[PATCH v2 02/21] KVM: arm64: Add SDEI virtualization infrastructure

[Gavin Shan <gshan@redhat.com>]

Software Delegated Exception Interface (SDEI) provides a mechanism for
registering and servicing system events. Those system events are high
priority events, which must be serviced immediately. It's going to be
used by Asynchronous Page Fault (APF) to deliver notification from KVM
to guest. It's noted that SDEI is defined by ARM DEN0054A specification.

This introduces SDEI virtualization infrastructure where the SDEI events
are registered and manuplated by the guest through hypercall. The SDEI
event is delivered to one specific vCPU by KVM once it's raised. This
introduces data structures to represent the needed objects to implement
the feature, which is highlighted as below. As those objects could be
migrated between VMs, these data structures are partially exported to
user space.

   * kvm_sdei_event
     SDEI events are exported from KVM so that guest is able to register
     and manuplate.
   * kvm_sdei_kvm_event
     SDEI event that has been registered by guest.
   * kvm_sdei_kvm_vcpu
     SDEI event that has been delivered to the target vCPU.
   * kvm_sdei_kvm
     Place holder of exported and registered SDEI events.
   * kvm_sdei_vcpu
     Auxiliary object to save the preempted context during SDEI event
     delivery.

The error is returned for all SDEI hypercalls for now. They will be
supported by subsequent patches.

Signed-off-by: Gavin Shan <gshan@redhat.com>
---
 arch/arm64/include/asm/kvm_host.h      |   4 +
 arch/arm64/include/asm/kvm_sdei.h      | 118 +++++++++++++++
 arch/arm64/include/uapi/asm/kvm.h      |   1 +
 arch/arm64/include/uapi/asm/kvm_sdei.h |  56 +++++++
 arch/arm64/kvm/Makefile                |   2 +-
 arch/arm64/kvm/arm.c                   |   7 +
 arch/arm64/kvm/hypercalls.c            |  18 +++
 arch/arm64/kvm/sdei.c                  | 198 +++++++++++++++++++++++++
 8 files changed, 403 insertions(+), 1 deletion(-)
 create mode 100644 arch/arm64/include/asm/kvm_sdei.h
 create mode 100644 arch/arm64/include/uapi/asm/kvm_sdei.h
 create mode 100644 arch/arm64/kvm/sdei.c

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 8fcfab0c2567..b2d51c6d055c 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -133,6 +133,8 @@ struct kvm_arch {
 
 	u8 pfr0_csv2;
 	u8 pfr0_csv3;
+
+	struct kvm_sdei_kvm *sdei;
 };
 
 struct kvm_vcpu_fault_info {
@@ -370,6 +372,8 @@ struct kvm_vcpu_arch {
 		u64 last_steal;
 		gpa_t base;
 	} steal;
+
+	struct kvm_sdei_vcpu *sdei;
 };
 
