x86: allow passing initrd to kernel without exposing it through the initial mapping

The (Dom0 only for now) kernel can indicate that it doesn't need its
initrd mapped through a newly added ELF note - it gets passed the PFN
of the initrd in this case instead of the virtual address.

Even for kernels not making use of the new feature, the initrd will
no longer get copied into the initial mapping, but the memory it lives
in will get assigned to and mapped for the guest instead.

Signed-off-by: Jan Beulich <jbeulich@novell.com>

diff --git a/xen/arch/x86/domain_build.c b/xen/arch/x86/domain_build.c
index 903be9a40e39044795331fd6b64c5b3be44e4fa2..73cf8a8c1ba4fe6c292522d87b170a8bccfe2402 100644 (file)
--- a/xen/arch/x86/domain_build.c
+++ b/xen/arch/x86/domain_build.c
@@ -225,7 +225,9 @@ static unsigned long __init compute_dom0_nr_pages(
         size_t sizeof_long = is_pv_32bit_domain(d) ? sizeof(int) : sizeof(long);
 
         vstart = parms->virt_base;
-        vend = round_pgup(parms->virt_kend) + round_pgup(initrd_len);
+        vend = round_pgup(parms->virt_kend);
+        if ( !parms->elf_notes[XEN_ELFNOTE_MOD_START_PFN].data.num )
+            vend += round_pgup(initrd_len);
         end = vend + nr_pages * sizeof_long;
 
         if ( end > vstart )
@@ -286,7 +288,7 @@ static void __init process_dom0_ioports_disable(void)
 int __init construct_dom0(
     struct domain *d,
     const module_t *image, unsigned long image_headroom,
-    const module_t *initrd,
+    module_t *initrd,
     void *(*bootstrap_map)(const module_t *),
     char *cmdline)
 {
@@ -297,6 +299,7 @@ int __init construct_dom0(
     unsigned long nr_pt_pages;
     unsigned long alloc_spfn;
     unsigned long alloc_epfn;
+    unsigned long initrd_pfn = -1, initrd_mfn = 0;
     unsigned long count;
     struct page_info *page = NULL;
     start_info_t *si;
@@ -449,9 +452,17 @@ int __init construct_dom0(
     v_start          = parms.virt_base;
     vkern_start      = parms.virt_kstart;
     vkern_end        = parms.virt_kend;
-    vinitrd_start    = round_pgup(vkern_end);
-    vinitrd_end      = vinitrd_start + initrd_len;
-    vphysmap_start   = round_pgup(vinitrd_end);
+    if ( parms.elf_notes[XEN_ELFNOTE_MOD_START_PFN].data.num )
+    {
+        vinitrd_start  = vinitrd_end = 0;
+        vphysmap_start = round_pgup(vkern_end);
+    }
+    else
+    {
+        vinitrd_start  = round_pgup(vkern_end);
+        vinitrd_end    = vinitrd_start + initrd_len;
+        vphysmap_start = round_pgup(vinitrd_end);
+    }
     vphysmap_end     = vphysmap_start + (nr_pages * (!is_pv_32on64_domain(d) ?
                                                      sizeof(unsigned long) :
                                                      sizeof(unsigned int)));
@@ -490,8 +501,11 @@ int __init construct_dom0(
 #endif
     }
 
-    order = get_order_from_bytes(v_end - v_start);
-    if ( (1UL << order) > nr_pages )
+    count = v_end - v_start;
+    if ( vinitrd_start )
+        count -= PAGE_ALIGN(initrd_len);
+    order = get_order_from_bytes(count);
+    if ( (1UL << order) + PFN_UP(initrd_len) > nr_pages )
         panic("Domain 0 allocation is too small for kernel image.\n");
 
     if ( parms.p2m_base != UNSET_ADDR )
@@ -510,12 +524,54 @@ int __init construct_dom0(
     alloc_spfn = page_to_mfn(page);
     alloc_epfn = alloc_spfn + d->tot_pages;
 
