Hi Weizhao,

• if (request_psci_features(ARM_SMCCC_ARCH_FEATURES) ==

• if (request_psci_features(ARM_SMCCC_VERSION) == PSCI_RET_NOT_SUPPORTED) return 0;

• if (invoke_psci_fn(ARM_SMCCC_VERSION, 0, 0, 0) < ARM_SMCCC_VERSION_1_1)

• return 0;
  

It makes sense to me, thanks.

diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h index f44e9e8f93..da3d29aabe 100644 --- a/include/linux/arm-smccc.h +++ b/include/linux/arm-smccc.h @@ -55,8 +55,14 @@ #define ARM_SMCCC_QUIRK_NONE 0 #define ARM_SMCCC_QUIRK_QCOM_A6 1 /* Save/restore register a6 */

+#define ARM_SMCCC_VERSION 0x80000000 #define ARM_SMCCC_ARCH_FEATURES 0x80000001

+#define ARM_SMCCC_VERSION_1_0 0x10000 +#define ARM_SMCCC_VERSION_1_1 0x10001 +#define ARM_SMCCC_VERSION_1_2 0x10002 +#define ARM_SMCCC_VERSION_1_3 0x10003

Apart from ARM_SMCCC_VERSION_1_1, are the other ARM_SMCCC_VERSION_1_x defines needed ?

Cheers, Abdellatif

Hello Weizhao,

On Wed, Jan 31, 2024 at 3:15 PM Weizhao Ouyang o451686892@gmail.com wrote:

According to PSCI specification DEN0022F, PSCI_FEATURES is used to check whether the SMCCC is implemented by discovering SMCCC_VERSION.

Could you please add more details to your commit message or as a comment explaining what exact steps should be done for a full discovery sequence of Arm Architecture Service functions, so people don't need to search for that information explicitly?

For instance: Step 1: Determine if SMCCC_VERSION is implemented - Use firmware data, device tree PSCI node, or ACPI FADT PSCI flag, to determine whether a PSCI implementation is present. - Use PSCI_VERSION to learn whether PSCI_FEATURES is provided. PSCI_FEATURES is mandatory from version 1.0 of PSCI Step 2. etc.

I would just pull that info from the latest SMC Calling Convention version 1.5, from 9 Appendix B: Discovery of Arm Architecture Service functions.

Thank you!

Signed-off-by: Weizhao Ouyang o451686892@gmail.com

v3: remove fallback smc call v2: check SMCCC_ARCH_FEATURES

---

drivers/firmware/psci.c | 5 ++++- include/linux/arm-smccc.h | 6 ++++++ 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/firmware/psci.c b/drivers/firmware/psci.c index c6b9efab41..03544d76ed 100644 --- a/drivers/firmware/psci.c +++ b/drivers/firmware/psci.c @@ -135,10 +135,13 @@ static int bind_smccc_features(struct udevice *dev, int psci_method) PSCI_VERSION_MAJOR(psci_0_2_get_version()) == 0) return 0;

•   if (request_psci_features(ARM_SMCCC_ARCH_FEATURES) ==
  

•   if (request_psci_features(ARM_SMCCC_VERSION) ==
        PSCI_RET_NOT_SUPPORTED)
            return 0;
  
  

•   if (invoke_psci_fn(ARM_SMCCC_VERSION, 0, 0, 0) < ARM_SMCCC_VERSION_1_1)
  

•           return 0;
  

IMO, to fully comply with SMC Calling Convention version 1.5 we should also check for SMCCC_ARCH_WORKAROUND_1:

