[xen staging] xen: Replace arch_mfn_in_directmap() with arch_mfns_in_directmap()

[patchbot@xxxxxxx]

commit 0a71ca9ab4c2d9a44f972c517bafa332b1622c10
Author:     Julien Grall <jgrall@xxxxxxxxxx>
AuthorDate: Wed Jan 26 15:59:19 2022 +0000
Commit:     Julien Grall <jgrall@xxxxxxxxxx>
CommitDate: Thu Jan 27 12:38:31 2022 +0000

    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@xxxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
    Acked-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
---
 xen/arch/arm/include/asm/arm32/mm.h | 2 +-
 xen/arch/arm/include/asm/arm64/mm.h | 2 +-
 xen/arch/x86/include/asm/mm.h       | 6 +++---
 xen/common/page_alloc.c             | 4 ++--
 4 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/xen/arch/arm/include/asm/arm32/mm.h 
b/xen/arch/arm/include/asm/arm32/mm.h
index 68612499bf..6b039d9cea 100644
--- 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 d0a3be7e15..aa2adac631 100644
--- 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 5dbcee8696..9b9de4c6be 100644
--- 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 38eea879c0..f8749b0787 100644
--- 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))) )
     {
--
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