+    if ( initrd_len )
+    {
+        initrd_pfn = vinitrd_start ?
+                     (vinitrd_start - v_start) >> PAGE_SHIFT :
+                     d->tot_pages;
+        initrd_mfn = mfn = initrd->mod_start;
+        count = PFN_UP(initrd_len);
+#ifdef __x86_64__
+        if ( d->arch.physaddr_bitsize &&
+             ((mfn + count - 1) >> (d->arch.physaddr_bitsize - PAGE_SHIFT)) )
+        {
+            order = get_order_from_pages(count);
+            page = alloc_domheap_pages(d, order, 0);
+            if ( !page )
+                panic("Not enough RAM for domain 0 initrd.\n");
+            for ( count = -count; order--; )
+                if ( count & (1UL << order) )
+                {
+                    free_domheap_pages(page, order);
+                    page += 1UL << order;
+                }
+            memcpy(page_to_virt(page), mfn_to_virt(initrd->mod_start),
+                   initrd_len);
+            mpt_alloc = (paddr_t)initrd->mod_start << PAGE_SHIFT;
+            init_domheap_pages(mpt_alloc,
+                               mpt_alloc + PAGE_ALIGN(initrd_len));
+            initrd->mod_start = initrd_mfn = page_to_mfn(page);
+        }
+        else
+#endif
+            while ( count-- )
+                if ( assign_pages(d, mfn_to_page(mfn++), 0, 0) )
+                    BUG();
+        initrd->mod_end = 0;
+    }
+
     printk("PHYSICAL MEMORY ARRANGEMENT:\n"
            " Dom0 alloc.:   %"PRIpaddr"->%"PRIpaddr,
            pfn_to_paddr(alloc_spfn), pfn_to_paddr(alloc_epfn));
     if ( d->tot_pages < nr_pages )
         printk(" (%lu pages to be allocated)",
                nr_pages - d->tot_pages);
+    if ( initrd )
+    {
+        mpt_alloc = (paddr_t)initrd->mod_start << PAGE_SHIFT;
+        printk("\n Init. ramdisk: %"PRIpaddr"->%"PRIpaddr,
+               mpt_alloc, mpt_alloc + initrd_len);
+    }
     printk("\nVIRTUAL MEMORY ARRANGEMENT:\n"
            " Loaded kernel: %p->%p\n"
            " Init. ramdisk: %p->%p\n"
@@ -534,6 +590,8 @@ int __init construct_dom0(
     printk(" ENTRY ADDRESS: %p\n", _p(parms.virt_entry));
 
     mpt_alloc = (vpt_start - v_start) + pfn_to_paddr(alloc_spfn);
+    if ( vinitrd_start )
+        mpt_alloc -= PAGE_ALIGN(initrd_len);
 
 #if defined(__i386__)
     /*
@@ -571,7 +629,7 @@ int __init construct_dom0(
             l2e_from_page(perdomain_pt_page(d, i), __PAGE_HYPERVISOR);
 
     l2tab += l2_linear_offset(v_start);
-    mfn = alloc_spfn;
+    pfn = alloc_spfn;
     for ( count = 0; count < ((v_end-v_start)>>PAGE_SHIFT); count++ )
     {
         if ( !((unsigned long)l1tab & (PAGE_SIZE-1)) )
@@ -584,14 +642,16 @@ int __init construct_dom0(
             if ( count == 0 )
                 l1tab += l1_table_offset(v_start);
         }
+        if ( count < initrd_pfn || count >= initrd_pfn + PFN_UP(initrd_len) )
+            mfn = pfn++;
+        else
+            mfn = initrd_mfn++;
         *l1tab = l1e_from_pfn(mfn, L1_PROT);
         l1tab++;
         
         page = mfn_to_page(mfn);
         if ( !get_page_and_type(page, d, PGT_writable_page) )
             BUG();
-
-        mfn++;
     }
 #undef MPT_ALLOC
 
