[PATCH v3 1/1] RISC-V: KVM: Add ONE_REG interface to enable/disable SBI extensions

From: Anup Patel
Date: Fri Mar 31 2023 - 08:40:04 EST

We add ONE_REG interface to enable/disable SBI extensions (just
like the ONE_REG interface for ISA extensions). This allows KVM
user-space to decide the set of SBI extension enabled for a Guest
and by default all SBI extensions are enabled.

Signed-off-by: Anup Patel <apatel@xxxxxxxxxxxxxxxx>
---
arch/riscv/include/asm/kvm_vcpu_sbi.h | 8 +-
arch/riscv/include/uapi/asm/kvm.h | 32 ++++
arch/riscv/kvm/vcpu.c | 2 +
arch/riscv/kvm/vcpu_sbi.c | 245 ++++++++++++++++++++++++--
arch/riscv/kvm/vcpu_sbi_base.c | 2 +-
5 files changed, 270 insertions(+), 19 deletions(-)

diff --git a/arch/riscv/include/asm/kvm_vcpu_sbi.h b/arch/riscv/include/asm/kvm_vcpu_sbi.h
index 8425556af7d1..4278125a38a5 100644
--- a/arch/riscv/include/asm/kvm_vcpu_sbi.h
+++ b/arch/riscv/include/asm/kvm_vcpu_sbi.h
@@ -16,6 +16,7 @@

struct kvm_vcpu_sbi_context {
int return_handled;
+ bool extension_disabled[KVM_RISCV_SBI_EXT_MAX];
};

struct kvm_vcpu_sbi_return {
@@ -45,7 +46,12 @@ void kvm_riscv_vcpu_sbi_system_reset(struct kvm_vcpu *vcpu,
struct kvm_run *run,
u32 type, u64 flags);
int kvm_riscv_vcpu_sbi_return(struct kvm_vcpu *vcpu, struct kvm_run *run);
-const struct kvm_vcpu_sbi_extension *kvm_vcpu_sbi_find_ext(unsigned long extid);
+int kvm_riscv_vcpu_set_reg_sbi_ext(struct kvm_vcpu *vcpu,
+ const struct kvm_one_reg *reg);
+int kvm_riscv_vcpu_get_reg_sbi_ext(struct kvm_vcpu *vcpu,
+ const struct kvm_one_reg *reg);
+const struct kvm_vcpu_sbi_extension *kvm_vcpu_sbi_find_ext(
+ struct kvm_vcpu *vcpu, unsigned long extid);
int kvm_riscv_vcpu_sbi_ecall(struct kvm_vcpu *vcpu, struct kvm_run *run);

#ifdef CONFIG_RISCV_SBI_V01
diff --git a/arch/riscv/include/uapi/asm/kvm.h b/arch/riscv/include/uapi/asm/kvm.h
index 92af6f3f057c..d8ead5952ed9 100644
--- a/arch/riscv/include/uapi/asm/kvm.h
+++ b/arch/riscv/include/uapi/asm/kvm.h
@@ -12,6 +12,7 @@
#ifndef __ASSEMBLY__

#include <linux/types.h>
+#include <asm/bitsperlong.h>
#include <asm/ptrace.h>

#define __KVM_HAVE_READONLY_MEM
@@ -108,6 +109,23 @@ enum KVM_RISCV_ISA_EXT_ID {
KVM_RISCV_ISA_EXT_MAX,
};

+/*
+ * SBI extension IDs specific to KVM. This is not the same as the SBI
+ * extension IDs defined by the RISC-V SBI specification.
+ */
+enum KVM_RISCV_SBI_EXT_ID {
+ KVM_RISCV_SBI_EXT_V01 = 0,
+ KVM_RISCV_SBI_EXT_TIME,
+ KVM_RISCV_SBI_EXT_IPI,
+ KVM_RISCV_SBI_EXT_RFENCE,
+ KVM_RISCV_SBI_EXT_SRST,
+ KVM_RISCV_SBI_EXT_HSM,
+ KVM_RISCV_SBI_EXT_PMU,
+ KVM_RISCV_SBI_EXT_EXPERIMENTAL,
+ KVM_RISCV_SBI_EXT_VENDOR,
+ KVM_RISCV_SBI_EXT_MAX,
+};
+
/* Possible states for kvm_riscv_timer */
#define KVM_RISCV_TIMER_STATE_OFF 0
#define KVM_RISCV_TIMER_STATE_ON 1
@@ -118,6 +136,8 @@ enum KVM_RISCV_ISA_EXT_ID {
/* If you need to interpret the index values, here is the key: */
#define KVM_REG_RISCV_TYPE_MASK 0x00000000FF000000
#define KVM_REG_RISCV_TYPE_SHIFT 24
+#define KVM_REG_RISCV_SUBTYPE_MASK 0x0000000000FF0000
+#define KVM_REG_RISCV_SUBTYPE_SHIFT 16

