[PATCH] sbi: fwft: clear the config lock when warm boot

[PATCH] sbi: fwft: clear the config lock when warm boot

[Nick Hu]

The hotplug cpu should clear the fwft config's SBI_FWFT_SET_FLAG_LOCK
in the warm boot flow otherwise the cpu can't set the menvcfg.sse by
SBI_EXT_FWFT_SET sbi call and cause the illegal instruction when
accessing the CSR_SSP in kernel.

Signed-off-by: Nick Hu <nick.hu@sifive.com>
---
 lib/sbi/sbi_fwft.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/lib/sbi/sbi_fwft.c b/lib/sbi/sbi_fwft.c
index 9cf14c16..0cb165b4 100644
--- a/lib/sbi/sbi_fwft.c
+++ b/lib/sbi/sbi_fwft.c
@@ -311,6 +311,18 @@ static int fwft_get_feature(enum sbi_fwft_feature_t feature,
 	return SBI_SUCCESS;
 }
 
+static void fwft_clear_config_lock(enum sbi_fwft_feature_t feature)
+{
+	int ret;
+	struct fwft_config *conf;
+
+	ret = fwft_get_feature(feature, &conf);
+	if (ret)
+		return;
+
+	conf->flags &= ~SBI_FWFT_SET_FLAG_LOCK;
+}
+
 int sbi_fwft_set(enum sbi_fwft_feature_t feature, unsigned long value,
 		 unsigned long flags)
 {
@@ -414,5 +426,8 @@ int sbi_fwft_init(struct sbi_scratch *scratch, bool cold_boot)
 		fwft_set_hart_state_ptr(scratch, fhs);
 	}
 
+	for (i = 0; i < array_size(features); i++)
+		fwft_clear_config_lock(features[i].id);
+
 	return 0;
 }
-- 
2.34.1

[PATCH] sbi: fwft: clear the config lock when warm boot

[Xiang W]

? 2024-11-15?? 15:33 +0800?Nick Hu???
> The hotplug cpu should clear the fwft config's SBI_FWFT_SET_FLAG_LOCK
> in the warm boot flow otherwise the cpu can't set the menvcfg.sse by
> SBI_EXT_FWFT_SET sbi call and cause the illegal instruction when
> accessing the CSR_SSP in kernel.
> 
> Signed-off-by: Nick Hu <nick.hu@sifive.com>

In sbi_fwft_init, the memory for fwft_hart_state is allocated by?
sbi_zalloc, which ensures that flags is 0. So no additional code
is needed to clear the SBI_FWFT_SET_FLAG_LOCK bit.

Regards,
Xiang W
> ---
> ?lib/sbi/sbi_fwft.c | 15 +++++++++++++++
> ?1 file changed, 15 insertions(+)
> 
> diff --git a/lib/sbi/sbi_fwft.c b/lib/sbi/sbi_fwft.c
> index 9cf14c16..0cb165b4 100644
> --- a/lib/sbi/sbi_fwft.c
> +++ b/lib/sbi/sbi_fwft.c
> @@ -311,6 +311,18 @@ static int fwft_get_feature(enum sbi_fwft_feature_t feature,
> ?	return SBI_SUCCESS;
> ?}
> ?
> +static void fwft_clear_config_lock(enum sbi_fwft_feature_t feature)
> +{
> +	int ret;
> +	struct fwft_config *conf;
> +
> +	ret = fwft_get_feature(feature, &conf);
> +	if (ret)
> +		return;
> +
> +	conf->flags &= ~SBI_FWFT_SET_FLAG_LOCK;
> +}
> +
> ?int sbi_fwft_set(enum sbi_fwft_feature_t feature, unsigned long value,
> ?		 unsigned long flags)
> ?{
> @@ -414,5 +426,8 @@ int sbi_fwft_init(struct sbi_scratch *scratch, bool cold_boot)
> ?		fwft_set_hart_state_ptr(scratch, fhs);
> ?	}
> ?
> +	for (i = 0; i < array_size(features); i++)
> +		fwft_clear_config_lock(features[i].id);
> +
> ?	return 0;
> ?}
> -- 
> 2.34.1
> 
> 

