Re: [PATCH v2] target/riscv/kvm/kvm-cpu.c: kvm_riscv_handle_sbi() fail with vendor-specific SBI

[Andrew Jones <ajones@ventanamicro.com>]

On Mon, Mar 25, 2024 at 04:01:16PM +0300, Alexei Filippov wrote:
> kvm_riscv_handle_sbi() may return not supported return code to not trigger
> qemu abort with vendor-specific sbi.
> 
> Added SBI related return code's defines.
> 
> Signed-off-by: Alexei Filippov <alexei.filippov@syntacore.com>
> Fixes: 4eb47125 ("target/riscv: Handle KVM_EXIT_RISCV_SBI exit")
> Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
> ---
> 
> Changes since v1:
>         -Add Fixes and Revied-by lines.
>  target/riscv/kvm/kvm-cpu.c         |  5 +++--
>  target/riscv/sbi_ecall_interface.h | 11 +++++++++++
>  2 files changed, 14 insertions(+), 2 deletions(-)
> 
> diff --git a/target/riscv/kvm/kvm-cpu.c b/target/riscv/kvm/kvm-cpu.c
> index 6a6c6cae80..a4f84ad950 100644
> --- a/target/riscv/kvm/kvm-cpu.c
> +++ b/target/riscv/kvm/kvm-cpu.c
> @@ -1404,7 +1404,7 @@ static int kvm_riscv_handle_sbi(CPUState *cs, struct kvm_run *run)
>          if (ret == sizeof(ch)) {
>              run->riscv_sbi.ret[0] = ch;
>          } else {
> -            run->riscv_sbi.ret[0] = -1;
> +            run->riscv_sbi.ret[0] = SBI_ERR_FAILURE;
>          }
>          ret = 0;
>          break;
> @@ -1412,7 +1412,8 @@ static int kvm_riscv_handle_sbi(CPUState *cs, struct kvm_run *run)
>          qemu_log_mask(LOG_UNIMP,
>                        "%s: un-handled SBI EXIT, specific reasons is %lu\n",
>                        __func__, run->riscv_sbi.extension_id);

While changing this, can we also change this log to something like

 "%s: Unhandled SBI exit with extension-id %lu\n", __func__, run->riscv_sbi.extension_id


> -        ret = -1;
> +        run->riscv_sbi.ret[0] = SBI_ERR_NOT_SUPPORTED;
> +        ret = 0;

We don't have any paths that set ret to anything other than zero now.
Let's return zero at the bottom of the function instead. And the top
of the function can then be cleaned up to

 unsigned char ch;
 int ret;

 switch (run->riscv_sbi.extension_id) {


>          break;
>      }
>      return ret;
> diff --git a/target/riscv/sbi_ecall_interface.h b/target/riscv/sbi_ecall_interface.h
> index 43899d08f6..0279e92a36 100644
> --- a/target/riscv/sbi_ecall_interface.h
> +++ b/target/riscv/sbi_ecall_interface.h
> @@ -69,4 +69,15 @@
>  #define SBI_EXT_VENDOR_END              0x09FFFFFF
>  /* clang-format on */
>  
> +/* SBI return error codes */
> +#define SBI_SUCCESS                  0
> +#define SBI_ERR_FAILURE             -1
> +#define SBI_ERR_NOT_SUPPORTED       -2
> +#define SBI_ERR_INVALID_PARAM       -3
> +#define SBI_ERR_DENIED              -4
> +#define SBI_ERR_INVALID_ADDRESS     -5
> +#define SBI_ERR_ALREADY_AVAILABLE   -6
> +#define SBI_ERR_ALREADY_STARTED     -7
> +#define SBI_ERR_ALREADY_STOPPED     -8

v2 of the spec has SBI_ERR_NO_SHMEM as well.

Thanks,
drew

> +
>  #endif
> -- 
> 2.34.1
> 
>