[PATCH 02/13] RISC-V: KVM: Don't treat SBI HFENCE calls as NOPs

Anup Patel apatel at ventanamicro.com
Wed Jun 4 23:14:47 PDT 2025


The SBI specification clearly states that SBI HFENCE calls should
return SBI_ERR_NOT_SUPPORTED when one of the target hart doesn’t
support hypervisor extension (aka nested virtualization in-case
of KVM RISC-V).

Fixes: c7fa3c48de86 ("RISC-V: KVM: Treat SBI HFENCE calls as NOPs")
Signed-off-by: Anup Patel <apatel at ventanamicro.com>
---
 arch/riscv/kvm/vcpu_sbi_replace.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/kvm/vcpu_sbi_replace.c b/arch/riscv/kvm/vcpu_sbi_replace.c
index 9752d2ffff68..b17fad091bab 100644
--- a/arch/riscv/kvm/vcpu_sbi_replace.c
+++ b/arch/riscv/kvm/vcpu_sbi_replace.c
@@ -127,9 +127,9 @@ static int kvm_sbi_ext_rfence_handler(struct kvm_vcpu *vcpu, struct kvm_run *run
 	case SBI_EXT_RFENCE_REMOTE_HFENCE_VVMA_ASID:
 		/*
 		 * Until nested virtualization is implemented, the
-		 * SBI HFENCE calls should be treated as NOPs
+		 * SBI HFENCE calls should return not supported
+		 * hence fallthrough.
 		 */
-		break;
 	default:
 		retdata->err_val = SBI_ERR_NOT_SUPPORTED;
 	}
-- 
2.43.0




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