RISC-V: KVM: Modify SBI extension handler to return SBI error code

Currently, the SBI extension handle is expected to return Linux error code.
The top SBI layer converts the Linux error code to SBI specific error code
that can be returned to guest invoking the SBI calls. This model works
as long as SBI error codes have 1-to-1 mappings between them.
However, that may not be true always. This patch attempts to disassociate
both these error codes by allowing the SBI extension implementation to
return SBI specific error codes as well.

The extension will continue to return the Linux error specific code which
will indicate any problem *with* the extension emulation while the
SBI specific error will indicate the problem *of* the emulation.

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

1 files changed, 20 insertions, 23 deletions

diff --git a/arch/riscv/kvm/vcpu_sbi_replace.c b/arch/riscv/kvm/vcpu_sbi_replace.c
index 03a0198389f0..38fa4c091f30 100644
--- a/arch/riscv/kvm/vcpu_sbi_replace.c
+++ b/arch/riscv/kvm/vcpu_sbi_replace.c
@@ -14,15 +14,15 @@
 #include <asm/kvm_vcpu_sbi.h>
 
 static int kvm_sbi_ext_time_handler(struct kvm_vcpu *vcpu, struct kvm_run *run,
-				    unsigned long *out_val,
-				    struct kvm_cpu_trap *utrap, bool *exit)
+				    struct kvm_vcpu_sbi_return *retdata)
 {
-	int ret = 0;
 	struct kvm_cpu_context *cp = &vcpu->arch.guest_context;
 	u64 next_cycle;
 
-	if (cp->a6 != SBI_EXT_TIME_SET_TIMER)
-		return -EINVAL;
+	if (cp->a6 != SBI_EXT_TIME_SET_TIMER) {
+		retdata->err_val = SBI_ERR_INVALID_PARAM;
+		return 0;
+	}
 
 #if __riscv_xlen == 32
 	next_cycle = ((u64)cp->a1 << 32) | (u64)cp->a0;
@@ -31,7 +31,7 @@ static int kvm_sbi_ext_time_handler(struct kvm_vcpu *vcpu, struct kvm_run *run,
 #endif
 	kvm_riscv_vcpu_timer_next_event(vcpu, next_cycle);
 
-	return ret;
+	return 0;
 }
 
 const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_time = {
@@ -41,8 +41,7 @@ const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_time = {
 };
 
 static int kvm_sbi_ext_ipi_handler(struct kvm_vcpu *vcpu, struct kvm_run *run,
-				   unsigned long *out_val,
-				   struct kvm_cpu_trap *utrap, bool *exit)
+				   struct kvm_vcpu_sbi_return *retdata)
 {
 	int ret = 0;
 	unsigned long i;
@@ -51,8 +50,10 @@ static int kvm_sbi_ext_ipi_handler(struct kvm_vcpu *vcpu, struct kvm_run *run,
 	unsigned long hmask = cp->a0;
 	unsigned long hbase = cp->a1;
 
-	if (cp->a6 != SBI_EXT_IPI_SEND_IPI)
-		return -EINVAL;
+	if (cp->a6 != SBI_EXT_IPI_SEND_IPI) {
+		retdata->err_val = SBI_ERR_INVALID_PARAM;
+		return 0;
+	}
 
 	kvm_for_each_vcpu(i, tmp, vcpu->kvm) {
 		if (hbase != -1UL) {
@@ -76,10 +77,8 @@ const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_ipi = {
 };
 
 static int kvm_sbi_ext_rfence_handler(struct kvm_vcpu *vcpu, struct kvm_run *run,
-				      unsigned long *out_val,
-				      struct kvm_cpu_trap *utrap, bool *exit)
+				      struct kvm_vcpu_sbi_return *retdata)
 {
-	int ret = 0;
 	struct kvm_cpu_context *cp = &vcpu->arch.guest_context;
 	unsigned long hmask = cp->a0;
 	unsigned long hbase = cp->a1;
@@ -116,10 +115,10 @@ static int kvm_sbi_ext_rfence_handler(struct kvm_vcpu *vcpu, struct kvm_run *run
 		 */
 		break;
 	default:
-		ret = -EOPNOTSUPP;
+		retdata->err_val = SBI_ERR_NOT_SUPPORTED;
 	}
 
-	return ret;
+	return 0;
 }
 
 const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_rfence = {
@@ -130,14 +129,12 @@ const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_rfence = {
 
 static int kvm_sbi_ext_srst_handler(struct kvm_vcpu *vcpu,
 				    struct kvm_run *run,
-				    unsigned long *out_val,
-				    struct kvm_cpu_trap *utrap, bool *exit)
+				    struct kvm_vcpu_sbi_return *retdata)
 {
 	struct kvm_cpu_context *cp = &vcpu->arch.guest_context;
 	unsigned long funcid = cp->a6;
 	u32 reason = cp->a1;
 	u32 type = cp->a0;
-	int ret = 0;
 
 	switch (funcid) {
 	case SBI_EXT_SRST_RESET:
@@ -146,24 +143,24 @@ static int kvm_sbi_ext_srst_handler(struct kvm_vcpu *vcpu,
 			kvm_riscv_vcpu_sbi_system_reset(vcpu, run,
 						KVM_SYSTEM_EVENT_SHUTDOWN,
 						reason);
-			*exit = true;
+			retdata->uexit = true;
 			break;
 		case SBI_SRST_RESET_TYPE_COLD_REBOOT:
 		case SBI_SRST_RESET_TYPE_WARM_REBOOT:
 			kvm_riscv_vcpu_sbi_system_reset(vcpu, run,
 						KVM_SYSTEM_EVENT_RESET,
 						reason);
-			*exit = true;
+			retdata->uexit = true;
 			break;
 		default:
-			ret = -EOPNOTSUPP;
+			retdata->err_val = SBI_ERR_NOT_SUPPORTED;
 		}
 		break;
 	default:
-		ret = -EOPNOTSUPP;
+		retdata->err_val = SBI_ERR_NOT_SUPPORTED;
 	}
 
-	return ret;
+	return 0;
 }
 
 const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_srst = {