[PATCH v2 16/22] KVM: arm64: Add pkvm_hyp_req infrastructure

[Vincent Donnefort <vdonnefort@google.com>]

The pKVM hypervisor depends on the host for a lot of operations like
memory allocation. Introduce a struct pkvm_hyp_req to enable the pKVM
hypervisor to request resources from the host.

Additionally, introduce a trace event to track the handling of these
requests.

Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
---
 arch/arm64/include/asm/kvm_asm.h  | 10 ++++---
 arch/arm64/include/asm/kvm_host.h | 12 +++++++++
 arch/arm64/include/asm/kvm_pkvm.h |  1 +
 arch/arm64/kvm/handle_exit.c      |  3 +++
 arch/arm64/kvm/pkvm.c             | 20 ++++++++++++++
 arch/arm64/kvm/trace_pkvm.h       | 43 +++++++++++++++++++++++++++++++
 6 files changed, 85 insertions(+), 4 deletions(-)
 create mode 100644 arch/arm64/kvm/trace_pkvm.h

diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
index 95dd62e5601b..ec59f0fe9374 100644
--- a/arch/arm64/include/asm/kvm_asm.h
+++ b/arch/arm64/include/asm/kvm_asm.h
@@ -17,10 +17,11 @@
 #define ARM_EXCEPTION_IS_TRAP(x)  (ARM_EXCEPTION_CODE((x)) == ARM_EXCEPTION_TRAP)
 #define ARM_SERROR_PENDING(x)	  !!((x) & (1U << ARM_EXIT_WITH_SERROR_BIT))
 
-#define ARM_EXCEPTION_IRQ	  0
-#define ARM_EXCEPTION_EL1_SERROR  1
-#define ARM_EXCEPTION_TRAP	  2
-#define ARM_EXCEPTION_IL	  3
+#define ARM_EXCEPTION_IRQ		0
+#define ARM_EXCEPTION_EL1_SERROR	1
+#define ARM_EXCEPTION_TRAP		2
+#define ARM_EXCEPTION_IL		3
+#define ARM_EXCEPTION_PKVM_HYP_REQ	4
 /* The hyp-stub will return this for any kvm_call_hyp() call */
 #define ARM_EXCEPTION_HYP_GONE	  HVC_STUB_ERR
 
@@ -28,6 +29,7 @@
 	{ARM_EXCEPTION_IRQ,		"IRQ"		},	\
 	{ARM_EXCEPTION_EL1_SERROR, 	"SERROR"	},	\
 	{ARM_EXCEPTION_TRAP, 		"TRAP"		},	\
+	{ARM_EXCEPTION_PKVM_HYP_REQ,	"PKVM_HYP_REQ"	},	\
 	{ARM_EXCEPTION_HYP_GONE,	"HYP_GONE"	}
 
 /*
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 27fe0cd5b2d7..ea76c0f3120e 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -85,6 +85,15 @@ u32 __attribute_const__ kvm_target_cpu(void);
 void kvm_reset_vcpu(struct kvm_vcpu *vcpu);
 void kvm_arm_vcpu_destroy(struct kvm_vcpu *vcpu);
 
+enum pkvm_hyp_req_type {
+	PKVM_HYP_NO_REQ = 0,
+	__PKVM_HYP_REQ_TYPE_MAX,
+};
+
+struct pkvm_hyp_req {
+	u8 type;
+};
+
 struct kvm_hyp_memcache {
 	phys_addr_t head;
 	unsigned long nr_pages;
@@ -929,6 +938,9 @@ struct kvm_vcpu_arch {
 	/* Pages to top-up the pKVM/EL2 guest pool */
 	struct kvm_hyp_memcache pkvm_memcache;
 
+	/* To be read on ARM_EXCEPTION_PKVM_HYP_REQ */
+	struct pkvm_hyp_req pkvm_hyp_req;
+
 	/* Virtual SError ESR to restore when HCR_EL2.VSE is set */
 	u64 vsesr_el2;
 
diff --git a/arch/arm64/include/asm/kvm_pkvm.h b/arch/arm64/include/asm/kvm_pkvm.h
index ff8e93efcd7a..7240dcc4f395 100644
--- a/arch/arm64/include/asm/kvm_pkvm.h
+++ b/arch/arm64/include/asm/kvm_pkvm.h
@@ -22,6 +22,7 @@ int pkvm_create_hyp_vm(struct kvm *kvm);
 bool pkvm_hyp_vm_is_created(struct kvm *kvm);
 void pkvm_destroy_hyp_vm(struct kvm *kvm);
 int pkvm_create_hyp_vcpu(struct kvm_vcpu *vcpu);
+int __pkvm_handle_vcpu_req(struct kvm_vcpu *vcpu);
 
