KVM: x86: Move MMU's PML logic to common code

Drop the facade of KVM's PML logic being vendor specific and move the
bits that aren't truly VMX specific into common x86 code.  The MMU logic
for dealing with PML is tightly coupled to the feature and to VMX's
implementation, bouncing through kvm_x86_ops obfuscates the code without
providing any meaningful separation of concerns or encapsulation.

No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210213005015.1651772-10-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/include/asm/kvm-x86-ops.h

@@ -93,10 +93,6 @@ KVM_X86_OP(check_intercept)
 KVM_X86_OP(handle_exit_irqoff)
 KVM_X86_OP_NULL(request_immediate_exit)
 KVM_X86_OP(sched_in)
-KVM_X86_OP_NULL(slot_enable_log_dirty)
-KVM_X86_OP_NULL(slot_disable_log_dirty)
-KVM_X86_OP_NULL(flush_log_dirty)
-KVM_X86_OP_NULL(enable_log_dirty_pt_masked)
 KVM_X86_OP_NULL(pre_block)
 KVM_X86_OP_NULL(post_block)
 KVM_X86_OP_NULL(vcpu_blocking)

arch/x86/include/asm/kvm_host.h

@@ -1271,29 +1271,9 @@ struct kvm_x86_ops {
 	void (*sched_in)(struct kvm_vcpu *kvm, int cpu);
 
 	/*
-	 * Arch-specific dirty logging hooks. These hooks are only supposed to
-	 * be valid if the specific arch has hardware-accelerated dirty logging
-	 * mechanism. Currently only for PML on VMX.
-	 *
-	 *  - slot_enable_log_dirty:
-	 *	called when enabling log dirty mode for the slot.
-	 *  - slot_disable_log_dirty:
-	 *	called when disabling log dirty mode for the slot.
-	 *	also called when slot is created with log dirty disabled.
-	 *  - flush_log_dirty:
-	 *	called before reporting dirty_bitmap to userspace.
-	 *  - enable_log_dirty_pt_masked:
-	 *	called when reenabling log dirty for the GFNs in the mask after
-	 *	corresponding bits are cleared in slot->dirty_bitmap.
+	 * Size of the CPU's dirty log buffer, i.e. VMX's PML buffer.  A zero
+	 * value indicates CPU dirty logging is unsupported or disabled.
 	 */
-	void (*slot_enable_log_dirty)(struct kvm *kvm,
-				      struct kvm_memory_slot *slot);
-	void (*slot_disable_log_dirty)(struct kvm *kvm,
-				       struct kvm_memory_slot *slot);
-	void (*flush_log_dirty)(struct kvm *kvm);
-	void (*enable_log_dirty_pt_masked)(struct kvm *kvm,
-					   struct kvm_memory_slot *slot,
-					   gfn_t offset, unsigned long mask);
 	int cpu_dirty_log_size;
 
 	/* pmu operations of sub-arch */
@@ -1439,9 +1419,6 @@ void kvm_mmu_slot_largepage_remove_write_access(struct kvm *kvm,
 					struct kvm_memory_slot *memslot);
 void kvm_mmu_slot_set_dirty(struct kvm *kvm,
 			    struct kvm_memory_slot *memslot);
-void kvm_mmu_clear_dirty_pt_masked(struct kvm *kvm,
-				   struct kvm_memory_slot *slot,
-				   gfn_t gfn_offset, unsigned long mask);
 void kvm_mmu_zap_all(struct kvm *kvm);
 void kvm_mmu_invalidate_mmio_sptes(struct kvm *kvm, u64 gen);
 unsigned long kvm_mmu_calculate_default_mmu_pages(struct kvm *kvm);

arch/x86/kvm/mmu/mmu.c

@@ -1250,9 +1250,9 @@ static void kvm_mmu_write_protect_pt_masked(struct kvm *kvm,
  *
  * Used for PML to re-log the dirty GPAs after userspace querying dirty_bitmap.
  */
-void kvm_mmu_clear_dirty_pt_masked(struct kvm *kvm,
-				     struct kvm_memory_slot *slot,
-				     gfn_t gfn_offset, unsigned long mask)
+static void kvm_mmu_clear_dirty_pt_masked(struct kvm *kvm,
+					 struct kvm_memory_slot *slot,
+					 gfn_t gfn_offset, unsigned long mask)
 {
 	struct kvm_rmap_head *rmap_head;
 
