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>

diff --git a/arch/riscv/include/asm/kvm_vcpu_sbi.h b/arch/riscv/include/asm/kvm_vcpu_sbi.h
index f79478a85d2dffc24934411789b13ba52b7c8055..45ba341e887a3df7166e22061582502d13c116d9 100644 (file)
--- 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
index 5d65c634d30127dff64438b8145770158b0fb65d..66398065a6a627fa3c8ac08e333ea951a40917b8 100644 (file)
--- 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;