| Message ID | 1405355225-4623-1-git-send-email-ian.campbell@citrix.com |
|---|---|
| State | New |
| Headers | show |
Hi Ian, On 07/14/2014 05:27 PM, Ian Campbell wrote: > If we handle a change in a superpage then we need to invalidate any cached > mappings further down, otherwise we risk using them because their offset might > match but be based on a different offset further up the table. > > Signed-off-by: Ian Campbell <ian.campbell@citrix.com> > --- > xen/arch/arm/p2m.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c > index c0c011a..917baa3 100644 > --- a/xen/arch/arm/p2m.c > +++ b/xen/arch/arm/p2m.c > @@ -719,6 +719,8 @@ static int apply_p2m_changes(struct domain *d, > goto out; > } > cur_first_page = p2m_first_level_index(addr); > + /* Any mapping further down is now invalid */ > + cur_second_offset = ~0; I think you miss to invalid cur_first_offset. Also, I think we have the same issue on Xen 4.4. Regards,
On Mon, 2014-07-14 at 19:17 +0100, Julien Grall wrote: > Hi Ian, > > On 07/14/2014 05:27 PM, Ian Campbell wrote: > > If we handle a change in a superpage then we need to invalidate any cached > > mappings further down, otherwise we risk using them because their offset might > > match but be based on a different offset further up the table. > > > > Signed-off-by: Ian Campbell <ian.campbell@citrix.com> > > --- > > xen/arch/arm/p2m.c | 4 ++++ > > 1 file changed, 4 insertions(+) > > > > diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c > > index c0c011a..917baa3 100644 > > --- a/xen/arch/arm/p2m.c > > +++ b/xen/arch/arm/p2m.c > > @@ -719,6 +719,8 @@ static int apply_p2m_changes(struct domain *d, > > goto out; > > } > > cur_first_page = p2m_first_level_index(addr); > > + /* Any mapping further down is now invalid */ > > + cur_second_offset = ~0; > > I think you miss to invalid cur_first_offset. I think you are right. > Also, I think we have the same issue on Xen 4.4. I'll add it to my list to check. I suspect the fix will need reimplementing there rather than backporting. Ian.
diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c index c0c011a..917baa3 100644 --- a/xen/arch/arm/p2m.c +++ b/xen/arch/arm/p2m.c @@ -719,6 +719,8 @@ static int apply_p2m_changes(struct domain *d, goto out; } cur_first_page = p2m_first_level_index(addr); + /* Any mapping further down is now invalid */ + cur_second_offset = ~0; } /* We only use a 3 level p2m at the moment, so no level 0, @@ -741,6 +743,8 @@ static int apply_p2m_changes(struct domain *d, if (second) unmap_domain_page(second); second = map_domain_page(first[first_table_offset(addr)].p2m.base); cur_first_offset = first_table_offset(addr); + /* Any mapping further down is now invalid */ + cur_second_offset = ~0; } /* else: second already valid */
If we handle a change in a superpage then we need to invalidate any cached mappings further down, otherwise we risk using them because their offset might match but be based on a different offset further up the table. Signed-off-by: Ian Campbell <ian.campbell@citrix.com> --- xen/arch/arm/p2m.c | 4 ++++ 1 file changed, 4 insertions(+)