[RFC,V2,1/4] RISC-V: paravirt: Add pvqspinlock KVM backend

Commit Message

Guo Ren Dec. 27, 2024, 1:10 a.m. UTC

From: Guo Ren <[e-mail]>

Add the files functions needed to support the SBI PVLOCK (paravirt
qspinlock kick_cpu) extension. Implement kvm_sbi_ext_pvlock_kick_-
cpu(), and we only need to call the kvm_vcpu_kick() and bring
target_vcpu from the halt state.

Reviewed-by: Leonardo Bras <[e-mail]>
Signed-off-by: Guo Ren <[e-mail]>
Signed-off-by: Guo Ren <[e-mail]>
---
 arch/riscv/include/asm/kvm_vcpu_sbi.h |  1 +
 arch/riscv/include/asm/sbi.h          |  5 +++
 arch/riscv/include/uapi/asm/kvm.h     |  1 +
 arch/riscv/kvm/Makefile               |  1 +
 arch/riscv/kvm/vcpu_sbi.c             |  4 ++
 arch/riscv/kvm/vcpu_sbi_pvlock.c      | 57 +++++++++++++++++++++++++++
 6 files changed, 69 insertions(+)
 create mode 100644 arch/riscv/kvm/vcpu_sbi_pvlock.c

Patch

diff --git a/arch/riscv/include/asm/kvm_vcpu_sbi.h b/arch/riscv/include/asm/kvm_vcpu_sbi.h
index b96705258cf9..bc37131938ad 100644
--- a/arch/riscv/include/asm/kvm_vcpu_sbi.h
+++ b/arch/riscv/include/asm/kvm_vcpu_sbi.h
@@ -88,6 +88,7 @@  extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_dbcn;
 extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_sta;
 extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_experimental;
 extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_vendor;
+extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_pvlock;
 
 #ifdef CONFIG_RISCV_PMU_SBI
 extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_pmu;
diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h
index 6c82318065cf..03e719f076ad 100644
--- a/arch/riscv/include/asm/sbi.h
+++ b/arch/riscv/include/asm/sbi.h
@@ -35,6 +35,7 @@  enum sbi_ext_id {
 	SBI_EXT_DBCN = 0x4442434E,
 	SBI_EXT_STA = 0x535441,
 	SBI_EXT_NACL = 0x4E41434C,
+	SBI_EXT_PVLOCK = 0x50564C4B,
 
 	/* Experimentals extensions must lie within this range */
 	SBI_EXT_EXPERIMENTAL_START = 0x08000000,
@@ -401,6 +402,10 @@  enum sbi_ext_nacl_feature {
 #define SBI_NACL_SHMEM_SRET_X(__i)		((__riscv_xlen / 8) * (__i))
 #define SBI_NACL_SHMEM_SRET_X_LAST		31
 
+enum sbi_ext_pvlock_fid {
+	SBI_EXT_PVLOCK_KICK_CPU = 0,
+};
+
 /* SBI spec version fields */
 #define SBI_SPEC_VERSION_DEFAULT	0x1
 #define SBI_SPEC_VERSION_MAJOR_SHIFT	24
diff --git a/arch/riscv/include/uapi/asm/kvm.h b/arch/riscv/include/uapi/asm/kvm.h
index 3482c9a73d1b..4590570a8fc3 100644
--- a/arch/riscv/include/uapi/asm/kvm.h
+++ b/arch/riscv/include/uapi/asm/kvm.h
@@ -198,6 +198,7 @@  enum KVM_RISCV_SBI_EXT_ID {
 	KVM_RISCV_SBI_EXT_VENDOR,
 	KVM_RISCV_SBI_EXT_DBCN,
 	KVM_RISCV_SBI_EXT_STA,
+	KVM_RISCV_SBI_EXT_PVLOCK,
 	KVM_RISCV_SBI_EXT_MAX,
 };
 
diff --git a/arch/riscv/kvm/Makefile b/arch/riscv/kvm/Makefile
index 0fb1840c3e0a..4e1a82a7eeab 100644
--- a/arch/riscv/kvm/Makefile
+++ b/arch/riscv/kvm/Makefile
@@ -32,6 +32,7 @@  kvm-y += vcpu_sbi_replace.o
 kvm-y += vcpu_sbi_sta.o
 kvm-$(CONFIG_RISCV_SBI_V01) += vcpu_sbi_v01.o
 kvm-y += vcpu_switch.o
+kvm-y += vcpu_sbi_pvlock.o
 kvm-y += vcpu_timer.o
 kvm-y += vcpu_vector.o
 kvm-y += vm.o
diff --git a/arch/riscv/kvm/vcpu_sbi.c b/arch/riscv/kvm/vcpu_sbi.c
index 6e704ed86a83..c770bef51a2f 100644
--- a/arch/riscv/kvm/vcpu_sbi.c
+++ b/arch/riscv/kvm/vcpu_sbi.c
@@ -82,6 +82,10 @@  static const struct kvm_riscv_sbi_extension_entry sbi_ext[] = {
 		.ext_idx = KVM_RISCV_SBI_EXT_VENDOR,
 		.ext_ptr = &vcpu_sbi_ext_vendor,
 	},
+	{
+		.ext_idx = KVM_RISCV_SBI_EXT_PVLOCK,
+		.ext_ptr = &vcpu_sbi_ext_pvlock,
+	},
 };
 
 static const struct kvm_riscv_sbi_extension_entry *
diff --git a/arch/riscv/kvm/vcpu_sbi_pvlock.c b/arch/riscv/kvm/vcpu_sbi_pvlock.c
new file mode 100644
index 000000000000..55d889ddc2cd
--- /dev/null
+++ b/arch/riscv/kvm/vcpu_sbi_pvlock.c
@@ -0,0 +1,57 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c), 2024 Alibaba Cloud
+ *
+ * Authors:
+ *     Guo Ren <[e-mail]>
+ */
+
+#include <linux/errno.h>
+#include <linux/err.h>
+#include <linux/kvm_host.h>
+#include <asm/sbi.h>
+#include <asm/kvm_vcpu_sbi.h>
+
+static int kvm_sbi_ext_pvlock_kick_cpu(struct kvm_vcpu *vcpu)
+{
+	struct kvm_cpu_context *cp = &vcpu->arch.guest_context;
+	struct kvm *kvm = vcpu->kvm;
+	struct kvm_vcpu *target;
+
+	target = kvm_get_vcpu_by_id(kvm, cp->a0);
+	if (!target)
+		return SBI_ERR_INVALID_PARAM;
+
+	kvm_vcpu_kick(target);
+
+	if (READ_ONCE(target->ready))
+		kvm_vcpu_yield_to(target);
+
+	return SBI_SUCCESS;
+}
+
+static int kvm_sbi_ext_pvlock_handler(struct kvm_vcpu *vcpu, struct kvm_run *run,
+				      struct kvm_vcpu_sbi_return *retdata)
+{
+	int ret = 0;
+	struct kvm_cpu_context *cp = &vcpu->arch.guest_context;
+	unsigned long funcid = cp->a6;
+
+	switch (funcid) {
+	case SBI_EXT_PVLOCK_KICK_CPU:
+		ret = kvm_sbi_ext_pvlock_kick_cpu(vcpu);
+		break;
+	default:
+		ret = SBI_ERR_NOT_SUPPORTED;
+	}
+
+	retdata->err_val = ret;
+
+	return 0;
+}
+
+const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_pvlock = {
+	.extid_start = SBI_EXT_PVLOCK,
+	.extid_end = SBI_EXT_PVLOCK,
+	.handler = kvm_sbi_ext_pvlock_handler,
+};