[PATCH 5/9] RISC-V: KVM: Provide UAPI for Zicboz block size

Andrew Jones ajones at ventanamicro.com
Thu Oct 27 06:02:43 PDT 2022


We're about to allow guests to use the Zicboz extension. KVM
userspace needs to know the cache block size in order to
properly advertise it to the guest. Provide a virtual config
register for userspace to get it with the GET_ONE_REG API, but
setting it cannot be supported, so disallow SET_ONE_REG.

Signed-off-by: Andrew Jones <ajones at ventanamicro.com>
---
 arch/riscv/include/uapi/asm/kvm.h | 1 +
 arch/riscv/kvm/vcpu.c             | 7 +++++++
 2 files changed, 8 insertions(+)

diff --git a/arch/riscv/include/uapi/asm/kvm.h b/arch/riscv/include/uapi/asm/kvm.h
index 8985ff234c01..4bbf55cb2b70 100644
--- a/arch/riscv/include/uapi/asm/kvm.h
+++ b/arch/riscv/include/uapi/asm/kvm.h
@@ -49,6 +49,7 @@ struct kvm_sregs {
 struct kvm_riscv_config {
 	unsigned long isa;
 	unsigned long zicbom_block_size;
+	unsigned long zicboz_block_size;
 };
 
 /* CORE registers for KVM_GET_ONE_REG and KVM_SET_ONE_REG */
diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
index 71ebbc4821f0..18a739070b51 100644
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -270,6 +270,11 @@ static int kvm_riscv_vcpu_get_reg_config(struct kvm_vcpu *vcpu,
 			return -EINVAL;
 		reg_val = riscv_cbom_block_size;
 		break;
+	case KVM_REG_RISCV_CONFIG_REG(zicboz_block_size):
+		if (!riscv_isa_extension_available(vcpu->arch.isa, ZICBOZ))
+			return -EINVAL;
+		reg_val = riscv_cboz_block_size;
+		break;
 	default:
 		return -EINVAL;
 	}
@@ -329,6 +334,8 @@ static int kvm_riscv_vcpu_set_reg_config(struct kvm_vcpu *vcpu,
 		break;
 	case KVM_REG_RISCV_CONFIG_REG(zicbom_block_size):
 		return -EOPNOTSUPP;
+	case KVM_REG_RISCV_CONFIG_REG(zicboz_block_size):
+		return -EOPNOTSUPP;
 	default:
 		return -EINVAL;
 	}
-- 
2.37.3




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