[PATCH v8 2/3] KVM: x86: Dirty quota-based throttling of vcpus

[Shivam Kumar <shivam.kumar1@nutanix.com>]

Call update_dirty_quota whenever a page is marked dirty with
appropriate arch-specific page size. Process the KVM request
KVM_REQ_DIRTY_QUOTA_EXIT (raised by update_dirty_quota) to exit to
userspace with exit reason KVM_EXIT_DIRTY_QUOTA_EXHAUSTED.

Suggested-by: Shaju Abraham <shaju.abraham@nutanix.com>
Suggested-by: Manish Mishra <manish.mishra@nutanix.com>
Co-developed-by: Anurag Madnawat <anurag.madnawat@nutanix.com>
Signed-off-by: Anurag Madnawat <anurag.madnawat@nutanix.com>
Signed-off-by: Shivam Kumar <shivam.kumar1@nutanix.com>
---
 arch/x86/kvm/Kconfig       |  1 +
 arch/x86/kvm/mmu/mmu.c     |  8 +++++++-
 arch/x86/kvm/mmu/spte.c    |  3 +++
 arch/x86/kvm/mmu/tdp_mmu.c |  3 +++
 arch/x86/kvm/vmx/vmx.c     |  5 +++++
 arch/x86/kvm/x86.c         | 16 ++++++++++++++++
 arch/x86/kvm/xen.c         | 12 +++++++++++-
 7 files changed, 46 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig
index 8e578311ca9d..8621a9512572 100644
--- a/arch/x86/kvm/Kconfig
+++ b/arch/x86/kvm/Kconfig
@@ -48,6 +48,7 @@ config KVM
 	select KVM_VFIO
 	select SRCU
 	select INTERVAL_TREE
+	select HAVE_KVM_DIRTY_QUOTA
 	select HAVE_KVM_PM_NOTIFIER if PM
 	select KVM_GENERIC_HARDWARE_ENABLING
 	help
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index c8ebe542c565..e0c8348ecdf1 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -3323,8 +3323,14 @@ fast_pf_fix_direct_spte(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault,
 	if (!try_cmpxchg64(sptep, &old_spte, new_spte))
 		return false;
 
-	if (is_writable_pte(new_spte) && !is_writable_pte(old_spte))
+	if (is_writable_pte(new_spte) && !is_writable_pte(old_spte)) {
+#ifdef CONFIG_HAVE_KVM_DIRTY_QUOTA
+		struct kvm_mmu_page *sp = sptep_to_sp(sptep);
+
+		update_dirty_quota(vcpu->kvm, (1L << SPTE_LEVEL_SHIFT(sp->role.level)));
+#endif
 		mark_page_dirty_in_slot(vcpu->kvm, fault->slot, fault->gfn);
+	}
 
 	return true;
 }
diff --git a/arch/x86/kvm/mmu/spte.c b/arch/x86/kvm/mmu/spte.c
index c15bfca3ed15..15f4f1d97ce9 100644
--- a/arch/x86/kvm/mmu/spte.c
+++ b/arch/x86/kvm/mmu/spte.c
@@ -243,6 +243,9 @@ bool make_spte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
 	if ((spte & PT_WRITABLE_MASK) && kvm_slot_dirty_track_enabled(slot)) {
 		/* Enforced by kvm_mmu_hugepage_adjust. */
 		WARN_ON(level > PG_LEVEL_4K);
+#ifdef CONFIG_HAVE_KVM_DIRTY_QUOTA
+		update_dirty_quota(vcpu->kvm, (1L << SPTE_LEVEL_SHIFT(level)));
+#endif
 		mark_page_dirty_in_slot(vcpu->kvm, slot, gfn);
 	}
 
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 7c25dbf32ecc..4bf98e96343d 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -358,6 +358,9 @@ static void handle_changed_spte_dirty_log(struct kvm *kvm, int as_id, gfn_t gfn,
 
 	if ((!is_writable_pte(old_spte) || pfn_changed) &&
 	    is_writable_pte(new_spte)) {
+#ifdef CONFIG_HAVE_KVM_DIRTY_QUOTA
+		update_dirty_quota(kvm, (1L << SPTE_LEVEL_SHIFT(level)));
+#endif
 		slot = __gfn_to_memslot(__kvm_memslots(kvm, as_id), gfn);
 		mark_page_dirty_in_slot(kvm, slot, gfn);
 	}
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index bcac3efcde41..da4c6342a647 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -5861,6 +5861,11 @@ static int handle_invalid_guest_state(struct kvm_vcpu *vcpu)
 		 */
 		if (__xfer_to_guest_mode_work_pending())
 			return 1;
+
+#ifdef CONFIG_HAVE_KVM_DIRTY_QUOTA
+		if (kvm_test_request(KVM_REQ_DIRTY_QUOTA_EXIT, vcpu))
+			return 1;
+#endif
 	}
 
