RISC-V: KVM: Add SBI STA extension skeleton

Add the files and functions needed to support the SBI STA
(steal-time accounting) extension. In the next patches we'll
complete the functions to fully enable SBI STA support.

Reviewed-by: Anup Patel <anup@brainfault.org>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Anup Patel <anup@brainfault.org>

3 files changed, 52 insertions, 0 deletions

diff --git a/arch/riscv/kvm/Makefile b/arch/riscv/kvm/Makefile
index 4c2067fc59fc..c9646521f113 100644
--- a/arch/riscv/kvm/Makefile
+++ b/arch/riscv/kvm/Makefile
@@ -26,6 +26,7 @@ kvm-$(CONFIG_RISCV_SBI_V01) += vcpu_sbi_v01.o
 kvm-y += vcpu_sbi_base.o
 kvm-y += vcpu_sbi_replace.o
 kvm-y += vcpu_sbi_hsm.o
+kvm-y += vcpu_sbi_sta.o
 kvm-y += vcpu_timer.o
 kvm-$(CONFIG_RISCV_PMU_SBI) += vcpu_pmu.o vcpu_sbi_pmu.o
 kvm-y += aia.o
diff --git a/arch/riscv/kvm/vcpu_sbi.c b/arch/riscv/kvm/vcpu_sbi.c
index dcdff4458190..088daaa23dd8 100644
--- a/arch/riscv/kvm/vcpu_sbi.c
+++ b/arch/riscv/kvm/vcpu_sbi.c
@@ -71,6 +71,10 @@ static const struct kvm_riscv_sbi_extension_entry sbi_ext[] = {
 		.ext_ptr = &vcpu_sbi_ext_dbcn,
 	},
 	{
+		.ext_idx = KVM_RISCV_SBI_EXT_STA,
+		.ext_ptr = &vcpu_sbi_ext_sta,
+	},
+	{
 		.ext_idx = KVM_RISCV_SBI_EXT_EXPERIMENTAL,
 		.ext_ptr = &vcpu_sbi_ext_experimental,
 	},
diff --git a/arch/riscv/kvm/vcpu_sbi_sta.c b/arch/riscv/kvm/vcpu_sbi_sta.c
new file mode 100644
index 000000000000..839911dcd837
--- /dev/null
+++ b/arch/riscv/kvm/vcpu_sbi_sta.c
@@ -0,0 +1,47 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2023 Ventana Micro Systems Inc.
+ */
+
+#include <linux/kvm_host.h>
+
+#include <asm/kvm_vcpu_sbi.h>
+#include <asm/sbi.h>
+
+static int kvm_sbi_sta_steal_time_set_shmem(struct kvm_vcpu *vcpu)
+{
+	return SBI_ERR_FAILURE;
+}
+
+static int kvm_sbi_ext_sta_handler(struct kvm_vcpu *vcpu, struct kvm_run *run,
+				   struct kvm_vcpu_sbi_return *retdata)
+{
+	struct kvm_cpu_context *cp = &vcpu->arch.guest_context;
+	unsigned long funcid = cp->a6;
+	int ret;
+
+	switch (funcid) {
+	case SBI_EXT_STA_STEAL_TIME_SET_SHMEM:
+		ret = kvm_sbi_sta_steal_time_set_shmem(vcpu);
+		break;
+	default:
+		ret = SBI_ERR_NOT_SUPPORTED;
+		break;
+	}
+
+	retdata->err_val = ret;
+
+	return 0;
+}
+
+static unsigned long kvm_sbi_ext_sta_probe(struct kvm_vcpu *vcpu)
+{
+	return 0;
+}
+
+const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_sta = {
+	.extid_start = SBI_EXT_STA,
+	.extid_end = SBI_EXT_STA,
+	.handler = kvm_sbi_ext_sta_handler,
+	.probe = kvm_sbi_ext_sta_probe,
+};