diff mbox series

lib: add Enhanced PMP support

Message ID 20200805032944.936-1-Ethan.Lee.QNL@gmail.com
State Under Review
Delegated to: Atish Patra
Headers show
Series lib: add Enhanced PMP support | expand

Commit Message

Hongzheng-Li Aug. 5, 2020, 3:29 a.m. UTC
From: Hongzheng-Li <ethan.lee.qnl@gmail.com>

The Enhanced PMP(ePMP) is used for memory access and execution prevention
on Machine mode.
The latest spec can be found here: https://docs.google.com/document/d/1Mh_aiHYxemL0umN3GTTw8vsbmzHZ_nxZXgjgOUzbvc8/edit?pli=1#heading=h.ab3kl2ch725u

Signed-off-by: Hongzheng-Li <ethan.lee.qnl@gmail.com>
Signed-off-by: Hou Weiying <weiying_hou@outlook.com>
---
 include/sbi/riscv_asm.h      |  4 ++++
 include/sbi/riscv_encoding.h |  1 +
 include/sbi/sbi_hart.h       |  9 ++++++---
 lib/sbi/riscv_asm.c          | 30 ++++++++++++++++++++++++++++++
 lib/sbi/sbi_hart.c           | 27 +++++++++++++++++++++++++++
 lib/sbi/sbi_init.c           |  1 +
 6 files changed, 69 insertions(+), 3 deletions(-)

Comments

Anup Patel Aug. 5, 2020, 3:46 a.m. UTC | #1
> -----Original Message-----
> From: opensbi <opensbi-bounces@lists.infradead.org> On Behalf Of
> Hongzheng-Li
> Sent: 05 August 2020 09:00
> To: opensbi@lists.infradead.org
> Cc: Hou Weiying <weiying_hou@outlook.com>; Hongzheng-Li
> <ethan.lee.qnl@gmail.com>
> Subject: [PATCH] lib: add Enhanced PMP support
> 
> From: Hongzheng-Li <ethan.lee.qnl@gmail.com>
> 
> The Enhanced PMP(ePMP) is used for memory access and execution
> prevention on Machine mode.
> The latest spec can be found here:
> https://docs.google.com/document/d/1Mh_aiHYxemL0umN3GTTw8vsbmzH
> Z_nxZXgjgOUzbvc8/edit?pli=1#heading=h.ab3kl2ch725u

As far as implementation goes, I only see only minor comments so no issues
on implementation part.

My concerns is the state of ePMP spec. My understanding is that ePMP is
still in draft state. We are fine with specs in draft state but spec should
be part of https://github.com/riscv/riscv-isa-manual (Just Hypervisor spec).

Another concerns is the mechanism to test this patch. We need some way
to test ePMP so we insist that someone please add QEMU emulation support
for ePMP. This will help users to test OpenSBI ePMP support on QEMU.

If above two concerns are addressed then we can certainly merge
ePMP support in OpenSBI.

Overall this is a good addition for OpenSBI. Thanks.