 /* Pointer to the vcpu's SVE FFR for sve_{save,load}_state() */
diff --git a/arch/arm64/include/asm/kvm_sdei.h b/arch/arm64/include/asm/kvm_sdei.h
new file mode 100644
index 000000000000..b0abc13a0256
--- /dev/null
+++ b/arch/arm64/include/asm/kvm_sdei.h
@@ -0,0 +1,118 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Definitions of various KVM SDEI events.
+ *
+ * Copyright (C) 2021 Red Hat, Inc.
+ *
+ * Author(s): Gavin Shan <gshan@redhat.com>
+ */
+
+#ifndef __ARM64_KVM_SDEI_H__
+#define __ARM64_KVM_SDEI_H__
+
+#include <uapi/linux/arm_sdei.h>
+#include <uapi/asm/kvm_sdei.h>
+#include <linux/bitmap.h>
+#include <linux/list.h>
+#include <linux/spinlock.h>
+
+struct kvm_sdei_event {
+	struct kvm_sdei_event_state		state;
+	struct kvm				*kvm;
+	struct list_head			link;
+};
+
+struct kvm_sdei_kvm_event {
+	struct kvm_sdei_kvm_event_state		state;
+	struct kvm_sdei_event			*kse;
+	struct kvm				*kvm;
+	struct list_head			link;
+};
+
+struct kvm_sdei_vcpu_event {
+	struct kvm_sdei_vcpu_event_state	state;
+	struct kvm_sdei_kvm_event		*kske;
+	struct kvm_vcpu				*vcpu;
+	struct list_head			link;
+};
+
+struct kvm_sdei_kvm {
+	spinlock_t		lock;
+	struct list_head	events;		/* kvm_sdei_event */
+	struct list_head	kvm_events;	/* kvm_sdei_kvm_event */
+};
+
+struct kvm_sdei_vcpu {
+	spinlock_t                      lock;
+	struct kvm_sdei_vcpu_state      state;
+	struct kvm_sdei_vcpu_event      *critical_event;
+	struct kvm_sdei_vcpu_event      *normal_event;
+	struct list_head                critical_events;
+	struct list_head                normal_events;
+};
+
+/*
+ * According to SDEI specification (v1.0), the event number spans 32-bits
+ * and the lower 24-bits are used as the (real) event number. I don't
+ * think we can use that much SDEI numbers in one system. So we reserve
+ * two bits from the 24-bits real event number, to indicate its types:
+ * physical event and virtual event. One reserved bit is enough for now,
+ * but two bits are reserved for possible extension in future.
+ *
+ * The physical events are owned by underly firmware while the virtual
+ * events are used by VMM and KVM.
+ */
+#define KVM_SDEI_EV_NUM_TYPE_SHIFT	22
+#define KVM_SDEI_EV_NUM_TYPE_MASK	3
+#define KVM_SDEI_EV_NUM_TYPE_PHYS	0
+#define KVM_SDEI_EV_NUM_TYPE_VIRT	1
+
+static inline bool kvm_sdei_is_valid_event_num(unsigned long num)
+{
+	unsigned long type;
+
+	if (num >> 32)
+		return false;
+
+	type = (num >> KVM_SDEI_EV_NUM_TYPE_SHIFT) & KVM_SDEI_EV_NUM_TYPE_MASK;
+	if (type != KVM_SDEI_EV_NUM_TYPE_VIRT)
+		return false;
+
+	return true;
+}
+
+/* Accessors for the registration or enablement states of KVM event */
+#define KVM_SDEI_FLAG_FUNC(field)					   \
+static inline bool kvm_sdei_is_##field(struct kvm_sdei_kvm_event *kske,	   \
+				       unsigned int index)		   \
+{									   \
+	return !!test_bit(index, (void *)(kske->state.field));		   \
+}									   \
+									   \
+static inline bool kvm_sdei_empty_##field(struct kvm_sdei_kvm_event *kske) \
+{									   \
+	return bitmap_empty((void *)(kske->state.field),		   \
+			    KVM_SDEI_MAX_VCPUS);			   \
+}									   \
+static inline void kvm_sdei_set_##field(struct kvm_sdei_kvm_event *kske,   \
+					unsigned int index)		   \
+{									   \
+	set_bit(index, (void *)(kske->state.field));			   \
+}									   \
+static inline void kvm_sdei_clear_##field(struct kvm_sdei_kvm_event *kske, \
+					  unsigned int index)		   \
+{									   \
+	clear_bit(index, (void *)(kske->state.field));			   \
+}
+
+KVM_SDEI_FLAG_FUNC(registered)
+KVM_SDEI_FLAG_FUNC(enabled)
+
+/* APIs */
+void kvm_sdei_init_vm(struct kvm *kvm);
+void kvm_sdei_create_vcpu(struct kvm_vcpu *vcpu);
+int kvm_sdei_hypercall(struct kvm_vcpu *vcpu);
+void kvm_sdei_destroy_vcpu(struct kvm_vcpu *vcpu);
+void kvm_sdei_destroy_vm(struct kvm *kvm);
+
+#endif /* __ARM64_KVM_SDEI_H__ */
diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
index 24223adae150..15499751997d 100644
--- a/arch/arm64/include/uapi/asm/kvm.h
+++ b/arch/arm64/include/uapi/asm/kvm.h
@@ -36,6 +36,7 @@
 #include <linux/types.h>
 #include <asm/ptrace.h>
 #include <asm/sve_context.h>
+#include <asm/kvm_sdei.h>
 
