[PATCH v6 18/21] RISC-V: KVM: Add SBI v0.1 support

[Anup Patel]

From: Atish Patra <atish.patra@xxxxxxx>

The KVM host kernel running in HS-mode needs to handle SBI calls coming
from guest kernel running in VS-mode.

This patch adds SBI v0.1 support in KVM RISC-V. All the SBI calls are
implemented correctly except remote tlb flushes. For remote TLB flushes,
we are doing full TLB flush and this will be optimized in future.

Signed-off-by: Atish Patra <atish.patra@xxxxxxx>
Signed-off-by: Anup Patel <anup.patel@xxxxxxx>
Acked-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Reviewed-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
---
 arch/riscv/include/asm/kvm_host.h |   2 +
 arch/riscv/kvm/Makefile           |   2 +-
 arch/riscv/kvm/vcpu_exit.c        |   3 +
 arch/riscv/kvm/vcpu_sbi.c         | 104 ++++++++++++++++++++++++++++++
 4 files changed, 110 insertions(+), 1 deletion(-)
 create mode 100644 arch/riscv/kvm/vcpu_sbi.c

diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h
index 30be3cef76b6..70b2e45a837b 100644
--- a/arch/riscv/include/asm/kvm_host.h
+++ b/arch/riscv/include/asm/kvm_host.h
@@ -250,4 +250,6 @@ bool kvm_riscv_vcpu_has_interrupt(struct kvm_vcpu *vcpu);
 void kvm_riscv_vcpu_power_off(struct kvm_vcpu *vcpu);
 void kvm_riscv_vcpu_power_on(struct kvm_vcpu *vcpu);
 
+int kvm_riscv_vcpu_sbi_ecall(struct kvm_vcpu *vcpu);
+
 #endif /* __RISCV_KVM_HOST_H__ */
diff --git a/arch/riscv/kvm/Makefile b/arch/riscv/kvm/Makefile
index 3e0c7558320d..b56dc1650d2c 100644
--- a/arch/riscv/kvm/Makefile
+++ b/arch/riscv/kvm/Makefile
@@ -9,6 +9,6 @@ ccflags-y := -Ivirt/kvm -Iarch/riscv/kvm
 kvm-objs := $(common-objs-y)
 
 kvm-objs += main.o vm.o vmid.o tlb.o mmu.o
-kvm-objs += vcpu.o vcpu_exit.o vcpu_switch.o vcpu_timer.o
+kvm-objs += vcpu.o vcpu_exit.o vcpu_switch.o vcpu_timer.o vcpu_sbi.o
 
 obj-$(CONFIG_KVM)	+= kvm.o
diff --git a/arch/riscv/kvm/vcpu_exit.c b/arch/riscv/kvm/vcpu_exit.c
index 321062fff65b..9079793ddfff 100644
--- a/arch/riscv/kvm/vcpu_exit.c
+++ b/arch/riscv/kvm/vcpu_exit.c
@@ -585,6 +585,9 @@ int kvm_riscv_vcpu_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
 		    (vcpu->arch.guest_context.hstatus & HSTATUS_STL))
 			ret = stage2_page_fault(vcpu, run, scause, stval);
 		break;
+	case EXC_SUPERVISOR_SYSCALL:
+		if (vcpu->arch.guest_context.hstatus & HSTATUS_SPV)
+			ret = kvm_riscv_vcpu_sbi_ecall(vcpu);
 	default:
 		break;
 	};
diff --git a/arch/riscv/kvm/vcpu_sbi.c b/arch/riscv/kvm/vcpu_sbi.c
new file mode 100644
index 000000000000..6190b5c68e2a
--- /dev/null
+++ b/arch/riscv/kvm/vcpu_sbi.c
@@ -0,0 +1,104 @@
+// SPDX-License-Identifier: GPL-2.0
+/**
+ * Copyright (c) 2019 Western Digital Corporation or its affiliates.
+ *
+ * Authors:
+ *     Atish Patra <atish.patra@xxxxxxx>
+ */
+
+#include <linux/errno.h>
+#include <linux/err.h>
+#include <linux/kvm_host.h>
+#include <asm/csr.h>
+#include <asm/kvm_vcpu_timer.h>
+
+#define SBI_VERSION_MAJOR			0
+#define SBI_VERSION_MINOR			1
+
+static void kvm_sbi_system_shutdown(struct kvm_vcpu *vcpu, u32 type)
+{
+	int i;
+	struct kvm_vcpu *tmp;
+
+	kvm_for_each_vcpu(i, tmp, vcpu->kvm)
+		tmp->arch.power_off = true;
+	kvm_make_all_cpus_request(vcpu->kvm, KVM_REQ_SLEEP);
+
+	memset(&vcpu->run->system_event, 0, sizeof(vcpu->run->system_event));
+	vcpu->run->system_event.type = type;
+	vcpu->run->exit_reason = KVM_EXIT_SYSTEM_EVENT;
+}
+
+int kvm_riscv_vcpu_sbi_ecall(struct kvm_vcpu *vcpu)
+{
+	int i, ret = 1;
+	u64 next_cycle;
+	struct kvm_vcpu *rvcpu;
+	bool next_sepc = true;
+	ulong hmask, ut_scause = 0, ut_stval = 0;
+	struct kvm_cpu_context *cp = &vcpu->arch.guest_context;
+
+	if (!cp)
+		return -EINVAL;
+
+	switch (cp->a7) {
+	case SBI_SET_TIMER:
+#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);
+		break;
+	case SBI_CLEAR_IPI:
+		kvm_riscv_vcpu_unset_interrupt(vcpu, IRQ_S_SOFT);
+		break;
+	case SBI_SEND_IPI:
+		hmask = kvm_riscv_vcpu_unpriv_read(vcpu, false, cp->a0,
+						   &ut_scause, &ut_stval);
+		if (ut_scause) {
+			kvm_riscv_vcpu_trap_redirect(vcpu, ut_scause,
+						     ut_stval);
+			next_sepc = false;
+		} else {
+			for_each_set_bit(i, &hmask, BITS_PER_LONG) {
+				rvcpu = kvm_get_vcpu_by_id(vcpu->kvm, i);
+				kvm_riscv_vcpu_set_interrupt(rvcpu, IRQ_S_SOFT);
+			}
+		}
+		break;
+	case SBI_SHUTDOWN:
+		kvm_sbi_system_shutdown(vcpu, KVM_SYSTEM_EVENT_SHUTDOWN);
+		ret = 0;
+		break;
+	case SBI_REMOTE_FENCE_I:
+		sbi_remote_fence_i(NULL);
+		break;
+	/*
+	 * TODO: There should be a way to call remote hfence.bvma.
+	 * Preferred method is now a SBI call. Until then, just flush
+	 * all tlbs.
+	 */
+	case SBI_REMOTE_SFENCE_VMA:
+		/* TODO: Parse vma range. */
+		sbi_remote_sfence_vma(NULL, 0, 0);
+		break;
+	case SBI_REMOTE_SFENCE_VMA_ASID:
+		/* TODO: Parse vma range for given ASID */
+		sbi_remote_sfence_vma(NULL, 0, 0);
+		break;
+	default:
+		/*
+		 * For now, just return error to Guest.
+		 * TODO: In-future, we will route unsupported SBI calls
+		 * to user-space.
+		 */
+		cp->a0 = -ENOTSUPP;
+		break;
+	};
+
+	if (ret >= 0)
+		cp->sepc += 4;
+
+	return ret;
+}
-- 
2.17.1