Create access bitmap for SPP subpages, 4KB/128B = 32bits,
for each 4KB physical page, 32bits are required. The bitmap can
be easily accessed with a gfn. The initial access bitmap for each
physical page is 0xFFFFFFFF, meaning SPP is not enabled for the
subpages.

Co-developed-by: He Chen <he.c...@linux.intel.com>
Signed-off-by: He Chen <he.c...@linux.intel.com>
Co-developed-by: Zhang Yi <yi.z.zh...@linux.intel.com>
Signed-off-by: Zhang Yi <yi.z.zh...@linux.intel.com>
Signed-off-by: Yang Weijiang <weijiang.y...@intel.com>
---
 arch/x86/include/asm/kvm_host.h |  1 +
 arch/x86/kvm/mmu.c              | 50 +++++++++++++++++++++++++++++++++
 arch/x86/kvm/x86.c              | 11 ++++++++
 3 files changed, 62 insertions(+)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 98e5158287d5..44f6e1757861 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -790,6 +790,7 @@ struct kvm_lpage_info {
 
 struct kvm_arch_memory_slot {
        struct kvm_rmap_head *rmap[KVM_NR_PAGE_SIZES];
+       u32 *subpage_wp_info;
        struct kvm_lpage_info *lpage_info[KVM_NR_PAGE_SIZES - 1];
        unsigned short *gfn_track[KVM_PAGE_TRACK_MAX];
 };
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 494ad2038f36..16e390fd6e58 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1485,6 +1485,56 @@ static u64 *rmap_get_next(struct rmap_iterator *iter)
        return sptep;
 }
 
+#define FULL_SPP_ACCESS                ((u32)((1ULL << 32) - 1))
+
+static int kvm_subpage_create_bitmaps(struct kvm *kvm)
+{
+       struct kvm_memslots *slots;
+       struct kvm_memory_slot *memslot;
+       int i, j, ret;
+       u32 *buff;
+
+       for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) {
+               slots = __kvm_memslots(kvm, i);
+               kvm_for_each_memslot(memslot, slots) {
+                       buff = kvzalloc(memslot->npages*
+                               sizeof(*memslot->arch.subpage_wp_info),
+                               GFP_KERNEL);
+
+                       if (!buff) {
+                             ret = -ENOMEM;
+                             goto out_free;
+                       }
+                       memslot->arch.subpage_wp_info = buff;
+
+                       for(j = 0; j< memslot->npages; j++)
+                             buff[j] = FULL_SPP_ACCESS;
+               }
+       }
+
+       return 0;
+out_free:
+       for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) {
+               slots = __kvm_memslots(kvm, i);
+               kvm_for_each_memslot(memslot, slots) {
+                       if (memslot->arch.subpage_wp_info) {
+                               kvfree(memslot->arch.subpage_wp_info);
+                               memslot->arch.subpage_wp_info = NULL;
+                       }
+               }
+       }
+
+       return ret;
+}
+
+static u32 *gfn_to_subpage_wp_info(struct kvm_memory_slot *slot, gfn_t gfn)
+{
+       unsigned long idx;
+
+       idx = gfn_to_index(gfn, slot->base_gfn, PT_PAGE_TABLE_LEVEL);
+       return &slot->arch.subpage_wp_info[idx];
+}
+
 #define for_each_rmap_spte(_rmap_head_, _iter_, _spte_)                        
\
        for (_spte_ = rmap_get_first(_rmap_head_, _iter_);              \
             _spte_; _spte_ = rmap_get_next(_iter_))
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index b5edc8e3ce1d..26e4c574731c 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -9317,6 +9317,17 @@ void kvm_arch_destroy_vm(struct kvm *kvm)
        kvm_hv_destroy_vm(kvm);
 }
 
+void kvm_subpage_free_memslot(struct kvm_memory_slot *free,
+                             struct kvm_memory_slot *dont)
+{
+
+       if (!dont || free->arch.subpage_wp_info !=
+           dont->arch.subpage_wp_info) {
+               kvfree(free->arch.subpage_wp_info);
+               free->arch.subpage_wp_info = NULL;
+       }
+}
+
 void kvm_arch_free_memslot(struct kvm *kvm, struct kvm_memory_slot *free,
                           struct kvm_memory_slot *dont)
 {
-- 
2.17.2

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