[PATCH 6/6] lib: sbi: sse: Add support for SSTATUS.SDT

[Andrew Jones]

On Mon, Mar 17, 2025 at 11:54:24AM +0100, Clément Léger wrote:
> Similarly to what is done for SPELP, handle SSTATUS.SDT upon event
> injection. In order to mimick an interrupt, set SDT to 1 for injection and
> save its previous value in interrupted_flags[5:5]. Restore it upon
> completion.
> 
> Signed-off-by: Clément Léger <cleger at rivosinc.com>
> ---
>  include/sbi/riscv_encoding.h      |  3 ++-
>  include/sbi/sbi_ecall_interface.h |  1 +
>  lib/sbi/sbi_sse.c                 | 12 ++++++++++--
>  3 files changed, 13 insertions(+), 3 deletions(-)
> 
> diff --git a/include/sbi/riscv_encoding.h b/include/sbi/riscv_encoding.h
> index 03c68a57..84d3c17b 100644
> --- a/include/sbi/riscv_encoding.h
> +++ b/include/sbi/riscv_encoding.h
> @@ -32,7 +32,8 @@
>  #define MSTATUS_TVM			_UL(0x00100000)
>  #define MSTATUS_TW			_UL(0x00200000)
>  #define MSTATUS_TSR			_UL(0x00400000)
> -#define MSTATUS_SPELP		_UL(0x00800000)
> +#define MSTATUS_SPELP			_UL(0x00800000)
> +#define MSTATUS_SDT			_UL(0x01000000)
>  #define MSTATUS32_SD			_UL(0x80000000)
>  #if __riscv_xlen == 64
>  #define MSTATUS_UXL			_ULL(0x0000000300000000)
> diff --git a/include/sbi/sbi_ecall_interface.h b/include/sbi/sbi_ecall_interface.h
> index a93e61fa..3d8bbcf3 100644
> --- a/include/sbi/sbi_ecall_interface.h
> +++ b/include/sbi/sbi_ecall_interface.h
> @@ -385,6 +385,7 @@ enum sbi_sse_attr_id {
>  #define SBI_SSE_ATTR_INTERRUPTED_FLAGS_HSTATUS_SPV	BIT(2)
>  #define SBI_SSE_ATTR_INTERRUPTED_FLAGS_HSTATUS_SPVP	BIT(3)
>  #define SBI_SSE_ATTR_INTERRUPTED_FLAGS_SSTATUS_SPELP	BIT(4)
> +#define SBI_SSE_ATTR_INTERRUPTED_FLAGS_SSTATUS_SDT	BIT(5)
>  
>  enum sbi_sse_state {
>  	SBI_SSE_STATE_UNUSED		= 0,
> diff --git a/lib/sbi/sbi_sse.c b/lib/sbi/sbi_sse.c
> index a45d3eeb..79c5bdb4 100644
> --- a/lib/sbi/sbi_sse.c
> +++ b/lib/sbi/sbi_sse.c
> @@ -431,7 +431,8 @@ static int sse_event_set_attr_check(struct sbi_sse_event *e, uint32_t attr_id,
>  			    SBI_SSE_ATTR_INTERRUPTED_FLAGS_SSTATUS_SPIE |
>  			    SBI_SSE_ATTR_INTERRUPTED_FLAGS_HSTATUS_SPV |
>  			    SBI_SSE_ATTR_INTERRUPTED_FLAGS_HSTATUS_SPVP |
> -			    SBI_SSE_ATTR_INTERRUPTED_FLAGS_SSTATUS_SPELP))
> +			    SBI_SSE_ATTR_INTERRUPTED_FLAGS_SSTATUS_SPELP |
> +			    SBI_SSE_ATTR_INTERRUPTED_FLAGS_SSTATUS_SDT))
>  			return SBI_EINVAL;
>  		__attribute__((__fallthrough__));
>  	case SBI_SSE_ATTR_INTERRUPTED_SEPC:
> @@ -519,6 +520,8 @@ static unsigned long sse_interrupted_flags(unsigned long mstatus)
>  		flags |= SBI_SSE_ATTR_INTERRUPTED_FLAGS_SSTATUS_SPP;
>  	if (mstatus & (MSTATUS_SPELP))
>  		flags |= SBI_SSE_ATTR_INTERRUPTED_FLAGS_SSTATUS_SPELP;
> +	if (mstatus & (MSTATUS_SDT))
> +		flags |= SBI_SSE_ATTR_INTERRUPTED_FLAGS_SSTATUS_SDT;
>  
>  	if (misa_extension('H')) {
>  		hstatus = csr_read(CSR_HSTATUS);
> @@ -578,10 +581,11 @@ static void sse_event_inject(struct sbi_sse_event *e,
>  
>  	/*
>  	 * Return to S-mode with virtualization disabled, no expected landing
> -	 * pad.
> +	 * pad, supervisor trap disabled.
>  	 */
>  	regs->mstatus &= ~(MSTATUS_MPP | MSTATUS_SIE | MSTATUS_SPELP);
>  	regs->mstatus |= (PRV_S << MSTATUS_MPP_SHIFT);
> +	regs->mstatus |= MSTATUS_SDT;
>  
>  #if __riscv_xlen == 64
>  	regs->mstatus &= ~MSTATUS_MPV;
> @@ -643,6 +647,10 @@ static void sse_event_resume(struct sbi_sse_event *e,
>  	if (i_ctx->flags & SBI_SSE_ATTR_INTERRUPTED_FLAGS_SSTATUS_SPELP)
>  		regs->mstatus |= MSTATUS_SPELP;
>  
> +	regs->mstatus &= ~MSTATUS_SDT;
> +	if (i_ctx->flags & SBI_SSE_ATTR_INTERRUPTED_FLAGS_SSTATUS_SDT)
> +		regs->mstatus |= MSTATUS_SDT;
> +
>  	regs->a7 = i_ctx->a7;
>  	regs->a6 = i_ctx->a6;
>  	csr_write(CSR_SEPC, i_ctx->sepc);
> -- 
> 2.47.2
>

Reviewed-by: Andrew Jones <ajones at ventanamicro.com>