[Xen-changelog] [qemu-upstream-unstable] address_space_translate: do not cross page boundaries

[patchbot@xxxxxxx]

commit a41087bc7110e8378cd49ddd06aa7c9d361f3673
Author:     Stefano Stabellini <Stefano.Stabellini@xxxxxxxxxxxxx>
AuthorDate: Thu Jan 30 12:46:05 2014 +0000
Commit:     Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
CommitDate: Mon Feb 3 10:50:03 2014 +0000

    address_space_translate: do not cross page boundaries
    
    The following commit:
    
    commit 149f54b53b7666a3facd45e86eece60ce7d3b114
    Author: Paolo Bonzini <pbonzini@xxxxxxxxxx>
    Date:   Fri May 24 12:59:37 2013 +0200
    
        memory: add address_space_translate
    
    breaks Xen support in QEMU, in particular the Xen mapcache. The effect
    is that one Windows XP installation out of ten would end up with BSOD.
    
    The reason is that after this commit l in address_space_rw can span a
    page boundary, however qemu_get_ram_ptr still calls xen_map_cache asking
    to map a single page (if block->offset == 0).
    
    Fix the issue by reverting to the previous behaviour: do not return a
    length from address_space_translate_internal that can span a page
    boundary.
    
    Also in address_space_translate do not ignore the length returned by
    address_space_translate_internal.
    
    This patch should be backported to QEMU 1.6.x.
    
    upstream-commit-id: 360e607b88a23d378f6efaa769c76d26f538234d
    
    Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
    Signed-off-by: Anthony Perard <anthony.perard@xxxxxxxxxx>
    Tested-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
    Acked-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
    Cc: qemu-stable@xxxxxxxxxx
---
 exec.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/exec.c b/exec.c
index 667a718..f3797b7 100644
--- a/exec.c
+++ b/exec.c
@@ -251,7 +251,7 @@ address_space_translate_internal(AddressSpaceDispatch *d, 
hwaddr addr, hwaddr *x
                                  hwaddr *plen, bool resolve_subpage)
 {
     MemoryRegionSection *section;
-    Int128 diff;
+    Int128 diff, diff_page;
 
     section = address_space_lookup_region(d, addr, resolve_subpage);
     /* Compute offset within MemoryRegionSection */
@@ -260,7 +260,9 @@ address_space_translate_internal(AddressSpaceDispatch *d, 
hwaddr addr, hwaddr *x
     /* Compute offset within MemoryRegion */
     *xlat = addr + section->offset_within_region;
 
+    diff_page = int128_make64(((addr & TARGET_PAGE_MASK) + TARGET_PAGE_SIZE) - 
addr);
     diff = int128_sub(section->mr->size, int128_make64(addr));
+    diff = int128_min(diff, diff_page);
     *plen = int128_get64(int128_min(diff, int128_make64(*plen)));
     return section;
 }
@@ -275,7 +277,7 @@ MemoryRegion *address_space_translate(AddressSpace *as, 
hwaddr addr,
     hwaddr len = *plen;
 
     for (;;) {
-        section = address_space_translate_internal(as->dispatch, addr, &addr, 
plen, true);
+        section = address_space_translate_internal(as->dispatch, addr, &addr, 
&len, true);
         mr = section->mr;
 
         if (!mr->iommu_ops) {
--
generated by git-patchbot for /home/xen/git/qemu-upstream-unstable.git

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