Regards,
Anup

> 
> Signed-off-by: Hongzheng-Li <ethan.lee.qnl@gmail.com>
> Signed-off-by: Hou Weiying <weiying_hou@outlook.com>
> ---
>  include/sbi/riscv_asm.h      |  4 ++++
>  include/sbi/riscv_encoding.h |  1 +
>  include/sbi/sbi_hart.h       |  9 ++++++---
>  lib/sbi/riscv_asm.c          | 30 ++++++++++++++++++++++++++++++
>  lib/sbi/sbi_hart.c           | 27 +++++++++++++++++++++++++++
>  lib/sbi/sbi_init.c           |  1 +
>  6 files changed, 69 insertions(+), 3 deletions(-)
> 
> diff --git a/include/sbi/riscv_asm.h b/include/sbi/riscv_asm.h index
> 6e093ca..badd8af 100644
> --- a/include/sbi/riscv_asm.h
> +++ b/include/sbi/riscv_asm.h
> @@ -182,6 +182,10 @@ int pmp_set(unsigned int n, unsigned long prot,
> unsigned long addr,  int pmp_get(unsigned int n, unsigned long *prot_out,
> unsigned long *addr_out,
>  	    unsigned long *size);
> 
> +int epmp_set(int rlb, int mmwp, int mml);
> +
> +int epmp_get(int *rlb, int *mmwp, int *mml);
> +
>  #endif /* !__ASSEMBLY__ */
> 
>  #endif
> diff --git a/include/sbi/riscv_encoding.h b/include/sbi/riscv_encoding.h
> index 827c86c..2052925 100644
> --- a/include/sbi/riscv_encoding.h
> +++ b/include/sbi/riscv_encoding.h
> @@ -279,6 +279,7 @@
>  #define CSR_PMPADDR13			0x3bd
>  #define CSR_PMPADDR14			0x3be
>  #define CSR_PMPADDR15			0x3bf
> +#define CSR_MSECCFG			0x390
>  #define CSR_TSELECT			0x7a0
>  #define CSR_TDATA1			0x7a1
>  #define CSR_TDATA2			0x7a2
> diff --git a/include/sbi/sbi_hart.h b/include/sbi/sbi_hart.h index
> 51c2c35..4ed882f 100644
> --- a/include/sbi/sbi_hart.h
> +++ b/include/sbi/sbi_hart.h
> @@ -16,12 +16,14 @@
>  enum sbi_hart_features {
>  	/** Hart has PMP support */
>  	SBI_HART_HAS_PMP = (1 << 0),
> +	/** enhanced PMP */
> +	SBI_HART_HAS_EPMP = (1 << 1),
>  	/** Hart has S-mode counter enable */
> -	SBI_HART_HAS_SCOUNTEREN = (1 << 1),
> +	SBI_HART_HAS_SCOUNTEREN = (1 << 2),
>  	/** Hart has M-mode counter enable */
> -	SBI_HART_HAS_MCOUNTEREN = (1 << 2),
> +	SBI_HART_HAS_MCOUNTEREN = (1 << 3),
>  	/** HART has timer csr implementation in hardware */
> -	SBI_HART_HAS_TIME = (1 << 3),
> +	SBI_HART_HAS_TIME = (1 << 4),
> 
>  	/** Last index of Hart features*/
>  	SBI_HART_HAS_LAST_FEATURE = SBI_HART_HAS_TIME, @@ -43,6
> +45,7 @@ int sbi_hart_pmp_get(struct sbi_scratch *scratch, unsigned int n,
>  		     unsigned long *prot_out, unsigned long *addr_out,
>  		     unsigned long *size);
>  void sbi_hart_pmp_dump(struct sbi_scratch *scratch);
> +void sbi_hart_epmp_dump(struct sbi_scratch *scratch);
>  int  sbi_hart_pmp_check_addr(struct sbi_scratch *scratch, unsigned long
> daddr,
>  			     unsigned long attr);
>  bool sbi_hart_has_feature(struct sbi_scratch *scratch, unsigned long
> feature); diff --git a/lib/sbi/riscv_asm.c b/lib/sbi/riscv_asm.c index
> 6dfebd9..4621f70 100644
> --- a/lib/sbi/riscv_asm.c
> +++ b/lib/sbi/riscv_asm.c
> @@ -349,3 +349,33 @@ int pmp_get(unsigned int n, unsigned long
> *prot_out, unsigned long *addr_out,
> 
>  	return 0;
>  }
> +
> +int epmp_set(int rlb, int mmwp, int mml) {
> +	unsigned long mseccfg;
> +
> +	if ((rlb | mmwp | mml) & ~1)
> +		return SBI_EINVAL;
> +
> +#if __riscv_xlen == 32 || __riscv_xlen == 64
> +	mseccfg = rlb << 2 | mmwp << 1 | mml;
> +#else
> +	mseccfg = -1;
> +#endif
> +	if (mseccfg < 0)
> +		return SBI_ENOTSUPP;
> +
> +	csr_write(CSR_MSECCFG, mseccfg);
> +
> +	return 0;
> +}
> +
> +int epmp_get(int *rlb, int *mmwp, int *mml) {
> +	unsigned long mseccfg = csr_read(CSR_MSECCFG);
> +	*rlb = (mseccfg >> 2) & 1;
> +	*mmwp = (mseccfg >> 1) & 1;
> +	*mml = mseccfg & 1;
> +
> +	return 0;
> +}
> diff --git a/lib/sbi/sbi_hart.c b/lib/sbi/sbi_hart.c index fa20bd2..c1c6957
> 100644
> --- a/lib/sbi/sbi_hart.c
> +++ b/lib/sbi/sbi_hart.c
> @@ -184,6 +184,18 @@ void sbi_hart_pmp_dump(struct sbi_scratch
> *scratch)
>  	}
>  }
> 
> +void sbi_hart_epmp_dump(struct sbi_scratch *scratch) {
> +	if (!sbi_hart_has_feature(scratch, SBI_HART_HAS_EPMP))
> +		return;
> +
> +	int rlb, mmwp, mml;
> +
> +	epmp_get(&rlb, &mmwp, &mml);
> +	sbi_printf("ePMP: RLB = %d, MMWP = %d, MML = %d\n",
> +				rlb, mmwp, mml);
> +}
> +
>  int sbi_hart_pmp_check_addr(struct sbi_scratch *scratch, unsigned long
> addr,
>  			    unsigned long attr)
>  {
> @@ -239,6 +251,9 @@ static int pmp_init(struct sbi_scratch *scratch, u32
> hartid)
>  	 */
>  	pmp_set(pmp_idx++, PMP_R | PMP_W | PMP_X, 0, __riscv_xlen);
> 
> +	if (sbi_hart_has_feature(scratch, SBI_HART_HAS_EPMP))
> +		epmp_set(0, 0, 0);
> +
>  	return 0;
>  }
> 
> @@ -288,6 +303,9 @@ static inline char
> *sbi_hart_feature_id2string(unsigned long feature)
>  	case SBI_HART_HAS_TIME:
>  		fstr = "time";
>  		break;
> +	case SBI_HART_HAS_EPMP:
> +		fstr = "epmp";
> +		break;
>  	default:
>  		break;
>  	}
> @@ -397,6 +415,15 @@ static void hart_detect_features(struct sbi_scratch
> *scratch)
>  			hfeatures->features |=
> SBI_HART_HAS_MCOUNTEREN;
>  	}
> 
> +	/* Detect if hart supports EPMP(enhanced PMP) feature */
> +	trap.cause = 0;
> +	val = csr_read_allowed(CSR_MSECCFG, (unsigned long)&trap);
> +	if (!trap.cause) {
> +		csr_write_allowed(CSR_MSECCFG, (unsigned long)&trap,
> val);
> +		if (!trap.cause)
> +			hfeatures->features |= SBI_HART_HAS_EPMP;
> +	}
> +
>  	/* Detect if hart supports time CSR */
>  	trap.cause = 0;
>  	csr_read_allowed(CSR_TIME, (unsigned long)&trap); diff --git
> a/lib/sbi/sbi_init.c b/lib/sbi/sbi_init.c index a7fb848..1ced76b 100644
> --- a/lib/sbi/sbi_init.c
> +++ b/lib/sbi/sbi_init.c
> @@ -82,6 +82,7 @@ static void sbi_boot_prints(struct sbi_scratch *scratch,
> u32 hartid)
> 
>  	sbi_hart_delegation_dump(scratch);
>  	sbi_hart_pmp_dump(scratch);
> +	sbi_hart_epmp_dump(scratch);
>  }
> 
>  static spinlock_t coldboot_lock = SPIN_LOCK_INITIALIZER;
> --
> 2.24.1.windows.2
> 
> 
> --
> opensbi mailing list
> opensbi@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/opensbi
Hongzheng-Li Aug. 5, 2020, 4:43 a.m. UTC | #2
Thanks!

We are adding ePMP support to QEMU at the moment and are ready to send
the patches. We have tested this patch with ePMP support we added to
QEMU and it all works fine so far. So I guess the second concern will
soon be solved.

Should I resend this patch when ePMP is taken into the RISC-V ISA manual?