 	return 1;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 7713420abab0..1733be829197 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3092,6 +3092,9 @@ static void kvm_setup_guest_pvclock(struct kvm_vcpu *v,
 
 	guest_hv_clock->version = ++vcpu->hv_clock.version;
 
+#ifdef CONFIG_HAVE_KVM_DIRTY_QUOTA
+	update_dirty_quota(v->kvm, PAGE_SIZE);
+#endif
 	mark_page_dirty_in_slot(v->kvm, gpc->memslot, gpc->gpa >> PAGE_SHIFT);
 	read_unlock_irqrestore(&gpc->lock, flags);
 
@@ -3566,6 +3569,9 @@ static void record_steal_time(struct kvm_vcpu *vcpu)
  out:
 	user_access_end();
  dirty:
+#ifdef CONFIG_HAVE_KVM_DIRTY_QUOTA
+	update_dirty_quota(vcpu->kvm, PAGE_SIZE);
+#endif
 	mark_page_dirty_in_slot(vcpu->kvm, ghc->memslot, gpa_to_gfn(ghc->gpa));
 }
 
@@ -4815,6 +4821,9 @@ static void kvm_steal_time_set_preempted(struct kvm_vcpu *vcpu)
 	if (!copy_to_user_nofault(&st->preempted, &preempted, sizeof(preempted)))
 		vcpu->arch.st.preempted = KVM_VCPU_PREEMPTED;
 
+#ifdef CONFIG_HAVE_KVM_DIRTY_QUOTA
+	update_dirty_quota(vcpu->kvm, PAGE_SIZE);
+#endif
 	mark_page_dirty_in_slot(vcpu->kvm, ghc->memslot, gpa_to_gfn(ghc->gpa));
 }
 
@@ -10514,6 +10523,13 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
 			r = 0;
 			goto out;
 		}
+#ifdef CONFIG_HAVE_KVM_DIRTY_QUOTA
+		if (kvm_check_request(KVM_REQ_DIRTY_QUOTA_EXIT, vcpu)) {
+			vcpu->run->exit_reason = KVM_EXIT_DIRTY_QUOTA_EXHAUSTED;
+			r = 0;
+			goto out;
+		}
+#endif
 
 		/*
 		 * KVM_REQ_HV_STIMER has to be processed after
diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c
index 40edf4d1974c..00a3ac438539 100644
--- a/arch/x86/kvm/xen.c
+++ b/arch/x86/kvm/xen.c
@@ -435,9 +435,16 @@ static void kvm_xen_update_runstate_guest(struct kvm_vcpu *v, bool atomic)
 
 	read_unlock_irqrestore(&gpc1->lock, flags);
 
+#ifdef CONFIG_HAVE_KVM_DIRTY_QUOTA
+	update_dirty_quota(v->kvm, PAGE_SIZE);
+#endif
 	mark_page_dirty_in_slot(v->kvm, gpc1->memslot, gpc1->gpa >> PAGE_SHIFT);
-	if (user_len2)
+	if (user_len2) {
+#ifdef CONFIG_HAVE_KVM_DIRTY_QUOTA
+		update_dirty_quota(v->kvm, PAGE_SIZE);
+#endif
 		mark_page_dirty_in_slot(v->kvm, gpc2->memslot, gpc2->gpa >> PAGE_SHIFT);
+	}
 }
 
 void kvm_xen_update_runstate(struct kvm_vcpu *v, int state)
@@ -549,6 +556,9 @@ void kvm_xen_inject_pending_events(struct kvm_vcpu *v)
 	if (v->arch.xen.upcall_vector)
 		kvm_xen_inject_vcpu_vector(v);
 
+#ifdef CONFIG_HAVE_KVM_DIRTY_QUOTA
+	update_dirty_quota(v->kvm, PAGE_SIZE);
+#endif
 	mark_page_dirty_in_slot(v->kvm, gpc->memslot, gpc->gpa >> PAGE_SHIFT);
 }
 
-- 
2.22.3