[PATCH v3 5/8] RISC-V: KVM: Implement subtype for CSR ONE_REG interface

Anup Patel
2023-04-03T09:34:39Z

To make the CSR ONE_REG interface extensible, we implement subtype
for the CSR ONE_REG IDs. The existing CSR ONE_REG IDs are treated
as subtype = 0 (aka General CSRs).

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
---
arch/riscv/include/uapi/asm/kvm.h | 3 +-
arch/riscv/kvm/vcpu.c | 88 +++++++++++++++++++++++--------
2 files changed, 69 insertions(+), 22 deletions(-)

diff --git a/arch/riscv/include/uapi/asm/kvm.h b/arch/riscv/include/uapi/asm/kvm.h
index 47a7c3958229..182023dc9a51 100644
--- a/arch/riscv/include/uapi/asm/kvm.h
+++ b/arch/riscv/include/uapi/asm/kvm.h
@@ -65,7 +65,7 @@ struct kvm_riscv_core {
#define KVM_RISCV_MODE_S 1
#define KVM_RISCV_MODE_U 0

-/* CSR registers for KVM_GET_ONE_REG and KVM_SET_ONE_REG */
+/* General CSR registers for KVM_GET_ONE_REG and KVM_SET_ONE_REG */
struct kvm_riscv_csr {
unsigned long sstatus;
unsigned long sie;
@@ -152,6 +152,7 @@ enum KVM_RISCV_SBI_EXT_ID {

/* Control and status registers are mapped as type 3 */
#define KVM_REG_RISCV_CSR (0x03 << KVM_REG_RISCV_TYPE_SHIFT)
+#define KVM_REG_RISCV_CSR_GENERAL (0x0 << KVM_REG_RISCV_SUBTYPE_SHIFT)
#define KVM_REG_RISCV_CSR_REG(name) \
(offsetof(struct kvm_riscv_csr, name) / sizeof(unsigned long))

diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
index 1fd54ec15622..aca6b4fb7519 100644
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -460,27 +460,72 @@ static int kvm_riscv_vcpu_set_reg_core(struct kvm_vcpu *vcpu,
return 0;
}

+static int kvm_riscv_vcpu_general_get_csr(struct kvm_vcpu *vcpu,
+ unsigned long reg_num,
+ unsigned long *out_val)
+{
+ struct kvm_vcpu_csr *csr = &vcpu->arch.guest_csr;
+
+ if (reg_num >= sizeof(struct kvm_riscv_csr) / sizeof(unsigned long))
+ return -EINVAL;
+
+ if (reg_num == KVM_REG_RISCV_CSR_REG(sip)) {
+ kvm_riscv_vcpu_flush_interrupts(vcpu);
+ *out_val = (csr->hvip >> VSIP_TO_HVIP_SHIFT) & VSIP_VALID_MASK;
+ } else
+ *out_val = ((unsigned long *)csr)[reg_num];
+
+ return 0;
+}
+
+static inline int kvm_riscv_vcpu_general_set_csr(struct kvm_vcpu *vcpu,
+ unsigned long reg_num,
+ unsigned long reg_val)
+{
+ struct kvm_vcpu_csr *csr = &vcpu->arch.guest_csr;
+
+ if (reg_num >= sizeof(struct kvm_riscv_csr) / sizeof(unsigned long))
+ return -EINVAL;
+
+ if (reg_num == KVM_REG_RISCV_CSR_REG(sip)) {
+ reg_val &= VSIP_VALID_MASK;
+ reg_val <<= VSIP_TO_HVIP_SHIFT;
+ }
+
+ ((unsigned long *)csr)[reg_num] = reg_val;
+
+ if (reg_num == KVM_REG_RISCV_CSR_REG(sip))
+ WRITE_ONCE(vcpu->arch.irqs_pending_mask, 0);
+
+ return 0;
+}
+
static int kvm_riscv_vcpu_get_reg_csr(struct kvm_vcpu *vcpu,
const struct kvm_one_reg *reg)
{
- struct kvm_vcpu_csr *csr = &vcpu->arch.guest_csr;
+ int rc;
unsigned long __user *uaddr =
(unsigned long __user *)(unsigned long)reg->addr;
unsigned long reg_num = reg->id & ~(KVM_REG_ARCH_MASK |
KVM_REG_SIZE_MASK |
KVM_REG_RISCV_CSR);
- unsigned long reg_val;
+ unsigned long reg_val, reg_subtype;

if (KVM_REG_SIZE(reg->id) != sizeof(unsigned long))
return -EINVAL;
- if (reg_num >= sizeof(struct kvm_riscv_csr) / sizeof(unsigned long))
- return -EINVAL;

- if (reg_num == KVM_REG_RISCV_CSR_REG(sip)) {
- kvm_riscv_vcpu_flush_interrupts(vcpu);
- reg_val = (csr->hvip >> VSIP_TO_HVIP_SHIFT) & VSIP_VALID_MASK;
- } else
- reg_val = ((unsigned long *)csr)[reg_num];
+ reg_subtype = reg_num & KVM_REG_RISCV_SUBTYPE_MASK;
+ reg_num &= ~KVM_REG_RISCV_SUBTYPE_MASK;
+ switch (reg_subtype) {
+ case KVM_REG_RISCV_CSR_GENERAL:
+ rc = kvm_riscv_vcpu_general_get_csr(vcpu, reg_num, &reg_val);
+ break;
+ default:
+ rc = -EINVAL;
+ break;
+ }
+ if (rc)
+ return rc;

if (copy_to_user(uaddr, &reg_val, KVM_REG_SIZE(reg->id)))
return -EFAULT;
@@ -491,31 +536,32 @@ static int kvm_riscv_vcpu_get_reg_csr(struct kvm_vcpu *vcpu,
static int kvm_riscv_vcpu_set_reg_csr(struct kvm_vcpu *vcpu,
const struct kvm_one_reg *reg)
{
- struct kvm_vcpu_csr *csr = &vcpu->arch.guest_csr;
+ int rc;
unsigned long __user *uaddr =
(unsigned long __user *)(unsigned long)reg->addr;
unsigned long reg_num = reg->id & ~(KVM_REG_ARCH_MASK |
KVM_REG_SIZE_MASK |
KVM_REG_RISCV_CSR);
- unsigned long reg_val;
+ unsigned long reg_val, reg_subtype;

if (KVM_REG_SIZE(reg->id) != sizeof(unsigned long))
return -EINVAL;
- if (reg_num >= sizeof(struct kvm_riscv_csr) / sizeof(unsigned long))
- return -EINVAL;

if (copy_from_user(&reg_val, uaddr, KVM_REG_SIZE(reg->id)))
return -EFAULT;

- if (reg_num == KVM_REG_RISCV_CSR_REG(sip)) {
- reg_val &= VSIP_VALID_MASK;
- reg_val <<= VSIP_TO_HVIP_SHIFT;
+ reg_subtype = reg_num & KVM_REG_RISCV_SUBTYPE_MASK;
+ reg_num &= ~KVM_REG_RISCV_SUBTYPE_MASK;
+ switch (reg_subtype) {
+ case KVM_REG_RISCV_CSR_GENERAL:
+ rc = kvm_riscv_vcpu_general_set_csr(vcpu, reg_num, reg_val);
+ break;
+ default:
+ rc = -EINVAL;
+ break;
}
-
- ((unsigned long *)csr)[reg_num] = reg_val;
-
- if (reg_num == KVM_REG_RISCV_CSR_REG(sip))
- WRITE_ONCE(vcpu->arch.irqs_pending_mask, 0);
+ if (rc)
+ return rc;

return 0;
}
--
2.34.1