xen: lazy-mmu operations

This patch uses the lazy-mmu hooks to batch mmu operations where
possible.  This is primarily useful for batching operations applied to
active pagetables, which happens during mprotect, munmap, mremap and
the like (mmap does not do bulk pagetable operations, so it isn't
helped).

Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Acked-by: Chris Wright <chrisw@sous-sol.org>

1 files changed, 39 insertions, 13 deletions

diff --git a/arch/i386/xen/mmu.c b/arch/i386/xen/mmu.c
index f431cf14e644..4ae038aa6c24 100644
--- a/arch/i386/xen/mmu.c
+++ b/arch/i386/xen/mmu.c
@@ -98,12 +98,20 @@ void make_lowmem_page_readwrite(void *vaddr)
 
 void xen_set_pmd(pmd_t *ptr, pmd_t val)
 {
-        struct mmu_update u;
+        struct multicall_space mcs;
+        struct mmu_update *u;
 
-        u.ptr = virt_to_machine(ptr).maddr;
-        u.val = pmd_val_ma(val);
-        if (HYPERVISOR_mmu_update(&u, 1, NULL, DOMID_SELF) < 0)
-                BUG();
+        preempt_disable();
+
+        mcs = xen_mc_entry(sizeof(*u));
+        u = mcs.args;
+        u->ptr = virt_to_machine(ptr).maddr;
+        u->val = pmd_val_ma(val);
+        MULTI_mmu_update(mcs.mc, u, 1, NULL, DOMID_SELF);
+
+        xen_mc_issue(PARAVIRT_LAZY_MMU);
+
+        preempt_enable();
 }
 
 /*
@@ -146,20 +154,38 @@ void set_pte_mfn(unsigned long vaddr, unsigned long mfn, pgprot_t flags)
 void xen_set_pte_at(struct mm_struct *mm, unsigned long addr,
                     pte_t *ptep, pte_t pteval)
 {
-        if ((mm != current->mm && mm != &init_mm) ||
-            HYPERVISOR_update_va_mapping(addr, pteval, 0) != 0)
-                xen_set_pte(ptep, pteval);
+        if (mm == current->mm || mm == &init_mm) {
+                if (xen_get_lazy_mode() == PARAVIRT_LAZY_MMU) {
+                        struct multicall_space mcs;
+                        mcs = xen_mc_entry(0);
+
+                        MULTI_update_va_mapping(mcs.mc, addr, pteval, 0);
+                        xen_mc_issue(PARAVIRT_LAZY_MMU);
+                        return;
+                } else
+                        if (HYPERVISOR_update_va_mapping(addr, pteval, 0) == 0)
+                                return;
+        }
+        xen_set_pte(ptep, pteval);
 }
 
 #ifdef CONFIG_X86_PAE
 void xen_set_pud(pud_t *ptr, pud_t val)
 {
-        struct mmu_update u;
+        struct multicall_space mcs;
+        struct mmu_update *u;
 
-        u.ptr = virt_to_machine(ptr).maddr;
-        u.val = pud_val_ma(val);
-        if (HYPERVISOR_mmu_update(&u, 1, NULL, DOMID_SELF) < 0)
-                BUG();
+        preempt_disable();
+
+        mcs = xen_mc_entry(sizeof(*u));
+        u = mcs.args;
+        u->ptr = virt_to_machine(ptr).maddr;
+        u->val = pud_val_ma(val);
+        MULTI_mmu_update(mcs.mc, u, 1, NULL, DOMID_SELF);
+
+        xen_mc_issue(PARAVIRT_LAZY_MMU);
+
+        preempt_enable();
 }
 
 void xen_set_pte(pte_t *ptep, pte_t pte)