@@ -1268,7 +1268,6 @@ void kvm_mmu_clear_dirty_pt_masked(struct kvm *kvm,
 		mask &= mask - 1;
 	}
 }
-EXPORT_SYMBOL_GPL(kvm_mmu_clear_dirty_pt_masked);
 
 /**
  * kvm_arch_mmu_enable_log_dirty_pt_masked - enable dirty logging for selected
@@ -1284,10 +1283,8 @@ void kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm,
 				struct kvm_memory_slot *slot,
 				gfn_t gfn_offset, unsigned long mask)
 {
-	if (kvm_x86_ops.enable_log_dirty_pt_masked)
-		static_call(kvm_x86_enable_log_dirty_pt_masked)(kvm, slot,
-								gfn_offset,
-								mask);
+	if (kvm_x86_ops.cpu_dirty_log_size)
+		kvm_mmu_clear_dirty_pt_masked(kvm, slot, gfn_offset, mask);
 	else
 		kvm_mmu_write_protect_pt_masked(kvm, slot, gfn_offset, mask);
 }
@@ -5616,7 +5613,6 @@ void kvm_mmu_slot_leaf_clear_dirty(struct kvm *kvm,
 	if (flush)
 		kvm_arch_flush_remote_tlbs_memslot(kvm, memslot);
 }
-EXPORT_SYMBOL_GPL(kvm_mmu_slot_leaf_clear_dirty);
 
 void kvm_mmu_slot_largepage_remove_write_access(struct kvm *kvm,
 					struct kvm_memory_slot *memslot)
@@ -5633,7 +5629,6 @@ void kvm_mmu_slot_largepage_remove_write_access(struct kvm *kvm,
 	if (flush)
 		kvm_arch_flush_remote_tlbs_memslot(kvm, memslot);
 }
-EXPORT_SYMBOL_GPL(kvm_mmu_slot_largepage_remove_write_access);
 
 void kvm_mmu_slot_set_dirty(struct kvm *kvm,
 			    struct kvm_memory_slot *memslot)
@@ -5649,7 +5644,6 @@ void kvm_mmu_slot_set_dirty(struct kvm *kvm,
 	if (flush)
 		kvm_arch_flush_remote_tlbs_memslot(kvm, memslot);
 }
-EXPORT_SYMBOL_GPL(kvm_mmu_slot_set_dirty);
 
 void kvm_mmu_zap_all(struct kvm *kvm)
 {

arch/x86/kvm/vmx/vmx.c

@@ -5766,24 +5766,6 @@ static void vmx_flush_pml_buffer(struct kvm_vcpu *vcpu)
 	vmcs_write16(GUEST_PML_INDEX, PML_ENTITY_NUM - 1);
 }
 
-/*
- * Flush all vcpus' PML buffer and update logged GPAs to dirty_bitmap.
- * Called before reporting dirty_bitmap to userspace.
- */
-static void kvm_flush_pml_buffers(struct kvm *kvm)
-{
-	int i;
-	struct kvm_vcpu *vcpu;
-	/*
-	 * We only need to kick vcpu out of guest mode here, as PML buffer
-	 * is flushed at beginning of all VMEXITs, and it's obvious that only
-	 * vcpus running in guest are possible to have unflushed GPAs in PML
-	 * buffer.
-	 */
-	kvm_for_each_vcpu(i, vcpu, kvm)
-		kvm_vcpu_kick(vcpu);
-}
-
 static void vmx_dump_sel(char *name, uint32_t sel)
 {
 	pr_err("%s sel=0x%04x, attr=0x%05x, limit=0x%08x, base=0x%016lx\n",
@@ -7509,32 +7491,6 @@ static void vmx_sched_in(struct kvm_vcpu *vcpu, int cpu)
 		shrink_ple_window(vcpu);
 }
 
