Merge branch 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git...

[platform/adaptation/renesas_rcar/renesas_kernel.git] / arch / x86 / xen / mmu.c

diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index 39ed567..b65a761 100644 (file)
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -308,8 +308,20 @@ static bool xen_batched_set_pte(pte_t *ptep, pte_t pteval)
 
 static inline void __xen_set_pte(pte_t *ptep, pte_t pteval)
 {
-       if (!xen_batched_set_pte(ptep, pteval))
-               native_set_pte(ptep, pteval);
+       if (!xen_batched_set_pte(ptep, pteval)) {
+               /*
+                * Could call native_set_pte() here and trap and
+                * emulate the PTE write but with 32-bit guests this
+                * needs two traps (one for each of the two 32-bit
+                * words in the PTE) so do one hypercall directly
+                * instead.
+                */
+               struct mmu_update u;
+
+               u.ptr = virt_to_machine(ptep).maddr | MMU_NORMAL_PT_UPDATE;
+               u.val = pte_val_ma(pteval);
+               HYPERVISOR_mmu_update(&u, 1, NULL, DOMID_SELF);
+       }
 }
 
 static void xen_set_pte(pte_t *ptep, pte_t pteval)
@@ -1416,13 +1428,28 @@ static pte_t __init mask_rw_pte(pte_t *ptep, pte_t pte)
 }
 #endif /* CONFIG_X86_64 */
 
-/* Init-time set_pte while constructing initial pagetables, which
-   doesn't allow RO pagetable pages to be remapped RW */
+/*
+ * Init-time set_pte while constructing initial pagetables, which
+ * doesn't allow RO page table pages to be remapped RW.
+ *
+ * If there is no MFN for this PFN then this page is initially
+ * ballooned out so clear the PTE (as in decrease_reservation() in
+ * drivers/xen/balloon.c).
+ *
+ * Many of these PTE updates are done on unpinned and writable pages
+ * and doing a hypercall for these is unnecessary and expensive.  At
+ * this point it is not possible to tell if a page is pinned or not,
+ * so always write the PTE directly and rely on Xen trapping and
+ * emulating any updates as necessary.
+ */
 static void __init xen_set_pte_init(pte_t *ptep, pte_t pte)
 {
-       pte = mask_rw_pte(ptep, pte);
+       if (pte_mfn(pte) != INVALID_P2M_ENTRY)
+               pte = mask_rw_pte(ptep, pte);
+       else
+               pte = __pte_ma(0);
 
-       xen_set_pte(ptep, pte);
+       native_set_pte(ptep, pte);
 }
 
 static void pin_pagetable_pfn(unsigned cmd, unsigned long pfn)