RISC-V: KVM: Make SBI uapi consistent with ISA uapi

When an SBI extension cannot be enabled, that's a distinct state vs.
enabled and disabled. Modify enum kvm_riscv_sbi_ext_status to
accommodate it, which allows KVM userspace to tell the difference
in state too, as the SBI extension register will disappear when it
cannot be enabled, i.e. accesses to it return ENOENT. get-reg-list is
updated as well to only add SBI extension registers to the list which
may be enabled. Returning ENOENT for SBI extension registers which
cannot be enabled makes them consistent with ISA extension registers.
Any SBI extensions which were enabled by default are still enabled by
default, if they can be enabled at all.

Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Signed-off-by: Anup Patel <anup@brainfault.org>

1 files changed, 43 insertions, 32 deletions

diff --git a/arch/riscv/kvm/vcpu_sbi.c b/arch/riscv/kvm/vcpu_sbi.c
index a04ff98085d9..dcdff4458190 100644
--- a/arch/riscv/kvm/vcpu_sbi.c
+++ b/arch/riscv/kvm/vcpu_sbi.c
@@ -80,6 +80,34 @@ static const struct kvm_riscv_sbi_extension_entry sbi_ext[] = {
 	},
 };
 
+static const struct kvm_riscv_sbi_extension_entry *
+riscv_vcpu_get_sbi_ext(struct kvm_vcpu *vcpu, unsigned long idx)
+{
+	const struct kvm_riscv_sbi_extension_entry *sext = NULL;
+
+	if (idx >= KVM_RISCV_SBI_EXT_MAX)
+		return NULL;
+
+	for (int i = 0; i < ARRAY_SIZE(sbi_ext); i++) {
+		if (sbi_ext[i].ext_idx == idx) {
+			sext = &sbi_ext[i];
+			break;
+		}
+	}
+
+	return sext;
+}
+
+bool riscv_vcpu_supports_sbi_ext(struct kvm_vcpu *vcpu, int idx)
+{
+	struct kvm_vcpu_sbi_context *scontext = &vcpu->arch.sbi_context;
+	const struct kvm_riscv_sbi_extension_entry *sext;
+
+	sext = riscv_vcpu_get_sbi_ext(vcpu, idx);
+
+	return sext && scontext->ext_status[sext->ext_idx] != KVM_RISCV_SBI_EXT_STATUS_UNAVAILABLE;
+}
+
 void kvm_riscv_vcpu_sbi_forward(struct kvm_vcpu *vcpu, struct kvm_run *run)
 {
 	struct kvm_cpu_context *cp = &vcpu->arch.guest_context;
@@ -140,28 +168,19 @@ 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)
-		return -ENOENT;
+	const struct kvm_riscv_sbi_extension_entry *sext;
 
 	if (reg_val != 1 && reg_val != 0)
 		return -EINVAL;
 
-	for (i = 0; i < ARRAY_SIZE(sbi_ext); i++) {
-		if (sbi_ext[i].ext_idx == reg_num) {
-			sext = &sbi_ext[i];
-			break;
-		}
-	}
-	if (!sext)
+	sext = riscv_vcpu_get_sbi_ext(vcpu, reg_num);
+	if (!sext || scontext->ext_status[sext->ext_idx] == KVM_RISCV_SBI_EXT_STATUS_UNAVAILABLE)
 		return -ENOENT;
 
 	scontext->ext_status[sext->ext_idx] = (reg_val) ?
-			KVM_RISCV_SBI_EXT_AVAILABLE :
-			KVM_RISCV_SBI_EXT_UNAVAILABLE;
+			KVM_RISCV_SBI_EXT_STATUS_ENABLED :
+			KVM_RISCV_SBI_EXT_STATUS_DISABLED;
 
 	return 0;
 }
@@ -170,24 +189,16 @@ 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;
+	const struct kvm_riscv_sbi_extension_entry *sext;
 
-	if (reg_num >= KVM_RISCV_SBI_EXT_MAX)
-		return -ENOENT;
-
-	for (i = 0; i < ARRAY_SIZE(sbi_ext); i++) {
-		if (sbi_ext[i].ext_idx == reg_num) {
-			sext = &sbi_ext[i];
-			break;
-		}
-	}
-	if (!sext)
+	sext = riscv_vcpu_get_sbi_ext(vcpu, reg_num);
+	if (!sext || scontext->ext_status[sext->ext_idx] == KVM_RISCV_SBI_EXT_STATUS_UNAVAILABLE)
 		return -ENOENT;
 
 	*reg_val = scontext->ext_status[sext->ext_idx] ==
-				KVM_RISCV_SBI_EXT_AVAILABLE;
+				KVM_RISCV_SBI_EXT_STATUS_ENABLED;
+
 	return 0;
 }
 
@@ -325,7 +336,7 @@ const struct kvm_vcpu_sbi_extension *kvm_vcpu_sbi_find_ext(
 		if (ext->extid_start <= extid && ext->extid_end >= extid) {
 			if (entry->ext_idx >= KVM_RISCV_SBI_EXT_MAX ||
 			    scontext->ext_status[entry->ext_idx] ==
-						KVM_RISCV_SBI_EXT_AVAILABLE)
+						KVM_RISCV_SBI_EXT_STATUS_ENABLED)
 				return ext;
 
 			return NULL;
@@ -413,12 +424,12 @@ void kvm_riscv_vcpu_sbi_init(struct kvm_vcpu *vcpu)
 
 		if (ext->probe && !ext->probe(vcpu)) {
 			scontext->ext_status[entry->ext_idx] =
-				KVM_RISCV_SBI_EXT_UNAVAILABLE;
+				KVM_RISCV_SBI_EXT_STATUS_UNAVAILABLE;
 			continue;
 		}
 
-		scontext->ext_status[entry->ext_idx] = ext->default_unavail ?
-					KVM_RISCV_SBI_EXT_UNAVAILABLE :
-					KVM_RISCV_SBI_EXT_AVAILABLE;
+		scontext->ext_status[entry->ext_idx] = ext->default_disabled ?
+					KVM_RISCV_SBI_EXT_STATUS_DISABLED :
+					KVM_RISCV_SBI_EXT_STATUS_ENABLED;
 	}
 }