[Xen-devel] [For Xen-4.10 RFC PATCH 1/3] Allow control of icache invalidations when calling flush_page_to_ram()

[Punit Agrawal <punit.agrawal@xxxxxxx>]

flush_page_to_ram() unconditionally drops the icache. In certain
situations this leads to execessive icache flushes when
flush_page_to_ram() ends up being repeatedly called in a loop.

Introduce a parameter to allow callers of flush_page_to_ram() to take
responsibility of synchronising the icache. This is in preparations for
adding logic to make the callers perform the necessary icache
maintenance operations.

Signed-off-by: Punit Agrawal <punit.agrawal@xxxxxxx>
---
 xen/arch/arm/mm.c              | 5 +++--
 xen/arch/arm/p2m.c             | 2 +-
 xen/common/page_alloc.c        | 2 +-
 xen/include/asm-arm/page.h     | 2 +-
 xen/include/asm-x86/flushtlb.h | 2 +-
 5 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
index f0a2eddaaf..e1ab5f8694 100644
--- a/xen/arch/arm/mm.c
+++ b/xen/arch/arm/mm.c
@@ -383,7 +383,7 @@ unsigned long domain_page_map_to_mfn(const void *ptr)
 }
 #endif
 
-void flush_page_to_ram(unsigned long mfn)
+void flush_page_to_ram(unsigned long mfn, bool sync_icache)
 {
     void *v = map_domain_page(_mfn(mfn));
 
@@ -398,7 +398,8 @@ void flush_page_to_ram(unsigned long mfn)
      * I-Cache (See D4.9.2 in ARM DDI 0487A.k_iss10775). Instead of using flush
      * by VA on select platforms, we just flush the entire cache here.
      */
-    invalidate_icache();
+    if (sync_icache)
+        invalidate_icache();
 }
 
 void __init arch_init_memory(void)
diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
index 626376090d..76cd1c34f3 100644
--- a/xen/arch/arm/p2m.c
+++ b/xen/arch/arm/p2m.c
@@ -1400,7 +1400,7 @@ int p2m_cache_flush(struct domain *d, gfn_t start, 
unsigned long nr)
         /* XXX: Implement preemption */
         while ( gfn_x(start) < gfn_x(next_gfn) )
         {
-            flush_page_to_ram(mfn_x(mfn));
+            flush_page_to_ram(mfn_x(mfn), true);
 
             start = gfn_add(start, 1);
             mfn = mfn_add(mfn, 1);
diff --git a/xen/common/page_alloc.c b/xen/common/page_alloc.c
index 42c20cb201..15450a3b6d 100644
--- a/xen/common/page_alloc.c
+++ b/xen/common/page_alloc.c
@@ -838,7 +838,7 @@ static struct page_info *alloc_heap_pages(
         /* Ensure cache and RAM are consistent for platforms where the
          * guest can control its own visibility of/through the cache.
          */
-        flush_page_to_ram(page_to_mfn(&pg[i]));
+        flush_page_to_ram(page_to_mfn(&pg[i]), true);
     }
 
     spin_unlock(&heap_lock);
diff --git a/xen/include/asm-arm/page.h b/xen/include/asm-arm/page.h
index 4b46e8831c..497b4c86ad 100644
--- a/xen/include/asm-arm/page.h
+++ b/xen/include/asm-arm/page.h
@@ -407,7 +407,7 @@ static inline void flush_xen_data_tlb_range_va(unsigned 
long va,
 }
 
 /* Flush the dcache for an entire page. */
-void flush_page_to_ram(unsigned long mfn);
+void flush_page_to_ram(unsigned long mfn, bool sync_icache);
 
 /*
  * Print a walk of a page table or p2m
diff --git a/xen/include/asm-x86/flushtlb.h b/xen/include/asm-x86/flushtlb.h
index 8b7adef7c5..bd2be7e482 100644
--- a/xen/include/asm-x86/flushtlb.h
+++ b/xen/include/asm-x86/flushtlb.h
@@ -118,7 +118,7 @@ void flush_area_mask(const cpumask_t *, const void *va, 
unsigned int flags);
 #define flush_tlb_one_all(v)                    \
     flush_tlb_one_mask(&cpu_online_map, v)
 
-static inline void flush_page_to_ram(unsigned long mfn) {}
+static inline void flush_page_to_ram(unsigned long mfn, bool sync_icache) {}
 static inline int invalidate_dcache_va_range(const void *p,
                                              unsigned long size)
 { return -EOPNOTSUPP; }
-- 
2.11.0


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