 #define __KVM_HAVE_GUEST_DEBUG
 #define __KVM_HAVE_IRQ_LINE
diff --git a/arch/arm64/include/uapi/asm/kvm_sdei.h b/arch/arm64/include/uapi/asm/kvm_sdei.h
new file mode 100644
index 000000000000..9dbda2fb457e
--- /dev/null
+++ b/arch/arm64/include/uapi/asm/kvm_sdei.h
@@ -0,0 +1,56 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/*
+ * Definitions of various KVM SDEI event states.
+ *
+ * Copyright (C) 2021 Red Hat, Inc.
+ *
+ * Author(s): Gavin Shan <gshan@redhat.com>
+ */
+
+#ifndef _UAPI__ASM_KVM_SDEI_H
+#define _UAPI__ASM_KVM_SDEI_H
+
+#define KVM_SDEI_MAX_VCPUS     512
+#define KVM_SDEI_INVALID_NUM   0
+#define KVM_SDEI_DEFAULT_NUM   0x40400000
+
+struct kvm_sdei_event_state {
+	uint64_t	num;
+
+	uint8_t		type;
+	uint8_t		signaled;
+	uint8_t		priority;
+};
+
+struct kvm_sdei_kvm_event_state {
+	uint64_t	num;
+	uint32_t	refcount;
+
+	uint8_t		route_mode;
+	uint64_t	route_affinity;
+	uint64_t	entries[KVM_SDEI_MAX_VCPUS];
+	uint64_t	params[KVM_SDEI_MAX_VCPUS];
+	uint64_t	registered[KVM_SDEI_MAX_VCPUS/64];
+	uint64_t	enabled[KVM_SDEI_MAX_VCPUS/64];
+};
+
+struct kvm_sdei_vcpu_event_state {
+	uint64_t	num;
+	uint32_t	refcount;
+};
+
+struct kvm_sdei_vcpu_regs {
+	uint64_t	regs[18];
+	uint64_t	pc;
+	uint64_t	pstate;
+};
+
+struct kvm_sdei_vcpu_state {
+	uint8_t				masked;
+	uint64_t			critical_num;
+	uint64_t			normal_num;
+	struct kvm_sdei_vcpu_regs	critical_regs;
+	struct kvm_sdei_vcpu_regs	normal_regs;
+};
+
+#endif /* _UAPI__ASM_KVM_SDEI_H */
diff --git a/arch/arm64/kvm/Makefile b/arch/arm64/kvm/Makefile
index 13b017284bf9..dcb353f29d20 100644
--- a/arch/arm64/kvm/Makefile
+++ b/arch/arm64/kvm/Makefile
@@ -16,7 +16,7 @@ kvm-y := $(KVM)/kvm_main.o $(KVM)/coalesced_mmio.o $(KVM)/eventfd.o \
 	 inject_fault.o va_layout.o handle_exit.o \
 	 guest.o debug.o reset.o sys_regs.o \
 	 vgic-sys-reg-v3.o fpsimd.o pmu.o \
-	 arch_timer.o \
+	 arch_timer.o sdei.o \
 	 vgic/vgic.o vgic/vgic-init.o \
 	 vgic/vgic-irqfd.o vgic/vgic-v2.o \
 	 vgic/vgic-v3.o vgic/vgic-v4.o \
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index fe60d25c000e..a7ae16df3df7 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -144,6 +144,8 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
 
 	kvm_vgic_early_init(kvm);
 
+	kvm_sdei_init_vm(kvm);
+
 	/* The maximum number of VCPUs is limited by the host's GIC model */
 	kvm->arch.max_vcpus = kvm_arm_default_max_vcpus();
 
@@ -173,6 +175,8 @@ void kvm_arch_destroy_vm(struct kvm *kvm)
 
 	kvm_vgic_destroy(kvm);
 
+	kvm_sdei_destroy_vm(kvm);
+
 	for (i = 0; i < KVM_MAX_VCPUS; ++i) {
 		if (kvm->vcpus[i]) {
 			kvm_vcpu_destroy(kvm->vcpus[i]);
@@ -321,6 +325,8 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
 
 	kvm_arm_pvtime_vcpu_init(&vcpu->arch);
 
+	kvm_sdei_create_vcpu(vcpu);
+
 	vcpu->arch.hw_mmu = &vcpu->kvm->arch.mmu;
 
 	err = kvm_vgic_vcpu_init(vcpu);
@@ -342,6 +348,7 @@ void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu)
 	kvm_mmu_free_memory_cache(&vcpu->arch.mmu_page_cache);
 	kvm_timer_vcpu_terminate(vcpu);
 	kvm_pmu_vcpu_destroy(vcpu);
+	kvm_sdei_destroy_vcpu(vcpu);
 