Best regards,
Hongzheng-Li

Anup Patel <Anup.Patel@wdc.com> 于2020年8月5日周三 上午11:46写道:
>
>
>
> > -----Original Message-----
> > From: opensbi <opensbi-bounces@lists.infradead.org> On Behalf Of
> > Hongzheng-Li
> > Sent: 05 August 2020 09:00
> > To: opensbi@lists.infradead.org
> > Cc: Hou Weiying <weiying_hou@outlook.com>; Hongzheng-Li
> > <ethan.lee.qnl@gmail.com>
> > Subject: [PATCH] lib: add Enhanced PMP support
> >
> > From: Hongzheng-Li <ethan.lee.qnl@gmail.com>
> >
> > The Enhanced PMP(ePMP) is used for memory access and execution
> > prevention on Machine mode.
> > The latest spec can be found here:
> > https://docs.google.com/document/d/1Mh_aiHYxemL0umN3GTTw8vsbmzH
> > Z_nxZXgjgOUzbvc8/edit?pli=1#heading=h.ab3kl2ch725u
>
> As far as implementation goes, I only see only minor comments so no issues
> on implementation part.
>
> My concerns is the state of ePMP spec. My understanding is that ePMP is
> still in draft state. We are fine with specs in draft state but spec should
> be part of https://github.com/riscv/riscv-isa-manual (Just Hypervisor spec).
>
> Another concerns is the mechanism to test this patch. We need some way
> to test ePMP so we insist that someone please add QEMU emulation support
> for ePMP. This will help users to test OpenSBI ePMP support on QEMU.
>
> If above two concerns are addressed then we can certainly merge
> ePMP support in OpenSBI.
>
> Overall this is a good addition for OpenSBI. Thanks.
>
> Regards,
> Anup
>
> >
> > Signed-off-by: Hongzheng-Li <ethan.lee.qnl@gmail.com>
> > Signed-off-by: Hou Weiying <weiying_hou@outlook.com>
> > ---
> >  include/sbi/riscv_asm.h      |  4 ++++
> >  include/sbi/riscv_encoding.h |  1 +
> >  include/sbi/sbi_hart.h       |  9 ++++++---
> >  lib/sbi/riscv_asm.c          | 30 ++++++++++++++++++++++++++++++
> >  lib/sbi/sbi_hart.c           | 27 +++++++++++++++++++++++++++
> >  lib/sbi/sbi_init.c           |  1 +
> >  6 files changed, 69 insertions(+), 3 deletions(-)
> >
> > diff --git a/include/sbi/riscv_asm.h b/include/sbi/riscv_asm.h index
> > 6e093ca..badd8af 100644
> > --- a/include/sbi/riscv_asm.h
> > +++ b/include/sbi/riscv_asm.h
> > @@ -182,6 +182,10 @@ int pmp_set(unsigned int n, unsigned long prot,
> > unsigned long addr,  int pmp_get(unsigned int n, unsigned long *prot_out,
> > unsigned long *addr_out,
> >           unsigned long *size);
> >
> > +int epmp_set(int rlb, int mmwp, int mml);
> > +
> > +int epmp_get(int *rlb, int *mmwp, int *mml);
> > +
> >  #endif /* !__ASSEMBLY__ */
> >
> >  #endif
> > diff --git a/include/sbi/riscv_encoding.h b/include/sbi/riscv_encoding.h
> > index 827c86c..2052925 100644
> > --- a/include/sbi/riscv_encoding.h
> > +++ b/include/sbi/riscv_encoding.h
> > @@ -279,6 +279,7 @@
> >  #define CSR_PMPADDR13                        0x3bd
> >  #define CSR_PMPADDR14                        0x3be
> >  #define CSR_PMPADDR15                        0x3bf
> > +#define CSR_MSECCFG                  0x390
> >  #define CSR_TSELECT                  0x7a0
> >  #define CSR_TDATA1                   0x7a1
> >  #define CSR_TDATA2                   0x7a2
> > diff --git a/include/sbi/sbi_hart.h b/include/sbi/sbi_hart.h index
> > 51c2c35..4ed882f 100644
> > --- a/include/sbi/sbi_hart.h
> > +++ b/include/sbi/sbi_hart.h
> > @@ -16,12 +16,14 @@
> >  enum sbi_hart_features {
> >       /** Hart has PMP support */
> >       SBI_HART_HAS_PMP = (1 << 0),
> > +     /** enhanced PMP */
> > +     SBI_HART_HAS_EPMP = (1 << 1),
> >       /** Hart has S-mode counter enable */
> > -     SBI_HART_HAS_SCOUNTEREN = (1 << 1),
> > +     SBI_HART_HAS_SCOUNTEREN = (1 << 2),
> >       /** Hart has M-mode counter enable */
> > -     SBI_HART_HAS_MCOUNTEREN = (1 << 2),
> > +     SBI_HART_HAS_MCOUNTEREN = (1 << 3),
> >       /** HART has timer csr implementation in hardware */
> > -     SBI_HART_HAS_TIME = (1 << 3),
> > +     SBI_HART_HAS_TIME = (1 << 4),
> >
> >       /** Last index of Hart features*/
> >       SBI_HART_HAS_LAST_FEATURE = SBI_HART_HAS_TIME, @@ -43,6
> > +45,7 @@ int sbi_hart_pmp_get(struct sbi_scratch *scratch, unsigned int n,
> >                    unsigned long *prot_out, unsigned long *addr_out,
> >                    unsigned long *size);
> >  void sbi_hart_pmp_dump(struct sbi_scratch *scratch);
> > +void sbi_hart_epmp_dump(struct sbi_scratch *scratch);
> >  int  sbi_hart_pmp_check_addr(struct sbi_scratch *scratch, unsigned long
> > daddr,
> >                            unsigned long attr);
> >  bool sbi_hart_has_feature(struct sbi_scratch *scratch, unsigned long
> > feature); diff --git a/lib/sbi/riscv_asm.c b/lib/sbi/riscv_asm.c index
> > 6dfebd9..4621f70 100644
> > --- a/lib/sbi/riscv_asm.c
> > +++ b/lib/sbi/riscv_asm.c
> > @@ -349,3 +349,33 @@ int pmp_get(unsigned int n, unsigned long
> > *prot_out, unsigned long *addr_out,
> >
> >       return 0;
> >  }
> > +
> > +int epmp_set(int rlb, int mmwp, int mml) {
> > +     unsigned long mseccfg;
> > +
> > +     if ((rlb | mmwp | mml) & ~1)
> > +             return SBI_EINVAL;
> > +
> > +#if __riscv_xlen == 32 || __riscv_xlen == 64
> > +     mseccfg = rlb << 2 | mmwp << 1 | mml;
> > +#else
> > +     mseccfg = -1;
> > +#endif
> > +     if (mseccfg < 0)
> > +             return SBI_ENOTSUPP;
> > +
> > +     csr_write(CSR_MSECCFG, mseccfg);
> > +
> > +     return 0;
> > +}
> > +
> > +int epmp_get(int *rlb, int *mmwp, int *mml) {
> > +     unsigned long mseccfg = csr_read(CSR_MSECCFG);
> > +     *rlb = (mseccfg >> 2) & 1;
> > +     *mmwp = (mseccfg >> 1) & 1;
> > +     *mml = mseccfg & 1;
> > +
> > +     return 0;
> > +}
> > diff --git a/lib/sbi/sbi_hart.c b/lib/sbi/sbi_hart.c index fa20bd2..c1c6957
> > 100644
> > --- a/lib/sbi/sbi_hart.c
> > +++ b/lib/sbi/sbi_hart.c
> > @@ -184,6 +184,18 @@ void sbi_hart_pmp_dump(struct sbi_scratch
> > *scratch)
> >       }
> >  }
> >
> > +void sbi_hart_epmp_dump(struct sbi_scratch *scratch) {
> > +     if (!sbi_hart_has_feature(scratch, SBI_HART_HAS_EPMP))
> > +             return;
> > +
> > +     int rlb, mmwp, mml;
> > +
> > +     epmp_get(&rlb, &mmwp, &mml);
> > +     sbi_printf("ePMP: RLB = %d, MMWP = %d, MML = %d\n",
> > +                             rlb, mmwp, mml);
> > +}
> > +
> >  int sbi_hart_pmp_check_addr(struct sbi_scratch *scratch, unsigned long
> > addr,
> >                           unsigned long attr)
> >  {
> > @@ -239,6 +251,9 @@ static int pmp_init(struct sbi_scratch *scratch, u32
> > hartid)
> >        */
> >       pmp_set(pmp_idx++, PMP_R | PMP_W | PMP_X, 0, __riscv_xlen);
> >
> > +     if (sbi_hart_has_feature(scratch, SBI_HART_HAS_EPMP))
> > +             epmp_set(0, 0, 0);
> > +
> >       return 0;
> >  }
> >
> > @@ -288,6 +303,9 @@ static inline char
> > *sbi_hart_feature_id2string(unsigned long feature)
> >       case SBI_HART_HAS_TIME:
> >               fstr = "time";
> >               break;
> > +     case SBI_HART_HAS_EPMP:
> > +             fstr = "epmp";
> > +             break;
> >       default:
> >               break;
> >       }
> > @@ -397,6 +415,15 @@ static void hart_detect_features(struct sbi_scratch
> > *scratch)
> >                       hfeatures->features |=
> > SBI_HART_HAS_MCOUNTEREN;
> >       }
> >
> > +     /* Detect if hart supports EPMP(enhanced PMP) feature */
> > +     trap.cause = 0;
> > +     val = csr_read_allowed(CSR_MSECCFG, (unsigned long)&trap);
> > +     if (!trap.cause) {
> > +             csr_write_allowed(CSR_MSECCFG, (unsigned long)&trap,
> > val);
> > +             if (!trap.cause)
> > +                     hfeatures->features |= SBI_HART_HAS_EPMP;
> > +     }
> > +
> >       /* Detect if hart supports time CSR */
> >       trap.cause = 0;
> >       csr_read_allowed(CSR_TIME, (unsigned long)&trap); diff --git
> > a/lib/sbi/sbi_init.c b/lib/sbi/sbi_init.c index a7fb848..1ced76b 100644
> > --- a/lib/sbi/sbi_init.c
> > +++ b/lib/sbi/sbi_init.c
> > @@ -82,6 +82,7 @@ static void sbi_boot_prints(struct sbi_scratch *scratch,
> > u32 hartid)
> >
> >       sbi_hart_delegation_dump(scratch);
> >       sbi_hart_pmp_dump(scratch);
> > +     sbi_hart_epmp_dump(scratch);
> >  }
> >
> >  static spinlock_t coldboot_lock = SPIN_LOCK_INITIALIZER;
> > --
> > 2.24.1.windows.2
> >
> >
> > --
> > opensbi mailing list
> > opensbi@lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/opensbi
Anup Patel Aug. 5, 2020, 6:56 a.m. UTC | #3
> -----Original Message-----
> From: Hongzheng Li <ethan.lee.qnl@gmail.com>
> Sent: 05 August 2020 10:14
> To: Anup Patel <Anup.Patel@wdc.com>
> Cc: opensbi@lists.infradead.org; Hou Weiying <weiying_hou@outlook.com>;
> Nick Kossifidis <mick@ics.forth.gr>; Nick Kossifidis <mickflemm@gmail.com>
> Subject: Re: [PATCH] lib: add Enhanced PMP support
> 
> Thanks!
> 
> We are adding ePMP support to QEMU at the moment and are ready to send
> the patches. We have tested this patch with ePMP support we added to
> QEMU and it all works fine so far. So I guess the second concern will soon be
> solved.
> 
> Should I resend this patch when ePMP is taken into the RISC-V ISA manual?

