diff mbox series

[2/5] lib: sbi: add Ssdbltrp ISA extension support

Message ID 20240912121052.2959596-3-cleger@rivosinc.com
State Superseded
Headers show
Series lib: sbi: add Ssdbltrp and Smdbltrp ISA extensions | expand

Commit Message

Clément Léger Sept. 12, 2024, 12:10 p.m. UTC 
Add Ssdbltrp trap handler support for S-mode double trap handling. If
the trap is received while in VS-mode, then the trap is redirected to
S-mode. If caught while in HS-mode, then a double trap SSE event is
delivered.

Signed-off-by: Clément Léger <cleger@rivosinc.com>
---
 include/sbi/riscv_encoding.h      |  2 ++
 include/sbi/sbi_ecall_interface.h |  2 ++
 include/sbi/sbi_hart.h            |  3 ++-
 include/sbi/sbi_trap_ldst.h       |  2 ++
 lib/sbi/objects.mk                |  1 +
 lib/sbi/sbi_double_trap.c         | 26 ++++++++++++++++++++++++++
 lib/sbi/sbi_hart.c                |  4 ++++
 lib/sbi/sbi_sse.c                 |  1 +
 lib/sbi/sbi_trap.c                |  4 ++++
 9 files changed, 44 insertions(+), 1 deletion(-)
 create mode 100644 lib/sbi/sbi_double_trap.c

Comments

Samuel Holland Sept. 12, 2024, 11:22 p.m. UTC | #1 
On 2024-09-12 7:10 AM, Clément Léger wrote:
> Add Ssdbltrp trap handler support for S-mode double trap handling. If
> the trap is received while in VS-mode, then the trap is redirected to
> S-mode. If caught while in HS-mode, then a double trap SSE event is
> delivered.
> 
> Signed-off-by: Clément Léger <cleger@rivosinc.com>
> ---
>  include/sbi/riscv_encoding.h      |  2 ++
>  include/sbi/sbi_ecall_interface.h |  2 ++
>  include/sbi/sbi_hart.h            |  3 ++-
>  include/sbi/sbi_trap_ldst.h       |  2 ++
>  lib/sbi/objects.mk                |  1 +
>  lib/sbi/sbi_double_trap.c         | 26 ++++++++++++++++++++++++++
>  lib/sbi/sbi_hart.c                |  4 ++++
>  lib/sbi/sbi_sse.c                 |  1 +
>  lib/sbi/sbi_trap.c                |  4 ++++
>  9 files changed, 44 insertions(+), 1 deletion(-)
>  create mode 100644 lib/sbi/sbi_double_trap.c
> 
> diff --git a/include/sbi/riscv_encoding.h b/include/sbi/riscv_encoding.h
> index 2e4391f..4728c63 100644
> --- a/include/sbi/riscv_encoding.h
> +++ b/include/sbi/riscv_encoding.h
> @@ -213,6 +213,7 @@
>  #define ENVCFG_PBMTE			(_ULL(1) << 62)
>  #define ENVCFG_ADUE			(_ULL(1) << 61)
>  #define ENVCFG_CDE			(_ULL(1) << 60)
> +#define ENVCFG_DTE			(_ULL(1) << 59)
>  #define ENVCFG_CBZE			(_UL(1) << 7)
>  #define ENVCFG_CBCFE			(_UL(1) << 6)
>  #define ENVCFG_CBIE_SHIFT		4
> @@ -763,6 +764,7 @@
>  #define CAUSE_FETCH_PAGE_FAULT		0xc
>  #define CAUSE_LOAD_PAGE_FAULT		0xd
>  #define CAUSE_STORE_PAGE_FAULT		0xf
> +#define CAUSE_DOUBLE_TRAP		0x10
>  #define CAUSE_FETCH_GUEST_PAGE_FAULT	0x14
>  #define CAUSE_LOAD_GUEST_PAGE_FAULT	0x15
>  #define CAUSE_VIRTUAL_INST_FAULT	0x16
> diff --git a/include/sbi/sbi_ecall_interface.h b/include/sbi/sbi_ecall_interface.h
> index e9a8167..d8077a7 100644
> --- a/include/sbi/sbi_ecall_interface.h
> +++ b/include/sbi/sbi_ecall_interface.h
> @@ -379,7 +379,9 @@ enum sbi_sse_state {
>  
>  /* SBI SSE Event IDs. */
>  #define SBI_SSE_EVENT_LOCAL_RAS			0x00000000
> +#define SBI_SSE_EVENT_LOCAL_DOUBLE_TRAP		0x00000001
>  #define SBI_SSE_EVENT_LOCAL_PLAT_0_START	0x00004000
> +#define	SBI_SSE_EVENT_LOCAL_PLAT_0_START	0x00004000

