KVM: x86/mmu: Move lpage_disallowed_link further "down" in kvm_mmu_page

Move "lpage_disallowed_link" out of the first 64 bytes, i.e. out of the
first cache line, of kvm_mmu_page so that "spt" and to a lesser extent
"gfns" land in the first cache line.  "lpage_disallowed_link" is accessed
relatively infrequently compared to "spt", which is accessed any time KVM
is walking and/or manipulating the shadow page tables.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210901221023.1303578-4-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/mmu/mmu_internal.h b/arch/x86/kvm/mmu/mmu_internal.h
index 4e7b634..bf2bdbf 100644 (file)
--- a/arch/x86/kvm/mmu/mmu_internal.h
+++ b/arch/x86/kvm/mmu/mmu_internal.h
@@ -31,9 +31,12 @@ extern bool dbg;
 #define IS_VALID_PAE_ROOT(x)   (!!(x))
 
 struct kvm_mmu_page {
+       /*
+        * Note, "link" through "spt" fit in a single 64 byte cache line on
+        * 64-bit kernels, keep it that way unless there's a reason not to.
+        */
        struct list_head link;
        struct hlist_node hash_link;
-       struct list_head lpage_disallowed_link;
 
        bool tdp_mmu_page;
        bool unsync;
@@ -59,6 +62,7 @@ struct kvm_mmu_page {
        struct kvm_rmap_head parent_ptes; /* rmap pointers to parent sptes */
        DECLARE_BITMAP(unsync_child_bitmap, 512);
 
+       struct list_head lpage_disallowed_link;
 #ifdef CONFIG_X86_32
        /*
         * Used out of the mmu-lock to avoid reading spte values while an