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From:   Anup Patel <apatel@ventanamicro.com>
To:     Paolo Bonzini <pbonzini@redhat.com>,
        Atish Patra <atishp@atishpatra.org>
Cc:     Palmer Dabbelt <palmer@dabbelt.com>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Alistair Francis <Alistair.Francis@wdc.com>,
        Anup Patel <anup@brainfault.org>, kvm@vger.kernel.org,
        kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org,
        linux-kernel@vger.kernel.org, Anup Patel <apatel@ventanamicro.com>
Subject: [PATCH 6/6] RISC-V: KVM: Implement SBI HSM suspend call
Date:   Tue,  1 Feb 2022 13:52:27 +0530
Message-Id: <20220201082227.361967-7-apatel@ventanamicro.com>
In-Reply-To: <20220201082227.361967-1-apatel@ventanamicro.com>
References: <20220201082227.361967-1-apatel@ventanamicro.com>
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The SBI v0.3 specification extends SBI HSM extension by adding SBI HSM
suspend call and related HART states. This patch extends the KVM RISC-V
HSM implementation to provide KVM guest a minimal SBI HSM suspend call
which is equivalent to a WFI instruction.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
---
 arch/riscv/kvm/vcpu_sbi_hsm.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/arch/riscv/kvm/vcpu_sbi_hsm.c b/arch/riscv/kvm/vcpu_sbi_hsm.c
index 1ac4b2e8e4ec..239dec0a628a 100644
--- a/arch/riscv/kvm/vcpu_sbi_hsm.c
+++ b/arch/riscv/kvm/vcpu_sbi_hsm.c
@@ -61,6 +61,8 @@ static int kvm_sbi_hsm_vcpu_get_status(struct kvm_vcpu *vcpu)
 		return -EINVAL;
 	if (!target_vcpu->arch.power_off)
 		return SBI_HSM_STATE_STARTED;
+	else if (vcpu->stat.generic.blocking)
+		return SBI_HSM_STATE_SUSPENDED;
 	else
 		return SBI_HSM_STATE_STOPPED;
 }
@@ -91,6 +93,18 @@ static int kvm_sbi_ext_hsm_handler(struct kvm_vcpu *vcpu, struct kvm_run *run,
 			ret = 0;
 		}
 		break;
+	case SBI_EXT_HSM_HART_SUSPEND:
+		switch (cp->a0) {
+		case SBI_HSM_SUSPEND_RET_DEFAULT:
+			kvm_riscv_vcpu_wfi(vcpu);
+			break;
+		case SBI_HSM_SUSPEND_NON_RET_DEFAULT:
+			ret = -EOPNOTSUPP;
+			break;
+		default:
+			ret = -EINVAL;
+		}
+		break;
 	default:
 		ret = -EOPNOTSUPP;
 	}
-- 
2.25.1