[Xen-devel] [PATCH 4/5] xen: fix handling framebuffer located above 4GB

[Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>]

On some machines (for example Thinkpad P52), UEFI GOP reports
framebuffer located above 4GB (0x4000000000 on that machine). This
address does not fit in {xen,dom0}_vga_console_info.u.vesa_lfb.lfb_base
field, which is 32bit. The overflow here cause all kind of memory
corruption when anything tries to write something on the screen,
starting with zeroing the whole framebuffer in vesa_init().

Fix this similar to how it's done in Linux: add ext_lfb_base field at
the end of the structure, to hold upper 32bits of the address. Since the
field is added at the end of the structure, it will work with older
Linux versions too (other than using possibly truncated address - no
worse than without this change). Thanks to ABI containing size of the
structure (start_info.console.dom0.info_size), Linux can detect when
this field is present and use it appropriately then.

Signed-off-by: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
---
 xen/arch/x86/efi/efi-boot.h |  1 +
 xen/drivers/video/vesa.c    | 15 +++++++++++----
 xen/include/public/xen.h    |  2 ++
 3 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/xen/arch/x86/efi/efi-boot.h b/xen/arch/x86/efi/efi-boot.h
index 5789d2c..7a13a30 100644
--- a/xen/arch/x86/efi/efi-boot.h
+++ b/xen/arch/x86/efi/efi-boot.h
@@ -550,6 +550,7 @@ static void __init 
efi_arch_video_init(EFI_GRAPHICS_OUTPUT_PROTOCOL *gop,
         vga_console_info.u.vesa_lfb.bytes_per_line =
             (mode_info->PixelsPerScanLine * bpp + 7) >> 3;
         vga_console_info.u.vesa_lfb.lfb_base = gop->Mode->FrameBufferBase;
+        vga_console_info.u.vesa_lfb.ext_lfb_base = gop->Mode->FrameBufferBase 
>> 32;
         vga_console_info.u.vesa_lfb.lfb_size =
             (gop->Mode->FrameBufferSize + 0xffff) >> 16;
     }
diff --git a/xen/drivers/video/vesa.c b/xen/drivers/video/vesa.c
index c92497e..f22cf7f 100644
--- a/xen/drivers/video/vesa.c
+++ b/xen/drivers/video/vesa.c
@@ -84,6 +84,7 @@ void __init vesa_early_init(void)
 void __init vesa_init(void)
 {
     struct lfb_prop lfbp;
+    unsigned long lfb_base;
 
     if ( !font )
         return;
@@ -97,15 +98,17 @@ void __init vesa_init(void)
     lfbp.text_columns = vlfb_info.width / font->width;
     lfbp.text_rows = vlfb_info.height / font->height;
 
-    lfbp.lfb = lfb = ioremap(vlfb_info.lfb_base, vram_remap);
+    lfb_base = vlfb_info.lfb_base;
+    lfb_base |= (unsigned long)vlfb_info.ext_lfb_base << 32;
+    lfbp.lfb = lfb = ioremap(lfb_base, vram_remap);
     if ( !lfb )
         return;
 
     memset(lfb, 0, vram_remap);
 
-    printk(XENLOG_INFO "vesafb: framebuffer at %#x, mapped to 0x%p, "
+    printk(XENLOG_INFO "vesafb: framebuffer at %#lx, mapped to 0x%p, "
            "using %uk, total %uk\n",
-           vlfb_info.lfb_base, lfb,
+           lfb_base, lfb,
            vram_remap >> 10, vram_total >> 10);
     printk(XENLOG_INFO "vesafb: mode is %dx%dx%u, linelength=%d, font %ux%u\n",
            vlfb_info.width, vlfb_info.height,
@@ -152,6 +155,10 @@ void __init vesa_mtrr_init(void)
         MTRR_TYPE_WRCOMB, MTRR_TYPE_WRTHROUGH };
     unsigned int size_total;
     int rc, type;
+    unsigned long lfb_base;
+
+    lfb_base = vlfb_info.lfb_base;
+    lfb_base |= (unsigned long)vlfb_info.ext_lfb_base << 32;
 
     if ( !lfb || (vesa_mtrr == 0) || (vesa_mtrr >= ARRAY_SIZE(mtrr_types)) )
         return;
@@ -167,7 +174,7 @@ void __init vesa_mtrr_init(void)
 
     /* Try and find a power of two to add */
     do {
-        rc = mtrr_add(vlfb_info.lfb_base, size_total, type, 1);
+        rc = mtrr_add(lfb_base, size_total, type, 1);
         size_total >>= 1;
     } while ( (size_total >= PAGE_SIZE) && (rc == -EINVAL) );
 }
diff --git a/xen/include/public/xen.h b/xen/include/public/xen.h
index ccdffc0..b0f0f7e 100644
--- a/xen/include/public/xen.h
+++ b/xen/include/public/xen.h
@@ -923,6 +923,8 @@ typedef struct dom0_vga_console_info {
             /* Mode attributes (offset 0x0, VESA command 0x4f01). */
             uint16_t mode_attrs;
 #endif
+            /* high 32 bits of lfb_base */
+            uint32_t ext_lfb_base;
         } vesa_lfb;
     } u;
 } dom0_vga_console_info_t;
-- 
git-series 0.9.1

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-devel