[Xen-devel] [PATCH v2 3/4] xen/arm: Add support to load initrd in dom0

[Julien Grall <julien.grall@xxxxxxxxxx>]

Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>

---
    Changes in v2:
        - Align the initrd and DTB length to 2MB
---
 xen/arch/arm/domain_build.c |  101 +++++++++++++++++++++++++++++++++++++------
 xen/arch/arm/kernel.c       |   20 +++++----
 xen/arch/arm/kernel.h       |    2 +
 3 files changed, 102 insertions(+), 21 deletions(-)

diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index b8c8a5d..7fc597f 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -163,12 +163,16 @@ static int write_properties(struct domain *d, struct 
kernel_info *kinfo,
          *
          * * remember xen,dom0-bootargs if we don't already have
          *   bootargs (from module #1, above).
-         * * remove bootargs,  xen,dom0-bootargs and xen,xen-bootargs.
+         * * remove bootargs,  xen,dom0-bootargs, xen,xen-bootargs,
+         *   linux,initrd-start and linux,initrd-end.
          */
         if ( dt_node_path_is_equal(np, "/chosen") )
         {
-            if ( dt_property_name_is_equal(pp, "xen,xen-bootargs") )
+            if ( dt_property_name_is_equal(pp, "xen,xen-bootargs") ||
+                 dt_property_name_is_equal(pp, "linux,initrd-start") ||
+                 dt_property_name_is_equal(pp, "linux,initrd-end") )
                 continue;
+
             if ( dt_property_name_is_equal(pp, "xen,dom0-bootargs") )
             {
                 had_dom0_bootargs = 1;
@@ -214,12 +218,22 @@ static int write_properties(struct domain *d, struct 
kernel_info *kinfo,
                            strlen(bootargs) + 1);
         if ( res )
             return res;
-    }
 
-    /*
-     * XXX should populate /chosen/linux,initrd-{start,end} here if we
-     * have module[2]
-     */
+        /*
+         * If the bootloader provides an initrd, we must create a placeholder
+         * for the initrd properties. The values will be replaced later.
+         */
+        if ( early_info.modules.module[MOD_INITRD].size )
+        {
+            res = fdt_property_cell(kinfo->fdt, "linux,initrd-start", 0);
+            if ( res )
+                return res;
+
+            res = fdt_property_cell(kinfo->fdt, "linux,initrd-end", 0);
+            if ( res )
+                return res;
+        }
+    }
 
     return 0;
 }
@@ -779,6 +793,8 @@ static int prepare_dtb(struct domain *d, struct kernel_info 
*kinfo)
     int new_size;
     int ret;
     paddr_t end;
+    paddr_t initrd_len;
+    paddr_t dtb_len;
 
     ASSERT(dt_host && (dt_host->sibling == NULL));
 
@@ -805,8 +821,10 @@ static int prepare_dtb(struct domain *d, struct 
kernel_info *kinfo)
     if ( ret < 0 )
         goto err;
 
-    /* Actual new size */
-    new_size = fdt_totalsize(kinfo->fdt);
+    /* Align DTB and initrd size to 2Mb. Linux only requires 4 byte alignment 
*/
+    initrd_len = ALIGN(early_info.modules.module[MOD_INITRD].size, MB(2));
+    dtb_len = ALIGN(fdt_totalsize(kinfo->fdt), MB(2));
+    new_size = initrd_len + dtb_len;
 
     /*
      * DTB must be loaded such that it does not conflict with the
@@ -815,14 +833,14 @@ static int prepare_dtb(struct domain *d, struct 
kernel_info *kinfo)
      * the recommendation in Documentation/arm64/booting.txt is below
      * 512MB. Place at 128MB, (or, if we have less RAM, as high as
      * possible) in order to satisfy both.
+     * If the bootloader provides an initrd, it will be loaded just
+     * after the DTB.
      */
     end = kinfo->mem.bank[0].start + kinfo->mem.bank[0].size;
     end = MIN(kinfo->mem.bank[0].start + (128<<20) + new_size, end);
 
-    kinfo->dtb_paddr = end - new_size;
-
-    /* Align the address to 2Mb. Linux only requires 4 byte alignment */
-    kinfo->dtb_paddr &= ~((2 << 20) - 1);
+    kinfo->initrd_paddr = end - initrd_len;
+    kinfo->dtb_paddr = kinfo->initrd_paddr - dtb_len;
 
     if ( kinfo->dtb_paddr < kinfo->mem.bank[0].start ||
          kinfo->mem.bank[0].start + new_size > end )
@@ -855,6 +873,61 @@ static void dtb_load(struct kernel_info *kinfo)
     xfree(kinfo->fdt);
 }
 