This duplicate definition looks like it was added accidentally. With this line
removed:

Reviewed-by: Samuel Holland <samuel.holland@sifive.com>

>  #define SBI_SSE_EVENT_LOCAL_PLAT_0_END		0x00007fff
>  #define SBI_SSE_EVENT_GLOBAL_RAS		0x00008000
>  #define SBI_SSE_EVENT_GLOBAL_PLAT_0_START	0x00004000
> diff --git a/include/sbi/sbi_hart.h b/include/sbi/sbi_hart.h
> index 81ec061..8aef2a1 100644
> --- a/include/sbi/sbi_hart.h
> +++ b/include/sbi/sbi_hart.h
> @@ -67,7 +67,8 @@ enum sbi_hart_extensions {
>  	SBI_HART_EXT_SVADE,
>  	/** Hart has Svadu extension */
>  	SBI_HART_EXT_SVADU,
> -
> +	/** Hart has Ssdbltrp extension */
> +	SBI_HART_EXT_SSDBLTRP,
>  	/** Maximum index of Hart extension */
>  	SBI_HART_EXT_MAX,
>  };
> diff --git a/include/sbi/sbi_trap_ldst.h b/include/sbi/sbi_trap_ldst.h
> index 8aee316..4c5cc37 100644
> --- a/include/sbi/sbi_trap_ldst.h
> +++ b/include/sbi/sbi_trap_ldst.h
> @@ -28,4 +28,6 @@ int sbi_load_access_handler(struct sbi_trap_context *tcntx);
>  
>  int sbi_store_access_handler(struct sbi_trap_context *tcntx);
>  
> +int sbi_double_trap_handler(struct sbi_trap_context *tcntx);
> +
>  #endif
> diff --git a/lib/sbi/objects.mk b/lib/sbi/objects.mk
> index 535aa70..7be943f 100644
> --- a/lib/sbi/objects.mk
> +++ b/lib/sbi/objects.mk
> @@ -66,6 +66,7 @@ libsbi-objs-y += sbi_bitops.o
>  libsbi-objs-y += sbi_console.o
>  libsbi-objs-y += sbi_domain_context.o
>  libsbi-objs-y += sbi_domain.o
> +libsbi-objs-y += sbi_double_trap.o
>  libsbi-objs-y += sbi_emulate_csr.o
>  libsbi-objs-y += sbi_fifo.o
>  libsbi-objs-y += sbi_fwft.o
> diff --git a/lib/sbi/sbi_double_trap.c b/lib/sbi/sbi_double_trap.c
> new file mode 100644
> index 0000000..af3c991
> --- /dev/null
> +++ b/lib/sbi/sbi_double_trap.c
> @@ -0,0 +1,26 @@
> +/*
> + * SPDX-License-Identifier: BSD-2-Clause
> + *
> + * Copyright (c) 2024 Rivos Inc.
> + *
> + * Authors:
> + *   Clément Léger <clement.leger@rivosinc.com>
> + */
> +
> +#include <sbi/sbi_console.h>
> +#include <sbi/sbi_ecall_interface.h>
> +#include <sbi/sbi_sse.h>
> +#include <sbi/sbi_trap.h>
> +
> +int sbi_double_trap_handler(struct sbi_trap_context *tcntx)
> +{
> +	struct sbi_trap_regs *regs = &tcntx->regs;
> +	const struct sbi_trap_info *trap = &tcntx->trap;
> +	bool prev_virt = sbi_regs_from_virt(regs);
> +
> +	/* Exception was taken in VS-mode, redirect it to S-mode */
> +	if (prev_virt)
> +		return sbi_trap_redirect(regs, trap);
> +
> +	return sbi_sse_inject_event(SBI_SSE_EVENT_LOCAL_DOUBLE_TRAP);
> +}
> diff --git a/lib/sbi/sbi_hart.c b/lib/sbi/sbi_hart.c
> index cc364fa..d6b9a0a 100644
> --- a/lib/sbi/sbi_hart.c
> +++ b/lib/sbi/sbi_hart.c
> @@ -117,6 +117,9 @@ static void mstatus_init(struct sbi_scratch *scratch)
>  		menvcfg_val |= ((uint64_t)csr_read(CSR_MENVCFGH)) << 32;
>  #endif
>  
> +		/* Disable double trap by default */
> +		menvcfg_val &= ~ENVCFG_DTE;
> +
>  #define __set_menvcfg_ext(__ext, __bits)				\
>  		if (sbi_hart_has_extension(scratch, __ext))		\
>  			menvcfg_val |= __bits;
> @@ -680,6 +683,7 @@ const struct sbi_hart_ext_data sbi_hart_ext[] = {
>  	__SBI_HART_EXT_DATA(ssccfg, SBI_HART_EXT_SSCCFG),
>  	__SBI_HART_EXT_DATA(svade, SBI_HART_EXT_SVADE),
>  	__SBI_HART_EXT_DATA(svadu, SBI_HART_EXT_SVADU),
> +	__SBI_HART_EXT_DATA(ssdbltrp, SBI_HART_EXT_SSDBLTRP),
>  };
>  
>  _Static_assert(SBI_HART_EXT_MAX == array_size(sbi_hart_ext),