-static void vmx_slot_enable_log_dirty(struct kvm *kvm,
-				     struct kvm_memory_slot *slot)
-{
-	if (!kvm_dirty_log_manual_protect_and_init_set(kvm))
-		kvm_mmu_slot_leaf_clear_dirty(kvm, slot);
-	kvm_mmu_slot_largepage_remove_write_access(kvm, slot);
-}
-
-static void vmx_slot_disable_log_dirty(struct kvm *kvm,
-				       struct kvm_memory_slot *slot)
-{
-	kvm_mmu_slot_set_dirty(kvm, slot);
-}
-
-static void vmx_flush_log_dirty(struct kvm *kvm)
-{
-	kvm_flush_pml_buffers(kvm);
-}
-
-static void vmx_enable_log_dirty_pt_masked(struct kvm *kvm,
-					   struct kvm_memory_slot *memslot,
-					   gfn_t offset, unsigned long mask)
-{
-	kvm_mmu_clear_dirty_pt_masked(kvm, memslot, offset, mask);
-}
-
 static int vmx_pre_block(struct kvm_vcpu *vcpu)
 {
 	if (pi_pre_block(vcpu))
@@ -7741,10 +7697,6 @@ static struct kvm_x86_ops vmx_x86_ops __initdata = {
 
 	.sched_in = vmx_sched_in,
 
-	.slot_enable_log_dirty = vmx_slot_enable_log_dirty,
-	.slot_disable_log_dirty = vmx_slot_disable_log_dirty,
-	.flush_log_dirty = vmx_flush_log_dirty,
-	.enable_log_dirty_pt_masked = vmx_enable_log_dirty_pt_masked,
 	.cpu_dirty_log_size = PML_ENTITY_NUM,
 
 	.pre_block = vmx_pre_block,
@@ -7889,13 +7841,8 @@ static __init int hardware_setup(void)
 	if (!enable_ept || !enable_ept_ad_bits || !cpu_has_vmx_pml())
 		enable_pml = 0;
 
-	if (!enable_pml) {
-		vmx_x86_ops.slot_enable_log_dirty = NULL;
-		vmx_x86_ops.slot_disable_log_dirty = NULL;
-		vmx_x86_ops.flush_log_dirty = NULL;
-		vmx_x86_ops.enable_log_dirty_pt_masked = NULL;
+	if (!enable_pml)
 		vmx_x86_ops.cpu_dirty_log_size = 0;
-	}
 
 	if (!cpu_has_vmx_preemption_timer())
 		enable_preemption_timer = false;

arch/x86/kvm/x86.c

@@ -5214,10 +5214,18 @@ static int kvm_vm_ioctl_reinject(struct kvm *kvm,
 
 void kvm_arch_sync_dirty_log(struct kvm *kvm, struct kvm_memory_slot *memslot)
 {
+
 	/*
-	 * Flush potentially hardware-cached dirty pages to dirty_bitmap.
+	 * Flush all CPUs' dirty log buffers to the  dirty_bitmap.  Called
+	 * before reporting dirty_bitmap to userspace.  KVM flushes the buffers
+	 * on all VM-Exits, thus we only need to kick running vCPUs to force a
+	 * VM-Exit.
 	 */
-	static_call_cond(kvm_x86_flush_log_dirty)(kvm);
+	struct kvm_vcpu *vcpu;
+	int i;
+
+	kvm_for_each_vcpu(i, vcpu, kvm)
+		kvm_vcpu_kick(vcpu);
 }
 
 int kvm_vm_ioctl_irq_line(struct kvm *kvm, struct kvm_irq_level *irq_event,
@@ -10809,8 +10817,10 @@ static void kvm_mmu_slot_apply_flags(struct kvm *kvm,
 	 * is enabled the D-bit or the W-bit will be cleared.
 	 */
 	if (new->flags & KVM_MEM_LOG_DIRTY_PAGES) {
-		if (kvm_x86_ops.slot_enable_log_dirty) {
-			static_call(kvm_x86_slot_enable_log_dirty)(kvm, new);
+		if (kvm_x86_ops.cpu_dirty_log_size) {
+			if (!kvm_dirty_log_manual_protect_and_init_set(kvm))
+				kvm_mmu_slot_leaf_clear_dirty(kvm, new);
+			kvm_mmu_slot_largepage_remove_write_access(kvm, new);
 		} else {
 			int level =
 				kvm_dirty_log_manual_protect_and_init_set(kvm) ?
@@ -10826,8 +10836,8 @@ static void kvm_mmu_slot_apply_flags(struct kvm *kvm,
 			 */
 			kvm_mmu_slot_remove_write_access(kvm, new, level);
 		}
-	} else {
-		static_call_cond(kvm_x86_slot_disable_log_dirty)(kvm, new);
+	} else if (kvm_x86_ops.cpu_dirty_log_size) {
+		kvm_mmu_slot_set_dirty(kvm, new);
 	}
 }