[Xen-devel] [PATCH 06/11] x86: properly use map_domain_page() during domain creation/destruction

["Jan Beulich" <JBeulich@xxxxxxxx>]

This involves no longer storing virtual addresses of the per-domain
mapping L2 and L3 page tables.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -289,9 +289,10 @@ static int setup_compat_l4(struct vcpu *
     /* This page needs to look like a pagetable so that it can be shadowed */
     pg->u.inuse.type_info = PGT_l4_page_table|PGT_validated|1;
 
-    l4tab = page_to_virt(pg);
+    l4tab = __map_domain_page(pg);
     clear_page(l4tab);
     init_guest_l4_table(l4tab, v->domain);
+    unmap_domain_page(l4tab);
 
     v->arch.guest_table = pagetable_from_page(pg);
     v->arch.guest_table_user = v->arch.guest_table;
@@ -383,17 +384,22 @@ int vcpu_initialise(struct vcpu *v)
 
     v->arch.flags = TF_kernel_mode;
 
-    idx = perdomain_pt_pgidx(v);
-    if ( !perdomain_pt_page(d, idx) )
+    idx = perdomain_pt_idx(v);
+    if ( !d->arch.perdomain_pts[idx] )
     {
-        struct page_info *pg;
-        pg = alloc_domheap_page(NULL, MEMF_node(vcpu_to_node(v)));
-        if ( !pg )
+        void *pt;
+        l2_pgentry_t *l2tab;
+
+        pt = alloc_xenheap_pages(0, MEMF_node(vcpu_to_node(v)));
+        if ( !pt )
             return -ENOMEM;
-        clear_page(page_to_virt(pg));
-        perdomain_pt_page(d, idx) = pg;
-        d->arch.mm_perdomain_l2[0][l2_table_offset(PERDOMAIN_VIRT_START)+idx]
-            = l2e_from_page(pg, __PAGE_HYPERVISOR);
+        clear_page(pt);
+        d->arch.perdomain_pts[idx] = pt;
+
+        l2tab = __map_domain_page(d->arch.perdomain_l2_pg[0]);
+        l2tab[l2_table_offset(PERDOMAIN_VIRT_START) + idx]
+            = l2e_from_paddr(__pa(pt), __PAGE_HYPERVISOR);
+        unmap_domain_page(l2tab);
     }
 
     rc = mapcache_vcpu_init(v);
@@ -484,6 +490,7 @@ void vcpu_destroy(struct vcpu *v)
 int arch_domain_create(struct domain *d, unsigned int domcr_flags)
 {
     struct page_info *pg;
+    l3_pgentry_t *l3tab;
     int i, paging_initialised = 0;
     int rc = -ENOMEM;
 
@@ -514,28 +521,29 @@ int arch_domain_create(struct domain *d,
                d->domain_id);
     }
 
-    BUILD_BUG_ON(PDPT_L2_ENTRIES * sizeof(*d->arch.mm_perdomain_pt_pages)
+    BUILD_BUG_ON(PDPT_L2_ENTRIES * sizeof(*d->arch.perdomain_pts)
                  != PAGE_SIZE);
-    pg = alloc_domheap_page(NULL, MEMF_node(domain_to_node(d)));
-    if ( !pg )
+    d->arch.perdomain_pts =
+        alloc_xenheap_pages(0, MEMF_node(domain_to_node(d)));
+    if ( !d->arch.perdomain_pts )
         goto fail;
-    d->arch.mm_perdomain_pt_pages = page_to_virt(pg);
-    clear_page(d->arch.mm_perdomain_pt_pages);
+    clear_page(d->arch.perdomain_pts);
 
     pg = alloc_domheap_page(NULL, MEMF_node(domain_to_node(d)));
     if ( pg == NULL )
         goto fail;
-    d->arch.mm_perdomain_l2[0] = page_to_virt(pg);
-    clear_page(d->arch.mm_perdomain_l2[0]);
+    d->arch.perdomain_l2_pg[0] = pg;
+    clear_domain_page(page_to_mfn(pg));
 
     pg = alloc_domheap_page(NULL, MEMF_node(domain_to_node(d)));
     if ( pg == NULL )
         goto fail;
-    d->arch.mm_perdomain_l3 = page_to_virt(pg);
-    clear_page(d->arch.mm_perdomain_l3);
-    d->arch.mm_perdomain_l3[l3_table_offset(PERDOMAIN_VIRT_START)] =
-        l3e_from_pfn(virt_to_mfn(d->arch.mm_perdomain_l2[0]),
-                     __PAGE_HYPERVISOR);
+    d->arch.perdomain_l3_pg = pg;
+    l3tab = __map_domain_page(pg);
+    clear_page(l3tab);
+    l3tab[l3_table_offset(PERDOMAIN_VIRT_START)] =
+        l3e_from_page(d->arch.perdomain_l2_pg[0], __PAGE_HYPERVISOR);
+    unmap_domain_page(l3tab);
 
     mapcache_domain_init(d);
 
