hw/i386/pc: run the multiboot loader before the PVH loader

Some multiboot images could be in the ELF format. In the current
implementation QEMU fails because we try to load these images
as a PVH image.

In order to fix this issue, we should try multiboot first (we
already check the multiboot magic header before to load it).
If it is not a multiboot image, we can try the PVH loader.

Fixes: ab969087da6 ("pvh: Boot uncompressed kernel using direct boot ABI", 2019-01-15)
Reported-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Message-Id: <20190214180216.246707-1-sgarzare@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 42128183e9af123c9a7c58d40ee189055bce7c1a..9c8f8332a9ed9145484205423d2798f4b3d5bde0 100644 (file)
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -1209,6 +1209,17 @@ static void load_linux(PCMachineState *pcms,
     if (ldl_p(header+0x202) == 0x53726448) {
         protocol = lduw_p(header+0x206);
     } else {
+        /*
+         * This could be a multiboot kernel. If it is, let's stop treating it
+         * like a Linux kernel.
+         * Note: some multiboot images could be in the ELF format (the same of
+         * PVH), so we try multiboot first since we check the multiboot magic
+         * header before to load it.
+         */
+        if (load_multiboot(fw_cfg, f, kernel_filename, initrd_filename,
+                           kernel_cmdline, kernel_size, header)) {
+            return;
+        }
         /*
          * Check if the file is an uncompressed kernel file (ELF) and load it,
          * saving the PVH entry point used by the x86/HVM direct boot ABI.
@@ -1262,12 +1273,6 @@ static void load_linux(PCMachineState *pcms,
 
             return;
         }
-        /* This looks like a multiboot kernel. If it is, let's stop
-           treating it like a Linux kernel. */
-        if (load_multiboot(fw_cfg, f, kernel_filename, initrd_filename,
-                           kernel_cmdline, kernel_size, header)) {
-            return;
-        }
         protocol = 0;
     }