/* Config registers are mapped as type 1 */
#define KVM_REG_RISCV_CONFIG (0x01 << KVM_REG_RISCV_TYPE_SHIFT)
@@ -152,6 +172,18 @@ enum KVM_RISCV_ISA_EXT_ID {
/* ISA Extension registers are mapped as type 7 */
#define KVM_REG_RISCV_ISA_EXT (0x07 << KVM_REG_RISCV_TYPE_SHIFT)

+/* SBI extension registers are mapped as type 8 */
+#define KVM_REG_RISCV_SBI_EXT (0x08 << KVM_REG_RISCV_TYPE_SHIFT)
+#define KVM_REG_RISCV_SBI_SINGLE (0x0 << KVM_REG_RISCV_SUBTYPE_SHIFT)
+#define KVM_REG_RISCV_SBI_MULTI_EN (0x1 << KVM_REG_RISCV_SUBTYPE_SHIFT)
+#define KVM_REG_RISCV_SBI_MULTI_DIS (0x2 << KVM_REG_RISCV_SUBTYPE_SHIFT)
+#define KVM_REG_RISCV_SBI_MULTI_REG(__ext_id) \
+ ((__ext_id) / __BITS_PER_LONG)
+#define KVM_REG_RISCV_SBI_MULTI_MASK(__ext_id) \
+ (1UL << ((__ext_id) % __BITS_PER_LONG))
+#define KVM_REG_RISCV_SBI_MULTI_REG_LAST \
+ KVM_REG_RISCV_SBI_MULTI_REG(KVM_RISCV_SBI_EXT_MAX - 1)
+
#endif

#endif /* __LINUX_KVM_RISCV_H */
diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
index 7d010b0be54e..311fd347c5a8 100644
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -601,6 +601,8 @@ static int kvm_riscv_vcpu_set_reg(struct kvm_vcpu *vcpu,
KVM_REG_RISCV_FP_D);
case KVM_REG_RISCV_ISA_EXT:
return kvm_riscv_vcpu_set_reg_isa_ext(vcpu, reg);
+ case KVM_REG_RISCV_SBI_EXT:
+ return kvm_riscv_vcpu_set_reg_sbi_ext(vcpu, reg);
default:
break;
}
diff --git a/arch/riscv/kvm/vcpu_sbi.c b/arch/riscv/kvm/vcpu_sbi.c
index 15fde15f9fb8..89e3e7bace6c 100644
--- a/arch/riscv/kvm/vcpu_sbi.c
+++ b/arch/riscv/kvm/vcpu_sbi.c
@@ -30,17 +30,52 @@ static const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_pmu = {
};
#endif

