[Xen-devel] [PATCH 11/15] xen/mmu: tune pgtable alloc/release

[Jeremy Fitzhardinge <jeremy@xxxxxxxx>]

From: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>

Make sure the fastpath code is inlined.  Batch the page permission change
and the pin/unpin, and make sure that it can be batched with any
adjacent set_pte/pmd/etc operations.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>
---
 arch/x86/xen/mmu.c |   49 ++++++++++++++++++++++++++++++++++++++++++-------
 1 files changed, 42 insertions(+), 7 deletions(-)

diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index 112259f..ebfdc3d 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -1492,22 +1492,52 @@ static void __init xen_release_pmd_init(unsigned long 
pfn)
        make_lowmem_page_readwrite(__va(PFN_PHYS(pfn)));
 }
 
+static inline void __pin_pagetable_pfn(unsigned cmd, unsigned long pfn)
+{
+       struct multicall_space mcs;
+       struct mmuext_op *op;
+
+       mcs = __xen_mc_entry(sizeof(*op));
+       op = mcs.args;
+       op->cmd = cmd;
+       op->arg1.mfn = pfn_to_mfn(pfn);
+
+       MULTI_mmuext_op(mcs.mc, mcs.args, 1, NULL, DOMID_SELF);
+}
+
+static inline void __set_pfn_prot(unsigned long pfn, pgprot_t prot)
+{
+       struct multicall_space mcs;
+       unsigned long addr = (unsigned long)__va(pfn << PAGE_SHIFT);
+
+       mcs = __xen_mc_entry(0);
+       MULTI_update_va_mapping(mcs.mc, (unsigned long)addr,
+                               pfn_pte(pfn, prot), 0);
+}
+
 /* This needs to make sure the new pte page is pinned iff its being
    attached to a pinned pagetable. */
-static void xen_alloc_ptpage(struct mm_struct *mm, unsigned long pfn, unsigned 
level)
+static inline void xen_alloc_ptpage(struct mm_struct *mm, unsigned long pfn,
+                                   unsigned level)
 {
-       struct page *page = pfn_to_page(pfn);
        int pinned = PagePinned(virt_to_page(mm->pgd));
  
        trace_xen_mmu_alloc_ptpage(mm, pfn, level, pinned);
 
        if (pinned) {
+               struct page *page = pfn_to_page(pfn);
+
                SetPagePinned(page);
 
                if (!PageHighMem(page)) {
-                       make_lowmem_page_readonly(__va(PFN_PHYS((unsigned 
long)pfn)));
+                       xen_mc_batch();
+
+                       __set_pfn_prot(pfn, PAGE_KERNEL_RO);
+
                        if (level == PT_PTE && USE_SPLIT_PTLOCKS)
-                               pin_pagetable_pfn(MMUEXT_PIN_L1_TABLE, pfn);
+                               __pin_pagetable_pfn(MMUEXT_PIN_L1_TABLE, pfn);
+
+                       xen_mc_issue(PARAVIRT_LAZY_MMU);
                } else {
                        /* make sure there are no stray mappings of
                           this page */
@@ -1527,7 +1557,7 @@ static void xen_alloc_pmd(struct mm_struct *mm, unsigned 
long pfn)
 }
 
 /* This should never happen until we're OK to use struct page */
-static void xen_release_ptpage(unsigned long pfn, unsigned level)
+static inline void xen_release_ptpage(unsigned long pfn, unsigned level)
 {
        struct page *page = pfn_to_page(pfn);
        bool pinned = PagePinned(page);
@@ -1536,9 +1566,14 @@ static void xen_release_ptpage(unsigned long pfn, 
unsigned level)
 
        if (pinned) {
                if (!PageHighMem(page)) {
+                       xen_mc_batch();
+
                        if (level == PT_PTE && USE_SPLIT_PTLOCKS)
-                               pin_pagetable_pfn(MMUEXT_UNPIN_TABLE, pfn);
-                       make_lowmem_page_readwrite(__va(PFN_PHYS(pfn)));
+                               __pin_pagetable_pfn(MMUEXT_UNPIN_TABLE, pfn);
+
+                       __set_pfn_prot(pfn, PAGE_KERNEL);
+
+                       xen_mc_issue(PARAVIRT_LAZY_MMU);
                }
                ClearPagePinned(page);
        }
-- 
1.7.5.4


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