> diff --git a/lib/sbi/sbi_sse.c b/lib/sbi/sbi_sse.c
> index 52172fc..b5f076a 100644
> --- a/lib/sbi/sbi_sse.c
> +++ b/lib/sbi/sbi_sse.c
> @@ -41,6 +41,7 @@
>  
>  static const uint32_t supported_events[] = {
>  	SBI_SSE_EVENT_LOCAL_RAS,
> +	SBI_SSE_EVENT_LOCAL_DOUBLE_TRAP,
>  	SBI_SSE_EVENT_GLOBAL_RAS,
>  	SBI_SSE_EVENT_LOCAL_PMU,
>  	SBI_SSE_EVENT_LOCAL_SOFTWARE,
> diff --git a/lib/sbi/sbi_trap.c b/lib/sbi/sbi_trap.c
> index 8bd2183..188f2a5 100644
> --- a/lib/sbi/sbi_trap.c
> +++ b/lib/sbi/sbi_trap.c
> @@ -330,6 +330,10 @@ struct sbi_trap_context *sbi_trap_handler(struct sbi_trap_context *tcntx)
>  		rc  = sbi_store_access_handler(tcntx);
>  		msg = "store fault handler failed";
>  		break;
> +	case CAUSE_DOUBLE_TRAP:
> +		rc  = sbi_double_trap_handler(tcntx);
> +		msg = "double trap handler failed";
> +		break;
>  	default:
>  		/* If the trap came from S or U mode, redirect it there */
>  		msg = "trap redirect failed";
Clément Léger Sept. 13, 2024, 6:34 a.m. UTC | #2 
On 13/09/2024 01:22, Samuel Holland wrote:
> On 2024-09-12 7:10 AM, Clément Léger wrote:
>> Add Ssdbltrp trap handler support for S-mode double trap handling. If
>> the trap is received while in VS-mode, then the trap is redirected to
>> S-mode. If caught while in HS-mode, then a double trap SSE event is
>> delivered.
>>
>> Signed-off-by: Clément Léger <cleger@rivosinc.com>
>> ---
>>  include/sbi/riscv_encoding.h      |  2 ++
>>  include/sbi/sbi_ecall_interface.h |  2 ++
>>  include/sbi/sbi_hart.h            |  3 ++-
>>  include/sbi/sbi_trap_ldst.h       |  2 ++
>>  lib/sbi/objects.mk                |  1 +
>>  lib/sbi/sbi_double_trap.c         | 26 ++++++++++++++++++++++++++
>>  lib/sbi/sbi_hart.c                |  4 ++++
>>  lib/sbi/sbi_sse.c                 |  1 +
>>  lib/sbi/sbi_trap.c                |  4 ++++
>>  9 files changed, 44 insertions(+), 1 deletion(-)
>>  create mode 100644 lib/sbi/sbi_double_trap.c
>>
>> diff --git a/include/sbi/riscv_encoding.h b/include/sbi/riscv_encoding.h
>> index 2e4391f..4728c63 100644
>> --- a/include/sbi/riscv_encoding.h
>> +++ b/include/sbi/riscv_encoding.h
>> @@ -213,6 +213,7 @@
>>  #define ENVCFG_PBMTE			(_ULL(1) << 62)
>>  #define ENVCFG_ADUE			(_ULL(1) << 61)
>>  #define ENVCFG_CDE			(_ULL(1) << 60)
>> +#define ENVCFG_DTE			(_ULL(1) << 59)
>>  #define ENVCFG_CBZE			(_UL(1) << 7)
>>  #define ENVCFG_CBCFE			(_UL(1) << 6)
>>  #define ENVCFG_CBIE_SHIFT		4
>> @@ -763,6 +764,7 @@
>>  #define CAUSE_FETCH_PAGE_FAULT		0xc
>>  #define CAUSE_LOAD_PAGE_FAULT		0xd
>>  #define CAUSE_STORE_PAGE_FAULT		0xf
>> +#define CAUSE_DOUBLE_TRAP		0x10
>>  #define CAUSE_FETCH_GUEST_PAGE_FAULT	0x14
>>  #define CAUSE_LOAD_GUEST_PAGE_FAULT	0x15
>>  #define CAUSE_VIRTUAL_INST_FAULT	0x16
>> diff --git a/include/sbi/sbi_ecall_interface.h b/include/sbi/sbi_ecall_interface.h
>> index e9a8167..d8077a7 100644
>> --- a/include/sbi/sbi_ecall_interface.h
>> +++ b/include/sbi/sbi_ecall_interface.h
>> @@ -379,7 +379,9 @@ enum sbi_sse_state {
>>  
>>  /* SBI SSE Event IDs. */
>>  #define SBI_SSE_EVENT_LOCAL_RAS			0x00000000
>> +#define SBI_SSE_EVENT_LOCAL_DOUBLE_TRAP		0x00000001
>>  #define SBI_SSE_EVENT_LOCAL_PLAT_0_START	0x00004000
>> +#define	SBI_SSE_EVENT_LOCAL_PLAT_0_START	0x00004000
> 
> This duplicate definition looks like it was added accidentally. With this line
> removed:

