RISC-V: KVM: Define a probe function for SBI extension data structures

Currently the probe function just checks if an SBI extension is registered or not. However, the extension may not want to advertise itself depending on some other condition. An additional extension specific probe function will allow extensions to decide if they want to be advertised to the caller or not. Any extension that does not require additional dependency checks can avoid implementing this function. Reviewed-by: Anup Patel <anup@brainfault.org> Reviewed-by: Andrew Jones <ajones@ventanamicro.com> Signed-off-by: Atish Patra <atishp@rivosinc.com> Signed-off-by: Anup Patel <anup@brainfault.org>
mariux64 · Feb 7, 2023 · 026bac4 · 026bac4
1 parent 2723fb7
commit 026bac4
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Showing 2 changed files with 9 additions and 2 deletions.
diff --git a/arch/riscv/include/asm/kvm_vcpu_sbi.h b/arch/riscv/include/asm/kvm_vcpu_sbi.h
@@ -29,6 +29,9 @@ struct kvm_vcpu_sbi_extension {
 	int (*handler)(struct kvm_vcpu *vcpu, struct kvm_run *run,
 		       unsigned long *out_val, struct kvm_cpu_trap *utrap,
 		       bool *exit);
+
+	/* Extension specific probe function */
+	unsigned long (*probe)(struct kvm_vcpu *vcpu);
 };
 
 void kvm_riscv_vcpu_sbi_forward(struct kvm_vcpu *vcpu, struct kvm_run *run);

diff --git a/arch/riscv/kvm/vcpu_sbi_base.c b/arch/riscv/kvm/vcpu_sbi_base.c
@@ -19,6 +19,7 @@ static int kvm_sbi_ext_base_handler(struct kvm_vcpu *vcpu, struct kvm_run *run,
 {
 	int ret = 0;
 	struct kvm_cpu_context *cp = &vcpu->arch.guest_context;
+	const struct kvm_vcpu_sbi_extension *sbi_ext;
 
 	switch (cp->a6) {
 	case SBI_EXT_BASE_GET_SPEC_VERSION:
@@ -43,8 +44,11 @@ static int kvm_sbi_ext_base_handler(struct kvm_vcpu *vcpu, struct kvm_run *run,
 			 */
 			kvm_riscv_vcpu_sbi_forward(vcpu, run);
 			*exit = true;
-		} else
-			*out_val = kvm_vcpu_sbi_find_ext(cp->a0) ? 1 : 0;
+		} else {
+			sbi_ext = kvm_vcpu_sbi_find_ext(cp->a0);
+			*out_val = sbi_ext && sbi_ext->probe ?
+					   sbi_ext->probe(vcpu) : !!sbi_ext;
+		}
 		break;
 	case SBI_EXT_BASE_GET_MVENDORID:
 		*out_val = vcpu->arch.mvendorid;