The SBI DBCN extension needs to be emulated in user-space so let
us forward console_puts() call to user-space.

Signed-off-by: Anup Patel <[email protected]>
---
 arch/riscv/include/asm/kvm_vcpu_sbi.h |  1 +
 arch/riscv/include/uapi/asm/kvm.h     |  1 +
 arch/riscv/kvm/vcpu_sbi.c             |  4 ++++
 arch/riscv/kvm/vcpu_sbi_replace.c     | 31 +++++++++++++++++++++++++++
 4 files changed, 37 insertions(+)

diff --git a/arch/riscv/include/asm/kvm_vcpu_sbi.h 
b/arch/riscv/include/asm/kvm_vcpu_sbi.h
index 8d6d4dce8a5e..a85f95eb6e85 100644
--- a/arch/riscv/include/asm/kvm_vcpu_sbi.h
+++ b/arch/riscv/include/asm/kvm_vcpu_sbi.h
@@ -69,6 +69,7 @@ extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_ipi;
 extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_rfence;
 extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_srst;
 extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_hsm;
+extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_dbcn;
 extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_experimental;
 extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_vendor;
 
diff --git a/arch/riscv/include/uapi/asm/kvm.h 
b/arch/riscv/include/uapi/asm/kvm.h
index 917d8cc2489e..60d3b21dead7 100644
--- a/arch/riscv/include/uapi/asm/kvm.h
+++ b/arch/riscv/include/uapi/asm/kvm.h
@@ -156,6 +156,7 @@ enum KVM_RISCV_SBI_EXT_ID {
        KVM_RISCV_SBI_EXT_PMU,
        KVM_RISCV_SBI_EXT_EXPERIMENTAL,
        KVM_RISCV_SBI_EXT_VENDOR,
+       KVM_RISCV_SBI_EXT_DBCN,
        KVM_RISCV_SBI_EXT_MAX,
 };
 
diff --git a/arch/riscv/kvm/vcpu_sbi.c b/arch/riscv/kvm/vcpu_sbi.c
index 9cd97091c723..b54fe52c915a 100644
--- a/arch/riscv/kvm/vcpu_sbi.c
+++ b/arch/riscv/kvm/vcpu_sbi.c
@@ -66,6 +66,10 @@ static const struct kvm_riscv_sbi_extension_entry sbi_ext[] 
= {
                .ext_idx = KVM_RISCV_SBI_EXT_PMU,
                .ext_ptr = &vcpu_sbi_ext_pmu,
        },
+       {
+               .ext_idx = KVM_RISCV_SBI_EXT_DBCN,
+               .ext_ptr = &vcpu_sbi_ext_dbcn,
+       },
        {
                .ext_idx = KVM_RISCV_SBI_EXT_EXPERIMENTAL,
                .ext_ptr = &vcpu_sbi_ext_experimental,
diff --git a/arch/riscv/kvm/vcpu_sbi_replace.c 
b/arch/riscv/kvm/vcpu_sbi_replace.c
index 7c4d5d38a339..347c5856347e 100644
--- a/arch/riscv/kvm/vcpu_sbi_replace.c
+++ b/arch/riscv/kvm/vcpu_sbi_replace.c
@@ -175,3 +175,34 @@ const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_srst = {
        .extid_end = SBI_EXT_SRST,
        .handler = kvm_sbi_ext_srst_handler,
 };
+
+static int kvm_sbi_ext_dbcn_handler(struct kvm_vcpu *vcpu,
+                                   struct kvm_run *run,
+                                   struct kvm_vcpu_sbi_return *retdata)
+{
+       struct kvm_cpu_context *cp = &vcpu->arch.guest_context;
+       unsigned long funcid = cp->a6;
+
+       switch (funcid) {
+       case SBI_EXT_DBCN_CONSOLE_WRITE:
+       case SBI_EXT_DBCN_CONSOLE_READ:
+       case SBI_EXT_DBCN_CONSOLE_WRITE_BYTE:
+               /*
+                * The SBI debug console functions are unconditionally
+                * forwarded to the userspace.
+                */
+               kvm_riscv_vcpu_sbi_forward(vcpu, run);
+               retdata->uexit = true;
+               break;
+       default:
+               retdata->err_val = SBI_ERR_NOT_SUPPORTED;
+       }
+
+       return 0;
+}
+
+const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_dbcn = {
+       .extid_start = SBI_EXT_DBCN,
+       .extid_end = SBI_EXT_DBCN,
+       .handler = kvm_sbi_ext_dbcn_handler,
+};
-- 
2.34.1

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