Missed that indeed. Saw aswell that I added  SSE event definition in the
same commit. I'll probably split that commit and add the SSE event
definition + usage in the double trap handler in a separate commit.

Thanks,

Clément

> 
> Reviewed-by: Samuel Holland <samuel.holland@sifive.com>
> 
>>  #define SBI_SSE_EVENT_LOCAL_PLAT_0_END		0x00007fff
>>  #define SBI_SSE_EVENT_GLOBAL_RAS		0x00008000
>>  #define SBI_SSE_EVENT_GLOBAL_PLAT_0_START	0x00004000
>> diff --git a/include/sbi/sbi_hart.h b/include/sbi/sbi_hart.h
>> index 81ec061..8aef2a1 100644
>> --- a/include/sbi/sbi_hart.h
>> +++ b/include/sbi/sbi_hart.h
>> @@ -67,7 +67,8 @@ enum sbi_hart_extensions {
>>  	SBI_HART_EXT_SVADE,
>>  	/** Hart has Svadu extension */
>>  	SBI_HART_EXT_SVADU,
>> -
>> +	/** Hart has Ssdbltrp extension */
>> +	SBI_HART_EXT_SSDBLTRP,
>>  	/** Maximum index of Hart extension */
>>  	SBI_HART_EXT_MAX,
>>  };
>> diff --git a/include/sbi/sbi_trap_ldst.h b/include/sbi/sbi_trap_ldst.h
>> index 8aee316..4c5cc37 100644
>> --- a/include/sbi/sbi_trap_ldst.h
>> +++ b/include/sbi/sbi_trap_ldst.h
>> @@ -28,4 +28,6 @@ int sbi_load_access_handler(struct sbi_trap_context *tcntx);
>>  
>>  int sbi_store_access_handler(struct sbi_trap_context *tcntx);
>>  
>> +int sbi_double_trap_handler(struct sbi_trap_context *tcntx);
>> +
>>  #endif
>> diff --git a/lib/sbi/objects.mk b/lib/sbi/objects.mk
>> index 535aa70..7be943f 100644
>> --- a/lib/sbi/objects.mk
>> +++ b/lib/sbi/objects.mk
>> @@ -66,6 +66,7 @@ libsbi-objs-y += sbi_bitops.o
>>  libsbi-objs-y += sbi_console.o
>>  libsbi-objs-y += sbi_domain_context.o
>>  libsbi-objs-y += sbi_domain.o
>> +libsbi-objs-y += sbi_double_trap.o
>>  libsbi-objs-y += sbi_emulate_csr.o
>>  libsbi-objs-y += sbi_fifo.o
>>  libsbi-objs-y += sbi_fwft.o
>> diff --git a/lib/sbi/sbi_double_trap.c b/lib/sbi/sbi_double_trap.c
>> new file mode 100644
>> index 0000000..af3c991
>> --- /dev/null
>> +++ b/lib/sbi/sbi_double_trap.c
>> @@ -0,0 +1,26 @@
>> +/*
>> + * SPDX-License-Identifier: BSD-2-Clause
>> + *
>> + * Copyright (c) 2024 Rivos Inc.
>> + *
>> + * Authors:
>> + *   Clément Léger <clement.leger@rivosinc.com>
>> + */
>> +
>> +#include <sbi/sbi_console.h>
>> +#include <sbi/sbi_ecall_interface.h>
>> +#include <sbi/sbi_sse.h>
>> +#include <sbi/sbi_trap.h>
>> +
