[xen staging] page-alloc: make scrub_one_page() static

[patchbot@xxxxxxx]

commit c8e3e39085bf97d1afb775d54884d239387e32cd
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Tue Nov 26 11:25:45 2024 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Tue Nov 26 11:25:45 2024 +0100

    page-alloc: make scrub_one_page() static
    
    Before starting to alter its properties, restrict the function's
    visibility. The only external user is mem-paging, which we can
    accommodate by different means.
    
    Also move the function up in its source file, so we won't need to
    forward-declare it. Constify its parameter at the same time.
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Acked-by: Julien Grall <jgrall@xxxxxxxxxx>
---
 xen/arch/x86/include/asm/mem_paging.h |  6 ------
 xen/arch/x86/mm/mem_paging.c          |  3 ---
 xen/common/page_alloc.c               | 40 ++++++++++++++++++-----------------
 xen/include/xen/mm.h                  |  2 --
 xen/include/xen/sched.h               |  6 ++++++
 5 files changed, 27 insertions(+), 30 deletions(-)

diff --git a/xen/arch/x86/include/asm/mem_paging.h 
b/xen/arch/x86/include/asm/mem_paging.h
index 5ae86669fb..2c618925d0 100644
--- a/xen/arch/x86/include/asm/mem_paging.h
+++ b/xen/arch/x86/include/asm/mem_paging.h
@@ -12,12 +12,6 @@
 
 int mem_paging_memop(XEN_GUEST_HANDLE_PARAM(xen_mem_paging_op_t) arg);
 
-#ifdef CONFIG_MEM_PAGING
-# define mem_paging_enabled(d) vm_event_check_ring((d)->vm_event_paging)
-#else
-# define mem_paging_enabled(d) false
-#endif
-
 #endif /*__ASM_X86_MEM_PAGING_H__ */
 
 /*
diff --git a/xen/arch/x86/mm/mem_paging.c b/xen/arch/x86/mm/mem_paging.c
index 541ecbeeb0..ac8d34ffa0 100644
--- a/xen/arch/x86/mm/mem_paging.c
+++ b/xen/arch/x86/mm/mem_paging.c
@@ -304,9 +304,6 @@ static int evict(struct domain *d, gfn_t gfn)
     ret = p2m_set_entry(p2m, gfn, INVALID_MFN, PAGE_ORDER_4K,
                         p2m_ram_paged, a);
 
-    /* Clear content before returning the page to Xen */
-    scrub_one_page(page);
-
     /* Track number of paged gfns */
     atomic_inc(&d->paged_pages);
 
diff --git a/xen/common/page_alloc.c b/xen/common/page_alloc.c
index 33c8c917d9..92abed6514 100644
--- a/xen/common/page_alloc.c
+++ b/xen/common/page_alloc.c
@@ -137,6 +137,7 @@
 #include <xen/sections.h>
 #include <xen/softirq.h>
 #include <xen/spinlock.h>
+#include <xen/vm_event.h>
 
 #include <asm/flushtlb.h>
 #include <asm/page.h>
@@ -774,6 +775,21 @@ static void page_list_add_scrub(struct page_info *pg, 
unsigned int node,
 #endif
 #define SCRUB_BYTE_PATTERN   (SCRUB_PATTERN & 0xff)
 
+static void scrub_one_page(const struct page_info *pg)
+{
+    if ( unlikely(pg->count_info & PGC_broken) )
+        return;
+
+#ifndef NDEBUG
+    /* Avoid callers relying on allocations returning zeroed pages. */
+    unmap_domain_page(memset(__map_domain_page(pg),
+                             SCRUB_BYTE_PATTERN, PAGE_SIZE));
+#else
+    /* For a production build, clear_page() is the fastest way to scrub. */
+    clear_domain_page(_mfn(page_to_mfn(pg)));
+#endif
+}
+
 static void poison_one_page(struct page_info *pg)
 {
 #ifdef CONFIG_SCRUB_DEBUG
@@ -2548,10 +2564,12 @@ void free_domheap_pages(struct page_info *pg, unsigned 
int order)
             /*
              * Normally we expect a domain to clear pages before freeing them,
              * if it cares about the secrecy of their contents. However, after
-             * a domain has died we assume responsibility for erasure. We do
-             * scrub regardless if option scrub_domheap is set.
+             * a domain has died or if it has mem-paging enabled we assume
+             * responsibility for erasure. We do scrub regardless if option
+             * scrub_domheap is set.
              */
-            scrub = d->is_dying || scrub_debug || opt_scrub_domheap;
+            scrub = d->is_dying || mem_paging_enabled(d) ||
+                    scrub_debug || opt_scrub_domheap;
         }
         else
         {
@@ -2635,22 +2653,6 @@ static __init int cf_check 
pagealloc_keyhandler_init(void)
 }
 __initcall(pagealloc_keyhandler_init);
 
-
-void scrub_one_page(struct page_info *pg)
-{
-    if ( unlikely(pg->count_info & PGC_broken) )
-        return;
-
-#ifndef NDEBUG
-    /* Avoid callers relying on allocations returning zeroed pages. */
-    unmap_domain_page(memset(__map_domain_page(pg),
-                             SCRUB_BYTE_PATTERN, PAGE_SIZE));
-#else
-    /* For a production build, clear_page() is the fastest way to scrub. */
-    clear_domain_page(_mfn(page_to_mfn(pg)));
-#endif
-}
-
 static void cf_check dump_heap(unsigned char key)
 {
     s_time_t      now = NOW();
diff --git a/xen/include/xen/mm.h b/xen/include/xen/mm.h
index 7561297a75..d7dcf0f063 100644
--- a/xen/include/xen/mm.h
+++ b/xen/include/xen/mm.h
@@ -532,8 +532,6 @@ static inline unsigned int get_order_from_pages(unsigned 
long nr_pages)
     return order;
 }
 
-void scrub_one_page(struct page_info *pg);
-
 #ifndef arch_free_heap_page
 #define arch_free_heap_page(d, pg) \
     page_list_del(pg, page_to_list(d, pg))
diff --git a/xen/include/xen/sched.h b/xen/include/xen/sched.h
index 90666576c2..76e39378b3 100644
--- a/xen/include/xen/sched.h
+++ b/xen/include/xen/sched.h
@@ -1203,6 +1203,12 @@ static always_inline bool is_iommu_enabled(const struct 
domain *d)
     return evaluate_nospec(d->options & XEN_DOMCTL_CDF_iommu);
 }
 
+#ifdef CONFIG_MEM_PAGING
+# define mem_paging_enabled(d) vm_event_check_ring((d)->vm_event_paging)
+#else
+# define mem_paging_enabled(d) false
+#endif
+
 extern bool sched_smt_power_savings;
 extern bool sched_disable_smt_switching;
 
--
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