3 files changed, 81 insertions, 26 deletions

diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index 846dad7d54a5..f6b8225c2a0b 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -230,18 +230,35 @@ static bool page_pinned(void *ptr)
         return PagePinned(page);
 }
 
-void xen_set_pmd_hyper(pmd_t *ptr, pmd_t val)
+static void extend_mmu_update(const struct mmu_update *update)
 {
         struct multicall_space mcs;
         struct mmu_update *u;
 
-        preempt_disable();
+        mcs = xen_mc_extend_args(__HYPERVISOR_mmu_update, sizeof(*u));
+
+        if (mcs.mc != NULL)
+                mcs.mc->args[1]++;
+        else {
+                mcs = __xen_mc_entry(sizeof(*u));
+                MULTI_mmu_update(mcs.mc, mcs.args, 1, NULL, DOMID_SELF);
+        }
 
-        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);
+        *u = *update;
+}
+
+void xen_set_pmd_hyper(pmd_t *ptr, pmd_t val)
+{
+        struct mmu_update u;
+
+        preempt_disable();
+
+        xen_mc_batch();
+
+        u.ptr = virt_to_machine(ptr).maddr;
+        u.val = pmd_val_ma(val);
+        extend_mmu_update(&u);
 
         xen_mc_issue(PARAVIRT_LAZY_MMU);
 
@@ -332,14 +349,13 @@ pte_t xen_ptep_modify_prot_start(struct mm_struct *mm, unsigned long addr, pte_t
 void xen_ptep_modify_prot_commit(struct mm_struct *mm, unsigned long addr,
                                  pte_t *ptep, pte_t pte)
 {
-        struct multicall_space mcs;
-        struct mmu_update *u;
+        struct mmu_update u;
 
-        mcs = xen_mc_entry(sizeof(*u));
-        u = mcs.args;
-        u->ptr = virt_to_machine(ptep).maddr | MMU_PT_UPDATE_PRESERVE_AD;
-        u->val = pte_val_ma(pte);
-        MULTI_mmu_update(mcs.mc, u, 1, NULL, DOMID_SELF);
+        xen_mc_batch();
+
+        u.ptr = virt_to_machine(ptep).maddr | MMU_PT_UPDATE_PRESERVE_AD;
+        u.val = pte_val_ma(pte);
+        extend_mmu_update(&u);
 
         xen_mc_issue(PARAVIRT_LAZY_MMU);
 }
@@ -396,16 +412,15 @@ pmdval_t xen_pmd_val(pmd_t pmd)
 
 void xen_set_pud_hyper(pud_t *ptr, pud_t val)
 {
-        struct multicall_space mcs;
-        struct mmu_update *u;
+        struct mmu_update u;
 
         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_batch();
+
+        u.ptr = virt_to_machine(ptr).maddr;
+        u.val = pud_val_ma(val);
+        extend_mmu_update(&u);
 
         xen_mc_issue(PARAVIRT_LAZY_MMU);
 
diff --git a/arch/x86/xen/multicalls.c b/arch/x86/xen/multicalls.c
index 5791eb2e3750..3c63c4da7ed1 100644
--- a/arch/x86/xen/multicalls.c
+++ b/arch/x86/xen/multicalls.c
@@ -29,14 +29,14 @@
 #define MC_DEBUG        1
 
 #define MC_BATCH        32
-#define MC_ARGS         (MC_BATCH * 16 / sizeof(u64))
+#define MC_ARGS         (MC_BATCH * 16)
 
 struct mc_buffer {
         struct multicall_entry entries[MC_BATCH];
 #if MC_DEBUG
         struct multicall_entry debug[MC_BATCH];
 #endif
-        u64 args[MC_ARGS];
+        unsigned char args[MC_ARGS];
         struct callback {
                 void (*fn)(void *);
                 void *data;
@@ -107,20 +107,48 @@ struct multicall_space __xen_mc_entry(size_t args)
 {
         struct mc_buffer *b = &__get_cpu_var(mc_buffer);
         struct multicall_space ret;
-        unsigned argspace = (args + sizeof(u64) - 1) / sizeof(u64);
+        unsigned argidx = roundup(b->argidx, sizeof(u64));
 
         BUG_ON(preemptible());
-        BUG_ON(argspace > MC_ARGS);
+        BUG_ON(b->argidx > MC_ARGS);
 
         if (b->mcidx == MC_BATCH ||
-            (b->argidx + argspace) > MC_ARGS)
+            (argidx + args) > MC_ARGS) {
                 xen_mc_flush();
+                argidx = roundup(b->argidx, sizeof(u64));
+        }
 
         ret.mc = &b->entries[b->mcidx];
         b->mcidx++;
+        ret.args = &b->args[argidx];
+        b->argidx = argidx + args;
+
+        BUG_ON(b->argidx > MC_ARGS);
+        return ret;
+}
+
+struct multicall_space xen_mc_extend_args(unsigned long op, size_t size)
+{
+        struct mc_buffer *b = &__get_cpu_var(mc_buffer);
+        struct multicall_space ret = { NULL, NULL };
+
+        BUG_ON(preemptible());
+        BUG_ON(b->argidx > MC_ARGS);
+
+        if (b->mcidx == 0)
+                return ret;
+
+        if (b->entries[b->mcidx - 1].op != op)
+                return ret;
+
+        if ((b->argidx + size) > MC_ARGS)
+                return ret;
+
+        ret.mc = &b->entries[b->mcidx - 1];
         ret.args = &b->args[b->argidx];
-        b->argidx += argspace;
+        b->argidx += size;
 
+        BUG_ON(b->argidx > MC_ARGS);
         return ret;
 }
 
diff --git a/arch/x86/xen/multicalls.h b/arch/x86/xen/multicalls.h
index 8bae996d99a3..858938241616 100644
--- a/arch/x86/xen/multicalls.h
+++ b/arch/x86/xen/multicalls.h
@@ -45,4 +45,16 @@ static inline void xen_mc_issue(unsigned mode)
 /* Set up a callback to be called when the current batch is flushed */
 void xen_mc_callback(void (*fn)(void *), void *data);
 
+/*
+ * Try to extend the arguments of the previous multicall command.  The
+ * previous command's op must match.  If it does, then it attempts to
+ * extend the argument space allocated to the multicall entry by
+ * arg_size bytes.
+ *
+ * The returned multicall_space will return with mc pointing to the
+ * command on success, or NULL on failure, and args pointing to the
+ * newly allocated space.
+ */
+struct multicall_space xen_mc_extend_args(unsigned long op, size_t arg_size);
+
 #endif /* _XEN_MULTICALLS_H */