-static const struct kvm_vcpu_sbi_extension *sbi_ext[] = {
- &vcpu_sbi_ext_v01,
- &vcpu_sbi_ext_base,
- &vcpu_sbi_ext_time,
- &vcpu_sbi_ext_ipi,
- &vcpu_sbi_ext_rfence,
- &vcpu_sbi_ext_srst,
- &vcpu_sbi_ext_hsm,
- &vcpu_sbi_ext_pmu,
- &vcpu_sbi_ext_experimental,
- &vcpu_sbi_ext_vendor,
+struct kvm_riscv_sbi_extension_entry {
+ enum KVM_RISCV_SBI_EXT_ID dis_idx;
+ const struct kvm_vcpu_sbi_extension *ext_ptr;
+};
+
+static const struct kvm_riscv_sbi_extension_entry sbi_ext[] = {
+ {
+ .dis_idx = KVM_RISCV_SBI_EXT_V01,
+ .ext_ptr = &vcpu_sbi_ext_v01,
+ },
+ {
+ .dis_idx = KVM_RISCV_SBI_EXT_MAX, /* Can't be disabled */
+ .ext_ptr = &vcpu_sbi_ext_base,
+ },
+ {
+ .dis_idx = KVM_RISCV_SBI_EXT_TIME,
+ .ext_ptr = &vcpu_sbi_ext_time,
+ },
+ {
+ .dis_idx = KVM_RISCV_SBI_EXT_IPI,
+ .ext_ptr = &vcpu_sbi_ext_ipi,
+ },
+ {
+ .dis_idx = KVM_RISCV_SBI_EXT_RFENCE,
+ .ext_ptr = &vcpu_sbi_ext_rfence,
+ },
+ {
+ .dis_idx = KVM_RISCV_SBI_EXT_SRST,
+ .ext_ptr = &vcpu_sbi_ext_srst,
+ },
+ {
+ .dis_idx = KVM_RISCV_SBI_EXT_HSM,
+ .ext_ptr = &vcpu_sbi_ext_hsm,
+ },
+ {
+ .dis_idx = KVM_RISCV_SBI_EXT_PMU,
+ .ext_ptr = &vcpu_sbi_ext_pmu,
+ },
+ {
+ .dis_idx = KVM_RISCV_SBI_EXT_EXPERIMENTAL,
+ .ext_ptr = &vcpu_sbi_ext_experimental,
+ },
+ {
+ .dis_idx = KVM_RISCV_SBI_EXT_VENDOR,
+ .ext_ptr = &vcpu_sbi_ext_vendor,
+ },
};

void kvm_riscv_vcpu_sbi_forward(struct kvm_vcpu *vcpu, struct kvm_run *run)
@@ -99,14 +134,190 @@ int kvm_riscv_vcpu_sbi_return(struct kvm_vcpu *vcpu, struct kvm_run *run)
return 0;
}

-const struct kvm_vcpu_sbi_extension *kvm_vcpu_sbi_find_ext(unsigned long extid)
+static int riscv_vcpu_set_sbi_ext_single(struct kvm_vcpu *vcpu,
+ unsigned long reg_num,
+ unsigned long reg_val)
+{
+ unsigned long i;
+ const struct kvm_riscv_sbi_extension_entry *sext = NULL;
+ struct kvm_vcpu_sbi_context *scontext = &vcpu->arch.sbi_context;
+
+ if (reg_num >= KVM_RISCV_SBI_EXT_MAX ||
+ (reg_val != 1 && reg_val != 0))
+ return -EINVAL;
+
+ for (i = 0; i < ARRAY_SIZE(sbi_ext); i++) {
+ if (sbi_ext[i].dis_idx == reg_num) {
+ sext = &sbi_ext[i];
+ break;
+ }
+ }
+ if (!sext)
+ return -ENOENT;
+
+ scontext->extension_disabled[sext->dis_idx] = !reg_val;
+
+ return 0;
+}
+
+static int riscv_vcpu_get_sbi_ext_single(struct kvm_vcpu *vcpu,
+ unsigned long reg_num,
+ unsigned long *reg_val)
+{
+ unsigned long i;
+ const struct kvm_riscv_sbi_extension_entry *sext = NULL;
+ struct kvm_vcpu_sbi_context *scontext = &vcpu->arch.sbi_context;
+
+ if (reg_num >= KVM_RISCV_SBI_EXT_MAX)
+ return -EINVAL;
+
+ for (i = 0; i < ARRAY_SIZE(sbi_ext); i++) {
+ if (sbi_ext[i].dis_idx == reg_num) {
+ sext = &sbi_ext[i];
+ break;
+ }
+ }
+ if (!sext)
+ return -ENOENT;
+
+ *reg_val = !scontext->extension_disabled[sext->dis_idx];
+
+ return 0;
+}
+
+static int riscv_vcpu_set_sbi_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_SBI_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_SBI_EXT_MAX)
+ break;
+
+ riscv_vcpu_set_sbi_ext_single(vcpu, ext_id, enable);
+ }
+
+ return 0;
+}
+
+static int riscv_vcpu_get_sbi_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_SBI_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_SBI_EXT_MAX)
+ break;
+
+ ext_val = 0;
+ riscv_vcpu_get_sbi_ext_single(vcpu, ext_id, &ext_val);
+ if (ext_val)
+ *reg_val |= KVM_REG_RISCV_SBI_MULTI_MASK(ext_id);
+ }
+
+ return 0;
+}
+
+int kvm_riscv_vcpu_set_reg_sbi_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_SBI_EXT);
+ unsigned long reg_val, reg_subtype;
+
+ if (KVM_REG_SIZE(reg->id) != sizeof(unsigned long))
+ return -EINVAL;
+
+ if (vcpu->arch.ran_atleast_once)
+ return -EBUSY;
+
+ 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_SBI_SINGLE:
+ return riscv_vcpu_set_sbi_ext_single(vcpu, reg_num, reg_val);
+ case KVM_REG_RISCV_SBI_MULTI_EN:
+ return riscv_vcpu_set_sbi_ext_multi(vcpu, reg_num, reg_val, true);
+ case KVM_REG_RISCV_SBI_MULTI_DIS:
+ return riscv_vcpu_set_sbi_ext_multi(vcpu, reg_num, reg_val, false);
+ default:
+ return -EINVAL;
+ };
+
+ return 0;
+}
+
+int kvm_riscv_vcpu_get_reg_sbi_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_SBI_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_SBI_SINGLE:
+ rc = riscv_vcpu_get_sbi_ext_single(vcpu, reg_num, &reg_val);
+ break;
+ case KVM_REG_RISCV_SBI_MULTI_EN:
+ case KVM_REG_RISCV_SBI_MULTI_DIS:
+ rc = riscv_vcpu_get_sbi_ext_multi(vcpu, reg_num, &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;
+}
+
+const struct kvm_vcpu_sbi_extension *kvm_vcpu_sbi_find_ext(
+ struct kvm_vcpu *vcpu, unsigned long extid)
{
- int i = 0;
+ int i;
+ const struct kvm_riscv_sbi_extension_entry *sext;
+ struct kvm_vcpu_sbi_context *scontext = &vcpu->arch.sbi_context;

