[PATCH 2/7] RISC-V: KVM: Extend ONE_REG to enable/disable multiple ISA extensions

From: Anup Patel
Date: Wed Jul 12 2023 - 12:11:20 EST

Currently, the ISA extension ONE_REG interface only allows enabling or
disabling one extension at a time. To improve this, we extend the ISA
extension ONE_REG interface (similar to SBI extension ONE_REG interface)
so that KVM user space can enable/disable multiple extensions in one
ioctl.

Signed-off-by: Anup Patel <apatel@xxxxxxxxxxxxxxxx>
---
arch/riscv/include/uapi/asm/kvm.h | 9 ++
arch/riscv/kvm/vcpu_onereg.c | 153 ++++++++++++++++++++++++------
2 files changed, 133 insertions(+), 29 deletions(-)

diff --git a/arch/riscv/include/uapi/asm/kvm.h b/arch/riscv/include/uapi/asm/kvm.h
index 930fdc4101cd..6c2285f86545 100644
--- a/arch/riscv/include/uapi/asm/kvm.h
+++ b/arch/riscv/include/uapi/asm/kvm.h
@@ -193,6 +193,15 @@ enum KVM_RISCV_SBI_EXT_ID {

/* ISA Extension registers are mapped as type 7 */
#define KVM_REG_RISCV_ISA_EXT (0x07 << KVM_REG_RISCV_TYPE_SHIFT)
+#define KVM_REG_RISCV_ISA_SINGLE (0x0 << KVM_REG_RISCV_SUBTYPE_SHIFT)
+#define KVM_REG_RISCV_ISA_MULTI_EN (0x1 << KVM_REG_RISCV_SUBTYPE_SHIFT)
+#define KVM_REG_RISCV_ISA_MULTI_DIS (0x2 << KVM_REG_RISCV_SUBTYPE_SHIFT)
+#define KVM_REG_RISCV_ISA_MULTI_REG(__ext_id) \
+ ((__ext_id) / __BITS_PER_LONG)
+#define KVM_REG_RISCV_ISA_MULTI_MASK(__ext_id) \
+ (1UL << ((__ext_id) % __BITS_PER_LONG))
+#define KVM_REG_RISCV_ISA_MULTI_REG_LAST \
+ KVM_REG_RISCV_ISA_MULTI_REG(KVM_RISCV_ISA_EXT_MAX - 1)

/* SBI extension registers are mapped as type 8 */
#define KVM_REG_RISCV_SBI_EXT (0x08 << KVM_REG_RISCV_TYPE_SHIFT)
diff --git a/arch/riscv/kvm/vcpu_onereg.c b/arch/riscv/kvm/vcpu_onereg.c
index 836ffe79311a..236359722364 100644
--- a/arch/riscv/kvm/vcpu_onereg.c
+++ b/arch/riscv/kvm/vcpu_onereg.c
@@ -408,55 +408,34 @@ static int kvm_riscv_vcpu_set_reg_csr(struct kvm_vcpu *vcpu,
return 0;
}

-static int kvm_riscv_vcpu_get_reg_isa_ext(struct kvm_vcpu *vcpu,
- const struct kvm_one_reg *reg)
+static int riscv_vcpu_get_isa_ext_single(struct kvm_vcpu *vcpu,
+ unsigned long reg_num,
+ unsigned long *reg_val)
{
- 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_ISA_EXT);
- unsigned long reg_val = 0;
unsigned long host_isa_ext;

- if (KVM_REG_SIZE(reg->id) != sizeof(unsigned long))
- return -EINVAL;
-
if (reg_num >= KVM_RISCV_ISA_EXT_MAX ||
reg_num >= ARRAY_SIZE(kvm_isa_ext_arr))
return -EINVAL;

+ *reg_val = 0;
host_isa_ext = kvm_isa_ext_arr[reg_num];
if (__riscv_isa_extension_available(vcpu->arch.isa, host_isa_ext))
- reg_val = 1; /* Mark the given extension as available */
-
- if (copy_to_user(uaddr, &reg_val, KVM_REG_SIZE(reg->id)))
- return -EFAULT;
+ *reg_val = 1; /* Mark the given extension as available */

return 0;
}

-static int kvm_riscv_vcpu_set_reg_isa_ext(struct kvm_vcpu *vcpu,
- const struct kvm_one_reg *reg)
+static int riscv_vcpu_set_isa_ext_single(struct kvm_vcpu *vcpu,
+ unsigned long reg_num,
+ unsigned long reg_val)
{
- 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_ISA_EXT);
- unsigned long reg_val;
unsigned long host_isa_ext;

- if (KVM_REG_SIZE(reg->id) != sizeof(unsigned long))
- return -EINVAL;
-
if (reg_num >= KVM_RISCV_ISA_EXT_MAX ||
reg_num >= ARRAY_SIZE(kvm_isa_ext_arr))
return -EINVAL;

