linux-kernel - [PATCH v2 3/7] RISC-V: KVM: Treat SBI HFENCE calls as NOPs

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Date:   Wed, 20 Apr 2022 16:54:46 +0530
From:   Anup Patel <apatel@...tanamicro.com>
To:     Paolo Bonzini <pbonzini@...hat.com>,
        Atish Patra <atishp@...shpatra.org>
Cc:     Palmer Dabbelt <palmer@...belt.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Alistair Francis <Alistair.Francis@....com>,
        Anup Patel <anup@...infault.org>, kvm@...r.kernel.org,
        kvm-riscv@...ts.infradead.org, linux-riscv@...ts.infradead.org,
        linux-kernel@...r.kernel.org, Anup Patel <apatel@...tanamicro.com>
Subject: [PATCH v2 3/7] RISC-V: KVM: Treat SBI HFENCE calls as NOPs

We should treat SBI HFENCE calls as NOPs until nested virtualization
is supported by KVM RISC-V. This will help us test booting a hypervisor
under KVM RISC-V.

Signed-off-by: Anup Patel <apatel@...tanamicro.com>
---
 arch/riscv/kvm/vcpu_sbi_replace.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/riscv/kvm/vcpu_sbi_replace.c b/arch/riscv/kvm/vcpu_sbi_replace.c
index 0f217365c287..3c1dcd38358e 100644
--- a/arch/riscv/kvm/vcpu_sbi_replace.c
+++ b/arch/riscv/kvm/vcpu_sbi_replace.c
@@ -117,7 +117,11 @@ static int kvm_sbi_ext_rfence_handler(struct kvm_vcpu *vcpu, struct kvm_run *run
 	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 */
+		/*
+		 * Until nested virtualization is implemented, the
+		 * SBI HFENCE calls should be treated as NOPs
+		 */
+		break;
 	default:
 		ret = -EOPNOTSUPP;
 	}
-- 
2.25.1