/kvm/book3s_64_vio_hv.c

@@ -187,12 +187,35 @@ long kvmppc_gpa_to_ua(struct kvm *kvm, unsigned long gpa,
 EXPORT_SYMBOL_GPL(kvmppc_gpa_to_ua);
 
 #ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
-static void kvmppc_rm_clear_tce(struct iommu_table *tbl, unsigned long entry)
+static long iommu_tce_xchg_rm(struct mm_struct *mm, struct iommu_table *tbl,
+		unsigned long entry, unsigned long *hpa,
+		enum dma_data_direction *direction)
+{
+	long ret;
+
+	ret = tbl->it_ops->exchange_rm(tbl, entry, hpa, direction);
+
+	if (!ret && ((*direction == DMA_FROM_DEVICE) ||
+				(*direction == DMA_BIDIRECTIONAL))) {
+		__be64 *pua = IOMMU_TABLE_USERSPACE_ENTRY_RM(tbl, entry);
+		/*
+		 * kvmppc_rm_tce_iommu_do_map() updates the UA cache after
+		 * calling this so we still get here a valid UA.
+		 */
+		if (pua && *pua)
+			mm_iommu_ua_mark_dirty_rm(mm, be64_to_cpu(*pua));
+	}
+
+	return ret;
+}
+
+static void kvmppc_rm_clear_tce(struct kvm *kvm, struct iommu_table *tbl,
+		unsigned long entry)
 {
 	unsigned long hpa = 0;
 	enum dma_data_direction dir = DMA_NONE;
 
-	iommu_tce_xchg_rm(tbl, entry, &hpa, &dir);
+	iommu_tce_xchg_rm(kvm->mm, tbl, entry, &hpa, &dir);
 }
 
 static long kvmppc_rm_tce_iommu_mapped_dec(struct kvm *kvm,
@@ -224,7 +247,7 @@ static long kvmppc_rm_tce_iommu_do_unmap(struct kvm *kvm,
 	unsigned long hpa = 0;
 	long ret;
 
-	if (iommu_tce_xchg_rm(tbl, entry, &hpa, &dir))
+	if (iommu_tce_xchg_rm(kvm->mm, tbl, entry, &hpa, &dir))
 		/*
 		 * real mode xchg can fail if struct page crosses
 		 * a page boundary
@@ -236,7 +259,7 @@ static long kvmppc_rm_tce_iommu_do_unmap(struct kvm *kvm,
 
 	ret = kvmppc_rm_tce_iommu_mapped_dec(kvm, tbl, entry);
 	if (ret)
-		iommu_tce_xchg_rm(tbl, entry, &hpa, &dir);
+		iommu_tce_xchg_rm(kvm->mm, tbl, entry, &hpa, &dir);
 
 	return ret;
 }
@@ -282,7 +305,7 @@ static long kvmppc_rm_tce_iommu_do_map(struct kvm *kvm, struct iommu_table *tbl,
 	if (WARN_ON_ONCE_RM(mm_iommu_mapped_inc(mem)))
 		return H_CLOSED;
 
-	ret = iommu_tce_xchg_rm(tbl, entry, &hpa, &dir);
+	ret = iommu_tce_xchg_rm(kvm->mm, tbl, entry, &hpa, &dir);
 	if (ret) {
 		mm_iommu_mapped_dec(mem);
 		/*
@@ -371,7 +394,7 @@ long kvmppc_rm_h_put_tce(struct kvm_vcpu *vcpu, unsigned long liobn,
 			return ret;
 
 		WARN_ON_ONCE_RM(1);
-		kvmppc_rm_clear_tce(stit->tbl, entry);
+		kvmppc_rm_clear_tce(vcpu->kvm, stit->tbl, entry);
 	}
 
 	kvmppc_tce_put(stt, entry, tce);
@@ -520,7 +543,7 @@ long kvmppc_rm_h_put_tce_indirect(struct kvm_vcpu *vcpu,
 				goto unlock_exit;
 
 			WARN_ON_ONCE_RM(1);
-			kvmppc_rm_clear_tce(stit->tbl, entry);
+			kvmppc_rm_clear_tce(vcpu->kvm, stit->tbl, entry);
 		}
 
 		kvmppc_tce_put(stt, entry + i, tce);
@@ -571,7 +594,7 @@ long kvmppc_rm_h_stuff_tce(struct kvm_vcpu *vcpu,
 				return ret;
 
 			WARN_ON_ONCE_RM(1);
-			kvmppc_rm_clear_tce(stit->tbl, entry);
+			kvmppc_rm_clear_tce(vcpu->kvm, stit->tbl, entry);
 		}
 	}
 

arch/powerpc/mm/init_64.c

@@ -308,55 +308,6 @@ void register_page_bootmem_memmap(unsigned long section_nr,
 {
 }
 
