x86/boot: Use boot_vid_info variable directly from C code

No more need to pass from assembly code.

Signed-off-by: Frediano Ziglio <frediano.ziglio@cloud.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>

xen/arch/x86/boot/build32.lds.S

@@ -50,6 +50,7 @@ SECTIONS
         DECLARE_IMPORT(__trampoline_seg_start);
         DECLARE_IMPORT(__trampoline_seg_stop);
         DECLARE_IMPORT(trampoline_phys);
+        DECLARE_IMPORT(boot_vid_info);
         . = . + GAP;
         *(.text)
         *(.text.*)

xen/arch/x86/boot/head.S

@@ -514,18 +514,10 @@ trampoline_setup:
         mov     sym_esi(trampoline_phys), %ecx
         add     $TRAMPOLINE_SPACE,%ecx
 
-#ifdef CONFIG_VIDEO
-        lea     sym_esi(boot_vid_info), %edx
-#else
-        xor     %edx, %edx
-#endif
-
         /* Save Multiboot / PVH info struct (after relocation) for later use. */
-        push    %edx                /* Boot video info to be filled from MB2. */
         mov     %ebx, %edx          /* Multiboot / PVH information address. */
-        /*      reloc(magic/eax, info/edx, trampoline/ecx, video/stk) using fastcall. */
+        /*      reloc(magic/eax, info/edx, trampoline/ecx) using fastcall. */
         call    reloc
-        add     $4, %esp
 
 #ifdef CONFIG_PVH_GUEST
         cmpb    $0, sym_esi(pvh_boot)

xen/arch/x86/boot/reloc.c

@@ -176,7 +176,7 @@ static multiboot_info_t *mbi_reloc(uint32_t mbi_in, memctx *ctx)
     return mbi_out;
 }
 
-static multiboot_info_t *mbi2_reloc(uint32_t mbi_in, uint32_t video_out, memctx *ctx)
+static multiboot_info_t *mbi2_reloc(uint32_t mbi_in, memctx *ctx)
 {
     const multiboot2_fixed_t *mbi_fix = _p(mbi_in);
     const multiboot2_memory_map_t *mmap_src;
@@ -185,7 +185,7 @@ static multiboot_info_t *mbi2_reloc(uint32_t mbi_in, uint32_t video_out, memctx
     memory_map_t *mmap_dst;
     multiboot_info_t *mbi_out;
 #ifdef CONFIG_VIDEO
-    struct boot_video_info *video = NULL;
+    struct boot_video_info *video = &boot_vid_info;
 #endif
     uint32_t ptr;
     unsigned int i, mod_idx = 0;
@@ -290,12 +290,11 @@ static multiboot_info_t *mbi2_reloc(uint32_t mbi_in, uint32_t video_out, memctx
 
 #ifdef CONFIG_VIDEO
         case MULTIBOOT2_TAG_TYPE_VBE:
-            if ( video_out )
+            if ( video )
             {
                 const struct vesa_ctrl_info *ci;
                 const struct vesa_mode_info *mi;
 
-                video = _p(video_out);
                 ci = (const void *)get_mb2_data(tag, vbe, vbe_control_info);
                 mi = (const void *)get_mb2_data(tag, vbe, vbe_mode_info);
 
@@ -321,7 +320,6 @@ static multiboot_info_t *mbi2_reloc(uint32_t mbi_in, uint32_t video_out, memctx
             if ( (get_mb2_data(tag, framebuffer, framebuffer_type) !=
                   MULTIBOOT2_FRAMEBUFFER_TYPE_RGB) )
             {
-                video_out = 0;
                 video = NULL;
             }
             break;
@@ -346,8 +344,7 @@ static multiboot_info_t *mbi2_reloc(uint32_t mbi_in, uint32_t video_out, memctx
 }
 
 /* SAF-1-safe */
-void *reloc(uint32_t magic, uint32_t in, uint32_t trampoline,
+void *reloc(uint32_t magic, uint32_t in, uint32_t trampoline)
-            uint32_t video_info)
 {
     memctx ctx = { trampoline };
 
@@ -357,7 +354,7 @@ void *reloc(uint32_t magic, uint32_t in, uint32_t trampoline,
         return mbi_reloc(in, &ctx);
 
     case MULTIBOOT2_BOOTLOADER_MAGIC:
-        return mbi2_reloc(in, video_info, &ctx);
+        return mbi2_reloc(in, &ctx);
 
     case XEN_HVM_START_MAGIC_VALUE:
         if ( IS_ENABLED(CONFIG_PVH_GUEST) )