>> +int sbi_double_trap_handler(struct sbi_trap_context *tcntx)
>> +{
>> +	struct sbi_trap_regs *regs = &tcntx->regs;
>> +	const struct sbi_trap_info *trap = &tcntx->trap;
>> +	bool prev_virt = sbi_regs_from_virt(regs);
>> +
>> +	/* Exception was taken in VS-mode, redirect it to S-mode */
>> +	if (prev_virt)
>> +		return sbi_trap_redirect(regs, trap);
>> +
>> +	return sbi_sse_inject_event(SBI_SSE_EVENT_LOCAL_DOUBLE_TRAP);
>> +}
>> diff --git a/lib/sbi/sbi_hart.c b/lib/sbi/sbi_hart.c
>> index cc364fa..d6b9a0a 100644
>> --- a/lib/sbi/sbi_hart.c
>> +++ b/lib/sbi/sbi_hart.c
>> @@ -117,6 +117,9 @@ static void mstatus_init(struct sbi_scratch *scratch)
>>  		menvcfg_val |= ((uint64_t)csr_read(CSR_MENVCFGH)) << 32;
>>  #endif
>>  
>> +		/* Disable double trap by default */
>> +		menvcfg_val &= ~ENVCFG_DTE;
>> +
>>  #define __set_menvcfg_ext(__ext, __bits)				\
>>  		if (sbi_hart_has_extension(scratch, __ext))		\
>>  			menvcfg_val |= __bits;
>> @@ -680,6 +683,7 @@ const struct sbi_hart_ext_data sbi_hart_ext[] = {
>>  	__SBI_HART_EXT_DATA(ssccfg, SBI_HART_EXT_SSCCFG),
>>  	__SBI_HART_EXT_DATA(svade, SBI_HART_EXT_SVADE),
>>  	__SBI_HART_EXT_DATA(svadu, SBI_HART_EXT_SVADU),
>> +	__SBI_HART_EXT_DATA(ssdbltrp, SBI_HART_EXT_SSDBLTRP),
>>  };
>>  
>>  _Static_assert(SBI_HART_EXT_MAX == array_size(sbi_hart_ext),
>> diff --git a/lib/sbi/sbi_sse.c b/lib/sbi/sbi_sse.c
>> index 52172fc..b5f076a 100644
>> --- a/lib/sbi/sbi_sse.c
>> +++ b/lib/sbi/sbi_sse.c
>> @@ -41,6 +41,7 @@
>>  
>>  static const uint32_t supported_events[] = {
>>  	SBI_SSE_EVENT_LOCAL_RAS,
>> +	SBI_SSE_EVENT_LOCAL_DOUBLE_TRAP,
>>  	SBI_SSE_EVENT_GLOBAL_RAS,
>>  	SBI_SSE_EVENT_LOCAL_PMU,
>>  	SBI_SSE_EVENT_LOCAL_SOFTWARE,
>> diff --git a/lib/sbi/sbi_trap.c b/lib/sbi/sbi_trap.c
>> index 8bd2183..188f2a5 100644
>> --- a/lib/sbi/sbi_trap.c
>> +++ b/lib/sbi/sbi_trap.c
>> @@ -330,6 +330,10 @@ struct sbi_trap_context *sbi_trap_handler(struct sbi_trap_context *tcntx)
>>  		rc  = sbi_store_access_handler(tcntx);
>>  		msg = "store fault handler failed";
>>  		break;
>> +	case CAUSE_DOUBLE_TRAP:
>> +		rc  = sbi_double_trap_handler(tcntx);
>> +		msg = "double trap handler failed";
>> +		break;
>>  	default:
>>  		/* If the trap came from S or U mode, redirect it there */
>>  		msg = "trap redirect failed";
>
diff mbox series