From 9 Appendix B: Discovery of Arm Architecture Service functions,

Step 2: Determine if Arm Architecture Service function is implemented - Use SMCCC_VERSION to learn whether the calling convention complies to version 1.1 or above. - Use SMCCC_ARCH_FEATURES to query whether the Arm Architecture Service function is implemented on this system <--- we lack of this step

    if (psci_method == PSCI_METHOD_HVC)
            pdata->invoke_fn = smccc_invoke_hvc;
    else

diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h index f44e9e8f93..da3d29aabe 100644 --- a/include/linux/arm-smccc.h +++ b/include/linux/arm-smccc.h @@ -55,8 +55,14 @@ #define ARM_SMCCC_QUIRK_NONE 0 #define ARM_SMCCC_QUIRK_QCOM_A6 1 /* Save/restore register a6 */

+#define ARM_SMCCC_VERSION 0x80000000 #define ARM_SMCCC_ARCH_FEATURES 0x80000001

+#define ARM_SMCCC_VERSION_1_0 0x10000 +#define ARM_SMCCC_VERSION_1_1 0x10001 +#define ARM_SMCCC_VERSION_1_2 0x10002 +#define ARM_SMCCC_VERSION_1_3 0x10003

#define ARM_SMCCC_RET_NOT_SUPPORTED ((unsigned long)-1)

#ifndef __ASSEMBLY__

2.39.2

Hello Weizhao,

On Fri, Feb 2, 2024 at 4:43 AM Weizhao Ouyang o451686892@gmail.com wrote:

Hi Igor,

On Thu, Feb 1, 2024 at 10:36 PM Igor Opaniuk igor.opaniuk@foundries.io wrote:

...

Hello Weizhao,

On Wed, Jan 31, 2024 at 3:15 PM Weizhao Ouyang o451686892@gmail.com wrote:

...

According to PSCI specification DEN0022F, PSCI_FEATURES is used to check whether the SMCCC is implemented by discovering SMCCC_VERSION.

Could you please add more details to your commit message or as a comment explaining what exact steps should be done for a full discovery sequence of Arm Architecture Service functions, so people don't need to search for that information explicitly?

For instance: Step 1: Determine if SMCCC_VERSION is implemented

• Use firmware data, device tree PSCI node, or ACPI FADT PSCI flag, to

determine whether a PSCI implementation is present.

• Use PSCI_VERSION to learn whether PSCI_FEATURES is provided. PSCI_FEATURES is

mandatory from version 1.0 of PSCI Step 2. etc.

I would just pull that info from the latest SMC Calling Convention version 1.5, from 9 Appendix B: Discovery of Arm Architecture Service functions.

Thank you!

...

Signed-off-by: Weizhao Ouyang o451686892@gmail.com

v3: remove fallback smc call v2: check SMCCC_ARCH_FEATURES

---

drivers/firmware/psci.c | 5 ++++- include/linux/arm-smccc.h | 6 ++++++ 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/firmware/psci.c b/drivers/firmware/psci.c index c6b9efab41..03544d76ed 100644 --- a/drivers/firmware/psci.c +++ b/drivers/firmware/psci.c @@ -135,10 +135,13 @@ static int bind_smccc_features(struct udevice *dev, int psci_method) PSCI_VERSION_MAJOR(psci_0_2_get_version()) == 0) return 0;

•   if (request_psci_features(ARM_SMCCC_ARCH_FEATURES) ==
  

•   if (request_psci_features(ARM_SMCCC_VERSION) ==
        PSCI_RET_NOT_SUPPORTED)
            return 0;
  
  

•   if (invoke_psci_fn(ARM_SMCCC_VERSION, 0, 0, 0) < ARM_SMCCC_VERSION_1_1)
  

•           return 0;
  

IMO, to fully comply with SMC Calling Convention version 1.5 we should also check for SMCCC_ARCH_WORKAROUND_1:

From 9 Appendix B: Discovery of Arm Architecture Service functions, Step 2: Determine if Arm Architecture Service function is implemented

• Use SMCCC_VERSION to learn whether the calling convention complies

to version 1.1 or above.

