KVM: cleanup allocation of rmaps and page tracking data

Unify the flags for rmaps and page tracking data, using a
single flag in struct kvm_arch and a single loop to go
over all the address spaces and memslots.  This avoids
code duplication between alloc_all_memslots_rmaps and
kvm_page_track_enable_mmu_write_tracking.

Signed-off-by: David Stevens <stevensd@chromium.org>
[This patch is the delta between David's v2 and v3, with conflicts
 fixed and my own commit message. - Paolo]
Co-developed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 15 insertions, 42 deletions

diff --git a/arch/x86/kvm/mmu/page_track.c b/arch/x86/kvm/mmu/page_track.c
index bb5d60bd4dbf..cc4eb5b7fb76 100644
--- a/arch/x86/kvm/mmu/page_track.c
+++ b/arch/x86/kvm/mmu/page_track.c
@@ -19,14 +19,10 @@
 #include "mmu.h"
 #include "mmu_internal.h"
 
-static bool write_tracking_enabled(struct kvm *kvm)
+bool kvm_page_track_write_tracking_enabled(struct kvm *kvm)
 {
-	/*
-	 * Read memslots_mmu_write_tracking before gfn_track pointers. Pairs
-	 * with smp_store_release in kvm_page_track_enable_mmu_write_tracking.
-	 */
 	return IS_ENABLED(CONFIG_KVM_EXTERNAL_WRITE_TRACKING) ||
-	       smp_load_acquire(&kvm->arch.memslots_mmu_write_tracking);
+	       !tdp_enabled || kvm_shadow_root_allocated(kvm);
 }
 
 void kvm_page_track_free_memslot(struct kvm_memory_slot *slot)
@@ -46,7 +42,8 @@ int kvm_page_track_create_memslot(struct kvm *kvm,
 	int i;
 
 	for (i = 0; i < KVM_PAGE_TRACK_MAX; i++) {
-		if (i == KVM_PAGE_TRACK_WRITE && !write_tracking_enabled(kvm))
+		if (i == KVM_PAGE_TRACK_WRITE &&
+		    !kvm_page_track_write_tracking_enabled(kvm))
 			continue;
 
 		slot->arch.gfn_track[i] =
@@ -71,43 +68,18 @@ static inline bool page_track_mode_is_valid(enum kvm_page_track_mode mode)
 	return true;
 }
 
-int kvm_page_track_enable_mmu_write_tracking(struct kvm *kvm)
+int kvm_page_track_write_tracking_alloc(struct kvm_memory_slot *slot)
 {
-	struct kvm_memslots *slots;
-	struct kvm_memory_slot *slot;
-	unsigned short **gfn_track;
-	int i;
+	unsigned short *gfn_track;
 
-	if (write_tracking_enabled(kvm))
+	if (slot->arch.gfn_track[KVM_PAGE_TRACK_WRITE])
 		return 0;
 
-	mutex_lock(&kvm->slots_arch_lock);
-
-	if (write_tracking_enabled(kvm)) {
-		mutex_unlock(&kvm->slots_arch_lock);
-		return 0;
-	}
-
-	for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) {
-		slots = __kvm_memslots(kvm, i);
-		kvm_for_each_memslot(slot, slots) {
-			gfn_track = slot->arch.gfn_track + KVM_PAGE_TRACK_WRITE;
-			*gfn_track = kvcalloc(slot->npages, sizeof(*gfn_track),
-					      GFP_KERNEL_ACCOUNT);
-			if (*gfn_track == NULL) {
-				mutex_unlock(&kvm->slots_arch_lock);
-				return -ENOMEM;
-			}
-		}
-	}
-
-	/*
-	 * Ensure that memslots_mmu_write_tracking becomes true strictly
-	 * after all the pointers are set.
-	 */
-	smp_store_release(&kvm->arch.memslots_mmu_write_tracking, true);
-	mutex_unlock(&kvm->slots_arch_lock);
+	gfn_track = kvcalloc(slot->npages, sizeof(*gfn_track), GFP_KERNEL_ACCOUNT);
+	if (gfn_track == NULL)
+		return -ENOMEM;
 
+	slot->arch.gfn_track[KVM_PAGE_TRACK_WRITE] = gfn_track;
 	return 0;
 }
 
@@ -147,7 +119,7 @@ void kvm_slot_page_track_add_page(struct kvm *kvm,
 		return;
 
 	if (WARN_ON(mode == KVM_PAGE_TRACK_WRITE &&
-		    !write_tracking_enabled(kvm)))
+		    !kvm_page_track_write_tracking_enabled(kvm)))
 		return;
 
 	update_gfn_track(slot, gfn, mode, 1);
@@ -185,7 +157,7 @@ void kvm_slot_page_track_remove_page(struct kvm *kvm,
 		return;
 
 	if (WARN_ON(mode == KVM_PAGE_TRACK_WRITE &&
-		    !write_tracking_enabled(kvm)))
+		    !kvm_page_track_write_tracking_enabled(kvm)))
 		return;
 
 	update_gfn_track(slot, gfn, mode, -1);
@@ -213,7 +185,8 @@ bool kvm_slot_page_track_is_active(struct kvm_vcpu *vcpu,
 	if (!slot)
 		return false;
 
-	if (mode == KVM_PAGE_TRACK_WRITE && !write_tracking_enabled(vcpu->kvm))
+	if (mode == KVM_PAGE_TRACK_WRITE &&
+	    !kvm_page_track_write_tracking_enabled(vcpu->kvm))
 		return false;
 
 	index = gfn_to_index(gfn, slot->base_gfn, PG_LEVEL_4K);