[Xen-changelog] [xen-unstable] linux/i386: allow CONFIG_HIGHPTE on i386

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User kfraser@xxxxxxxxxxxxxxxxxxxxx
# Date 1168597734 0
# Node ID 648e58e31c26c200e17c77c44e9658385f65db04
# Parent  7c5c72a0283f433949d9da82ae197da4f27861eb
linux/i386: allow CONFIG_HIGHPTE on i386

While, as discussed, the performance impact of this option is
certainly higher than on native Linux, the option should not be
entirely disallowed if people want to sacrifice performance for less
lowmem pressure.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>
---
 linux-2.6-xen-sparse/arch/i386/Kconfig                       |    2 
 linux-2.6-xen-sparse/arch/i386/mm/highmem-xen.c              |    1 
 linux-2.6-xen-sparse/arch/i386/mm/pgtable-xen.c              |   30 ++++++++---
 linux-2.6-xen-sparse/include/asm-i386/mach-xen/asm/pgalloc.h |    2 
 4 files changed, 27 insertions(+), 8 deletions(-)

diff -r 7c5c72a0283f -r 648e58e31c26 linux-2.6-xen-sparse/arch/i386/Kconfig
--- a/linux-2.6-xen-sparse/arch/i386/Kconfig    Fri Jan 12 10:22:36 2007 +0000
+++ b/linux-2.6-xen-sparse/arch/i386/Kconfig    Fri Jan 12 10:28:54 2007 +0000
@@ -594,7 +594,7 @@ config HAVE_ARCH_EARLY_PFN_TO_NID
 
 config HIGHPTE
        bool "Allocate 3rd-level pagetables from highmem"
-       depends on (HIGHMEM4G || HIGHMEM64G) && !X86_XEN
+       depends on HIGHMEM4G || HIGHMEM64G
        help
          The VM uses one page table entry for each page of physical memory.
          For systems with a lot of RAM, this can be wasteful of precious
diff -r 7c5c72a0283f -r 648e58e31c26 
linux-2.6-xen-sparse/arch/i386/mm/highmem-xen.c
--- a/linux-2.6-xen-sparse/arch/i386/mm/highmem-xen.c   Fri Jan 12 10:22:36 
2007 +0000
+++ b/linux-2.6-xen-sparse/arch/i386/mm/highmem-xen.c   Fri Jan 12 10:28:54 
2007 +0000
@@ -129,5 +129,6 @@ EXPORT_SYMBOL(kmap);
 EXPORT_SYMBOL(kmap);
 EXPORT_SYMBOL(kunmap);
 EXPORT_SYMBOL(kmap_atomic);
+EXPORT_SYMBOL(kmap_atomic_pte);
 EXPORT_SYMBOL(kunmap_atomic);
 EXPORT_SYMBOL(kmap_atomic_to_page);
diff -r 7c5c72a0283f -r 648e58e31c26 
linux-2.6-xen-sparse/arch/i386/mm/pgtable-xen.c
--- a/linux-2.6-xen-sparse/arch/i386/mm/pgtable-xen.c   Fri Jan 12 10:22:36 
2007 +0000
+++ b/linux-2.6-xen-sparse/arch/i386/mm/pgtable-xen.c   Fri Jan 12 10:28:54 
2007 +0000
@@ -238,23 +238,41 @@ struct page *pte_alloc_one(struct mm_str
 
 #ifdef CONFIG_HIGHPTE
        pte = alloc_pages(GFP_KERNEL|__GFP_HIGHMEM|__GFP_REPEAT|__GFP_ZERO, 0);
+       if (pte && PageHighMem(pte)) {
+               struct mmuext_op op;
+
+               kmap_flush_unused();
+               op.cmd = MMUEXT_PIN_L1_TABLE;
+               op.arg1.mfn = pfn_to_mfn(page_to_pfn(pte));
+               BUG_ON(HYPERVISOR_mmuext_op(&op, 1, NULL, DOMID_SELF) < 0);
+       }
 #else
        pte = alloc_pages(GFP_KERNEL|__GFP_REPEAT|__GFP_ZERO, 0);
+#endif
        if (pte) {
                SetPageForeign(pte, pte_free);
                set_page_count(pte, 1);
        }
-#endif
        return pte;
 }
 
 void pte_free(struct page *pte)
 {
-       unsigned long va = (unsigned long)__va(page_to_pfn(pte)<<PAGE_SHIFT);
-
-       if (!pte_write(*virt_to_ptep(va)))
-               BUG_ON(HYPERVISOR_update_va_mapping(
-                       va, pfn_pte(page_to_pfn(pte), PAGE_KERNEL), 0));
+       unsigned long pfn = page_to_pfn(pte);
+
+       if (!PageHighMem(pte)) {
+               unsigned long va = (unsigned long)__va(pfn << PAGE_SHIFT);
+
+               if (!pte_write(*virt_to_ptep(va)))
+                       BUG_ON(HYPERVISOR_update_va_mapping(
+                              va, pfn_pte(pfn, PAGE_KERNEL), 0));
+       } else {
+               struct mmuext_op op;
+
+               op.cmd = MMUEXT_UNPIN_TABLE;
+               op.arg1.mfn = pfn_to_mfn(pfn);
+               BUG_ON(HYPERVISOR_mmuext_op(&op, 1, NULL, DOMID_SELF) < 0);
+       }
 
        ClearPageForeign(pte);
        set_page_count(pte, 1);
diff -r 7c5c72a0283f -r 648e58e31c26 
linux-2.6-xen-sparse/include/asm-i386/mach-xen/asm/pgalloc.h
--- a/linux-2.6-xen-sparse/include/asm-i386/mach-xen/asm/pgalloc.h      Fri Jan 
12 10:22:36 2007 +0000
+++ b/linux-2.6-xen-sparse/include/asm-i386/mach-xen/asm/pgalloc.h      Fri Jan 
12 10:28:54 2007 +0000
@@ -42,7 +42,7 @@ static inline void pte_free_kernel(pte_t
 static inline void pte_free_kernel(pte_t *pte)
 {
        free_page((unsigned long)pte);
-       make_page_writable(pte, XENFEAT_writable_page_tables);
+       make_lowmem_page_writable(pte, XENFEAT_writable_page_tables);
 }
 
 extern void pte_free(struct page *pte);

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