[Xen-changelog] [xen master] x86: change default load address from 1 MiB to 2 MiB

[patchbot@xxxxxxx]

commit 7ed93f3a0dff8f1d999ae5b541886eb8ff2f7842
Author:     Daniel Kiper <daniel.kiper@xxxxxxxxxx>
AuthorDate: Fri Apr 7 13:35:32 2017 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri Apr 7 13:35:32 2017 +0200

    x86: change default load address from 1 MiB to 2 MiB
    
    Subsequent patches introducing relocatable early boot code play with
    page tables using 2 MiB huge pages. If load address is not aligned at
    2 MiB then code touching such page tables must have special cases for
    start and end of Xen image memory region. So, let's make life easier
    and move default load address from 1 MiB to 2 MiB. This way page table
    code will be nice and easy. Hence, there is a chance that it will be
    less error prone too... :-)))
    
    Additionally, drop first 2 MiB mapping from Xen image mapping.
    It is no longer needed.
    
    Signed-off-by: Daniel Kiper <daniel.kiper@xxxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Doug Goldstein <cardoe@xxxxxxxxxx>
---
 xen/arch/x86/Makefile      | 2 +-
 xen/arch/x86/Rules.mk      | 3 +++
 xen/arch/x86/boot/head.S   | 8 --------
 xen/arch/x86/boot/x86_64.S | 5 +++--
 xen/arch/x86/setup.c       | 3 ++-
 xen/arch/x86/xen.lds.S     | 2 +-
 6 files changed, 10 insertions(+), 13 deletions(-)

diff --git a/xen/arch/x86/Makefile b/xen/arch/x86/Makefile
index 2331246..a1494c3 100644
--- a/xen/arch/x86/Makefile
+++ b/xen/arch/x86/Makefile
@@ -94,7 +94,7 @@ syms-warn-dup-y := --warn-dup
 syms-warn-dup-$(CONFIG_SUPPRESS_DUPLICATE_SYMBOL_WARNINGS) :=
 
 $(TARGET): $(TARGET)-syms $(efi-y) boot/mkelf32
-       ./boot/mkelf32 $(notes_phdrs) $(TARGET)-syms $(TARGET) 0x100000 \
+       ./boot/mkelf32 $(notes_phdrs) $(TARGET)-syms $(TARGET) 
$(XEN_IMG_OFFSET) \
                       `$(NM) $(TARGET)-syms | sed -ne 's/^\([^ ]*\) . 
__2M_rwdata_end$$/0x\1/p'`
 
 ALL_OBJS := $(BASEDIR)/arch/x86/boot/built_in.o 
$(BASEDIR)/arch/x86/efi/built_in.o $(ALL_OBJS)
diff --git a/xen/arch/x86/Rules.mk b/xen/arch/x86/Rules.mk
index 72be8b2..568657e 100644
--- a/xen/arch/x86/Rules.mk
+++ b/xen/arch/x86/Rules.mk
@@ -1,9 +1,12 @@
 ########################################
 # x86-specific definitions
 
+XEN_IMG_OFFSET := 0x200000
+
 CFLAGS += -I$(BASEDIR)/include
 CFLAGS += -I$(BASEDIR)/include/asm-x86/mach-generic
 CFLAGS += -I$(BASEDIR)/include/asm-x86/mach-default
+CFLAGS += -DXEN_IMG_OFFSET=$(XEN_IMG_OFFSET)
 CFLAGS += '-D__OBJECT_LABEL__=$(subst /,$$,$(subst -,_,$(subst 
$(BASEDIR)/,,$(CURDIR))/$@))'
 
 # Prevent floating-point variables from creeping into Xen.
diff --git a/xen/arch/x86/boot/head.S b/xen/arch/x86/boot/head.S
index a2177c3..b5d9ec8 100644
--- a/xen/arch/x86/boot/head.S
+++ b/xen/arch/x86/boot/head.S
@@ -524,14 +524,6 @@ trampoline_setup:
         mov     %eax,sym_phys(boot_tsc_stamp)
         mov     %edx,sym_phys(boot_tsc_stamp+4)
 
-        /*
-         * During boot, hook 4kB mappings of first 2MB of memory into L2.
-         * This avoids mixing cachability for the legacy VGA region, and is
-         * corrected when Xen relocates itself.
-         */
-        mov     $sym_phys(l1_identmap)+__PAGE_HYPERVISOR,%edi
-        mov     %edi,sym_phys(l2_xenmap)
-
         /* Apply relocations to bootstrap trampoline. */
         mov     sym_phys(trampoline_phys),%edx
         mov     $sym_phys(__trampoline_rel_start),%edi
diff --git a/xen/arch/x86/boot/x86_64.S b/xen/arch/x86/boot/x86_64.S
index 4d507fb..f9d1022 100644
--- a/xen/arch/x86/boot/x86_64.S
+++ b/xen/arch/x86/boot/x86_64.S
@@ -121,8 +121,9 @@ GLOBAL(l2_identmap)
  * page.
  */
 GLOBAL(l2_xenmap)
-        idx = 0
-        .rept 8
+        .quad 0
+        idx = 1
+        .rept 7
         .quad sym_phys(__image_base__) + (idx << L2_PAGETABLE_SHIFT) + 
(PAGE_HYPERVISOR | _PAGE_PSE)
         idx = idx + 1
         .endr
diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c
index be10a4f..e5690b3 100644
--- a/xen/arch/x86/setup.c
+++ b/xen/arch/x86/setup.c
@@ -1007,7 +1007,8 @@ void __init noreturn __start_xen(unsigned long mbi_p)
              * Undo the temporary-hooking of the l1_identmap.  __2M_text_start
              * is contained in this PTE.
              */
-            BUG_ON(l2_table_offset((unsigned long)_erodata) ==
+            BUG_ON(using_2M_mapping() &&
+                   l2_table_offset((unsigned long)_erodata) ==
                    l2_table_offset((unsigned long)_stext));
             *pl2e++ = l2e_from_pfn(xen_phys_start >> PAGE_SHIFT,
                                    PAGE_HYPERVISOR_RX | _PAGE_PSE);
diff --git a/xen/arch/x86/xen.lds.S b/xen/arch/x86/xen.lds.S
index 1462194..8289a1b 100644
--- a/xen/arch/x86/xen.lds.S
+++ b/xen/arch/x86/xen.lds.S
@@ -54,7 +54,7 @@ SECTIONS
   __2M_text_start = .;         /* Start of 2M superpages, mapped RX. */
 #endif
 
-  . = __XEN_VIRT_START + MB(1);
+  . = __XEN_VIRT_START + XEN_IMG_OFFSET;
   _start = .;
   .text : {
         _stext = .;            /* Text and read-only data */
--
generated by git-patchbot for /home/xen/git/xen.git#master

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