Kernel KVM virtualization development
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From: Anup Patel <apatel@ventanamicro.com>
To: Atish Patra <atish.patra@linux.dev>
Cc: Palmer Dabbelt <palmer@dabbelt.com>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Alexandre Ghiti <alex@ghiti.fr>,
	Andrew Jones <ajones@ventanamicro.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 02/13] RISC-V: KVM: Don't treat SBI HFENCE calls as NOPs
Date: Thu,  5 Jun 2025 11:44:47 +0530	[thread overview]
Message-ID: <20250605061458.196003-3-apatel@ventanamicro.com> (raw)
In-Reply-To: <20250605061458.196003-1-apatel@ventanamicro.com>

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@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


  parent reply	other threads:[~2025-06-05  6:15 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-06-05  6:14 [PATCH 00/13] MMU related improvements for KVM RISC-V Anup Patel
2025-06-05  6:14 ` [PATCH 01/13] RISC-V: KVM: Fix the size parameter check in SBI SFENCE calls Anup Patel
2025-06-06  0:00   ` Atish Patra
2025-06-09  4:43   ` Anup Patel
2025-06-05  6:14 ` Anup Patel [this message]
2025-06-06  0:11   ` [PATCH 02/13] RISC-V: KVM: Don't treat SBI HFENCE calls as NOPs Atish Patra
2025-06-09  4:43   ` Anup Patel
2025-06-05  6:14 ` [PATCH 03/13] RISC-V: KVM: Check kvm_riscv_vcpu_alloc_vector_context() return value Anup Patel
2025-06-06  0:16   ` Atish Patra
2025-06-09  5:01     ` Anup Patel
2025-06-05  6:14 ` [PATCH 04/13] RISC-V: KVM: Drop the return value of kvm_riscv_vcpu_aia_init() Anup Patel
2025-06-06  0:52   ` Atish Patra
2025-06-06  4:14   ` Nutty Liu
2025-06-05  6:14 ` [PATCH 05/13] RISC-V: KVM: Rename and move kvm_riscv_local_tlb_sanitize() Anup Patel
2025-06-06  1:21   ` Atish Patra
2025-06-06  4:25   ` Nutty Liu
2025-06-05  6:14 ` [PATCH 06/13] RISC-V: KVM: Replace KVM_REQ_HFENCE_GVMA_VMID_ALL with KVM_REQ_TLB_FLUSH Anup Patel
2025-06-06  1:24   ` Atish Patra
2025-06-05  6:14 ` [PATCH 07/13] RISC-V: KVM: Don't flush TLB in gstage_set_pte() when PTE is unchanged Anup Patel
2025-06-05  6:14 ` [PATCH 08/13] RISC-V: KVM: Implement kvm_arch_flush_remote_tlbs_range() Anup Patel
2025-06-05  6:14 ` [PATCH 09/13] RISC-V: KVM: Factor-out MMU related declarations into separate headers Anup Patel
2025-06-05  6:14 ` [PATCH 10/13] RISC-V: KVM: Introduce struct kvm_gstage_mapping Anup Patel
2025-06-05  6:14 ` [PATCH 11/13] RISC-V: KVM: Add vmid field to struct kvm_riscv_hfence Anup Patel
2025-06-05  6:14 ` [PATCH 12/13] RISC-V: KVM: Factor-out g-stage page table management Anup Patel
2025-06-05  6:14 ` [PATCH 13/13] RISC-V: KVM: Pass VMID as parameter to kvm_riscv_hfence_xyz() APIs Anup Patel

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