 	kvm_arm_vcpu_destroy(vcpu);
 }
diff --git a/arch/arm64/kvm/hypercalls.c b/arch/arm64/kvm/hypercalls.c
index 25ea4ecb6449..a54c4805f2a6 100644
--- a/arch/arm64/kvm/hypercalls.c
+++ b/arch/arm64/kvm/hypercalls.c
@@ -71,6 +71,24 @@ int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
 		if (gpa != GPA_INVALID)
 			val = gpa;
 		break;
+	case SDEI_1_0_FN_SDEI_VERSION:
+	case SDEI_1_0_FN_SDEI_EVENT_REGISTER:
+	case SDEI_1_0_FN_SDEI_EVENT_ENABLE:
+	case SDEI_1_0_FN_SDEI_EVENT_DISABLE:
+	case SDEI_1_0_FN_SDEI_EVENT_CONTEXT:
+	case SDEI_1_0_FN_SDEI_EVENT_COMPLETE:
+	case SDEI_1_0_FN_SDEI_EVENT_COMPLETE_AND_RESUME:
+	case SDEI_1_0_FN_SDEI_EVENT_UNREGISTER:
+	case SDEI_1_0_FN_SDEI_EVENT_STATUS:
+	case SDEI_1_0_FN_SDEI_EVENT_GET_INFO:
+	case SDEI_1_0_FN_SDEI_EVENT_ROUTING_SET:
+	case SDEI_1_0_FN_SDEI_PE_MASK:
+	case SDEI_1_0_FN_SDEI_PE_UNMASK:
+	case SDEI_1_0_FN_SDEI_INTERRUPT_BIND:
+	case SDEI_1_0_FN_SDEI_INTERRUPT_RELEASE:
+	case SDEI_1_0_FN_SDEI_PRIVATE_RESET:
+	case SDEI_1_0_FN_SDEI_SHARED_RESET:
+		return kvm_sdei_hypercall(vcpu);
 	default:
 		return kvm_psci_call(vcpu);
 	}
diff --git a/arch/arm64/kvm/sdei.c b/arch/arm64/kvm/sdei.c
new file mode 100644
index 000000000000..ab330b74a965
--- /dev/null
+++ b/arch/arm64/kvm/sdei.c
@@ -0,0 +1,198 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * SDEI virtualization support.
+ *
+ * Copyright (C) 2021 Red Hat, Inc.
+ *
+ * Author(s): Gavin Shan <gshan@redhat.com>
+ */
+
+#include <linux/kernel.h>
+#include <linux/kvm_host.h>
+#include <linux/spinlock.h>
+#include <linux/slab.h>
+#include <kvm/arm_hypercalls.h>
+
+static struct kvm_sdei_event_state defined_kse[] = {
+	{ KVM_SDEI_DEFAULT_NUM,
+	  SDEI_EVENT_TYPE_PRIVATE,
+	  1,
+	  SDEI_EVENT_PRIORITY_CRITICAL
+	},
+};
+
+static void kvm_sdei_remove_events(struct kvm *kvm)
+{
+	struct kvm_sdei_kvm *ksdei = kvm->arch.sdei;
+	struct kvm_sdei_event *kse, *tmp;
+
+	list_for_each_entry_safe(kse, tmp, &ksdei->events, link) {
+		list_del(&kse->link);
+		kfree(kse);
+	}
+}
+
+static void kvm_sdei_remove_kvm_events(struct kvm *kvm,
+				       unsigned int mask,
+				       bool force)
+{
+	struct kvm_sdei_kvm *ksdei = kvm->arch.sdei;
+	struct kvm_sdei_event *kse;
+	struct kvm_sdei_kvm_event *kske, *tmp;
+
+	list_for_each_entry_safe(kske, tmp, &ksdei->kvm_events, link) {
+		kse = kske->kse;
+
+		if (!((1 << kse->state.type) & mask))
+			continue;
+
+		if (!force && kske->state.refcount)
+			continue;
+
+		list_del(&kske->link);
+		kfree(kske);
+	}
+}
+
+static void kvm_sdei_remove_vcpu_events(struct kvm_vcpu *vcpu)
+{
+	struct kvm_sdei_vcpu *vsdei = vcpu->arch.sdei;
+	struct kvm_sdei_vcpu_event *ksve, *tmp;
+
+	list_for_each_entry_safe(ksve, tmp, &vsdei->critical_events, link) {
+		list_del(&ksve->link);
+		kfree(ksve);
+	}
+
+	list_for_each_entry_safe(ksve, tmp, &vsdei->normal_events, link) {
+		list_del(&ksve->link);
+		kfree(ksve);
+	}
+}
+
+int kvm_sdei_hypercall(struct kvm_vcpu *vcpu)
+{
+	u32 func = smccc_get_function(vcpu);