@@ -611,12 +619,12 @@ int arch_domain_create(struct domain *d,
     if ( paging_initialised )
         paging_final_teardown(d);
     mapcache_domain_exit(d);
-    if ( d->arch.mm_perdomain_l2[0] )
-        free_domheap_page(virt_to_page(d->arch.mm_perdomain_l2[0]));
-    if ( d->arch.mm_perdomain_l3 )
-        free_domheap_page(virt_to_page(d->arch.mm_perdomain_l3));
-    if ( d->arch.mm_perdomain_pt_pages )
-        free_domheap_page(virt_to_page(d->arch.mm_perdomain_pt_pages));
+    for ( i = 0; i < PERDOMAIN_SLOTS; ++i)
+        if ( d->arch.perdomain_l2_pg[i] )
+            free_domheap_page(d->arch.perdomain_l2_pg[i]);
+    if ( d->arch.perdomain_l3_pg )
+        free_domheap_page(d->arch.perdomain_l3_pg);
+    free_xenheap_page(d->arch.perdomain_pts);
     return rc;
 }
 
@@ -638,13 +646,12 @@ void arch_domain_destroy(struct domain *
     mapcache_domain_exit(d);
 
     for ( i = 0; i < PDPT_L2_ENTRIES; ++i )
-    {
-        if ( perdomain_pt_page(d, i) )
-            free_domheap_page(perdomain_pt_page(d, i));
-    }
-    free_domheap_page(virt_to_page(d->arch.mm_perdomain_pt_pages));
-    free_domheap_page(virt_to_page(d->arch.mm_perdomain_l2[0]));
-    free_domheap_page(virt_to_page(d->arch.mm_perdomain_l3));
+        free_xenheap_page(d->arch.perdomain_pts[i]);
+    free_xenheap_page(d->arch.perdomain_pts);
+    for ( i = 0; i < PERDOMAIN_SLOTS; ++i)
+        if ( d->arch.perdomain_l2_pg[i] )
+            free_domheap_page(d->arch.perdomain_l2_pg[i]);
+    free_domheap_page(d->arch.perdomain_l3_pg);
 
     free_xenheap_page(d->shared_info);
     cleanup_domain_irq_mapping(d);
@@ -810,9 +817,10 @@ int arch_set_info_guest(
                 fail |= xen_pfn_to_cr3(pfn) != c.nat->ctrlreg[1];
             }
         } else {
-            l4_pgentry_t *l4tab = __va(pfn_to_paddr(pfn));
+            l4_pgentry_t *l4tab = map_domain_page(pfn);
 
             pfn = l4e_get_pfn(*l4tab);
+            unmap_domain_page(l4tab);
             fail = compat_pfn_to_cr3(pfn) != c.cmp->ctrlreg[3];
         }
 
@@ -951,9 +959,10 @@ int arch_set_info_guest(
             return -EINVAL;
         }
 
-        l4tab = __va(pagetable_get_paddr(v->arch.guest_table));
+        l4tab = map_domain_page(pagetable_get_pfn(v->arch.guest_table));
         *l4tab = l4e_from_pfn(page_to_mfn(cr3_page),
             _PAGE_PRESENT|_PAGE_RW|_PAGE_USER|_PAGE_ACCESSED);
+        unmap_domain_page(l4tab);
     }
 
     if ( v->vcpu_id == 0 )
@@ -1971,12 +1980,13 @@ static int relinquish_memory(
 static void vcpu_destroy_pagetables(struct vcpu *v)
 {
     struct domain *d = v->domain;
-    unsigned long pfn;
+    unsigned long pfn = pagetable_get_pfn(v->arch.guest_table);
 
     if ( is_pv_32on64_vcpu(v) )
     {
-        pfn = l4e_get_pfn(*(l4_pgentry_t *)
-                          __va(pagetable_get_paddr(v->arch.guest_table)));
+        l4_pgentry_t *l4tab = map_domain_page(pfn);
+
+        pfn = l4e_get_pfn(*l4tab);
 
         if ( pfn != 0 )
         {
@@ -1986,15 +1996,12 @@ static void vcpu_destroy_pagetables(stru
                 put_page_and_type(mfn_to_page(pfn));
         }
 