We can have your patches reviewed first but we will merge it after
RISC-V ISA manual and QEMU patches are available. Does that sound okay?

Regards,
Anup

> 
> Best regards,
> Hongzheng-Li
> 
> Anup Patel <Anup.Patel@wdc.com> 于2020年8月5日周三 上午11:46写道
> :
> >
> >
> >
> > > -----Original Message-----
> > > From: opensbi <opensbi-bounces@lists.infradead.org> On Behalf Of
> > > Hongzheng-Li
> > > Sent: 05 August 2020 09:00
> > > To: opensbi@lists.infradead.org
> > > Cc: Hou Weiying <weiying_hou@outlook.com>; Hongzheng-Li
> > > <ethan.lee.qnl@gmail.com>
> > > Subject: [PATCH] lib: add Enhanced PMP support
> > >
> > > From: Hongzheng-Li <ethan.lee.qnl@gmail.com>
> > >
> > > The Enhanced PMP(ePMP) is used for memory access and execution
> > > prevention on Machine mode.
> > > The latest spec can be found here:
> > >
> https://docs.google.com/document/d/1Mh_aiHYxemL0umN3GTTw8vsbmzH
> > > Z_nxZXgjgOUzbvc8/edit?pli=1#heading=h.ab3kl2ch725u
> >
> > As far as implementation goes, I only see only minor comments so no
> > issues on implementation part.
> >
> > My concerns is the state of ePMP spec. My understanding is that ePMP
> > is still in draft state. We are fine with specs in draft state but
> > spec should be part of https://github.com/riscv/riscv-isa-manual (Just
> Hypervisor spec).
> >
> > Another concerns is the mechanism to test this patch. We need some way
> > to test ePMP so we insist that someone please add QEMU emulation
> > support for ePMP. This will help users to test OpenSBI ePMP support on
> QEMU.
> >
> > If above two concerns are addressed then we can certainly merge ePMP
> > support in OpenSBI.
> >
> > Overall this is a good addition for OpenSBI. Thanks.
> >
> > Regards,
> > Anup
> >
> > >
> > > Signed-off-by: Hongzheng-Li <ethan.lee.qnl@gmail.com>
> > > Signed-off-by: Hou Weiying <weiying_hou@outlook.com>
> > > ---
> > >  include/sbi/riscv_asm.h      |  4 ++++
> > >  include/sbi/riscv_encoding.h |  1 +
> > >  include/sbi/sbi_hart.h       |  9 ++++++---
> > >  lib/sbi/riscv_asm.c          | 30 ++++++++++++++++++++++++++++++
> > >  lib/sbi/sbi_hart.c           | 27 +++++++++++++++++++++++++++
> > >  lib/sbi/sbi_init.c           |  1 +
> > >  6 files changed, 69 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/include/sbi/riscv_asm.h b/include/sbi/riscv_asm.h index
> > > 6e093ca..badd8af 100644
> > > --- a/include/sbi/riscv_asm.h
> > > +++ b/include/sbi/riscv_asm.h
> > > @@ -182,6 +182,10 @@ int pmp_set(unsigned int n, unsigned long prot,
> > > unsigned long addr,  int pmp_get(unsigned int n, unsigned long
> > > *prot_out, unsigned long *addr_out,
> > >           unsigned long *size);
> > >
> > > +int epmp_set(int rlb, int mmwp, int mml);
> > > +
> > > +int epmp_get(int *rlb, int *mmwp, int *mml);
> > > +
> > >  #endif /* !__ASSEMBLY__ */
> > >
> > >  #endif
> > > diff --git a/include/sbi/riscv_encoding.h
> > > b/include/sbi/riscv_encoding.h index 827c86c..2052925 100644
> > > --- a/include/sbi/riscv_encoding.h
> > > +++ b/include/sbi/riscv_encoding.h
> > > @@ -279,6 +279,7 @@
> > >  #define CSR_PMPADDR13                        0x3bd
> > >  #define CSR_PMPADDR14                        0x3be
> > >  #define CSR_PMPADDR15                        0x3bf
> > > +#define CSR_MSECCFG                  0x390
> > >  #define CSR_TSELECT                  0x7a0
> > >  #define CSR_TDATA1                   0x7a1
> > >  #define CSR_TDATA2                   0x7a2
> > > diff --git a/include/sbi/sbi_hart.h b/include/sbi/sbi_hart.h index
> > > 51c2c35..4ed882f 100644
> > > --- a/include/sbi/sbi_hart.h
> > > +++ b/include/sbi/sbi_hart.h
> > > @@ -16,12 +16,14 @@
> > >  enum sbi_hart_features {
> > >       /** Hart has PMP support */
> > >       SBI_HART_HAS_PMP = (1 << 0),
> > > +     /** enhanced PMP */
> > > +     SBI_HART_HAS_EPMP = (1 << 1),
> > >       /** Hart has S-mode counter enable */
> > > -     SBI_HART_HAS_SCOUNTEREN = (1 << 1),
> > > +     SBI_HART_HAS_SCOUNTEREN = (1 << 2),
> > >       /** Hart has M-mode counter enable */
> > > -     SBI_HART_HAS_MCOUNTEREN = (1 << 2),
> > > +     SBI_HART_HAS_MCOUNTEREN = (1 << 3),
> > >       /** HART has timer csr implementation in hardware */
> > > -     SBI_HART_HAS_TIME = (1 << 3),
> > > +     SBI_HART_HAS_TIME = (1 << 4),
> > >
> > >       /** Last index of Hart features*/
> > >       SBI_HART_HAS_LAST_FEATURE = SBI_HART_HAS_TIME, @@ -43,6
> > > +45,7 @@ int sbi_hart_pmp_get(struct sbi_scratch *scratch, unsigned
> > > +int n,
> > >                    unsigned long *prot_out, unsigned long *addr_out,
