From: Andrew Jones <ajones@xxxxxxxxxxxxxxxx>
[ Upstream commit afd5dde9a186b8fc5742fff707f184760c4af1a9 ]
We're about to allow guests to use the Zicbom 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@xxxxxxxxxxxxxxxx>
Reviewed-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx>
Reviewed-by: Atish Patra <atishp@xxxxxxxxxxxx>
Signed-off-by: Anup Patel <anup@xxxxxxxxxxxxxx>
Stable-dep-of: 5c20a3a9df19 ("RISC-V: Fix compilation without RISCV_ISA_ZICBOM")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
arch/riscv/include/uapi/asm/kvm.h | 1 +
arch/riscv/kvm/vcpu.c | 8 ++++++++
arch/riscv/mm/dma-noncoherent.c | 2 ++
3 files changed, 11 insertions(+)
diff --git a/arch/riscv/include/uapi/asm/kvm.h b/arch/riscv/include/uapi/asm/kvm.h
index 7351417afd62..b9a4cf36be4b 100644
--- a/arch/riscv/include/uapi/asm/kvm.h
+++ b/arch/riscv/include/uapi/asm/kvm.h
@@ -48,6 +48,7 @@ struct kvm_sregs {
/* CONFIG registers for KVM_GET_ONE_REG and KVM_SET_ONE_REG */
struct kvm_riscv_config {
unsigned long isa;
+ unsigned long zicbom_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 d0f08d5b4282..2ef33d5d94d1 100644
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -18,6 +18,7 @@
#include <linux/fs.h>
#include <linux/kvm_host.h>
#include <asm/csr.h>
+#include <asm/cacheflush.h>
#include <asm/hwcap.h>
const struct _kvm_stats_desc kvm_vcpu_stats_desc[] = {
@@ -254,6 +255,11 @@ static int kvm_riscv_vcpu_get_reg_config(struct kvm_vcpu *vcpu,
case KVM_REG_RISCV_CONFIG_REG(isa):
reg_val = vcpu->arch.isa[0] & KVM_RISCV_BASE_ISA_MASK;
break;
+ case KVM_REG_RISCV_CONFIG_REG(zicbom_block_size):
+ if (!riscv_isa_extension_available(vcpu->arch.isa, ZICBOM))
+ return -EINVAL;
+ reg_val = riscv_cbom_block_size;
+ break;
default:
return -EINVAL;
}
@@ -311,6 +317,8 @@ static int kvm_riscv_vcpu_set_reg_config(struct kvm_vcpu *vcpu,
return -EOPNOTSUPP;
}
break;
+ case KVM_REG_RISCV_CONFIG_REG(zicbom_block_size):
+ return -EOPNOTSUPP;
default:
return -EINVAL;
}
diff --git a/arch/riscv/mm/dma-noncoherent.c b/arch/riscv/mm/dma-noncoherent.c
index e3f9bdf47c5f..b0add983530a 100644
--- a/arch/riscv/mm/dma-noncoherent.c
+++ b/arch/riscv/mm/dma-noncoherent.c
@@ -13,6 +13,8 @@
#include <asm/cacheflush.h>
unsigned int riscv_cbom_block_size;
+EXPORT_SYMBOL_GPL(riscv_cbom_block_size);
+
static bool noncoherent_supported;
void arch_sync_dma_for_device(phys_addr_t paddr, size_t size,
--
2.35.1
