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From: Bibo Mao <maobibo@loongson.cn>
To: Huacai Chen <chenhuacai@kernel.org>,
	Tianrui Zhao <zhaotianrui@loongson.cn>,
	Juergen Gross <jgross@suse.com>
Cc: loongarch@lists.linux.dev,
	linux-kernel@vger.kernel.org,
	virtualization@lists.linux.dev,
	kvm@vger.kernel.org
Subject: [PATCH v2 1/6] LoongArch: KVM: Add hypercall instruction emulation support
Date: Mon,  8 Jan 2024 14:40:51 +0800
Message-Id: <20240108064056.232546-2-maobibo@loongson.cn>
In-Reply-To: <20240108064056.232546-1-maobibo@loongson.cn>
References: <20240108064056.232546-1-maobibo@loongson.cn>
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On LoongArch system, hypercall instruction is supported when system
runs on VM mode. This patch adds dummy function with hypercall
instruction emulation, rather than inject EXCCODE_INE invalid
instruction exception.

Signed-off-by: Bibo Mao <maobibo@loongson.cn>
---
 arch/loongarch/include/asm/Kbuild      |  1 -
 arch/loongarch/include/asm/kvm_para.h  | 26 ++++++++++++++++++++++++++
 arch/loongarch/include/uapi/asm/Kbuild |  2 --
 arch/loongarch/kvm/exit.c              | 10 ++++++++++
 4 files changed, 36 insertions(+), 3 deletions(-)
 create mode 100644 arch/loongarch/include/asm/kvm_para.h
 delete mode 100644 arch/loongarch/include/uapi/asm/Kbuild

diff --git a/arch/loongarch/include/asm/Kbuild b/arch/loongarch/include/asm/Kbuild
index 93783fa24f6e..22991a6f0e2b 100644
--- a/arch/loongarch/include/asm/Kbuild
+++ b/arch/loongarch/include/asm/Kbuild
@@ -23,4 +23,3 @@ generic-y += poll.h
 generic-y += param.h
 generic-y += posix_types.h
 generic-y += resource.h
-generic-y += kvm_para.h
diff --git a/arch/loongarch/include/asm/kvm_para.h b/arch/loongarch/include/asm/kvm_para.h
new file mode 100644
index 000000000000..9425d3b7e486
--- /dev/null
+++ b/arch/loongarch/include/asm/kvm_para.h
@@ -0,0 +1,26 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_LOONGARCH_KVM_PARA_H
+#define _ASM_LOONGARCH_KVM_PARA_H
+
+/*
+ * LoongArch hypcall return code
+ */
+#define KVM_HC_STATUS_SUCCESS		0
+#define KVM_HC_INVALID_CODE		-1UL
+#define KVM_HC_INVALID_PARAMETER	-2UL
+
+static inline unsigned int kvm_arch_para_features(void)
+{
+	return 0;
+}
+
+static inline unsigned int kvm_arch_para_hints(void)
+{
+	return 0;
+}
+
+static inline bool kvm_check_and_clear_guest_paused(void)
+{
+	return false;
+}
+#endif /* _ASM_LOONGARCH_KVM_PARA_H */
diff --git a/arch/loongarch/include/uapi/asm/Kbuild b/arch/loongarch/include/uapi/asm/Kbuild
deleted file mode 100644
index 4aa680ca2e5f..000000000000
--- a/arch/loongarch/include/uapi/asm/Kbuild
+++ /dev/null
@@ -1,2 +0,0 @@
-# SPDX-License-Identifier: GPL-2.0
-generic-y += kvm_para.h
diff --git a/arch/loongarch/kvm/exit.c b/arch/loongarch/kvm/exit.c
index e708a1786d6b..59e5fe221982 100644
--- a/arch/loongarch/kvm/exit.c
+++ b/arch/loongarch/kvm/exit.c
@@ -650,6 +650,15 @@ static int kvm_handle_fpu_disabled(struct kvm_vcpu *vcpu)
 	return RESUME_GUEST;
 }
 
+static int kvm_handle_hypcall(struct kvm_vcpu *vcpu)
+{
+	update_pc(&vcpu->arch);
+
+	/* Treat it as noop intruction, only set return value */
+	vcpu->arch.gprs[LOONGARCH_GPR_A0] = KVM_HC_INVALID_CODE;
+	return RESUME_GUEST;
+}
+
 /*
  * LoongArch KVM callback handling for unimplemented guest exiting
  */
@@ -679,6 +688,7 @@ static exit_handle_fn kvm_fault_tables[EXCCODE_INT_START] = {
 	[EXCCODE_TLBM]			= kvm_handle_write_fault,
 	[EXCCODE_FPDIS]			= kvm_handle_fpu_disabled,
 	[EXCCODE_GSPR]			= kvm_handle_gspr,
+	[EXCCODE_HVC]			= kvm_handle_hypcall,
 };
 
 int kvm_handle_fault(struct kvm_vcpu *vcpu, int fault)
-- 
2.39.3