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* [Qemu-devel] [PATCH] address_space_translate: do not cross page boundaries
@ 2014-01-30 12:46 ` Stefano Stabellini
  0 siblings, 0 replies; 4+ messages in thread
From: Stefano Stabellini @ 2014-01-30 12:46 UTC (permalink / raw)
  To: Paolo Bonzini
  Cc: Anthony PERARD, george.dunlap, xen-devel, qemu-devel, Stefano Stabellini

The following commit:

commit 149f54b53b7666a3facd45e86eece60ce7d3b114
Author: Paolo Bonzini <pbonzini@redhat.com>
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.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: Anthony Perard <anthony.perard@citrix.com>

---
 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) {

^ permalink raw reply related	[flat|nested] 4+ messages in thread
* [PATCH] address_space_translate: do not cross page boundaries
@ 2014-01-30 12:46 ` Stefano Stabellini
  0 siblings, 0 replies; 4+ messages in thread
From: Stefano Stabellini @ 2014-01-30 12:46 UTC (permalink / raw)
  To: Paolo Bonzini
  Cc: Anthony PERARD, george.dunlap, xen-devel, qemu-devel, Stefano Stabellini

The following commit:

commit 149f54b53b7666a3facd45e86eece60ce7d3b114
Author: Paolo Bonzini <pbonzini@redhat.com>
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.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: Anthony Perard <anthony.perard@citrix.com>

---
 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) {

^ permalink raw reply related	[flat|nested] 4+ messages in thread
* Re: [Qemu-devel] [PATCH] address_space_translate: do not cross page boundaries
  2014-01-30 12:46 ` Stefano Stabellini
@ 2014-01-30 13:38   ` Paolo Bonzini
  -1 siblings, 0 replies; 4+ messages in thread
From: Paolo Bonzini @ 2014-01-30 13:38 UTC (permalink / raw)
  To: Stefano Stabellini
  Cc: Anthony PERARD, george.dunlap, xen-devel, qemu-devel, qemu-stable

Il 30/01/2014 13:46, Stefano Stabellini ha scritto:
> The following commit:
>
> commit 149f54b53b7666a3facd45e86eece60ce7d3b114
> Author: Paolo Bonzini <pbonzini@redhat.com>
> 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.
>
> Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
> Signed-off-by: Anthony Perard <anthony.perard@citrix.com>

Tested-by: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: qemu-stable@nongnu.org

> ---
>  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) {
>
>

^ permalink raw reply	[flat|nested] 4+ messages in thread
* Re: [PATCH] address_space_translate: do not cross page boundaries
@ 2014-01-30 13:38   ` Paolo Bonzini
  0 siblings, 0 replies; 4+ messages in thread
From: Paolo Bonzini @ 2014-01-30 13:38 UTC (permalink / raw)
  To: Stefano Stabellini
  Cc: Anthony PERARD, george.dunlap, xen-devel, qemu-devel, qemu-stable

Il 30/01/2014 13:46, Stefano Stabellini ha scritto:
> The following commit:
>
> commit 149f54b53b7666a3facd45e86eece60ce7d3b114
> Author: Paolo Bonzini <pbonzini@redhat.com>
> 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.
>
> Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
> Signed-off-by: Anthony Perard <anthony.perard@citrix.com>

Tested-by: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: qemu-stable@nongnu.org

> ---
>  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) {
>
>

^ permalink raw reply	[flat|nested] 4+ messages in thread
end of thread, other threads:[~2014-01-30 13:39 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2014-01-30 12:46 [Qemu-devel] [PATCH] address_space_translate: do not cross page boundaries Stefano Stabellini
2014-01-30 12:46 ` Stefano Stabellini
2014-01-30 13:38 ` [Qemu-devel] " Paolo Bonzini
2014-01-30 13:38   ` Paolo Bonzini

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