-        l4e_write(
-            (l4_pgentry_t *)__va(pagetable_get_paddr(v->arch.guest_table)),
-            l4e_empty());
+        l4e_write(l4tab, l4e_empty());
 
         v->arch.cr3 = 0;
         return;
     }
 
-    pfn = pagetable_get_pfn(v->arch.guest_table);
     if ( pfn != 0 )
     {
         if ( paging_mode_refcounts(d) )
--- a/xen/arch/x86/domain_page.c
+++ b/xen/arch/x86/domain_page.c
@@ -241,6 +241,8 @@ void copy_domain_page(unsigned long dmfn
 int mapcache_domain_init(struct domain *d)
 {
     struct mapcache_domain *dcache = &d->arch.pv_domain.mapcache;
+    l3_pgentry_t *l3tab;
+    l2_pgentry_t *l2tab;
     unsigned int i, bitmap_pages, memf = MEMF_node(domain_to_node(d));
     unsigned long *end;
 
@@ -251,14 +253,18 @@ int mapcache_domain_init(struct domain *
         return 0;
 
     dcache->l1tab = xzalloc_array(l1_pgentry_t *, MAPCACHE_L2_ENTRIES + 1);
-    d->arch.mm_perdomain_l2[MAPCACHE_SLOT] = alloc_xenheap_pages(0, memf);
-    if ( !dcache->l1tab || !d->arch.mm_perdomain_l2[MAPCACHE_SLOT] )
+    d->arch.perdomain_l2_pg[MAPCACHE_SLOT] = alloc_domheap_page(NULL, memf);
+    if ( !dcache->l1tab || !d->arch.perdomain_l2_pg[MAPCACHE_SLOT] )
         return -ENOMEM;
 
-    clear_page(d->arch.mm_perdomain_l2[MAPCACHE_SLOT]);
-    d->arch.mm_perdomain_l3[l3_table_offset(MAPCACHE_VIRT_START)] =
-        l3e_from_paddr(__pa(d->arch.mm_perdomain_l2[MAPCACHE_SLOT]),
-                       __PAGE_HYPERVISOR);
+    clear_domain_page(page_to_mfn(d->arch.perdomain_l2_pg[MAPCACHE_SLOT]));
+    l3tab = __map_domain_page(d->arch.perdomain_l3_pg);
+    l3tab[l3_table_offset(MAPCACHE_VIRT_START)] =
+        l3e_from_page(d->arch.perdomain_l2_pg[MAPCACHE_SLOT],
+                      __PAGE_HYPERVISOR);
+    unmap_domain_page(l3tab);
+
+    l2tab = __map_domain_page(d->arch.perdomain_l2_pg[MAPCACHE_SLOT]);
 
     BUILD_BUG_ON(MAPCACHE_VIRT_END + 3 +
                  2 * PFN_UP(BITS_TO_LONGS(MAPCACHE_ENTRIES) * sizeof(long)) >
@@ -275,12 +281,16 @@ int mapcache_domain_init(struct domain *
         ASSERT(i <= MAPCACHE_L2_ENTRIES);
         dcache->l1tab[i] = alloc_xenheap_pages(0, memf);
         if ( !dcache->l1tab[i] )
+        {
+            unmap_domain_page(l2tab);
             return -ENOMEM;
+        }
         clear_page(dcache->l1tab[i]);
-        d->arch.mm_perdomain_l2[MAPCACHE_SLOT][i] =
-            l2e_from_paddr(__pa(dcache->l1tab[i]), __PAGE_HYPERVISOR);
+        l2tab[i] = l2e_from_paddr(__pa(dcache->l1tab[i]), __PAGE_HYPERVISOR);
     }
 
+    unmap_domain_page(l2tab);
+
     spin_lock_init(&dcache->lock);
 
     return 0;
@@ -315,19 +325,21 @@ void mapcache_domain_exit(struct domain 
 
         xfree(dcache->l1tab);
     }
-    free_xenheap_page(d->arch.mm_perdomain_l2[MAPCACHE_SLOT]);
 }
 
 int mapcache_vcpu_init(struct vcpu *v)
 {
     struct domain *d = v->domain;
     struct mapcache_domain *dcache = &d->arch.pv_domain.mapcache;
+    l2_pgentry_t *l2tab;
     unsigned long i;
     unsigned int memf = MEMF_node(vcpu_to_node(v));
 
     if ( is_hvm_vcpu(v) || !dcache->l1tab )
         return 0;
 
