[PATCH v8 4/7] KVM: arm64: Enable ring-based dirty memory tracking

[Gavin Shan <gshan@redhat.com>]

Enable ring-based dirty memory tracking on arm64 by selecting
CONFIG_HAVE_KVM_DIRTY_{RING_ACQ_REL, RING_WITH_BITMAP} and providing
the ring buffer's physical page offset (KVM_DIRTY_LOG_PAGE_OFFSET).

Besides, helper kvm_vgic_save_its_tables_in_progress() is added to
indicate if vgic/its tables are being saved or not. The helper is used
in ARM64's kvm_arch_allow_write_without_running_vcpu() to keep the
site of saving vgic/its tables out of no-running-vcpu radar.

Signed-off-by: Gavin Shan <gshan@redhat.com>
---
 Documentation/virt/kvm/api.rst     |  2 +-
 arch/arm64/include/uapi/asm/kvm.h  |  1 +
 arch/arm64/kvm/Kconfig             |  2 ++
 arch/arm64/kvm/arm.c               |  3 +++
 arch/arm64/kvm/mmu.c               | 15 +++++++++++++++
 arch/arm64/kvm/vgic/vgic-its.c     |  3 +++
 arch/arm64/kvm/vgic/vgic-mmio-v3.c |  7 +++++++
 include/kvm/arm_vgic.h             |  2 ++
 8 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index 2ec32bd41792..2fc68f684ad8 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -7921,7 +7921,7 @@ regardless of what has actually been exposed through the CPUID leaf.
 8.29 KVM_CAP_DIRTY_LOG_RING/KVM_CAP_DIRTY_LOG_RING_ACQ_REL
 ----------------------------------------------------------
 
-:Architectures: x86
+:Architectures: x86, arm64
 :Parameters: args[0] - size of the dirty log ring
 
 KVM is capable of tracking dirty memory using ring buffers that are
diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
index 316917b98707..a7a857f1784d 100644
--- a/arch/arm64/include/uapi/asm/kvm.h
+++ b/arch/arm64/include/uapi/asm/kvm.h
@@ -43,6 +43,7 @@
 #define __KVM_HAVE_VCPU_EVENTS
 
 #define KVM_COALESCED_MMIO_PAGE_OFFSET 1
+#define KVM_DIRTY_LOG_PAGE_OFFSET 64
 
 #define KVM_REG_SIZE(id)						\
 	(1U << (((id) & KVM_REG_SIZE_MASK) >> KVM_REG_SIZE_SHIFT))
diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig
index 815cc118c675..066b053e9eb9 100644
--- a/arch/arm64/kvm/Kconfig
+++ b/arch/arm64/kvm/Kconfig
@@ -32,6 +32,8 @@ menuconfig KVM
 	select KVM_VFIO
 	select HAVE_KVM_EVENTFD
 	select HAVE_KVM_IRQFD
+	select HAVE_KVM_DIRTY_RING_ACQ_REL
+	select HAVE_KVM_DIRTY_RING_WITH_BITMAP
 	select HAVE_KVM_MSI
 	select HAVE_KVM_IRQCHIP
 	select HAVE_KVM_IRQ_ROUTING
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 94d33e296e10..6b097605e38c 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -746,6 +746,9 @@ static int check_vcpu_requests(struct kvm_vcpu *vcpu)
 
 		if (kvm_check_request(KVM_REQ_SUSPEND, vcpu))
 			return kvm_vcpu_suspend(vcpu);
+
+		if (kvm_dirty_ring_check_request(vcpu))
+			return 0;
 	}
 
 	return 1;
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 60ee3d9f01f8..fbeb55e45f53 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -932,6 +932,21 @@ void kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm,
 	kvm_mmu_write_protect_pt_masked(kvm, slot, gfn_offset, mask);
 }
 