> > >                    unsigned long *size);  void
> > > sbi_hart_pmp_dump(struct sbi_scratch *scratch);
> > > +void sbi_hart_epmp_dump(struct sbi_scratch *scratch);
> > >  int  sbi_hart_pmp_check_addr(struct sbi_scratch *scratch, unsigned
> > > long daddr,
> > >                            unsigned long attr);  bool
> > > sbi_hart_has_feature(struct sbi_scratch *scratch, unsigned long
> > > feature); diff --git a/lib/sbi/riscv_asm.c b/lib/sbi/riscv_asm.c
> > > index
> > > 6dfebd9..4621f70 100644
> > > --- a/lib/sbi/riscv_asm.c
> > > +++ b/lib/sbi/riscv_asm.c
> > > @@ -349,3 +349,33 @@ int pmp_get(unsigned int n, unsigned long
> > > *prot_out, unsigned long *addr_out,
> > >
> > >       return 0;
> > >  }
> > > +
> > > +int epmp_set(int rlb, int mmwp, int mml) {
> > > +     unsigned long mseccfg;
> > > +
> > > +     if ((rlb | mmwp | mml) & ~1)
> > > +             return SBI_EINVAL;
> > > +
> > > +#if __riscv_xlen == 32 || __riscv_xlen == 64
> > > +     mseccfg = rlb << 2 | mmwp << 1 | mml; #else
> > > +     mseccfg = -1;
> > > +#endif
> > > +     if (mseccfg < 0)
> > > +             return SBI_ENOTSUPP;
> > > +
> > > +     csr_write(CSR_MSECCFG, mseccfg);
> > > +
> > > +     return 0;
> > > +}
> > > +
> > > +int epmp_get(int *rlb, int *mmwp, int *mml) {
> > > +     unsigned long mseccfg = csr_read(CSR_MSECCFG);
> > > +     *rlb = (mseccfg >> 2) & 1;
> > > +     *mmwp = (mseccfg >> 1) & 1;
> > > +     *mml = mseccfg & 1;
> > > +
> > > +     return 0;
> > > +}
> > > diff --git a/lib/sbi/sbi_hart.c b/lib/sbi/sbi_hart.c index
> > > fa20bd2..c1c6957
> > > 100644
> > > --- a/lib/sbi/sbi_hart.c
> > > +++ b/lib/sbi/sbi_hart.c
> > > @@ -184,6 +184,18 @@ void sbi_hart_pmp_dump(struct sbi_scratch
> > > *scratch)
> > >       }
> > >  }
> > >
> > > +void sbi_hart_epmp_dump(struct sbi_scratch *scratch) {
> > > +     if (!sbi_hart_has_feature(scratch, SBI_HART_HAS_EPMP))
> > > +             return;
> > > +
> > > +     int rlb, mmwp, mml;
> > > +
> > > +     epmp_get(&rlb, &mmwp, &mml);
> > > +     sbi_printf("ePMP: RLB = %d, MMWP = %d, MML = %d\n",
> > > +                             rlb, mmwp, mml); }
> > > +
> > >  int sbi_hart_pmp_check_addr(struct sbi_scratch *scratch, unsigned
> > > long addr,
> > >                           unsigned long attr)  { @@ -239,6 +251,9 @@
> > > static int pmp_init(struct sbi_scratch *scratch, u32
> > > hartid)
> > >        */
> > >       pmp_set(pmp_idx++, PMP_R | PMP_W | PMP_X, 0, __riscv_xlen);
> > >
> > > +     if (sbi_hart_has_feature(scratch, SBI_HART_HAS_EPMP))
> > > +             epmp_set(0, 0, 0);
> > > +
> > >       return 0;
> > >  }
> > >
> > > @@ -288,6 +303,9 @@ static inline char
> > > *sbi_hart_feature_id2string(unsigned long feature)
> > >       case SBI_HART_HAS_TIME:
> > >               fstr = "time";
> > >               break;
> > > +     case SBI_HART_HAS_EPMP:
> > > +             fstr = "epmp";
> > > +             break;
> > >       default:
> > >               break;
> > >       }
> > > @@ -397,6 +415,15 @@ static void hart_detect_features(struct
> > > sbi_scratch
> > > *scratch)
> > >                       hfeatures->features |=
> > > SBI_HART_HAS_MCOUNTEREN;
> > >       }
> > >
> > > +     /* Detect if hart supports EPMP(enhanced PMP) feature */
> > > +     trap.cause = 0;
> > > +     val = csr_read_allowed(CSR_MSECCFG, (unsigned long)&trap);
> > > +     if (!trap.cause) {
> > > +             csr_write_allowed(CSR_MSECCFG, (unsigned long)&trap,
> > > val);
> > > +             if (!trap.cause)
> > > +                     hfeatures->features |= SBI_HART_HAS_EPMP;
> > > +     }
> > > +
> > >       /* Detect if hart supports time CSR */
> > >       trap.cause = 0;
> > >       csr_read_allowed(CSR_TIME, (unsigned long)&trap); diff --git
> > > a/lib/sbi/sbi_init.c b/lib/sbi/sbi_init.c index a7fb848..1ced76b
> > > 100644
> > > --- a/lib/sbi/sbi_init.c
> > > +++ b/lib/sbi/sbi_init.c
> > > @@ -82,6 +82,7 @@ static void sbi_boot_prints(struct sbi_scratch
> > > *scratch,
> > > u32 hartid)
> > >
> > >       sbi_hart_delegation_dump(scratch);
> > >       sbi_hart_pmp_dump(scratch);
> > > +     sbi_hart_epmp_dump(scratch);
> > >  }
> > >
> > >  static spinlock_t coldboot_lock = SPIN_LOCK_INITIALIZER;
> > > --
> > > 2.24.1.windows.2
> > >
> > >
> > > --
> > > opensbi mailing list
> > > opensbi@lists.infradead.org
> > > http://lists.infradead.org/mailman/listinfo/opensbi
Hongzheng-Li Aug. 5, 2020, 10:16 a.m. UTC | #4
That would be great, thanks!

