Hi Stefano,
On 27/07/16 18:56, Stefano Stabellini wrote:
On Wed, 27 Jul 2016, Julien Grall wrote:
On 26/07/16 23:44, Stefano Stabellini wrote:
On Wed, 20 Jul 2016, Julien Grall wrote:
Currently, the check in get_page_from_gfn is using a blacklist. This is
very fragile because we may forgot to update the check when a new p2m
type is added.
To avoid any possible issue, use a whitelist. All type backed by a RAM
page can could potential be valid. The check is borrowed from x86.
Signed-off-by: Julien Grall <julien.gr...@arm.com>
---
xen/include/asm-arm/p2m.h | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/xen/include/asm-arm/p2m.h b/xen/include/asm-arm/p2m.h
index 3091c04..78d37ab 100644
--- a/xen/include/asm-arm/p2m.h
+++ b/xen/include/asm-arm/p2m.h
@@ -104,9 +104,16 @@ typedef enum {
#define P2M_RAM_TYPES (p2m_to_mask(p2m_ram_rw) | \
p2m_to_mask(p2m_ram_ro))
+/* Grant mapping types, which map to a real frame in another VM */
+#define P2M_GRANT_TYPES (p2m_to_mask(p2m_grant_map_rw) | \
+ p2m_to_mask(p2m_grant_map_ro))
+
/* Useful predicates */
#define p2m_is_ram(_t) (p2m_to_mask(_t) & P2M_RAM_TYPES)
#define p2m_is_foreign(_t) (p2m_to_mask(_t) &
p2m_to_mask(p2m_map_foreign))
+#define p2m_is_any_ram(_t) (p2m_to_mask(_t) & \
+ (P2M_RAM_TYPES | P2M_GRANT_TYPES | \
+ p2m_to_mask(p2m_map_foreign)))
static inline
void p2m_mem_access_emulate_check(struct vcpu *v,
@@ -224,7 +231,7 @@ static inline struct page_info *get_page_from_gfn(
if (t)
*t = p2mt;
- if ( p2mt == p2m_invalid || p2mt == p2m_mmio_direct )
+ if ( !p2m_is_any_ram(p2mt) )
return NULL;
What about the iommu mappings?
iommu mappings (p2m_iommu_map_*) are special mappings for the direct mapping
workaround. They should not be used in get_page_from_gfn.
Make sense. I think they deserve to be mentioned in the commit message,
as this patch changes behavior for them.
Good point. I will update the commit message.
Regards,
--
Julien Grall
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