for (i = 0; i < ARRAY_SIZE(sbi_ext); i++) {
- if (sbi_ext[i]->extid_start <= extid &&
- sbi_ext[i]->extid_end >= extid)
- return sbi_ext[i];
+ sext = &sbi_ext[i];
+ if (sext->ext_ptr->extid_start <= extid &&
+ sext->ext_ptr->extid_end >= extid) {
+ if (sext->dis_idx < KVM_RISCV_SBI_EXT_MAX &&
+ scontext->extension_disabled[sext->dis_idx])
+ return NULL;
+ return sbi_ext[i].ext_ptr;
+ }
}

return NULL;
@@ -126,7 +337,7 @@ int kvm_riscv_vcpu_sbi_ecall(struct kvm_vcpu *vcpu, struct kvm_run *run)
};
bool ext_is_v01 = false;

- sbi_ext = kvm_vcpu_sbi_find_ext(cp->a7);
+ sbi_ext = kvm_vcpu_sbi_find_ext(vcpu, cp->a7);
if (sbi_ext && sbi_ext->handler) {
#ifdef CONFIG_RISCV_SBI_V01
if (cp->a7 >= SBI_EXT_0_1_SET_TIMER &&
diff --git a/arch/riscv/kvm/vcpu_sbi_base.c b/arch/riscv/kvm/vcpu_sbi_base.c
index 9945aff34c14..5bc570b984f4 100644
--- a/arch/riscv/kvm/vcpu_sbi_base.c
+++ b/arch/riscv/kvm/vcpu_sbi_base.c
@@ -44,7 +44,7 @@ static int kvm_sbi_ext_base_handler(struct kvm_vcpu *vcpu, struct kvm_run *run,
kvm_riscv_vcpu_sbi_forward(vcpu, run);
retdata->uexit = true;
} else {
- sbi_ext = kvm_vcpu_sbi_find_ext(cp->a0);
+ sbi_ext = kvm_vcpu_sbi_find_ext(vcpu, cp->a0);
*out_val = sbi_ext && sbi_ext->probe ?
sbi_ext->probe(vcpu) : !!sbi_ext;
}
--
2.34.1