RISC-V: KVM: Add v0.1 replacement SBI extensions defined in v0.2

The SBI v0.2 contains some of the improved versions of required v0.1
extensions such as remote fence, timer and IPI.

This patch implements those extensions.

Signed-off-by: Atish Patra <atish.patra@wdc.com>
Signed-off-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Anup Patel <anup.patel@wdc.com>

arch/riscv/kvm/Makefile

@@ -21,4 +21,5 @@ kvm-y += vcpu_switch.o
 kvm-y += vcpu_sbi.o
 kvm-$(CONFIG_RISCV_SBI_V01) += vcpu_sbi_v01.o
 kvm-y += vcpu_sbi_base.o
+kvm-y += vcpu_sbi_replace.o
 kvm-y += vcpu_timer.o

arch/riscv/kvm/vcpu_sbi.c

@@ -40,9 +40,16 @@ static const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_v01 = {
 };
 #endif
 extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_base;
+extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_time;
+extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_ipi;
+extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_rfence;
+
 static const struct kvm_vcpu_sbi_extension *sbi_ext[] = {
 	&vcpu_sbi_ext_v01,
 	&vcpu_sbi_ext_base,
+	&vcpu_sbi_ext_time,
+	&vcpu_sbi_ext_ipi,
+	&vcpu_sbi_ext_rfence,
 };
 
 void kvm_riscv_vcpu_sbi_forward(struct kvm_vcpu *vcpu, struct kvm_run *run)

arch/riscv/kvm/vcpu_sbi_replace.c

@@ -0,0 +1,135 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2021 Western Digital Corporation or its affiliates.
+ *
+ * Authors:
+ *     Atish Patra <atish.patra@wdc.com>
+ */
+
+#include <linux/errno.h>
+#include <linux/err.h>
+#include <linux/kvm_host.h>
+#include <asm/csr.h>
+#include <asm/sbi.h>
+#include <asm/kvm_vcpu_timer.h>
+#include <asm/kvm_vcpu_sbi.h>
+
+static int kvm_sbi_ext_time_handler(struct kvm_vcpu *vcpu, struct kvm_run *run,
+				    unsigned long *out_val,
+				    struct kvm_cpu_trap *utrap, bool *exit)
+{
+	int ret = 0;
+	struct kvm_cpu_context *cp = &vcpu->arch.guest_context;
+	u64 next_cycle;
+
+	if (cp->a6 != SBI_EXT_TIME_SET_TIMER)
+		return -EINVAL;
+
+#if __riscv_xlen == 32
+	next_cycle = ((u64)cp->a1 << 32) | (u64)cp->a0;
+#else
+	next_cycle = (u64)cp->a0;
+#endif
+	kvm_riscv_vcpu_timer_next_event(vcpu, next_cycle);
+
+	return ret;
+}
+
+const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_time = {
+	.extid_start = SBI_EXT_TIME,
+	.extid_end = SBI_EXT_TIME,
+	.handler = kvm_sbi_ext_time_handler,
+};
+
+static int kvm_sbi_ext_ipi_handler(struct kvm_vcpu *vcpu, struct kvm_run *run,
+				   unsigned long *out_val,
+				   struct kvm_cpu_trap *utrap, bool *exit)
+{
+	int ret = 0;
+	unsigned long i;
+	struct kvm_vcpu *tmp;
+	struct kvm_cpu_context *cp = &vcpu->arch.guest_context;
+	unsigned long hmask = cp->a0;
+	unsigned long hbase = cp->a1;
+
+	if (cp->a6 != SBI_EXT_IPI_SEND_IPI)
+		return -EINVAL;
+
+	kvm_for_each_vcpu(i, tmp, vcpu->kvm) {
+		if (hbase != -1UL) {
+			if (tmp->vcpu_id < hbase)
+				continue;
+			if (!(hmask & (1UL << (tmp->vcpu_id - hbase))))
+				continue;
+		}
+		ret = kvm_riscv_vcpu_set_interrupt(tmp, IRQ_VS_SOFT);
+		if (ret < 0)
+			break;
+	}
+
+	return ret;
+}
+
+const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_ipi = {
+	.extid_start = SBI_EXT_IPI,
+	.extid_end = SBI_EXT_IPI,
+	.handler = kvm_sbi_ext_ipi_handler,
+};
+
+static int kvm_sbi_ext_rfence_handler(struct kvm_vcpu *vcpu, struct kvm_run *run,
+				      unsigned long *out_val,
+				      struct kvm_cpu_trap *utrap, bool *exit)
+{
+	int ret = 0;
+	unsigned long i;
+	struct cpumask cm, hm;
+	struct kvm_vcpu *tmp;
+	struct kvm_cpu_context *cp = &vcpu->arch.guest_context;
+	unsigned long hmask = cp->a0;
+	unsigned long hbase = cp->a1;
+	unsigned long funcid = cp->a6;
+
+	cpumask_clear(&cm);
+	cpumask_clear(&hm);
+	kvm_for_each_vcpu(i, tmp, vcpu->kvm) {
+		if (hbase != -1UL) {
+			if (tmp->vcpu_id < hbase)
+				continue;
+			if (!(hmask & (1UL << (tmp->vcpu_id - hbase))))
+				continue;
+		}
+		if (tmp->cpu < 0)
+			continue;
+		cpumask_set_cpu(tmp->cpu, &cm);
+	}
+
+	riscv_cpuid_to_hartid_mask(&cm, &hm);
+
+	switch (funcid) {
+	case SBI_EXT_RFENCE_REMOTE_FENCE_I:
+		ret = sbi_remote_fence_i(cpumask_bits(&hm));
+		break;
+	case SBI_EXT_RFENCE_REMOTE_SFENCE_VMA:
+		ret = sbi_remote_hfence_vvma(cpumask_bits(&hm), cp->a2, cp->a3);
+		break;
+	case SBI_EXT_RFENCE_REMOTE_SFENCE_VMA_ASID:
+		ret = sbi_remote_hfence_vvma_asid(cpumask_bits(&hm), cp->a2,
+						  cp->a3, cp->a4);
+		break;
+	case SBI_EXT_RFENCE_REMOTE_HFENCE_GVMA:
+	case SBI_EXT_RFENCE_REMOTE_HFENCE_GVMA_VMID:
+	case SBI_EXT_RFENCE_REMOTE_HFENCE_VVMA:
+	case SBI_EXT_RFENCE_REMOTE_HFENCE_VVMA_ASID:
+	/* TODO: implement for nested hypervisor case */
+	default:
+		ret = -EOPNOTSUPP;
+	}
+
+	return ret;
+}
+
+const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_rfence = {
+	.extid_start = SBI_EXT_RFENCE,
+	.extid_end = SBI_EXT_RFENCE,
+	.handler = kvm_sbi_ext_rfence_handler,
+};