xen/grant-table: pre-populate kernel unmap ops for xen_gnttab_unmap_refs()

When unmapping grants, instead of converting the kernel map ops to
unmap ops on the fly, pre-populate the set of unmap ops.

This allows the grant unmap for the kernel mappings to be trivially
batched in the future.

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Reviewed-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>

1 files changed, 10 insertions, 11 deletions

diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c
index 70fb5075c901..df40b2888eae 100644
--- a/arch/x86/xen/p2m.c
+++ b/arch/x86/xen/p2m.c
@@ -816,7 +816,7 @@ static struct page *m2p_find_override(unsigned long mfn)
 }
 
 static int m2p_remove_override(struct page *page,
-                               struct gnttab_map_grant_ref *kmap_op,
+                               struct gnttab_unmap_grant_ref *kunmap_op,
                                unsigned long mfn)
 {
         unsigned long flags;
@@ -840,7 +840,7 @@ static int m2p_remove_override(struct page *page,
         list_del(&page->lru);
         spin_unlock_irqrestore(&m2p_override_lock, flags);
 
-        if (kmap_op != NULL) {
+        if (kunmap_op != NULL) {
                 if (!PageHighMem(page)) {
                         struct multicall_space mcs;
                         struct gnttab_unmap_and_replace *unmap_op;
@@ -855,13 +855,13 @@ static int m2p_remove_override(struct page *page,
                          * issued. In this case handle is going to -1 because
                          * it hasn't been modified yet.
                          */
-                        if (kmap_op->handle == -1)
+                        if (kunmap_op->handle == -1)
                                 xen_mc_flush();
                         /*
                          * Now if kmap_op->handle is negative it means that the
                          * hypercall actually returned an error.
                          */
-                        if (kmap_op->handle == GNTST_general_error) {
+                        if (kunmap_op->handle == GNTST_general_error) {
                                 pr_warn("m2p_remove_override: pfn %lx mfn %lx, failed to modify kernel mappings",
                                         pfn, mfn);
                                 put_balloon_scratch_page();
@@ -873,9 +873,9 @@ static int m2p_remove_override(struct page *page,
                         mcs = __xen_mc_entry(
                                 sizeof(struct gnttab_unmap_and_replace));
                         unmap_op = mcs.args;
-                        unmap_op->host_addr = kmap_op->host_addr;
+                        unmap_op->host_addr = kunmap_op->host_addr;
                         unmap_op->new_addr = scratch_page_address;
-                        unmap_op->handle = kmap_op->handle;
+                        unmap_op->handle = kunmap_op->handle;
 
                         MULTI_grant_table_op(mcs.mc,
                                 GNTTABOP_unmap_and_replace, unmap_op, 1);
@@ -887,7 +887,6 @@ static int m2p_remove_override(struct page *page,
 
                         xen_mc_issue(PARAVIRT_LAZY_MMU);
 
-                        kmap_op->host_addr = 0;
                         put_balloon_scratch_page();
                 }
         }
@@ -912,7 +911,7 @@ static int m2p_remove_override(struct page *page,
 }
 
 int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref *unmap_ops,
-                              struct gnttab_map_grant_ref *kmap_ops,
+                              struct gnttab_unmap_grant_ref *kunmap_ops,
                               struct page **pages, unsigned int count)
 {
         int i, ret = 0;
@@ -921,7 +920,7 @@ int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref *unmap_ops,
         if (xen_feature(XENFEAT_auto_translated_physmap))
                 return 0;
 
-        if (kmap_ops &&
+        if (kunmap_ops &&
             !in_interrupt() &&
             paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE) {
                 arch_enter_lazy_mmu_mode();
@@ -942,8 +941,8 @@ int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref *unmap_ops,
                 ClearPagePrivate(pages[i]);
                 set_phys_to_machine(pfn, pages[i]->index);
 
-                if (kmap_ops)
-                        ret = m2p_remove_override(pages[i], &kmap_ops[i], mfn);
+                if (kunmap_ops)
+                        ret = m2p_remove_override(pages[i], &kunmap_ops[i], mfn);
                 if (ret)
                         goto out;
         }