[PATCH v4 7/8] RISC-V: KVM: Provide UAPI for Zicboz block size

Andrew Jones
2023-02-09T15:26:51Z

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@ventanamicro.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
---
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 92af6f3f057c..c1a1bb0fa91c 100644
--- a/arch/riscv/include/uapi/asm/kvm.h
+++ b/arch/riscv/include/uapi/asm/kvm.h
@@ -52,6 +52,7 @@ struct kvm_riscv_config {
unsigned long mvendorid;
unsigned long marchid;
unsigned long mimpid;
+ 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 7c08567097f0..e5126cefbc87 100644
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -276,6 +276,11 @@ 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;
case KVM_REG_RISCV_CONFIG_REG(mvendorid):
reg_val = vcpu->arch.mvendorid;
break;
@@ -347,6 +352,8 @@ 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;
case KVM_REG_RISCV_CONFIG_REG(mvendorid):
if (!vcpu->arch.ran_atleast_once)
vcpu->arch.mvendorid = reg_val;
--
2.39.1