Patch

diff --git a/include/sbi/riscv_encoding.h b/include/sbi/riscv_encoding.h
index 2e4391f..4728c63 100644
--- a/include/sbi/riscv_encoding.h
+++ b/include/sbi/riscv_encoding.h
@@ -213,6 +213,7 @@ 
 #define ENVCFG_PBMTE			(_ULL(1) << 62)
 #define ENVCFG_ADUE			(_ULL(1) << 61)
 #define ENVCFG_CDE			(_ULL(1) << 60)
+#define ENVCFG_DTE			(_ULL(1) << 59)
 #define ENVCFG_CBZE			(_UL(1) << 7)
 #define ENVCFG_CBCFE			(_UL(1) << 6)
 #define ENVCFG_CBIE_SHIFT		4
@@ -763,6 +764,7 @@ 
 #define CAUSE_FETCH_PAGE_FAULT		0xc
 #define CAUSE_LOAD_PAGE_FAULT		0xd
 #define CAUSE_STORE_PAGE_FAULT		0xf
+#define CAUSE_DOUBLE_TRAP		0x10
 #define CAUSE_FETCH_GUEST_PAGE_FAULT	0x14
 #define CAUSE_LOAD_GUEST_PAGE_FAULT	0x15
 #define CAUSE_VIRTUAL_INST_FAULT	0x16
diff --git a/include/sbi/sbi_ecall_interface.h b/include/sbi/sbi_ecall_interface.h
index e9a8167..d8077a7 100644
--- a/include/sbi/sbi_ecall_interface.h
+++ b/include/sbi/sbi_ecall_interface.h
@@ -379,7 +379,9 @@  enum sbi_sse_state {
 
 /* SBI SSE Event IDs. */
 #define SBI_SSE_EVENT_LOCAL_RAS			0x00000000
+#define SBI_SSE_EVENT_LOCAL_DOUBLE_TRAP		0x00000001
 #define SBI_SSE_EVENT_LOCAL_PLAT_0_START	0x00004000
+#define	SBI_SSE_EVENT_LOCAL_PLAT_0_START	0x00004000
 #define SBI_SSE_EVENT_LOCAL_PLAT_0_END		0x00007fff
 #define SBI_SSE_EVENT_GLOBAL_RAS		0x00008000
 #define SBI_SSE_EVENT_GLOBAL_PLAT_0_START	0x00004000
diff --git a/include/sbi/sbi_hart.h b/include/sbi/sbi_hart.h
index 81ec061..8aef2a1 100644
--- a/include/sbi/sbi_hart.h
+++ b/include/sbi/sbi_hart.h
@@ -67,7 +67,8 @@  enum sbi_hart_extensions {
 	SBI_HART_EXT_SVADE,
 	/** Hart has Svadu extension */
 	SBI_HART_EXT_SVADU,
-
+	/** Hart has Ssdbltrp extension */
+	SBI_HART_EXT_SSDBLTRP,
 	/** Maximum index of Hart extension */
 	SBI_HART_EXT_MAX,
 };
diff --git a/include/sbi/sbi_trap_ldst.h b/include/sbi/sbi_trap_ldst.h
index 8aee316..4c5cc37 100644
--- a/include/sbi/sbi_trap_ldst.h
+++ b/include/sbi/sbi_trap_ldst.h
@@ -28,4 +28,6 @@  int sbi_load_access_handler(struct sbi_trap_context *tcntx);
 
 int sbi_store_access_handler(struct sbi_trap_context *tcntx);
 
