KVM: PPC: Check if IOMMU page is contained in the pinned physical page

[mirror_ubuntu-bionic-kernel.git] / arch / powerpc / mm / mmu_context_iommu.c

diff --git a/arch/powerpc/mm/mmu_context_iommu.c b/arch/powerpc/mm/mmu_context_iommu.c
index e0a2d8e806edb01a3b24ab063ec41e87defb0e1f..816055927ee47ba05db7e1d3675461de66052636 100644 (file)
--- a/arch/powerpc/mm/mmu_context_iommu.c
+++ b/arch/powerpc/mm/mmu_context_iommu.c
@@ -19,6 +19,7 @@
 #include <linux/hugetlb.h>
 #include <linux/swap.h>
 #include <asm/mmu_context.h>
+#include <asm/pte-walk.h>
 
 static DEFINE_MUTEX(mem_list_mutex);
 
@@ -27,6 +28,7 @@ struct mm_iommu_table_group_mem_t {
        struct rcu_head rcu;
        unsigned long used;
        atomic64_t mapped;
+       unsigned int pageshift;
        u64 ua;                 /* userspace address */
        u64 entries;            /* number of entries in hpas[] */
        u64 *hpas;              /* vmalloc'ed */
@@ -126,6 +128,8 @@ long mm_iommu_get(struct mm_struct *mm, unsigned long ua, unsigned long entries,
 {
        struct mm_iommu_table_group_mem_t *mem;
        long i, j, ret = 0, locked_entries = 0;
+       unsigned int pageshift;
+       unsigned long flags;
        struct page *page = NULL;
 
        mutex_lock(&mem_list_mutex);
@@ -160,6 +164,12 @@ long mm_iommu_get(struct mm_struct *mm, unsigned long ua, unsigned long entries,
                goto unlock_exit;
        }
 
+       /*
+        * For a starting point for a maximum page size calculation
+        * we use @ua and @entries natural alignment to allow IOMMU pages
+        * smaller than huge pages but still bigger than PAGE_SIZE.
+        */
+       mem->pageshift = __ffs(ua | (entries << PAGE_SHIFT));
        mem->hpas = vzalloc(entries * sizeof(mem->hpas[0]));
        if (!mem->hpas) {
                kfree(mem);
@@ -200,6 +210,23 @@ long mm_iommu_get(struct mm_struct *mm, unsigned long ua, unsigned long entries,
                        }
                }
 populate:
+               pageshift = PAGE_SHIFT;
+               if (PageCompound(page)) {
+                       pte_t *pte;
+                       struct page *head = compound_head(page);
+                       unsigned int compshift = compound_order(head);
+
+                       local_irq_save(flags); /* disables as well */
+                       pte = find_linux_pte(mm->pgd, ua, NULL, &pageshift);
+                       local_irq_restore(flags);
+
+                       /* Double check it is still the same pinned page */
+                       if (pte && pte_page(*pte) == head &&
+                                       pageshift == compshift)
+                               pageshift = max_t(unsigned int, pageshift,
+                                               PAGE_SHIFT);
+               }
+               mem->pageshift = min(mem->pageshift, pageshift);
                mem->hpas[i] = page_to_pfn(page) << PAGE_SHIFT;
        }
 
@@ -350,7 +377,7 @@ struct mm_iommu_table_group_mem_t *mm_iommu_find(struct mm_struct *mm,
 EXPORT_SYMBOL_GPL(mm_iommu_find);
 
 long mm_iommu_ua_to_hpa(struct mm_iommu_table_group_mem_t *mem,
-               unsigned long ua, unsigned long *hpa)
+               unsigned long ua, unsigned int pageshift, unsigned long *hpa)
 {
        const long entry = (ua - mem->ua) >> PAGE_SHIFT;
        u64 *va = &mem->hpas[entry];
@@ -358,6 +385,9 @@ long mm_iommu_ua_to_hpa(struct mm_iommu_table_group_mem_t *mem,
        if (entry >= mem->entries)
                return -EFAULT;
 
+       if (pageshift > mem->pageshift)
+               return -EFAULT;
+
        *hpa = *va | (ua & ~PAGE_MASK);
 
        return 0;
@@ -365,7 +395,7 @@ long mm_iommu_ua_to_hpa(struct mm_iommu_table_group_mem_t *mem,
 EXPORT_SYMBOL_GPL(mm_iommu_ua_to_hpa);
 
 long mm_iommu_ua_to_hpa_rm(struct mm_iommu_table_group_mem_t *mem,
-               unsigned long ua, unsigned long *hpa)
+               unsigned long ua, unsigned int pageshift, unsigned long *hpa)
 {
        const long entry = (ua - mem->ua) >> PAGE_SHIFT;
        void *va = &mem->hpas[entry];
@@ -374,6 +404,9 @@ long mm_iommu_ua_to_hpa_rm(struct mm_iommu_table_group_mem_t *mem,
        if (entry >= mem->entries)
                return -EFAULT;
 
+       if (pageshift > mem->pageshift)
+               return -EFAULT;
+
        pa = (void *) vmalloc_to_phys(va);
        if (!pa)
                return -EFAULT;