 #ifdef CONFIG_NVHE_EL2_DEBUG
 void pkvm_ownership_selftest(void);
diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c
index db37678dcb05..90500b204e16 100644
--- a/arch/arm64/kvm/handle_exit.c
+++ b/arch/arm64/kvm/handle_exit.c
@@ -18,6 +18,7 @@
 #include <asm/kvm_emulate.h>
 #include <asm/kvm_mmu.h>
 #include <asm/kvm_nested.h>
+#include <asm/kvm_pkvm.h>
 #include <asm/debug-monitors.h>
 #include <asm/stacktrace/nvhe.h>
 #include <asm/traps.h>
@@ -464,6 +465,8 @@ int handle_exit(struct kvm_vcpu *vcpu, int exception_index)
 		return 1;
 	case ARM_EXCEPTION_TRAP:
 		return handle_trap_exceptions(vcpu);
+	case ARM_EXCEPTION_PKVM_HYP_REQ:
+		return __pkvm_handle_vcpu_req(vcpu);
 	case ARM_EXCEPTION_HYP_GONE:
 		/*
 		 * EL2 has been reset to the hyp-stub. This happens when a guest
diff --git a/arch/arm64/kvm/pkvm.c b/arch/arm64/kvm/pkvm.c
index ae434f806455..02ad686d7661 100644
--- a/arch/arm64/kvm/pkvm.c
+++ b/arch/arm64/kvm/pkvm.c
@@ -16,6 +16,9 @@
 
 #include "hyp_constants.h"
 
+#define CREATE_TRACE_POINTS
+#include "trace_pkvm.h"
+
 DEFINE_STATIC_KEY_FALSE(kvm_protected_mode_initialized);
 
 static struct memblock_region *hyp_memory = kvm_nvhe_sym(hyp_memory);
@@ -632,3 +635,20 @@ bool pkvm_force_reclaim_guest_page(phys_addr_t phys)
 
 	return !ret || ret == -EAGAIN;
 }
+
+static int pkvm_hyp_req_handle(struct pkvm_hyp_req *req, struct kvm_vcpu *vcpu)
+{
+	int ret = -EINVAL;
+
+	switch (req->type) {
+	}
+
+	trace_kvm_handle_pkvm_hyp_req(req, ret);
+
+	return ret;
+}
+
+int __pkvm_handle_vcpu_req(struct kvm_vcpu *vcpu)
+{
+	return pkvm_hyp_req_handle(&vcpu->arch.pkvm_hyp_req, vcpu) ?: 1;
+}
diff --git a/arch/arm64/kvm/trace_pkvm.h b/arch/arm64/kvm/trace_pkvm.h
new file mode 100644
index 000000000000..3966c111e3ad
--- /dev/null
+++ b/arch/arm64/kvm/trace_pkvm.h
@@ -0,0 +1,43 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#if !defined(_TRACE_PKVM_ARM64_KVM_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_PKVM_ARM64_KVM_H
+
+#include <linux/tracepoint.h>
+#include <asm/kvm_pkvm.h>
+
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM kvm
+
+TRACE_DEFINE_ENUM(PKVM_HYP_NO_REQ);
+
+#define PKVM_HYP_REQ_TYPES \
+	{ PKVM_HYP_NO_REQ, "NO_REQ" }
+
+TRACE_EVENT(kvm_handle_pkvm_hyp_req,
+	TP_PROTO(struct pkvm_hyp_req *req, int ret),
+	TP_ARGS(req, ret),
+
+	TP_STRUCT__entry(
+		__field(u8,	type)
+		__field(int,	ret)
+	),
+
+	TP_fast_assign(
+		__entry->type = req->type;
+		__entry->ret = ret;
+	),
+
+	TP_printk("type: %s ret: %d",
+		  __print_symbolic(__entry->type, PKVM_HYP_REQ_TYPES),
+		  __entry->ret)
+);
+
+#endif /* _TRACE_PKVM_ARM64_KVM_H */
+
+#undef TRACE_INCLUDE_PATH
+#define TRACE_INCLUDE_PATH .
+#undef TRACE_INCLUDE_FILE
+#define TRACE_INCLUDE_FILE trace_pkvm
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>
-- 
2.55.0.1007.g17ff1f9808-goog