x86/PVH: account for module command line length

As per observation in practice, initrd->cmdline_pa is not normally zero.
Hence so far we always appended at least one byte. That alone may
already render insufficient the "allocation" made by find_memory().
Things would be worse when there's actually a (perhaps long) command
line.

Skip setup when the command line is empty. Amend the "allocation" size
by padding and actual size of module command line. Along these lines
also skip initrd setup when the initrd is zero size.

Fixes: 0ecb8eb09f9f ("x86/pvh: pass module command line to dom0")
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Jason Andryuk <jason.andryuk@amd.com>

diff --git a/xen/arch/x86/hvm/dom0_build.c b/xen/arch/x86/hvm/dom0_build.c
index 13a73854326f3b2e5d96b0859e2f9c08391ab6fa..daf1b6f88b14631b165b7d8262eef1cabfc695c9 100644 (file)
--- a/xen/arch/x86/hvm/dom0_build.c
+++ b/xen/arch/x86/hvm/dom0_build.c
@@ -652,6 +652,7 @@ static int __init pvh_load_kernel(
     unsigned long image_len = image->size;
     unsigned long initrd_len = initrd ? initrd->size : 0;
     const char *cmdline = image->cmdline_pa ? __va(image->cmdline_pa) : NULL;
+    const char *initrd_cmdline = NULL;
     struct elf_binary elf;
     struct elf_dom_parms parms;
     size_t extra_space;
@@ -715,7 +716,23 @@ static int __init pvh_load_kernel(
     extra_space = sizeof(start_info);
 
     if ( initrd )
-        extra_space += sizeof(mod) + ROUNDUP(initrd_len, PAGE_SIZE);
+    {
+        size_t initrd_space = elf_round_up(&elf, initrd_len);
+
+        if ( initrd->cmdline_pa )
+        {
+            initrd_cmdline = __va(initrd->cmdline_pa);
+            if ( !*initrd_cmdline )
+                initrd_cmdline = NULL;
+        }
+        if ( initrd_cmdline )
+            initrd_space += strlen(initrd_cmdline) + 1;
+
+        if ( initrd_space )
+            extra_space += ROUNDUP(initrd_space, PAGE_SIZE) + sizeof(mod);
+        else
+            initrd = NULL;
+    }
 
     if ( cmdline )
         extra_space += elf_round_up(&elf, strlen(cmdline) + 1);
@@ -740,12 +757,11 @@ static int __init pvh_load_kernel(
         mod.paddr = last_addr;
         mod.size = initrd_len;
         last_addr += elf_round_up(&elf, initrd_len);
-        if ( initrd->cmdline_pa )
+        if ( initrd_cmdline )
         {
-            char *str = __va(initrd->cmdline_pa);
-            size_t len = strlen(str) + 1;
+            size_t len = strlen(initrd_cmdline) + 1;
 
-            rc = hvm_copy_to_guest_phys(last_addr, str, len, v);
+            rc = hvm_copy_to_guest_phys(last_addr, initrd_cmdline, len, v);
             if ( rc )
             {
                 printk("Unable to copy module command line\n");