[lkml]   [2012]   [Jul]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
Patch in this message
Subject[PATCH 7/7] xen/mmu: Remove from __ka space PMD entries for pagetables.
Please first read the description in "xen/mmu: Copy and revector the
P2M tree."

At this stage, the __ka address space (which is what the old
P2M tree was using) is partially disassembled. The cleanup_highmap
has removed the PMD entries from 0-16MB and anything past _brk_end
up to the max_pfn_mapped (which is the end of the ramdisk).

The xen_remove_p2m_tree and code around has ripped out the __ka for
the old P2M array.

Here we continue on doing it to where the Xen page-tables were.
It is safe to do it, as the page-tables are addressed using __va.
For good measure we delete anything that is within MODULES_VADDR
and up to the end of the PMD.

At this point the __ka only contains PMD entries for the start
of the kernel up to __brk.

Signed-off-by: Konrad Rzeszutek Wilk <>
arch/x86/xen/mmu.c | 20 ++++++++++++++++++++
1 files changed, 20 insertions(+), 0 deletions(-)

diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index 05e8492..738feca 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -1241,6 +1241,26 @@ static void __init xen_pagetable_setup_done(pgd_t *base)
xen_start_info->mfn_list = new_mfn_list;
+#ifdef CONFIG_X86_64
+ /* At this stage, cleanup_highmap has already cleaned __ka space
+ * from _brk_limit way up to the max_pfn_mapped (which is the end of
+ * the ramdisk). We continue on, erasing PMD entries that point to page
+ * tables - do note that they are accessible at this stage via __va.
+ * For good measure we also round up to the PMD - which means that if
+ * anybody is using __ka address to the initial boot-stack - and try
+ * to use it - they are going to crash. The xen_start_info has been
+ * taken care of already in xen_setup_kernel_pagetable. */
+ addr = xen_start_info->pt_base;
+ size = roundup(xen_start_info->nr_pt_frames * PAGE_SIZE, PMD_SIZE);
+ xen_cleanhighmap(addr, addr + size);
+ xen_start_info->pt_base = (unsigned long)__va(__pa(xen_start_info->pt_base));
+ /* This is superflous and shouldn't be neccessary, but you know what
+ * lets do it. The MODULES_VADDR -> MODULES_END should be clear of
+ * anything at this stage. */
+ xen_cleanhighmap(MODULES_VADDR, roundup(MODULES_VADDR, PUD_SIZE) - 1);


 \ /
  Last update: 2012-07-26 23:41    [W:0.112 / U:5.400 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site