Best regards,
Hongzheng-Li

On Wed, Aug 5, 2020 at 2:56 PM Anup Patel <Anup.Patel@wdc.com> wrote:
>
>
>
> > -----Original Message-----
> > From: Hongzheng Li <ethan.lee.qnl@gmail.com>
> > Sent: 05 August 2020 10:14
> > To: Anup Patel <Anup.Patel@wdc.com>
> > Cc: opensbi@lists.infradead.org; Hou Weiying <weiying_hou@outlook.com>;
> > Nick Kossifidis <mick@ics.forth.gr>; Nick Kossifidis <mickflemm@gmail.com>
> > Subject: Re: [PATCH] lib: add Enhanced PMP support
> >
> > Thanks!
> >
> > We are adding ePMP support to QEMU at the moment and are ready to send
> > the patches. We have tested this patch with ePMP support we added to
> > QEMU and it all works fine so far. So I guess the second concern will soon be
> > solved.
> >
> > Should I resend this patch when ePMP is taken into the RISC-V ISA manual?
>
> We can have your patches reviewed first but we will merge it after
> RISC-V ISA manual and QEMU patches are available. Does that sound okay?
>
> Regards,
> Anup
>
> >
> > Best regards,
> > Hongzheng-Li
> >
> > Anup Patel <Anup.Patel@wdc.com> 于2020年8月5日周三 上午11:46写道
> > :
> > >
> > >
> > >
> > > > -----Original Message-----
> > > > From: opensbi <opensbi-bounces@lists.infradead.org> On Behalf Of
> > > > Hongzheng-Li
> > > > Sent: 05 August 2020 09:00
> > > > To: opensbi@lists.infradead.org
> > > > Cc: Hou Weiying <weiying_hou@outlook.com>; Hongzheng-Li
> > > > <ethan.lee.qnl@gmail.com>
> > > > Subject: [PATCH] lib: add Enhanced PMP support
> > > >
> > > > From: Hongzheng-Li <ethan.lee.qnl@gmail.com>
> > > >
> > > > The Enhanced PMP(ePMP) is used for memory access and execution
> > > > prevention on Machine mode.
> > > > The latest spec can be found here:
> > > >
> > https://docs.google.com/document/d/1Mh_aiHYxemL0umN3GTTw8vsbmzH
> > > > Z_nxZXgjgOUzbvc8/edit?pli=1#heading=h.ab3kl2ch725u
> > >
> > > As far as implementation goes, I only see only minor comments so no
> > > issues on implementation part.
> > >
> > > My concerns is the state of ePMP spec. My understanding is that ePMP
> > > is still in draft state. We are fine with specs in draft state but
> > > spec should be part of https://github.com/riscv/riscv-isa-manual (Just
> > Hypervisor spec).
> > >
> > > Another concerns is the mechanism to test this patch. We need some way
> > > to test ePMP so we insist that someone please add QEMU emulation
> > > support for ePMP. This will help users to test OpenSBI ePMP support on
> > QEMU.
> > >
> > > If above two concerns are addressed then we can certainly merge ePMP
> > > support in OpenSBI.
> > >
> > > Overall this is a good addition for OpenSBI. Thanks.
> > >
> > > Regards,
> > > Anup
> > >
> > > >
> > > > Signed-off-by: Hongzheng-Li <ethan.lee.qnl@gmail.com>
> > > > Signed-off-by: Hou Weiying <weiying_hou@outlook.com>
> > > > ---
> > > >  include/sbi/riscv_asm.h      |  4 ++++
> > > >  include/sbi/riscv_encoding.h |  1 +
> > > >  include/sbi/sbi_hart.h       |  9 ++++++---
> > > >  lib/sbi/riscv_asm.c          | 30 ++++++++++++++++++++++++++++++
> > > >  lib/sbi/sbi_hart.c           | 27 +++++++++++++++++++++++++++
> > > >  lib/sbi/sbi_init.c           |  1 +
> > > >  6 files changed, 69 insertions(+), 3 deletions(-)
> > > >
> > > > diff --git a/include/sbi/riscv_asm.h b/include/sbi/riscv_asm.h index
> > > > 6e093ca..badd8af 100644
> > > > --- a/include/sbi/riscv_asm.h
> > > > +++ b/include/sbi/riscv_asm.h
> > > > @@ -182,6 +182,10 @@ int pmp_set(unsigned int n, unsigned long prot,
> > > > unsigned long addr,  int pmp_get(unsigned int n, unsigned long
> > > > *prot_out, unsigned long *addr_out,
> > > >           unsigned long *size);
> > > >
> > > > +int epmp_set(int rlb, int mmwp, int mml);
> > > > +
> > > > +int epmp_get(int *rlb, int *mmwp, int *mml);
> > > > +
> > > >  #endif /* !__ASSEMBLY__ */
> > > >
> > > >  #endif
> > > > diff --git a/include/sbi/riscv_encoding.h
> > > > b/include/sbi/riscv_encoding.h index 827c86c..2052925 100644
> > > > --- a/include/sbi/riscv_encoding.h
> > > > +++ b/include/sbi/riscv_encoding.h
> > > > @@ -279,6 +279,7 @@
> > > >  #define CSR_PMPADDR13                        0x3bd
> > > >  #define CSR_PMPADDR14                        0x3be
> > > >  #define CSR_PMPADDR15                        0x3bf
> > > > +#define CSR_MSECCFG                  0x390
> > > >  #define CSR_TSELECT                  0x7a0
> > > >  #define CSR_TDATA1                   0x7a1
> > > >  #define CSR_TDATA2                   0x7a2
> > > > diff --git a/include/sbi/sbi_hart.h b/include/sbi/sbi_hart.h index
> > > > 51c2c35..4ed882f 100644
> > > > --- a/include/sbi/sbi_hart.h
> > > > +++ b/include/sbi/sbi_hart.h
> > > > @@ -16,12 +16,14 @@
> > > >  enum sbi_hart_features {
> > > >       /** Hart has PMP support */
> > > >       SBI_HART_HAS_PMP = (1 << 0),
> > > > +     /** enhanced PMP */
> > > > +     SBI_HART_HAS_EPMP = (1 << 1),
> > > >       /** Hart has S-mode counter enable */
> > > > -     SBI_HART_HAS_SCOUNTEREN = (1 << 1),
> > > > +     SBI_HART_HAS_SCOUNTEREN = (1 << 2),
> > > >       /** Hart has M-mode counter enable */
> > > > -     SBI_HART_HAS_MCOUNTEREN = (1 << 2),
> > > > +     SBI_HART_HAS_MCOUNTEREN = (1 << 3),
