[PATCH v3 4/9] KVM: VMX: Introduce SPP access bitmap and operation functions

[Yang Weijiang]

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.

Signed-off-by: Yang Weijiang <weijiang.yang@xxxxxxxxx>
---
 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