+int sbi_double_trap_handler(struct sbi_trap_context *tcntx);
+
 #endif
diff --git a/lib/sbi/objects.mk b/lib/sbi/objects.mk
index 535aa70..7be943f 100644
--- a/lib/sbi/objects.mk
+++ b/lib/sbi/objects.mk
@@ -66,6 +66,7 @@  libsbi-objs-y += sbi_bitops.o
 libsbi-objs-y += sbi_console.o
 libsbi-objs-y += sbi_domain_context.o
 libsbi-objs-y += sbi_domain.o
+libsbi-objs-y += sbi_double_trap.o
 libsbi-objs-y += sbi_emulate_csr.o
 libsbi-objs-y += sbi_fifo.o
 libsbi-objs-y += sbi_fwft.o
diff --git a/lib/sbi/sbi_double_trap.c b/lib/sbi/sbi_double_trap.c
new file mode 100644
index 0000000..af3c991
--- /dev/null
+++ b/lib/sbi/sbi_double_trap.c
@@ -0,0 +1,26 @@ 
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2024 Rivos Inc.
+ *
+ * Authors:
+ *   Clément Léger <clement.leger@rivosinc.com>
+ */
+
+#include <sbi/sbi_console.h>
+#include <sbi/sbi_ecall_interface.h>
+#include <sbi/sbi_sse.h>
+#include <sbi/sbi_trap.h>
+
+int sbi_double_trap_handler(struct sbi_trap_context *tcntx)
+{
+	struct sbi_trap_regs *regs = &tcntx->regs;
+	const struct sbi_trap_info *trap = &tcntx->trap;
+	bool prev_virt = sbi_regs_from_virt(regs);
+
+	/* Exception was taken in VS-mode, redirect it to S-mode */
+	if (prev_virt)
+		return sbi_trap_redirect(regs, trap);
+
+	return sbi_sse_inject_event(SBI_SSE_EVENT_LOCAL_DOUBLE_TRAP);
+}
diff --git a/lib/sbi/sbi_hart.c b/lib/sbi/sbi_hart.c
index cc364fa..d6b9a0a 100644
--- a/lib/sbi/sbi_hart.c
+++ b/lib/sbi/sbi_hart.c
@@ -117,6 +117,9 @@  static void mstatus_init(struct sbi_scratch *scratch)
 		menvcfg_val |= ((uint64_t)csr_read(CSR_MENVCFGH)) << 32;
 #endif
 
+		/* Disable double trap by default */
+		menvcfg_val &= ~ENVCFG_DTE;
+
 #define __set_menvcfg_ext(__ext, __bits)				\
 		if (sbi_hart_has_extension(scratch, __ext))		\
 			menvcfg_val |= __bits;
@@ -680,6 +683,7 @@  const struct sbi_hart_ext_data sbi_hart_ext[] = {
 	__SBI_HART_EXT_DATA(ssccfg, SBI_HART_EXT_SSCCFG),
 	__SBI_HART_EXT_DATA(svade, SBI_HART_EXT_SVADE),
 	__SBI_HART_EXT_DATA(svadu, SBI_HART_EXT_SVADU),
+	__SBI_HART_EXT_DATA(ssdbltrp, SBI_HART_EXT_SSDBLTRP),
 };
 
 _Static_assert(SBI_HART_EXT_MAX == array_size(sbi_hart_ext),
diff --git a/lib/sbi/sbi_sse.c b/lib/sbi/sbi_sse.c
index 52172fc..b5f076a 100644
--- a/lib/sbi/sbi_sse.c
+++ b/lib/sbi/sbi_sse.c
@@ -41,6 +41,7 @@ 
 
 static const uint32_t supported_events[] = {
 	SBI_SSE_EVENT_LOCAL_RAS,
+	SBI_SSE_EVENT_LOCAL_DOUBLE_TRAP,
 	SBI_SSE_EVENT_GLOBAL_RAS,
 	SBI_SSE_EVENT_LOCAL_PMU,
 	SBI_SSE_EVENT_LOCAL_SOFTWARE,
diff --git a/lib/sbi/sbi_trap.c b/lib/sbi/sbi_trap.c
index 8bd2183..188f2a5 100644
--- a/lib/sbi/sbi_trap.c
+++ b/lib/sbi/sbi_trap.c
@@ -330,6 +330,10 @@  struct sbi_trap_context *sbi_trap_handler(struct sbi_trap_context *tcntx)
 		rc  = sbi_store_access_handler(tcntx);
 		msg = "store fault handler failed";
 		break;
+	case CAUSE_DOUBLE_TRAP:
+		rc  = sbi_double_trap_handler(tcntx);
+		msg = "double trap handler failed";
+		break;
 	default:
 		/* If the trap came from S or U mode, redirect it there */
 		msg = "trap redirect failed";