-/*
- * We do not have access to the sparsemem vmemmap, so we fallback to
- * walking the list of sparsemem blocks which we already maintain for
- * the sake of crashdump. In the long run, we might want to maintain
- * a tree if performance of that linear walk becomes a problem.
- *
- * realmode_pfn_to_page functions can fail due to:
- * 1) As real sparsemem blocks do not lay in RAM continously (they
- * are in virtual address space which is not available in the real mode),
- * the requested page struct can be split between blocks so get_page/put_page
- * may fail.
- * 2) When huge pages are used, the get_page/put_page API will fail
- * in real mode as the linked addresses in the page struct are virtual
- * too.
- */
-struct page *realmode_pfn_to_page(unsigned long pfn)
-{
-	struct vmemmap_backing *vmem_back;
-	struct page *page;
-	unsigned long page_size = 1 << mmu_psize_defs[mmu_vmemmap_psize].shift;
-	unsigned long pg_va = (unsigned long) pfn_to_page(pfn);
-
-	for (vmem_back = vmemmap_list; vmem_back; vmem_back = vmem_back->list) {
-		if (pg_va < vmem_back->virt_addr)
-			continue;
-
-		/* After vmemmap_list entry free is possible, need check all */
-		if ((pg_va + sizeof(struct page)) <=
-				(vmem_back->virt_addr + page_size)) {
-			page = (struct page *) (vmem_back->phys + pg_va -
-				vmem_back->virt_addr);
-			return page;
-		}
-	}
-
-	/* Probably that page struct is split between real pages */
-	return NULL;
-}
-EXPORT_SYMBOL_GPL(realmode_pfn_to_page);
-
-#else
-
-struct page *realmode_pfn_to_page(unsigned long pfn)
-{
-	struct page *page = pfn_to_page(pfn);
-	return page;
-}
-EXPORT_SYMBOL_GPL(realmode_pfn_to_page);
-
 #endif /* CONFIG_SPARSEMEM_VMEMMAP */
 
 #ifdef CONFIG_PPC_BOOK3S_64

arch/powerpc/mm/mmu_context_iommu.c

@@ -18,11 +18,15 @@
 #include <linux/migrate.h>
 #include <linux/hugetlb.h>
 #include <linux/swap.h>
+#include <linux/sizes.h>
 #include <asm/mmu_context.h>
 #include <asm/pte-walk.h>
 
 static DEFINE_MUTEX(mem_list_mutex);
 
+#define MM_IOMMU_TABLE_GROUP_PAGE_DIRTY	0x1
+#define MM_IOMMU_TABLE_GROUP_PAGE_MASK	~(SZ_4K - 1)
+
 struct mm_iommu_table_group_mem_t {
 	struct list_head next;
 	struct rcu_head rcu;
@@ -263,6 +267,9 @@ static void mm_iommu_unpin(struct mm_iommu_table_group_mem_t *mem)
 		if (!page)
 			continue;
 
+		if (mem->hpas[i] & MM_IOMMU_TABLE_GROUP_PAGE_DIRTY)
+			SetPageDirty(page);
+
 		put_page(page);
 		mem->hpas[i] = 0;
 	}
@@ -360,7 +367,6 @@ struct mm_iommu_table_group_mem_t *mm_iommu_lookup_rm(struct mm_struct *mm,
 
 	return ret;
 }
-EXPORT_SYMBOL_GPL(mm_iommu_lookup_rm);
 
 struct mm_iommu_table_group_mem_t *mm_iommu_find(struct mm_struct *mm,
 		unsigned long ua, unsigned long entries)
@@ -390,7 +396,7 @@ long mm_iommu_ua_to_hpa(struct mm_iommu_table_group_mem_t *mem,
 	if (pageshift > mem->pageshift)
 		return -EFAULT;
 
-	*hpa = *va | (ua & ~PAGE_MASK);
+	*hpa = (*va & MM_IOMMU_TABLE_GROUP_PAGE_MASK) | (ua & ~PAGE_MASK);
 
 	return 0;
 }
@@ -413,11 +419,31 @@ long mm_iommu_ua_to_hpa_rm(struct mm_iommu_table_group_mem_t *mem,
 	if (!pa)
 		return -EFAULT;
 
-	*hpa = *pa | (ua & ~PAGE_MASK);
+	*hpa = (*pa & MM_IOMMU_TABLE_GROUP_PAGE_MASK) | (ua & ~PAGE_MASK);
 
 	return 0;
 }
-EXPORT_SYMBOL_GPL(mm_iommu_ua_to_hpa_rm);
+
+extern void mm_iommu_ua_mark_dirty_rm(struct mm_struct *mm, unsigned long ua)
+{
+	struct mm_iommu_table_group_mem_t *mem;
+	long entry;
+	void *va;
+	unsigned long *pa;
+
+	mem = mm_iommu_lookup_rm(mm, ua, PAGE_SIZE);
+	if (!mem)
+		return;
+
+	entry = (ua - mem->ua) >> PAGE_SHIFT;
+	va = &mem->hpas[entry];
+
+	pa = (void *) vmalloc_to_phys(va);
+	if (!pa)
+		return;
+
+	*pa |= MM_IOMMU_TABLE_GROUP_PAGE_DIRTY;
+}
 
 long mm_iommu_mapped_inc(struct mm_iommu_table_group_mem_t *mem)
 {