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

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We're about to allow guests to use the Zicbop 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: Quan Zhou <zhouquan@iscas.ac.cn>
Reviewed-by: Nutty Liu <nutty.liu@hotmail.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Link: https://lore.kernel.org/r/befd8403cd76d7adb97231ac993eaeb86bf2582c.1754646071.git.zhouquan@iscas.ac.cn
Signed-off-by: Anup Patel <anup@brainfault.org>
This commit is contained in:
Quan Zhou
2025-08-08 18:18:34 +08:00
committed by Anup Patel
parent eca26eadd2
commit 48e2febcda
2 changed files with 15 additions and 0 deletions
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arch/riscv/include/uapi/asm/kvm.h
+1
View File
@@ -56,6 +56,7 @@ struct kvm_riscv_config {
unsigned long mimpid;
unsigned long zicboz_block_size;
unsigned long satp_mode;
unsigned long zicbop_block_size;
};
/* CORE registers for KVM_GET_ONE_REG and KVM_SET_ONE_REG */
arch/riscv/kvm/vcpu_onereg.c
+14
View File
@@ -285,6 +285,11 @@ static int kvm_riscv_vcpu_get_reg_config(struct kvm_vcpu *vcpu,
return -ENOENT;
reg_val = riscv_cboz_block_size;
break;
case KVM_REG_RISCV_CONFIG_REG(zicbop_block_size):
if (!riscv_isa_extension_available(NULL, ZICBOP))
return -ENOENT;
reg_val = riscv_cbop_block_size;
break;
case KVM_REG_RISCV_CONFIG_REG(mvendorid):
reg_val = vcpu->arch.mvendorid;
break;
@@ -376,6 +381,12 @@ static int kvm_riscv_vcpu_set_reg_config(struct kvm_vcpu *vcpu,
if (reg_val != riscv_cboz_block_size)
return -EINVAL;
break;
case KVM_REG_RISCV_CONFIG_REG(zicbop_block_size):
if (!riscv_isa_extension_available(NULL, ZICBOP))
return -ENOENT;
if (reg_val != riscv_cbop_block_size)
return -EINVAL;
break;
case KVM_REG_RISCV_CONFIG_REG(mvendorid):
if (reg_val == vcpu->arch.mvendorid)
break;
@@ -821,6 +832,9 @@ static int copy_config_reg_indices(const struct kvm_vcpu *vcpu,
else if (i == KVM_REG_RISCV_CONFIG_REG(zicboz_block_size) &&
!riscv_isa_extension_available(NULL, ZICBOZ))
continue;
else if (i == KVM_REG_RISCV_CONFIG_REG(zicbop_block_size) &&
!riscv_isa_extension_available(NULL, ZICBOP))
continue;
size = IS_ENABLED(CONFIG_32BIT) ? KVM_REG_SIZE_U32 : KVM_REG_SIZE_U64;
reg = KVM_REG_RISCV | size | KVM_REG_RISCV_CONFIG | i;