RISC-V: KVM: Allow some SBI extensions to be disabled by default

Currently, all SBI extensions are enabled by default which is
problematic for SBI extensions (such as DBCN) which are forwarded
to the KVM user-space because we might have an older KVM user-space
which is not aware/ready to handle newer SBI extensions. Ideally,
the SBI extensions forwarded to the KVM user-space must be
disabled by default.

To address above, we allow certain SBI extensions to be disabled
by default so that KVM user-space must explicitly enable such
SBI extensions to receive forwarded calls from Guest VCPU.

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

1 files changed, 4 insertions, 0 deletions

diff --git a/arch/riscv/include/asm/kvm_vcpu_sbi.h b/arch/riscv/include/asm/kvm_vcpu_sbi.h
index 8d6d4dce8a5e..c02bda5559d7 100644
--- a/arch/riscv/include/asm/kvm_vcpu_sbi.h
+++ b/arch/riscv/include/asm/kvm_vcpu_sbi.h
@@ -35,6 +35,9 @@ struct kvm_vcpu_sbi_return {
 struct kvm_vcpu_sbi_extension {
 	unsigned long extid_start;
 	unsigned long extid_end;
+
+	bool default_unavail;
+
 	/**
 	 * SBI extension handler. It can be defined for a given extension or group of
 	 * extension. But it should always return linux error codes rather than SBI
@@ -59,6 +62,7 @@ int kvm_riscv_vcpu_get_reg_sbi_ext(struct kvm_vcpu *vcpu,
 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);
+void kvm_riscv_vcpu_sbi_init(struct kvm_vcpu *vcpu);
 
 #ifdef CONFIG_RISCV_SBI_V01
 extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_v01;