+    l2tab = __map_domain_page(d->arch.perdomain_l2_pg[MAPCACHE_SLOT]);
+
     while ( dcache->entries < d->max_vcpus * MAPCACHE_VCPU_ENTRIES )
     {
         unsigned int ents = dcache->entries + MAPCACHE_VCPU_ENTRIES;
@@ -338,10 +350,13 @@ int mapcache_vcpu_init(struct vcpu *v)
         {
             dcache->l1tab[i] = alloc_xenheap_pages(0, memf);
             if ( !dcache->l1tab[i] )
+            {
+                unmap_domain_page(l2tab);
                 return -ENOMEM;
+            }
             clear_page(dcache->l1tab[i]);
-            d->arch.mm_perdomain_l2[MAPCACHE_SLOT][i] =
-                l2e_from_paddr(__pa(dcache->l1tab[i]), __PAGE_HYPERVISOR);
+            l2tab[i] = l2e_from_paddr(__pa(dcache->l1tab[i]),
+                                      __PAGE_HYPERVISOR);
         }
 
         /* Populate bit maps. */
@@ -351,18 +366,22 @@ int mapcache_vcpu_init(struct vcpu *v)
         {
             struct page_info *pg = alloc_domheap_page(NULL, memf);
 
+            if ( pg )
+            {
+                clear_domain_page(page_to_mfn(pg));
+                *pl1e = l1e_from_page(pg, __PAGE_HYPERVISOR);
+                pg = alloc_domheap_page(NULL, memf);
+            }
             if ( !pg )
+            {
+                unmap_domain_page(l2tab);
                 return -ENOMEM;
-            clear_domain_page(page_to_mfn(pg));
-            *pl1e = l1e_from_page(pg, __PAGE_HYPERVISOR);
+            }
 
             i = (unsigned long)(dcache->garbage + BITS_TO_LONGS(ents));
             pl1e = &dcache->l1tab[l2_table_offset(i)][l1_table_offset(i)];
             ASSERT(!l1e_get_flags(*pl1e));
 
-            pg = alloc_domheap_page(NULL, memf);
-            if ( !pg )
-                return -ENOMEM;
             clear_domain_page(page_to_mfn(pg));
             *pl1e = l1e_from_page(pg, __PAGE_HYPERVISOR);
         }
@@ -370,6 +389,8 @@ int mapcache_vcpu_init(struct vcpu *v)
         dcache->entries = ents;
     }
 
+    unmap_domain_page(l2tab);
+
     /* Mark all maphash entries as not in use. */
     BUILD_BUG_ON(MAPHASHENT_NOTINUSE < MAPCACHE_ENTRIES);
     for ( i = 0; i < MAPHASH_ENTRIES; i++ )
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -1322,9 +1322,9 @@ void init_guest_l4_table(l4_pgentry_t l4
            &idle_pg_table[ROOT_PAGETABLE_FIRST_XEN_SLOT],
            ROOT_PAGETABLE_XEN_SLOTS * sizeof(l4_pgentry_t));
     l4tab[l4_table_offset(LINEAR_PT_VIRT_START)] =
-        l4e_from_pfn(virt_to_mfn(l4tab), __PAGE_HYPERVISOR);
+        l4e_from_pfn(domain_page_map_to_mfn(l4tab), __PAGE_HYPERVISOR);
     l4tab[l4_table_offset(PERDOMAIN_VIRT_START)] =
-        l4e_from_pfn(virt_to_mfn(d->arch.mm_perdomain_l3), __PAGE_HYPERVISOR);
+        l4e_from_page(d->arch.perdomain_l3_pg, __PAGE_HYPERVISOR);
 }
 
 static int alloc_l4_table(struct page_info *page, int preemptible)
--- a/xen/arch/x86/mm/hap/hap.c
+++ b/xen/arch/x86/mm/hap/hap.c
@@ -369,7 +369,7 @@ static void hap_install_xen_entries_in_l
 
     /* Install the per-domain mappings for this domain */
     l4e[l4_table_offset(PERDOMAIN_VIRT_START)] =
-        l4e_from_pfn(mfn_x(page_to_mfn(virt_to_page(d->arch.mm_perdomain_l3))),
+        l4e_from_pfn(mfn_x(page_to_mfn(d->arch.perdomain_l3_pg)),
                      __PAGE_HYPERVISOR);
 
     /* Install a linear mapping */
--- a/xen/arch/x86/mm/shadow/multi.c
+++ b/xen/arch/x86/mm/shadow/multi.c
@@ -1449,7 +1449,7 @@ void sh_install_xen_entries_in_l4(struct
 