+/*
+ * kvm_arch_allow_write_without_running_vcpu - allow writing guest memory
+ * without the running VCPU when dirty ring is enabled.
+ *
+ * The running VCPU is required to track dirty guest pages when dirty ring
+ * is enabled. Otherwise, the backup bitmap should be used to track the
+ * dirty guest pages. When vgic/its tables are being saved, the backup
+ * bitmap is used to track the dirty guest pages due to the missed running
+ * VCPU in the period.
+ */
+bool kvm_arch_allow_write_without_running_vcpu(struct kvm *kvm)
+{
+	return kvm_vgic_save_its_tables_in_progress(kvm);
+}
+
 static void kvm_send_hwpoison_signal(unsigned long address, short lsb)
 {
 	send_sig_mceerr(BUS_MCEERR_AR, (void __user *)address, lsb, current);
diff --git a/arch/arm64/kvm/vgic/vgic-its.c b/arch/arm64/kvm/vgic/vgic-its.c
index 733b53055f97..dd340bb812bd 100644
--- a/arch/arm64/kvm/vgic/vgic-its.c
+++ b/arch/arm64/kvm/vgic/vgic-its.c
@@ -2743,6 +2743,7 @@ static int vgic_its_has_attr(struct kvm_device *dev,
 static int vgic_its_ctrl(struct kvm *kvm, struct vgic_its *its, u64 attr)
 {
 	const struct vgic_its_abi *abi = vgic_its_get_abi(its);
+	struct vgic_dist *dist = &kvm->arch.vgic;
 	int ret = 0;
 
 	if (attr == KVM_DEV_ARM_VGIC_CTRL_INIT) /* Nothing to do */
@@ -2762,7 +2763,9 @@ static int vgic_its_ctrl(struct kvm *kvm, struct vgic_its *its, u64 attr)
 		vgic_its_reset(kvm, its);
 		break;
 	case KVM_DEV_ARM_ITS_SAVE_TABLES:
+		dist->save_its_tables_in_progress = true;
 		ret = abi->save_tables(its);
+		dist->save_its_tables_in_progress = false;
 		break;
 	case KVM_DEV_ARM_ITS_RESTORE_TABLES:
 		ret = abi->restore_tables(its);
diff --git a/arch/arm64/kvm/vgic/vgic-mmio-v3.c b/arch/arm64/kvm/vgic/vgic-mmio-v3.c
index 91201f743033..b63898f86e9e 100644
--- a/arch/arm64/kvm/vgic/vgic-mmio-v3.c
+++ b/arch/arm64/kvm/vgic/vgic-mmio-v3.c
@@ -54,6 +54,13 @@ bool vgic_supports_direct_msis(struct kvm *kvm)
 		(kvm_vgic_global_state.has_gicv4 && vgic_has_its(kvm)));
 }
 
+bool kvm_vgic_save_its_tables_in_progress(struct kvm *kvm)
+{
+	struct vgic_dist *dist = &kvm->arch.vgic;
+
+	return dist->save_its_tables_in_progress;
+}
+
 /*
  * The Revision field in the IIDR have the following meanings:
  *
diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
index 4df9e73a8bb5..db42fbd47bcf 100644
--- a/include/kvm/arm_vgic.h
+++ b/include/kvm/arm_vgic.h
@@ -263,6 +263,7 @@ struct vgic_dist {
 	struct vgic_io_device	dist_iodev;
 
 	bool			has_its;
+	bool			save_its_tables_in_progress;
 
 	/*
 	 * Contains the attributes and gpa of the LPI configuration table.
@@ -374,6 +375,7 @@ int kvm_vgic_map_resources(struct kvm *kvm);
 int kvm_vgic_hyp_init(void);
 void kvm_vgic_init_cpu_hardware(void);
 
+bool kvm_vgic_save_its_tables_in_progress(struct kvm *kvm);
 int kvm_vgic_inject_irq(struct kvm *kvm, int cpuid, unsigned int intid,
 			bool level, void *owner);
 int kvm_vgic_map_phys_irq(struct kvm_vcpu *vcpu, unsigned int host_irq,
-- 
2.23.0

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