xen p2m: clear the old pte when adding a page to m2p_override

[firefly-linux-kernel-4.4.55.git] / arch / x86 / xen / p2m.c

diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c
index b3b19d43b95128a5759c2f7b7fe55f94b943d296..40d51225ff084ac95e2c166b32c329784f13d272 100644 (file)
--- a/arch/x86/xen/p2m.c
+++ b/arch/x86/xen/p2m.c
@@ -29,6 +29,7 @@
 #include <linux/module.h>
 #include <linux/list.h>
 #include <linux/hash.h>
+#include <linux/sched.h>
 
 #include <asm/cache.h>
 #include <asm/setup.h>
@@ -404,34 +405,74 @@ static unsigned long mfn_hash(unsigned long mfn)
 }
 
 /* Add an MFN override for a particular page */
-void m2p_add_override(unsigned long mfn, struct page *page)
+int m2p_add_override(unsigned long mfn, struct page *page)
 {
        unsigned long flags;
-       unsigned long pfn = page_to_pfn(page);
+       unsigned long pfn;
+       unsigned long address;
+       unsigned level;
+       pte_t *ptep = NULL;
+
+       pfn = page_to_pfn(page);
+       if (!PageHighMem(page)) {
+               address = (unsigned long)__va(pfn << PAGE_SHIFT);
+               ptep = lookup_address(address, &level);
+
+               if (WARN(ptep == NULL || level != PG_LEVEL_4K,
+                                       "m2p_add_override: pfn %lx not mapped", pfn))
+                       return -EINVAL;
+       }
+
        page->private = mfn;
        page->index = pfn_to_mfn(pfn);
 
        __set_phys_to_machine(pfn, FOREIGN_FRAME(mfn));
+       if (!PageHighMem(page))
+               /* Just zap old mapping for now */
+               pte_clear(&init_mm, address, ptep);
+
        spin_lock_irqsave(&m2p_override_lock, flags);
        list_add(&page->lru,  &m2p_overrides[mfn_hash(mfn)]);
        spin_unlock_irqrestore(&m2p_override_lock, flags);
+
+       return 0;
 }
 
-void m2p_remove_override(struct page *page)
+int m2p_remove_override(struct page *page)
 {
        unsigned long flags;
        unsigned long mfn;
        unsigned long pfn;
+       unsigned long address;
+       unsigned level;
+       pte_t *ptep = NULL;
 
        pfn = page_to_pfn(page);
        mfn = get_phys_to_machine(pfn);
        if (mfn == INVALID_P2M_ENTRY || !(mfn & FOREIGN_FRAME_BIT))
-               return;
+               return -EINVAL;
+
+       if (!PageHighMem(page)) {
+               address = (unsigned long)__va(pfn << PAGE_SHIFT);
+               ptep = lookup_address(address, &level);
+
+               if (WARN(ptep == NULL || level != PG_LEVEL_4K,
+                                       "m2p_remove_override: pfn %lx not mapped", pfn))
+                       return -EINVAL;
+       }
 
        spin_lock_irqsave(&m2p_override_lock, flags);
        list_del(&page->lru);
        spin_unlock_irqrestore(&m2p_override_lock, flags);
        __set_phys_to_machine(pfn, page->index);
+
+       if (!PageHighMem(page))
+               set_pte_at(&init_mm, address, ptep,
+                               pfn_pte(pfn, PAGE_KERNEL));
+               /* No tlb flush necessary because the caller already
+                * left the pte unmapped. */
+
+       return 0;
 }
 
 struct page *m2p_find_override(unsigned long mfn)