@@ -688,7 +748,7 @@ int __init construct_dom0(
         v->arch.guest_table_user = v->arch.guest_table;
 
     l4tab += l4_table_offset(v_start);
-    mfn = alloc_spfn;
+    pfn = alloc_spfn;
     for ( count = 0; count < ((v_end-v_start)>>PAGE_SHIFT); count++ )
     {
         if ( !((unsigned long)l1tab & (PAGE_SIZE-1)) )
@@ -722,6 +782,10 @@ int __init construct_dom0(
             *l2tab = l2e_from_paddr(__pa(l1start), L2_PROT);
             l2tab++;
         }
+        if ( count < initrd_pfn || count >= initrd_pfn + PFN_UP(initrd_len) )
+            mfn = pfn++;
+        else
+            mfn = initrd_mfn++;
         *l1tab = l1e_from_pfn(mfn, (!is_pv_32on64_domain(d) ?
                                     L1_PROT : COMPAT_L1_PROT));
         l1tab++;
@@ -730,8 +794,6 @@ int __init construct_dom0(
         if ( (page->u.inuse.type_info == 0) &&
              !get_page_and_type(page, d, PGT_writable_page) )
             BUG();
-
-        mfn++;
     }
 
     if ( is_pv_32on64_domain(d) )
@@ -837,15 +899,6 @@ int __init construct_dom0(
             d, (void *)(unsigned long)parms.virt_hypercall);
     }
 
-    /* Copy the initial ramdisk. */
-    if ( initrd_len != 0 )
-    {
-        char *initrd_start = bootstrap_map(initrd);
-
-        memcpy((void *)vinitrd_start, initrd_start, initrd_len);
-        bootstrap_map(NULL);
-    }
-
     /* Free temporary buffers. */
     discard_initial_images();
 
@@ -857,6 +910,8 @@ int __init construct_dom0(
     si->shared_info = virt_to_maddr(d->shared_info);
 
     si->flags        = SIF_PRIVILEGED | SIF_INITDOMAIN;
+    if ( !vinitrd_start && initrd_len )
+        si->flags   |= SIF_MOD_START_PFN;
     si->flags       |= (xen_processor_pmbits << 8) & SIF_PM_MASK;
     si->pt_base      = vpt_start + 2 * PAGE_SIZE * !!is_pv_32on64_domain(d);
     si->nr_pt_frames = nr_pt_pages;
@@ -971,9 +1026,16 @@ int __init construct_dom0(
     for ( pfn = 0; pfn < count; pfn++ )
     {
         mfn = pfn + alloc_spfn;
+        if ( pfn >= initrd_pfn )
+        {
+            if ( pfn < initrd_pfn + PFN_UP(initrd_len) )
+                mfn = initrd->mod_start + (pfn - initrd_pfn);
+            else
+                mfn -= PFN_UP(initrd_len);
+        }
 #ifndef NDEBUG
 #define REVERSE_START ((v_end - v_start) >> PAGE_SHIFT)
-        if ( pfn > REVERSE_START )
+        if ( pfn > REVERSE_START && (vinitrd_start || pfn < initrd_pfn) )
             mfn = alloc_epfn - (pfn - REVERSE_START);
 #endif
         if ( !is_pv_32on64_domain(d) )
@@ -999,14 +1061,14 @@ int __init construct_dom0(
             ((unsigned long *)vphysmap_start)[pfn] = mfn;
             set_gpfn_from_mfn(mfn, pfn);
             ++pfn;
-#ifndef NDEBUG
-            ++alloc_epfn;
-#endif
             if (!(pfn & 0xfffff))
                 process_pending_softirqs();
         }
     }
     BUG_ON(pfn != d->tot_pages);
+#ifndef NDEBUG
+    alloc_epfn += PFN_UP(initrd_len) + si->nr_p2m_frames;
+#endif
     while ( pfn < nr_pages )
     {
         if ( (page = alloc_chunk(d, nr_pages - d->tot_pages)) == NULL )
@@ -1031,7 +1093,7 @@ int __init construct_dom0(
 
     if ( initrd_len != 0 )
     {
-        si->mod_start = vinitrd_start;
+        si->mod_start = vinitrd_start ?: initrd_pfn;
         si->mod_len   = initrd_len;
     }
 

