xen: Replace arch_mfn_in_directmap() with arch_mfns_in_directmap()

The name of arch_mfn_in_directmap() suggests that it will check against
that the passed MFN should be in the directmap.

However, the current callers are passing the next MFN and the
implementation will return true for up to one MFN past the directmap.

It would be more meaningful to test the exact MFN rather than the
next one.

That said, the current expectation is the memory will be direct-mapped
from 0 up to a given MFN. This may not be a valid assumption on all
the architectures.

For instance, on Arm32 only the xenheap that will be direct-mapped.
This may not be allocated a the beginning of the RAM.

So take the opportunity to rework the parameters and pass the
number of pages we want to check. This also requires to rename
the helper to better match the implementation.

Note that the implementation of the helper on arm32 is left as-is
for now.

Signed-off-by: Julien Grall <jgrall@amazon.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Stefano Stabellini <sstabellini@kernel.org>

diff --git a/xen/arch/arm/include/asm/arm32/mm.h b/xen/arch/arm/include/asm/arm32/mm.h
index 68612499bf6cc42ea815a0289fceb9771532a3fb..6b039d9ceaa2cef3d60b006202779493dfe52fa8 100644 (file)
--- a/xen/arch/arm/include/asm/arm32/mm.h
+++ b/xen/arch/arm/include/asm/arm32/mm.h
@@ -5,7 +5,7 @@
  * Only a limited amount of RAM, called xenheap, is always mapped on ARM32.
  * For convenience always return false.
  */
-static inline bool arch_mfn_in_directmap(unsigned long mfn)
+static inline bool arch_mfns_in_directmap(unsigned long mfn, unsigned long nr)
 {
     return false;
 }

diff --git a/xen/arch/arm/include/asm/arm64/mm.h b/xen/arch/arm/include/asm/arm64/mm.h
index d0a3be7e15a473d79390e8637ebf9fb73c497461..aa2adac63189829b8cb50e860e4991eb2402b70b 100644 (file)
--- a/xen/arch/arm/include/asm/arm64/mm.h
+++ b/xen/arch/arm/include/asm/arm64/mm.h
@@ -5,7 +5,7 @@
  * On ARM64, all the RAM is currently direct mapped in Xen.
  * Hence return always true.
  */
-static inline bool arch_mfn_in_directmap(unsigned long mfn)
+static inline bool arch_mfns_in_directmap(unsigned long mfn, unsigned long nr)
 {
     return true;
 }

diff --git a/xen/arch/x86/include/asm/mm.h b/xen/arch/x86/include/asm/mm.h
index 5dbcee869624d22bc62c859d31c73cfd72b014e5..9b9de4c6bef730801b824e97504557c98a648054 100644 (file)
--- a/xen/arch/x86/include/asm/mm.h
+++ b/xen/arch/x86/include/asm/mm.h
@@ -635,13 +635,13 @@ void write_32bit_pse_identmap(uint32_t *l2);
 
 /*
  * x86 maps part of physical memory via the directmap region.
- * Return whether the input MFN falls in that range.
+ * Return whether the range of MFN falls in the directmap region.
  */
-static inline bool arch_mfn_in_directmap(unsigned long mfn)
+static inline bool arch_mfns_in_directmap(unsigned long mfn, unsigned long nr)
 {
     unsigned long eva = min(DIRECTMAP_VIRT_END, HYPERVISOR_VIRT_END);
 
-    return mfn <= (virt_to_mfn(eva - 1) + 1);
+    return (mfn + nr) <= (virt_to_mfn(eva - 1) + 1);
 }
 
 #endif /* __ASM_X86_MM_H__ */

diff --git a/xen/common/page_alloc.c b/xen/common/page_alloc.c
index 38eea879c04a48c293ac69ca2a59cfabf156d6e8..f8749b0787a69e1dcdafde8f2b421af88c427c68 100644 (file)
--- a/xen/common/page_alloc.c
+++ b/xen/common/page_alloc.c
@@ -588,7 +588,7 @@ static unsigned long init_node_heap(int node, unsigned long mfn,
         needed = 0;
     }
     else if ( *use_tail && nr >= needed &&
-              arch_mfn_in_directmap(mfn + nr) &&
+              arch_mfns_in_directmap(mfn + nr - needed, needed) &&
               (!xenheap_bits ||
                !((mfn + nr - 1) >> (xenheap_bits - PAGE_SHIFT))) )
     {
@@ -597,7 +597,7 @@ static unsigned long init_node_heap(int node, unsigned long mfn,
                       PAGE_SIZE - sizeof(**avail) * NR_ZONES;
     }
     else if ( nr >= needed &&
-              arch_mfn_in_directmap(mfn + needed) &&
+              arch_mfns_in_directmap(mfn, needed) &&
               (!xenheap_bits ||
                !((mfn + needed - 1) >> (xenheap_bits - PAGE_SHIFT))) )
     {