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RISC-V: KVM: Provide UAPI for Zicboz block size

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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>
Link: https://lore.kernel.org/r/20230224162631.405473-8-ajones@ventanamicro.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
This commit is contained in:
Andrew Jones 2023-02-24 17:26:30 +01:00 committed by Palmer Dabbelt
parent ab0f77465e
commit 665fd88624
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GPG key ID: 2E1319F35FBB1889
2 changed files with 8 additions and 0 deletions
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1
arch/riscv/include/uapi/asm/kvm.h
View file

@ -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 */

7
arch/riscv/kvm/vcpu.c
View file

@ -283,6 +283,11 @@ 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;
@ -354,6 +359,8 @@ 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;