diff --git a/xen/common/libelf/libelf-dominfo.c b/xen/common/libelf/libelf-dominfo.c
index 08f8e51e4d0c6c779deb1f0d3c581ab1ff4719ef..29c3339088f1a2eb490357e7e30ad7cbc1193510 100644 (file)
--- a/xen/common/libelf/libelf-dominfo.c
+++ b/xen/common/libelf/libelf-dominfo.c
@@ -115,6 +115,7 @@ int elf_xen_parse_note(struct elf_binary *elf,
         [XEN_ELFNOTE_FEATURES] = { "FEATURES", 1},
         [XEN_ELFNOTE_BSD_SYMTAB] = { "BSD_SYMTAB", 1},
         [XEN_ELFNOTE_SUSPEND_CANCEL] = { "SUSPEND_CANCEL", 0 },
+        [XEN_ELFNOTE_MOD_START_PFN] = { "MOD_START_PFN", 0 },
     };
 /* *INDENT-ON* */
 

diff --git a/xen/include/asm-x86/setup.h b/xen/include/asm-x86/setup.h
index d157196f475fced6cb0d61d5acf1d999a65a053f..5f3e65c37468372c060b39dcd59f13212c6253a5 100644 (file)
--- a/xen/include/asm-x86/setup.h
+++ b/xen/include/asm-x86/setup.h
@@ -30,7 +30,7 @@ void vesa_mtrr_init(void);
 int construct_dom0(
     struct domain *d,
     const module_t *kernel, unsigned long kernel_headroom,
-    const module_t *initrd,
+    module_t *initrd,
     void *(*bootstrap_map)(const module_t *),
     char *cmdline);
 

diff --git a/xen/include/public/elfnote.h b/xen/include/public/elfnote.h
index 3888cc0c836c7ae64a3b77dad078a94eb8399b92..2159c04907b093e93b41f3adb651f7d2afe5779f 100644 (file)
--- a/xen/include/public/elfnote.h
+++ b/xen/include/public/elfnote.h
@@ -172,10 +172,16 @@
  */
 #define XEN_ELFNOTE_INIT_P2M      15
 
+/*
+ * Whether or not the guest can deal with being passed an initrd not
+ * mapped through its initial page tables.
+ */
+#define XEN_ELFNOTE_MOD_START_PFN 16
+
 /*
  * The number of the highest elfnote defined.
  */
-#define XEN_ELFNOTE_MAX XEN_ELFNOTE_INIT_P2M
+#define XEN_ELFNOTE_MAX XEN_ELFNOTE_MOD_START_PFN
 
 /*
  * System information exported through crash notes.

diff --git a/xen/include/public/xen.h b/xen/include/public/xen.h
index 6c783412cfe0a4b72f330a219a547c2d4091acb2..572d98c66c78893f3f8377679dcdb59c75cce579 100644 (file)
--- a/xen/include/public/xen.h
+++ b/xen/include/public/xen.h
@@ -581,7 +581,9 @@ struct start_info {
     unsigned long pt_base;      /* VIRTUAL address of page directory.     */
     unsigned long nr_pt_frames; /* Number of bootstrap p.t. frames.       */
     unsigned long mfn_list;     /* VIRTUAL address of page-frame list.    */
-    unsigned long mod_start;    /* VIRTUAL address of pre-loaded module.  */
+    unsigned long mod_start;    /* VIRTUAL address of pre-loaded module   */
+                                /* (PFN of pre-loaded module if           */
+                                /*  SIF_MOD_START_PFN set in flags).      */
     unsigned long mod_len;      /* Size (bytes) of pre-loaded module.     */
     int8_t cmd_line[MAX_GUEST_CMDLINE];
     /* The pfn range here covers both page table and p->m table frames.   */
@@ -600,6 +602,7 @@ typedef struct start_info start_info_t;
 #define SIF_PRIVILEGED    (1<<0)  /* Is the domain privileged? */
 #define SIF_INITDOMAIN    (1<<1)  /* Is this the initial control domain? */
 #define SIF_MULTIBOOT_MOD (1<<2)  /* Is mod_start a multiboot module? */
+#define SIF_MOD_START_PFN (1<<3)  /* Is mod_start a PFN? */
 #define SIF_PM_MASK       (0xFF<<8) /* reserve 1 byte for xen-pm options */
 
 /*