     /* Install the per-domain mappings for this domain */
     sl4e[shadow_l4_table_offset(PERDOMAIN_VIRT_START)] =
-        shadow_l4e_from_mfn(page_to_mfn(virt_to_page(d->arch.mm_perdomain_l3)),
+        shadow_l4e_from_mfn(page_to_mfn(d->arch.perdomain_l3_pg),
                             __PAGE_HYPERVISOR);
 
     /* Shadow linear mapping for 4-level shadows.  N.B. for 3-level
--- a/xen/arch/x86/x86_64/mm.c
+++ b/xen/arch/x86/x86_64/mm.c
@@ -823,9 +823,8 @@ void __init setup_idle_pagetable(void)
 {
     /* Install per-domain mappings for idle domain. */
     l4e_write(&idle_pg_table[l4_table_offset(PERDOMAIN_VIRT_START)],
-              l4e_from_page(
-                  virt_to_page(idle_vcpu[0]->domain->arch.mm_perdomain_l3),
-                  __PAGE_HYPERVISOR));
+              l4e_from_page(idle_vcpu[0]->domain->arch.perdomain_l3_pg,
+                            __PAGE_HYPERVISOR));
 }
 
 void __init zap_low_mappings(void)
@@ -850,21 +849,18 @@ void *compat_arg_xlat_virt_base(void)
 int setup_compat_arg_xlat(struct vcpu *v)
 {
     unsigned int order = get_order_from_bytes(COMPAT_ARG_XLAT_SIZE);
-    struct page_info *pg;
 
-    pg = alloc_domheap_pages(NULL, order, 0);
-    if ( pg == NULL )
-        return -ENOMEM;
+    v->arch.compat_arg_xlat = alloc_xenheap_pages(order,
+                                                  MEMF_node(vcpu_to_node(v)));
 
-    v->arch.compat_arg_xlat = page_to_virt(pg);
-    return 0;
+    return v->arch.compat_arg_xlat ? 0 : -ENOMEM;
 }
 
 void free_compat_arg_xlat(struct vcpu *v)
 {
     unsigned int order = get_order_from_bytes(COMPAT_ARG_XLAT_SIZE);
-    if ( v->arch.compat_arg_xlat != NULL )
-        free_domheap_pages(virt_to_page(v->arch.compat_arg_xlat), order);
+
+    free_xenheap_pages(v->arch.compat_arg_xlat, order);
     v->arch.compat_arg_xlat = NULL;
 }
 
--- a/xen/include/asm-x86/domain.h
+++ b/xen/include/asm-x86/domain.h
@@ -241,9 +241,9 @@ struct pv_domain
 
 struct arch_domain
 {
-    struct page_info **mm_perdomain_pt_pages;
-    l2_pgentry_t *mm_perdomain_l2[PERDOMAIN_SLOTS];
-    l3_pgentry_t *mm_perdomain_l3;
+    void **perdomain_pts;
+    struct page_info *perdomain_l2_pg[PERDOMAIN_SLOTS];
+    struct page_info *perdomain_l3_pg;
 
     unsigned int hv_compat_vstart;
 
@@ -318,13 +318,11 @@ struct arch_domain
 #define has_arch_pdevs(d)    (!list_empty(&(d)->arch.pdev_list))
 #define has_arch_mmios(d)    (!rangeset_is_empty((d)->iomem_caps))
 
-#define perdomain_pt_pgidx(v) \
+#define perdomain_pt_idx(v) \
       ((v)->vcpu_id >> (PAGETABLE_ORDER - GDT_LDT_VCPU_SHIFT))
 #define perdomain_ptes(d, v) \
-    ((l1_pgentry_t *)page_to_virt((d)->arch.mm_perdomain_pt_pages \
-      [perdomain_pt_pgidx(v)]) + (((v)->vcpu_id << GDT_LDT_VCPU_SHIFT) & \
-                                  (L1_PAGETABLE_ENTRIES - 1)))
-#define perdomain_pt_page(d, n) ((d)->arch.mm_perdomain_pt_pages[n])
+    ((l1_pgentry_t *)(d)->arch.perdomain_pts[perdomain_pt_idx(v)] + \
+     (((v)->vcpu_id << GDT_LDT_VCPU_SHIFT) & (L1_PAGETABLE_ENTRIES - 1)))
 
 struct pv_vcpu
 {

Attachment: x86-map-domain-create.patch
Description: Text document

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