+static void initrd_load(struct kernel_info *kinfo)
+{
+    paddr_t load_addr = kinfo->initrd_paddr;
+    paddr_t paddr = early_info.modules.module[MOD_INITRD].start;
+    paddr_t len = early_info.modules.module[MOD_INITRD].size;
+    unsigned long offs;
+    int node;
+    int res;
+
+    if ( !len )
+        return;
+
+    printk("Loading dom0 initrd from %"PRIpaddr" to 
0x%"PRIpaddr"-0x%"PRIpaddr"\n",
+           paddr, load_addr, load_addr + len);
+
+    /* Fix up linux,initrd-start and linux,initrd-end in /chosen */
+    node = fdt_path_offset(kinfo->fdt, "/chosen");
+    if ( node < 0 )
+        panic("Cannot find the /chosen node");
+
+    res = fdt_setprop_inplace_cell(kinfo->fdt, node, "linux,initrd-start",
+                                   load_addr);
+    if ( res )
+        panic("Cannot fix up \"linux,initrd-start\" property\n");
+
+    res = fdt_setprop_inplace_cell(kinfo->fdt, node, "linux,initrd-end",
+                                   load_addr + len);
+    if ( res )
+        panic("Cannot fix up \"linux,initrd-end\" property\n");
+
+    for ( offs = 0; offs < len; )
+    {
+        int rc;
+        paddr_t s, l, ma;
+        void *dst;
+
+        s = offs & ~PAGE_MASK;
+        l = min(PAGE_SIZE - s, len);
+
+        rc = gvirt_to_maddr(load_addr + offs, &ma);
+        if ( rc )
+        {
+            panic("\nUnable to translate guest address\n");
+            return;
+        }
+
+        dst = map_domain_page(ma>>PAGE_SHIFT);
+
+        copy_from_paddr(dst + s, paddr + offs, l, BUFFERABLE);
+
+        unmap_domain_page(dst);
+        offs += l;
+    }
+}
+
 int construct_dom0(struct domain *d)
 {
     struct kernel_info kinfo = {};
@@ -891,6 +964,8 @@ int construct_dom0(struct domain *d)
     p2m_load_VTTBR(d);
 
     kernel_load(&kinfo);
+    /* initrd_load will fix up the fdt, so call it before dtb_load */
+    initrd_load(&kinfo);
     dtb_load(&kinfo);
 
     discard_initial_modules();
diff --git a/xen/arch/arm/kernel.c b/xen/arch/arm/kernel.c
index 7a91d60..bd59d74 100644
--- a/xen/arch/arm/kernel.c
+++ b/xen/arch/arm/kernel.c
@@ -71,15 +71,22 @@ static void kernel_zimage_check_overlap(struct kernel_info 
*info)
 {
     paddr_t zimage_start = info->zimage.load_addr;
     paddr_t zimage_end = info->zimage.load_addr + info->zimage.len;
-    paddr_t dtb_start = info->dtb_paddr;
-    paddr_t dtb_end = info->dtb_paddr + fdt_totalsize(info->fdt);
+    paddr_t start = info->dtb_paddr;
+    paddr_t end;
 
-    if ( (dtb_start > zimage_end) || (dtb_end < zimage_start) )
+    end = info->initrd_paddr + early_info.modules.module[MOD_INITRD].size;
+
+    /*
+     * In the dom0 memory, the initrd will be just after the DTB. So we
+     * only need to check if the zImage range will overlap the
+     * DTB-initrd range.
+     */
+    if ( (start > zimage_end) || (end < zimage_start) )
         return;
 
     panic(XENLOG_ERR "The kernel(0x%"PRIpaddr"-0x%"PRIpaddr
-          ") is overlapping the DTB(0x%"PRIpaddr"-0x%"PRIpaddr")\n",
-          zimage_start, zimage_end, dtb_start, dtb_end);
+          ") is overlapping the DTB-initrd(0x%"PRIpaddr"-0x%"PRIpaddr")\n",
+          zimage_start, zimage_end, start, end);
 }
 
 static void kernel_zimage_load(struct kernel_info *info)
@@ -328,9 +335,6 @@ int kernel_prepare(struct kernel_info *info)
 
     paddr_t start, size;
 
-    if ( early_info.modules.nr_mods > MOD_INITRD )
-        panic("Cannot handle dom0 initrd yet\n");
-
     if ( early_info.modules.nr_mods < MOD_KERNEL )
     {
         printk("No boot modules found, trying flash\n");
diff --git a/xen/arch/arm/kernel.h b/xen/arch/arm/kernel.h
index c900e74..debf590 100644
--- a/xen/arch/arm/kernel.h
+++ b/xen/arch/arm/kernel.h
@@ -21,6 +21,8 @@ struct kernel_info {
     paddr_t dtb_paddr;
     paddr_t entry;
 
+    paddr_t initrd_paddr;
+
     void *kernel_img;
     unsigned kernel_order;
 
-- 
1.7.10.4


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