[v2,16/30] xen/x86: parse Dom0 kernel for PVHv2

Commit Message

Roger Pau Monne Sept. 27, 2016, 3:57 p.m. UTC

Introduce a helper to parse the Dom0 kernel.

Signed-off-by: Roger Pau Monné <[e-mail]>
---
Cc: Jan Beulich <[e-mail]>
Cc: Andrew Cooper <[e-mail]>
---
 xen/arch/x86/domain_build.c | 138 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 138 insertions(+)

Comments

Jan Beulich Oct. 6, 2016, 3:14 p.m. UTC | #1

>>> On 27.09.16 at 17:57, <[e-mail]> wrote:
> +    start_info.modlist_paddr = last_addr;
> +    start_info.nr_modules = 1;
> +    last_addr += sizeof(mod);

How can this be unconditionally 1? It is certainly possible to boot
without initrd.

Jan

Roger Pau Monne Oct. 11, 2016, 3:02 p.m. UTC | #2

On Thu, Oct 06, 2016 at 09:14:18AM -0600, Jan Beulich wrote:
> >>> On 27.09.16 at 17:57, <[e-mail]> wrote:
> > +    start_info.modlist_paddr = last_addr;
> > +    start_info.nr_modules = 1;
> > +    last_addr += sizeof(mod);
> 
> How can this be unconditionally 1? It is certainly possible to boot
> without initrd.

Yes, it seems like I left this here and forgot to finish it, so an initrd 
was assumed to be present (here and in the code further up). It should now 
be able to handle booting Dom0 without any initrd.

Roger.

Patch

diff --git a/xen/arch/x86/domain_build.c b/xen/arch/x86/domain_build.c
index c590c58..effebf1 100644
--- a/xen/arch/x86/domain_build.c
+++ b/xen/arch/x86/domain_build.c
@@ -39,6 +39,7 @@ 
 #include <asm/hpet.h>
 
 #include <public/version.h>
+#include <public/arch-x86/hvm/start_info.h>
 
 static long __initdata dom0_nrpages;
 static long __initdata dom0_min_nrpages;
@@ -1886,12 +1887,141 @@  static int __init hvm_setup_p2m(struct domain *d)
     return 0;
 }
 
+static int __init hvm_load_kernel(struct domain *d, const module_t *image,
+                                  unsigned long image_headroom,
+                                  module_t *initrd, char *image_base,
+                                  char *cmdline, paddr_t *entry,
+                                  paddr_t *start_info_addr)
+{
+    char *image_start = image_base + image_headroom;
+    unsigned long image_len = image->mod_end;
+    struct elf_binary elf;
+    struct elf_dom_parms parms;
+    paddr_t last_addr;
+    struct hvm_start_info start_info;
+    struct hvm_modlist_entry mod;
+    struct vcpu *saved_current, *v = d->vcpu[0];
+    int rc;
+
+    printk("** Parsing Dom0 kernel **\n");
+
+    if ( (rc = bzimage_parse(image_base, &image_start, &image_len)) != 0 )
+    {
+        printk("Error trying to detect bz compressed kernel\n");
+        return rc;
+    }
+
+    if ( (rc = elf_init(&elf, image_start, image_len)) != 0 )
+    {
+        printk("Unable to init ELF\n");
+        return rc;
+    }
+#ifdef VERBOSE
+    elf_set_verbose(&elf);
+#endif
+    elf_parse_binary(&elf);
+    if ( (rc = elf_xen_parse(&elf, &parms)) != 0 )
+    {
+        printk("Unable to parse kernel for ELFNOTES\n");
+        return rc;
+    }
+
+    if ( parms.phys_entry == UNSET_ADDR32 ) {
+        printk("Unable to find kernel entry point, aborting\n");
+        return -EINVAL;
+    }
+
+    printk("OS: %s version: %s loader: %s bitness: %s\n", parms.guest_os,
+           parms.guest_ver, parms.loader,
+           elf_64bit(&elf) ? "64-bit" : "32-bit");
+
+    printk("** Loading Dom0 kernel **\n");
+    /* Copy the OS image and free temporary buffer. */
+    elf.dest_base = (void *)(parms.virt_kstart - parms.virt_base);
+    elf.dest_size = parms.virt_kend - parms.virt_kstart;
+
+    saved_current = current;
+    set_current(v);
+
+    rc = elf_load_binary(&elf);
+    if ( rc < 0 )
+    {
+        printk("Failed to load kernel: %d\n", rc);
+        printk("Xen dom0 kernel broken ELF: %s\n", elf_check_broken(&elf));
+        goto out;
+    }
+
+    last_addr = ROUNDUP(parms.virt_kend - parms.virt_base, PAGE_SIZE);
+    printk("** Copying Dom0 modules **\n");
+
+    rc = hvm_copy_to_guest_phys(last_addr, mfn_to_virt(initrd->mod_start),
+                                initrd->mod_end);
+    if ( rc != HVMCOPY_okay )
+    {
+        printk("Unable to copy initrd to guest\n");
+        rc = -EFAULT;
+        goto out;
+    }
+
+    mod.paddr = last_addr;
+    mod.size = initrd->mod_end;
+    last_addr += ROUNDUP(initrd->mod_end, PAGE_SIZE);
+
+    /* Free temporary buffers. */
+    discard_initial_images();
+
+    printk("** Setting up start-of-day info **\n");
+
+    memset(&start_info, 0, sizeof(start_info));
+    if ( cmdline != NULL )
+    {
+        rc = hvm_copy_to_guest_phys(last_addr, cmdline, strlen(cmdline) + 1);
+        if ( rc != HVMCOPY_okay )
+        {
+            printk("Unable to copy guest command line\n");
+            rc = -EFAULT;
+            goto out;
+        }
+        start_info.cmdline_paddr = last_addr;
+        last_addr += ROUNDUP(strlen(cmdline) + 1, 8);
+    }
+    rc = hvm_copy_to_guest_phys(last_addr, &mod, sizeof(mod));
+    if ( rc != HVMCOPY_okay )
+    {
+        printk("Unable to copy guest modules\n");
+        rc = -EFAULT;
+        goto out;
+    }
+
+    start_info.modlist_paddr = last_addr;
+    start_info.nr_modules = 1;
+    last_addr += sizeof(mod);
+    start_info.magic = XEN_HVM_START_MAGIC_VALUE;
+    start_info.flags = SIF_PRIVILEGED | SIF_INITDOMAIN;
+    rc = hvm_copy_to_guest_phys(last_addr, &start_info, sizeof(start_info));
+    if ( rc != HVMCOPY_okay )
+    {
+        printk("Unable to copy start info to guest\n");
+        rc = -EFAULT;
+        goto out;
+    }
+
+    *entry = parms.phys_entry;
+    *start_info_addr = last_addr;
+    rc = 0;
+
+out:
+    set_current(saved_current);
+    return rc;
+}
+
 static int __init construct_dom0_hvm(struct domain *d, const module_t *image,
                                      unsigned long image_headroom,
                                      module_t *initrd,
                                      void *(*bootstrap_map)(const module_t *),
                                      char *cmdline)
 {
+    paddr_t entry, start_info;
     int rc;
 
     printk("** Building a PVH Dom0 **\n");
@@ -1911,6 +2041,14 @@  static int __init construct_dom0_hvm(struct domain *d, const module_t *image,
         return rc;
     }
 
+    rc = hvm_load_kernel(d, image, image_headroom, initrd, bootstrap_map(image),
+                         cmdline, &entry, &start_info);
+    if ( rc )
+    {
+        printk("Failed to load Dom0 kernel\n");
+        return rc;
+    }
+
     return 0;
 }