[PATCH v8 3/3] KVM: arm64: 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/arm64/kvm/Kconfig | 1 +
 arch/arm64/kvm/arm.c   | 7 +++++++
 arch/arm64/kvm/mmu.c   | 3 +++
 3 files changed, 11 insertions(+)

diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig
index ca6eadeb7d1a..8e7dea2c3a9f 100644
--- a/arch/arm64/kvm/Kconfig
+++ b/arch/arm64/kvm/Kconfig
@@ -44,6 +44,7 @@ menuconfig KVM
 	select SCHED_INFO
 	select GUEST_PERF_EVENTS if PERF_EVENTS
 	select INTERVAL_TREE
+	select HAVE_KVM_DIRTY_QUOTA
 	help
 	  Support hosting virtualized guest machines.
 
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 3bd732eaf087..5162b2fc46a1 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -757,6 +757,13 @@ static int check_vcpu_requests(struct kvm_vcpu *vcpu)
 
 		if (kvm_dirty_ring_check_request(vcpu))
 			return 0;
+
+#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;
+			return 0;
+		}
+#endif
 	}
 
 	return 1;
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 7113587222ff..baf416046f46 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -1390,6 +1390,9 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
 	/* Mark the page dirty only if the fault is handled successfully */
 	if (writable && !ret) {
 		kvm_set_pfn_dirty(pfn);
+#ifdef CONFIG_HAVE_KVM_DIRTY_QUOTA
+		update_dirty_quota(kvm, fault_granule);
+#endif
 		mark_page_dirty_in_slot(kvm, memslot, gfn);
 	}
 
-- 
2.22.3