> > > >       /** HART has timer csr implementation in hardware */
> > > > -     SBI_HART_HAS_TIME = (1 << 3),
> > > > +     SBI_HART_HAS_TIME = (1 << 4),
> > > >
> > > >       /** Last index of Hart features*/
> > > >       SBI_HART_HAS_LAST_FEATURE = SBI_HART_HAS_TIME, @@ -43,6
> > > > +45,7 @@ int sbi_hart_pmp_get(struct sbi_scratch *scratch, unsigned
> > > > +int n,
> > > >                    unsigned long *prot_out, unsigned long *addr_out,
> > > >                    unsigned long *size);  void
> > > > sbi_hart_pmp_dump(struct sbi_scratch *scratch);
> > > > +void sbi_hart_epmp_dump(struct sbi_scratch *scratch);
> > > >  int  sbi_hart_pmp_check_addr(struct sbi_scratch *scratch, unsigned
> > > > long daddr,
> > > >                            unsigned long attr);  bool
> > > > sbi_hart_has_feature(struct sbi_scratch *scratch, unsigned long
> > > > feature); diff --git a/lib/sbi/riscv_asm.c b/lib/sbi/riscv_asm.c
> > > > index
> > > > 6dfebd9..4621f70 100644
> > > > --- a/lib/sbi/riscv_asm.c
> > > > +++ b/lib/sbi/riscv_asm.c
> > > > @@ -349,3 +349,33 @@ int pmp_get(unsigned int n, unsigned long
> > > > *prot_out, unsigned long *addr_out,
> > > >
> > > >       return 0;
> > > >  }
> > > > +
> > > > +int epmp_set(int rlb, int mmwp, int mml) {
> > > > +     unsigned long mseccfg;
> > > > +
> > > > +     if ((rlb | mmwp | mml) & ~1)
> > > > +             return SBI_EINVAL;
> > > > +
> > > > +#if __riscv_xlen == 32 || __riscv_xlen == 64
> > > > +     mseccfg = rlb << 2 | mmwp << 1 | mml; #else
> > > > +     mseccfg = -1;
> > > > +#endif
> > > > +     if (mseccfg < 0)
> > > > +             return SBI_ENOTSUPP;
> > > > +
> > > > +     csr_write(CSR_MSECCFG, mseccfg);
> > > > +
> > > > +     return 0;
> > > > +}
> > > > +
> > > > +int epmp_get(int *rlb, int *mmwp, int *mml) {
> > > > +     unsigned long mseccfg = csr_read(CSR_MSECCFG);
> > > > +     *rlb = (mseccfg >> 2) & 1;
> > > > +     *mmwp = (mseccfg >> 1) & 1;
> > > > +     *mml = mseccfg & 1;
> > > > +
> > > > +     return 0;
> > > > +}
> > > > diff --git a/lib/sbi/sbi_hart.c b/lib/sbi/sbi_hart.c index
> > > > fa20bd2..c1c6957
> > > > 100644
> > > > --- a/lib/sbi/sbi_hart.c
> > > > +++ b/lib/sbi/sbi_hart.c
> > > > @@ -184,6 +184,18 @@ void sbi_hart_pmp_dump(struct sbi_scratch
> > > > *scratch)
> > > >       }
> > > >  }
> > > >
> > > > +void sbi_hart_epmp_dump(struct sbi_scratch *scratch) {
> > > > +     if (!sbi_hart_has_feature(scratch, SBI_HART_HAS_EPMP))
> > > > +             return;
> > > > +
> > > > +     int rlb, mmwp, mml;
> > > > +
> > > > +     epmp_get(&rlb, &mmwp, &mml);
> > > > +     sbi_printf("ePMP: RLB = %d, MMWP = %d, MML = %d\n",
> > > > +                             rlb, mmwp, mml); }
> > > > +
> > > >  int sbi_hart_pmp_check_addr(struct sbi_scratch *scratch, unsigned
> > > > long addr,
> > > >                           unsigned long attr)  { @@ -239,6 +251,9 @@
> > > > static int pmp_init(struct sbi_scratch *scratch, u32
> > > > hartid)
> > > >        */
> > > >       pmp_set(pmp_idx++, PMP_R | PMP_W | PMP_X, 0, __riscv_xlen);
> > > >
> > > > +     if (sbi_hart_has_feature(scratch, SBI_HART_HAS_EPMP))
> > > > +             epmp_set(0, 0, 0);
> > > > +
> > > >       return 0;
> > > >  }
> > > >
> > > > @@ -288,6 +303,9 @@ static inline char
> > > > *sbi_hart_feature_id2string(unsigned long feature)
> > > >       case SBI_HART_HAS_TIME:
> > > >               fstr = "time";
> > > >               break;
> > > > +     case SBI_HART_HAS_EPMP:
> > > > +             fstr = "epmp";
> > > > +             break;
> > > >       default:
> > > >               break;
> > > >       }
> > > > @@ -397,6 +415,15 @@ static void hart_detect_features(struct
> > > > sbi_scratch
> > > > *scratch)
> > > >                       hfeatures->features |=
> > > > SBI_HART_HAS_MCOUNTEREN;
> > > >       }
> > > >
> > > > +     /* Detect if hart supports EPMP(enhanced PMP) feature */
> > > > +     trap.cause = 0;
> > > > +     val = csr_read_allowed(CSR_MSECCFG, (unsigned long)&trap);
> > > > +     if (!trap.cause) {
> > > > +             csr_write_allowed(CSR_MSECCFG, (unsigned long)&trap,
> > > > val);
> > > > +             if (!trap.cause)
> > > > +                     hfeatures->features |= SBI_HART_HAS_EPMP;
> > > > +     }
> > > > +
> > > >       /* Detect if hart supports time CSR */
> > > >       trap.cause = 0;
> > > >       csr_read_allowed(CSR_TIME, (unsigned long)&trap); diff --git
> > > > a/lib/sbi/sbi_init.c b/lib/sbi/sbi_init.c index a7fb848..1ced76b
> > > > 100644
> > > > --- a/lib/sbi/sbi_init.c
> > > > +++ b/lib/sbi/sbi_init.c
> > > > @@ -82,6 +82,7 @@ static void sbi_boot_prints(struct sbi_scratch
> > > > *scratch,
> > > > u32 hartid)
> > > >
> > > >       sbi_hart_delegation_dump(scratch);
> > > >       sbi_hart_pmp_dump(scratch);
> > > > +     sbi_hart_epmp_dump(scratch);
> > > >  }
> > > >
> > > >  static spinlock_t coldboot_lock = SPIN_LOCK_INITIALIZER;
> > > > --
> > > > 2.24.1.windows.2
> > > >
> > > >
> > > > --
> > > > opensbi mailing list
> > > > opensbi@lists.infradead.org
> > > > http://lists.infradead.org/mailman/listinfo/opensbi
diff mbox series