- if (copy_from_user(&reg_val, uaddr, KVM_REG_SIZE(reg->id)))
- return -EFAULT;
-
host_isa_ext = kvm_isa_ext_arr[reg_num];
if (!__riscv_isa_extension_available(NULL, host_isa_ext))
return -EOPNOTSUPP;
@@ -482,6 +461,122 @@ static int kvm_riscv_vcpu_set_reg_isa_ext(struct kvm_vcpu *vcpu,
return 0;
}

+static int riscv_vcpu_get_isa_ext_multi(struct kvm_vcpu *vcpu,
+ unsigned long reg_num,
+ unsigned long *reg_val)
+{
+ unsigned long i, ext_id, ext_val;
+
+ if (reg_num > KVM_REG_RISCV_ISA_MULTI_REG_LAST)
+ return -EINVAL;
+
+ for (i = 0; i < BITS_PER_LONG; i++) {
+ ext_id = i + reg_num * BITS_PER_LONG;
+ if (ext_id >= KVM_RISCV_ISA_EXT_MAX)
+ break;
+
+ ext_val = 0;
+ riscv_vcpu_get_isa_ext_single(vcpu, ext_id, &ext_val);
+ if (ext_val)
+ *reg_val |= KVM_REG_RISCV_ISA_MULTI_MASK(ext_id);
+ }
+
+ return 0;
+}
+
+static int riscv_vcpu_set_isa_ext_multi(struct kvm_vcpu *vcpu,
+ unsigned long reg_num,
+ unsigned long reg_val, bool enable)
+{
+ unsigned long i, ext_id;
+
+ if (reg_num > KVM_REG_RISCV_ISA_MULTI_REG_LAST)
+ return -EINVAL;
+
+ for_each_set_bit(i, &reg_val, BITS_PER_LONG) {
+ ext_id = i + reg_num * BITS_PER_LONG;
+ if (ext_id >= KVM_RISCV_ISA_EXT_MAX)
+ break;
+
+ riscv_vcpu_set_isa_ext_single(vcpu, ext_id, enable);
+ }
+
+ return 0;
+}
+
+static int kvm_riscv_vcpu_get_reg_isa_ext(struct kvm_vcpu *vcpu,
+ const struct kvm_one_reg *reg)
+{
+ 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_ISA_EXT);
+ unsigned long reg_val, reg_subtype;
+
+ if (KVM_REG_SIZE(reg->id) != sizeof(unsigned long))
+ return -EINVAL;
+
+ reg_subtype = reg_num & KVM_REG_RISCV_SUBTYPE_MASK;
+ reg_num &= ~KVM_REG_RISCV_SUBTYPE_MASK;
+
+ reg_val = 0;
+ switch (reg_subtype) {
+ case KVM_REG_RISCV_ISA_SINGLE:
+ rc = riscv_vcpu_get_isa_ext_single(vcpu, reg_num, &reg_val);
+ break;
+ case KVM_REG_RISCV_ISA_MULTI_EN:
+ case KVM_REG_RISCV_ISA_MULTI_DIS:
+ rc = riscv_vcpu_get_isa_ext_multi(vcpu, reg_num, &reg_val);
+ if (!rc && reg_subtype == KVM_REG_RISCV_ISA_MULTI_DIS)
+ reg_val = ~reg_val;
+ break;
+ default:
+ rc = -EINVAL;
+ }
+ if (rc)
+ return rc;
+
+ if (copy_to_user(uaddr, &reg_val, KVM_REG_SIZE(reg->id)))
+ return -EFAULT;
+
+ return 0;
+}
+
+static int kvm_riscv_vcpu_set_reg_isa_ext(struct kvm_vcpu *vcpu,
+ const struct kvm_one_reg *reg)
+{
+ 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_ISA_EXT);
+ unsigned long reg_val, reg_subtype;
+
+ if (KVM_REG_SIZE(reg->id) != sizeof(unsigned long))
+ return -EINVAL;
+
+ reg_subtype = reg_num & KVM_REG_RISCV_SUBTYPE_MASK;
+ reg_num &= ~KVM_REG_RISCV_SUBTYPE_MASK;
+
+ if (copy_from_user(&reg_val, uaddr, KVM_REG_SIZE(reg->id)))
+ return -EFAULT;
+
+ switch (reg_subtype) {
+ case KVM_REG_RISCV_ISA_SINGLE:
+ return riscv_vcpu_set_isa_ext_single(vcpu, reg_num, reg_val);
+ case KVM_REG_RISCV_SBI_MULTI_EN:
+ return riscv_vcpu_set_isa_ext_multi(vcpu, reg_num, reg_val, true);
+ case KVM_REG_RISCV_SBI_MULTI_DIS:
+ return riscv_vcpu_set_isa_ext_multi(vcpu, reg_num, reg_val, false);
+ default:
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
int kvm_riscv_vcpu_set_reg(struct kvm_vcpu *vcpu,
const struct kvm_one_reg *reg)
{
--
2.34.1