[PATCH] sbi: fwft: clear the config lock when warm boot

[Samuel Holland]

Hi Xiang,

On 2024-11-21 8:45 PM, Xiang W wrote:
> ? 2024-11-15?? 15:33 +0800?Nick Hu???
>> The hotplug cpu should clear the fwft config's SBI_FWFT_SET_FLAG_LOCK
>> in the warm boot flow otherwise the cpu can't set the menvcfg.sse by
>> SBI_EXT_FWFT_SET sbi call and cause the illegal instruction when
>> accessing the CSR_SSP in kernel.
>>
>> Signed-off-by: Nick Hu <nick.hu@sifive.com>
> 
> In sbi_fwft_init, the memory for fwft_hart_state is allocated by?
> sbi_zalloc, which ensures that flags is 0. So no additional code
> is needed to clear the SBI_FWFT_SET_FLAG_LOCK bit.

That allocation only occurs the first time a hart is started. After a
sbi_hsm_hart_stop() and sbi_hsm_hart_start(), the FWFT features will be reset to
their default values per the SBI spec, and the flags need to be reset as well.

Regards,
Samuel

>> ---
>> ?lib/sbi/sbi_fwft.c | 15 +++++++++++++++
>> ?1 file changed, 15 insertions(+)
>>
>> diff --git a/lib/sbi/sbi_fwft.c b/lib/sbi/sbi_fwft.c
>> index 9cf14c16..0cb165b4 100644
>> --- a/lib/sbi/sbi_fwft.c
>> +++ b/lib/sbi/sbi_fwft.c
>> @@ -311,6 +311,18 @@ static int fwft_get_feature(enum sbi_fwft_feature_t feature,
>> ?	return SBI_SUCCESS;
>> ?}
>> ?
>> +static void fwft_clear_config_lock(enum sbi_fwft_feature_t feature)
>> +{
>> +	int ret;
>> +	struct fwft_config *conf;
>> +
>> +	ret = fwft_get_feature(feature, &conf);
>> +	if (ret)
>> +		return;
>> +
>> +	conf->flags &= ~SBI_FWFT_SET_FLAG_LOCK;
>> +}
>> +
>> ?int sbi_fwft_set(enum sbi_fwft_feature_t feature, unsigned long value,
>> ?		 unsigned long flags)
>> ?{
>> @@ -414,5 +426,8 @@ int sbi_fwft_init(struct sbi_scratch *scratch, bool cold_boot)
>> ?		fwft_set_hart_state_ptr(scratch, fhs);
>> ?	}
>> ?
>> +	for (i = 0; i < array_size(features); i++)
>> +		fwft_clear_config_lock(features[i].id);
>> +
>> ?	return 0;
>> ?}
>> -- 
>> 2.34.1
>>
>>
> 
> 

[PATCH] sbi: fwft: clear the config lock when warm boot

[Xiang W]

? 2024-11-21?? 21:24 -0600?Samuel Holland???
> Hi Xiang,
> 
> On 2024-11-21 8:45 PM, Xiang W wrote:
> > ? 2024-11-15?? 15:33 +0800?Nick Hu???
> > > The hotplug cpu should clear the fwft config's SBI_FWFT_SET_FLAG_LOCK
> > > in the warm boot flow otherwise the cpu can't set the menvcfg.sse by
> > > SBI_EXT_FWFT_SET sbi call and cause the illegal instruction when
> > > accessing the CSR_SSP in kernel.
> > > 
> > > Signed-off-by: Nick Hu <nick.hu@sifive.com>
> > 
> > In sbi_fwft_init, the memory for fwft_hart_state is allocated by?
> > sbi_zalloc, which ensures that flags is 0. So no additional code
> > is needed to clear the SBI_FWFT_SET_FLAG_LOCK bit.
> 
> That allocation only occurs the first time a hart is started. After a
> sbi_hsm_hart_stop() and sbi_hsm_hart_start(), the FWFT features will be reset to
> their default values per the SBI spec, and the flags need to be reset as well.
> 
Yes, you are right, I ignored the situation you mentioned.