Patch

diff --git a/include/sbi/riscv_asm.h b/include/sbi/riscv_asm.h
index 6e093ca..badd8af 100644
--- a/include/sbi/riscv_asm.h
+++ b/include/sbi/riscv_asm.h
@@ -182,6 +182,10 @@  int pmp_set(unsigned int n, unsigned long prot, unsigned long addr,
 int pmp_get(unsigned int n, unsigned long *prot_out, unsigned long *addr_out,
 	    unsigned long *size);
 
+int epmp_set(int rlb, int mmwp, int mml);
+
+int epmp_get(int *rlb, int *mmwp, int *mml);
+
 #endif /* !__ASSEMBLY__ */
 
 #endif
diff --git a/include/sbi/riscv_encoding.h b/include/sbi/riscv_encoding.h
index 827c86c..2052925 100644
--- a/include/sbi/riscv_encoding.h
+++ b/include/sbi/riscv_encoding.h
@@ -279,6 +279,7 @@ 
 #define CSR_PMPADDR13			0x3bd
 #define CSR_PMPADDR14			0x3be
 #define CSR_PMPADDR15			0x3bf
+#define CSR_MSECCFG			0x390
 #define CSR_TSELECT			0x7a0
 #define CSR_TDATA1			0x7a1
 #define CSR_TDATA2			0x7a2
diff --git a/include/sbi/sbi_hart.h b/include/sbi/sbi_hart.h
index 51c2c35..4ed882f 100644
--- a/include/sbi/sbi_hart.h
+++ b/include/sbi/sbi_hart.h
@@ -16,12 +16,14 @@ 
 enum sbi_hart_features {
 	/** Hart has PMP support */
 	SBI_HART_HAS_PMP = (1 << 0),
+	/** enhanced PMP */
+	SBI_HART_HAS_EPMP = (1 << 1),
 	/** Hart has S-mode counter enable */
-	SBI_HART_HAS_SCOUNTEREN = (1 << 1),
+	SBI_HART_HAS_SCOUNTEREN = (1 << 2),
 	/** Hart has M-mode counter enable */
-	SBI_HART_HAS_MCOUNTEREN = (1 << 2),
+	SBI_HART_HAS_MCOUNTEREN = (1 << 3),
 	/** HART has timer csr implementation in hardware */
-	SBI_HART_HAS_TIME = (1 << 3),
+	SBI_HART_HAS_TIME = (1 << 4),
 
 	/** Last index of Hart features*/
 	SBI_HART_HAS_LAST_FEATURE = SBI_HART_HAS_TIME,
@@ -43,6 +45,7 @@  int sbi_hart_pmp_get(struct sbi_scratch *scratch, unsigned int n,
 		     unsigned long *prot_out, unsigned long *addr_out,
 		     unsigned long *size);
 void sbi_hart_pmp_dump(struct sbi_scratch *scratch);
+void sbi_hart_epmp_dump(struct sbi_scratch *scratch);
 int  sbi_hart_pmp_check_addr(struct sbi_scratch *scratch, unsigned long daddr,
 			     unsigned long attr);
 bool sbi_hart_has_feature(struct sbi_scratch *scratch, unsigned long feature);
diff --git a/lib/sbi/riscv_asm.c b/lib/sbi/riscv_asm.c
index 6dfebd9..4621f70 100644
--- a/lib/sbi/riscv_asm.c
+++ b/lib/sbi/riscv_asm.c
@@ -349,3 +349,33 @@  int pmp_get(unsigned int n, unsigned long *prot_out, unsigned long *addr_out,
 
 	return 0;
 }
+
+int epmp_set(int rlb, int mmwp, int mml)
+{
+	unsigned long mseccfg;
+
+	if ((rlb | mmwp | mml) & ~1)
+		return SBI_EINVAL;
+
+#if __riscv_xlen == 32 || __riscv_xlen == 64
+	mseccfg = rlb << 2 | mmwp << 1 | mml;
+#else
+	mseccfg = -1;
+#endif
+	if (mseccfg < 0)
+		return SBI_ENOTSUPP;
+
+	csr_write(CSR_MSECCFG, mseccfg);
+
+	return 0;
+}
+
+int epmp_get(int *rlb, int *mmwp, int *mml)
+{
+	unsigned long mseccfg = csr_read(CSR_MSECCFG);
+	*rlb = (mseccfg >> 2) & 1;
+	*mmwp = (mseccfg >> 1) & 1;
+	*mml = mseccfg & 1;
+
+	return 0;
+}
diff --git a/lib/sbi/sbi_hart.c b/lib/sbi/sbi_hart.c
index fa20bd2..c1c6957 100644
--- a/lib/sbi/sbi_hart.c
+++ b/lib/sbi/sbi_hart.c
@@ -184,6 +184,18 @@  void sbi_hart_pmp_dump(struct sbi_scratch *scratch)
 	}
 }
 
+void sbi_hart_epmp_dump(struct sbi_scratch *scratch)
+{
+	if (!sbi_hart_has_feature(scratch, SBI_HART_HAS_EPMP))
+		return;
+
+	int rlb, mmwp, mml;
+
+	epmp_get(&rlb, &mmwp, &mml);
+	sbi_printf("ePMP: RLB = %d, MMWP = %d, MML = %d\n",
+				rlb, mmwp, mml);
+}
+
 int sbi_hart_pmp_check_addr(struct sbi_scratch *scratch, unsigned long addr,
 			    unsigned long attr)
 {
@@ -239,6 +251,9 @@  static int pmp_init(struct sbi_scratch *scratch, u32 hartid)
 	 */
 	pmp_set(pmp_idx++, PMP_R | PMP_W | PMP_X, 0, __riscv_xlen);
 
+	if (sbi_hart_has_feature(scratch, SBI_HART_HAS_EPMP))
+		epmp_set(0, 0, 0);
+
 	return 0;
 }
 
@@ -288,6 +303,9 @@  static inline char *sbi_hart_feature_id2string(unsigned long feature)
 	case SBI_HART_HAS_TIME:
 		fstr = "time";
 		break;
+	case SBI_HART_HAS_EPMP:
+		fstr = "epmp";
+		break;
 	default:
 		break;
 	}
@@ -397,6 +415,15 @@  static void hart_detect_features(struct sbi_scratch *scratch)
 			hfeatures->features |= SBI_HART_HAS_MCOUNTEREN;
 	}
 
+	/* Detect if hart supports EPMP(enhanced PMP) feature */
+	trap.cause = 0;
+	val = csr_read_allowed(CSR_MSECCFG, (unsigned long)&trap);
+	if (!trap.cause) {
+		csr_write_allowed(CSR_MSECCFG, (unsigned long)&trap, val);
+		if (!trap.cause)
+			hfeatures->features |= SBI_HART_HAS_EPMP;
+	}
+
 	/* Detect if hart supports time CSR */
 	trap.cause = 0;
 	csr_read_allowed(CSR_TIME, (unsigned long)&trap);
diff --git a/lib/sbi/sbi_init.c b/lib/sbi/sbi_init.c
index a7fb848..1ced76b 100644
--- a/lib/sbi/sbi_init.c
+++ b/lib/sbi/sbi_init.c
@@ -82,6 +82,7 @@  static void sbi_boot_prints(struct sbi_scratch *scratch, u32 hartid)
 
 	sbi_hart_delegation_dump(scratch);
 	sbi_hart_pmp_dump(scratch);
+	sbi_hart_epmp_dump(scratch);
 }
 
 static spinlock_t coldboot_lock = SPIN_LOCK_INITIALIZER;