+	bool has_result = true;
+	unsigned long ret;
+
+	switch (func) {
+	case SDEI_1_0_FN_SDEI_VERSION:
+	case SDEI_1_0_FN_SDEI_EVENT_REGISTER:
+	case SDEI_1_0_FN_SDEI_EVENT_ENABLE:
+	case SDEI_1_0_FN_SDEI_EVENT_DISABLE:
+	case SDEI_1_0_FN_SDEI_EVENT_CONTEXT:
+	case SDEI_1_0_FN_SDEI_EVENT_COMPLETE:
+	case SDEI_1_0_FN_SDEI_EVENT_COMPLETE_AND_RESUME:
+	case SDEI_1_0_FN_SDEI_EVENT_UNREGISTER:
+	case SDEI_1_0_FN_SDEI_EVENT_STATUS:
+	case SDEI_1_0_FN_SDEI_EVENT_GET_INFO:
+	case SDEI_1_0_FN_SDEI_EVENT_ROUTING_SET:
+	case SDEI_1_0_FN_SDEI_PE_MASK:
+	case SDEI_1_0_FN_SDEI_PE_UNMASK:
+	case SDEI_1_0_FN_SDEI_INTERRUPT_BIND:
+	case SDEI_1_0_FN_SDEI_INTERRUPT_RELEASE:
+	case SDEI_1_0_FN_SDEI_PRIVATE_RESET:
+	case SDEI_1_0_FN_SDEI_SHARED_RESET:
+	default:
+		ret = SDEI_NOT_SUPPORTED;
+	}
+
+	/*
+	 * We don't have return value for COMPLETE or COMPLETE_AND_RESUME
+	 * hypercalls. Otherwise, the restored context will be corrupted.
+	 */
+	if (has_result)
+		smccc_set_retval(vcpu, ret, 0, 0, 0);
+
+	return 1;
+}
+
+void kvm_sdei_init_vm(struct kvm *kvm)
+{
+	struct kvm_sdei_kvm *ksdei;
+	struct kvm_sdei_event *kse;
+	int i;
+
+	ksdei = kzalloc(sizeof(*ksdei), GFP_KERNEL);
+	if (!ksdei)
+		return;
+
+	spin_lock_init(&ksdei->lock);
+	INIT_LIST_HEAD(&ksdei->events);
+	INIT_LIST_HEAD(&ksdei->kvm_events);
+
+	/*
+	 * Populate the defined KVM SDEI events. The whole functionality
+	 * will be disabled on any errors.
+	 */
+	for (i = 0; i < ARRAY_SIZE(defined_kse); i++) {
+		kse = kzalloc(sizeof(*kse), GFP_KERNEL);
+		if (!kse) {
+			kvm_sdei_remove_events(kvm);
+			kfree(ksdei);
+			return;
+		}
+
+		kse->kvm   = kvm;
+		kse->state = defined_kse[i];
+		list_add_tail(&kse->link, &ksdei->events);
+	}
+
+	kvm->arch.sdei = ksdei;
+}
+
+void kvm_sdei_create_vcpu(struct kvm_vcpu *vcpu)
+{
+	struct kvm *kvm = vcpu->kvm;
+	struct kvm_sdei_vcpu *vsdei;
+
+	if (!kvm->arch.sdei)
+		return;
+
+	vsdei = kzalloc(sizeof(*vsdei), GFP_KERNEL);
+	if (!vsdei)
+		return;
+
+	spin_lock_init(&vsdei->lock);
+	vsdei->state.masked       = 1;
+	vsdei->state.critical_num = KVM_SDEI_INVALID_NUM;
+	vsdei->state.normal_num   = KVM_SDEI_INVALID_NUM;
+	vsdei->critical_event     = NULL;
+	vsdei->normal_event       = NULL;
+	INIT_LIST_HEAD(&vsdei->critical_events);
+	INIT_LIST_HEAD(&vsdei->normal_events);
+
+	vcpu->arch.sdei = vsdei;
+}
+
+void kvm_sdei_destroy_vcpu(struct kvm_vcpu *vcpu)
+{
+	struct kvm_sdei_vcpu *vsdei = vcpu->arch.sdei;
+
+	if (vsdei) {
+		spin_lock(&vsdei->lock);
+		kvm_sdei_remove_vcpu_events(vcpu);
+		spin_unlock(&vsdei->lock);
+
+		kfree(vsdei);
+		vcpu->arch.sdei = NULL;
+	}
+}
+
+void kvm_sdei_destroy_vm(struct kvm *kvm)
+{
+	struct kvm_sdei_kvm *ksdei = kvm->arch.sdei;
+	unsigned int mask = (1 << SDEI_EVENT_TYPE_PRIVATE) |
+			    (1 << SDEI_EVENT_TYPE_SHARED);
+
+	if (ksdei) {
+		spin_lock(&ksdei->lock);
+		kvm_sdei_remove_kvm_events(kvm, mask, true);
+		kvm_sdei_remove_events(kvm);
+		spin_unlock(&ksdei->lock);
+
+		kfree(ksdei);
+		kvm->arch.sdei = NULL;
+	}
+}
-- 
2.23.0