Regards,
Xiang W
> Regards,
> Samuel
> 
> > > ---
> > > ?lib/sbi/sbi_fwft.c | 15 +++++++++++++++
> > > ?1 file changed, 15 insertions(+)
> > > 
> > > diff --git a/lib/sbi/sbi_fwft.c b/lib/sbi/sbi_fwft.c
> > > index 9cf14c16..0cb165b4 100644
> > > --- a/lib/sbi/sbi_fwft.c
> > > +++ b/lib/sbi/sbi_fwft.c
> > > @@ -311,6 +311,18 @@ static int fwft_get_feature(enum sbi_fwft_feature_t feature,
> > > ?	return SBI_SUCCESS;
> > > ?}
> > > ?
> > > +static void fwft_clear_config_lock(enum sbi_fwft_feature_t feature)
> > > +{
> > > +	int ret;
> > > +	struct fwft_config *conf;
> > > +
> > > +	ret = fwft_get_feature(feature, &conf);
> > > +	if (ret)
> > > +		return;
> > > +
> > > +	conf->flags &= ~SBI_FWFT_SET_FLAG_LOCK;
> > > +}
> > > +
> > > ?int sbi_fwft_set(enum sbi_fwft_feature_t feature, unsigned long value,
> > > ?		 unsigned long flags)
> > > ?{
> > > @@ -414,5 +426,8 @@ int sbi_fwft_init(struct sbi_scratch *scratch, bool cold_boot)
> > > ?		fwft_set_hart_state_ptr(scratch, fhs);
> > > ?	}
> > > ?
> > > +	for (i = 0; i < array_size(features); i++)
> > > +		fwft_clear_config_lock(features[i].id);
> > > +
> > > ?	return 0;
> > > ?}
> > > -- 
> > > 2.34.1
> > > 
> > > 
> > 
> > 
> 
> 

[PATCH] sbi: fwft: clear the config lock when warm boot

[Anup Patel]

On Fri, Nov 15, 2024 at 1:03?PM Nick Hu <nick.hu@sifive.com> wrote:
>
> The hotplug cpu should clear the fwft config's SBI_FWFT_SET_FLAG_LOCK
> in the warm boot flow otherwise the cpu can't set the menvcfg.sse by
> SBI_EXT_FWFT_SET sbi call and cause the illegal instruction when
> accessing the CSR_SSP in kernel.
>
> Signed-off-by: Nick Hu <nick.hu@sifive.com>

LGTM.

Reviewed-by: Anup Patel <anup@brainfault.org>

Applied this patch to the riscv/opensbi repo.

Thanks,
Anup

> ---
>  lib/sbi/sbi_fwft.c | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
>
> diff --git a/lib/sbi/sbi_fwft.c b/lib/sbi/sbi_fwft.c
> index 9cf14c16..0cb165b4 100644
> --- a/lib/sbi/sbi_fwft.c
> +++ b/lib/sbi/sbi_fwft.c
> @@ -311,6 +311,18 @@ static int fwft_get_feature(enum sbi_fwft_feature_t feature,
>         return SBI_SUCCESS;
>  }
>
> +static void fwft_clear_config_lock(enum sbi_fwft_feature_t feature)
> +{
> +       int ret;
> +       struct fwft_config *conf;
> +
> +       ret = fwft_get_feature(feature, &conf);
> +       if (ret)
> +               return;
> +
> +       conf->flags &= ~SBI_FWFT_SET_FLAG_LOCK;
> +}
> +
>  int sbi_fwft_set(enum sbi_fwft_feature_t feature, unsigned long value,
>                  unsigned long flags)
>  {
> @@ -414,5 +426,8 @@ int sbi_fwft_init(struct sbi_scratch *scratch, bool cold_boot)
>                 fwft_set_hart_state_ptr(scratch, fhs);
>         }
>
> +       for (i = 0; i < array_size(features); i++)
> +               fwft_clear_config_lock(features[i].id);
> +
>         return 0;
>  }
> --
> 2.34.1
>
>
> --
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