• Use SMCCC_ARCH_FEATURES to query whether the Arm Architecture

Service function is implemented on this system <--- we lack of this step

Thanks for your review. The 9 Appendix B describes an approach to discovery the maximize ability without causing unsafe behavior on existing platforms. Regarding the second step, it is just using SMCCC_ARCH_WORKAROUND_1 as an example to test SMCCC_ARCH_FEATURES.

For the U-Boot case, we can revisit this from two perspectives:

1. SMCCC_ARCH_FEATURES is MANDATORY from SMCCC v1.1.
2. SMCCC_VERSION is OPTIONAL for SMCCC v1.0, so we should consider a

safe behavior. 3. U-Boot is using CONFIG_ARM_SMCCC_FEATURES to probe and bind SMCCC service driver if this driver is reported as supported. 4. U-Boot SMCCC service driver can embed its discovery process in is_supported() callback.

So now we can choose the following approach in U-Boot:

• Use firmware data (check "arm,psci-1.0") to determine whether a PSCI

implementation is present.

• Use PSCI_VERSION (psci_0_2_get_version() major version >= 0) to learn

whether PSCI_FEATURES is provided.

• Use PSCI_FEATURES with the SMCCC_VERSION Function Identifier as a

parameter to determine that SMCCC_VERSION is implemented.

• Use SMCCC_VERSION to learn whether the calling convention complies to

version 1.1 or above.

• Trying to probe and bind SMCCC service driver.

Thanks for the detailed explanation! Reviewed-by: Igor Opaniuk igor.opaniuk@foundries.io

BR, Weizhao

...

...

    if (psci_method == PSCI_METHOD_HVC)
            pdata->invoke_fn = smccc_invoke_hvc;
    else

diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h index f44e9e8f93..da3d29aabe 100644 --- a/include/linux/arm-smccc.h +++ b/include/linux/arm-smccc.h @@ -55,8 +55,14 @@ #define ARM_SMCCC_QUIRK_NONE 0 #define ARM_SMCCC_QUIRK_QCOM_A6 1 /* Save/restore register a6 */

+#define ARM_SMCCC_VERSION 0x80000000 #define ARM_SMCCC_ARCH_FEATURES 0x80000001

+#define ARM_SMCCC_VERSION_1_0 0x10000 +#define ARM_SMCCC_VERSION_1_1 0x10001 +#define ARM_SMCCC_VERSION_1_2 0x10002 +#define ARM_SMCCC_VERSION_1_3 0x10003

#define ARM_SMCCC_RET_NOT_SUPPORTED ((unsigned long)-1)

#ifndef __ASSEMBLY__

2.39.2

-- Best regards - Freundliche Grüsse - Meilleures salutations

Igor Opaniuk Senior Software Engineer, Embedded & Security E: igor.opaniuk@foundries.io W: www.foundries.io

On Wed, Jan 31, 2024 at 02:14:25PM +0000, Weizhao Ouyang wrote:

Fix a SMCCC TRNG null pointer crash due to a failed smccc feature binding.

Fixes: 53355bb86c25 ("drivers: rng: add smccc trng driver") Reviewed-by: Heinrich Schuchardt xypron.glpk@gmx.de Signed-off-by: Weizhao Ouyang o451686892@gmail.com

Reviewed-by: Matthias Brugger mbrugger@suse.com

---

v3: add Fixes tag

drivers/rng/smccc_trng.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/rng/smccc_trng.c b/drivers/rng/smccc_trng.c index 3a4bb33941..3087cb991a 100644 --- a/drivers/rng/smccc_trng.c +++ b/drivers/rng/smccc_trng.c @@ -166,7 +166,7 @@ static int smccc_trng_probe(struct udevice *dev) struct smccc_trng_priv *priv = dev_get_priv(dev); struct arm_smccc_res res;

• if (!(smccc_trng_is_supported(smccc->invoke_fn)))

• if (!smccc || !(smccc_trng_is_supported(smccc->invoke_fn))) return -ENODEV;

  /* At least one of 64bit and 32bit interfaces is available */

-- 2.39.2

On Wed, Jan 31, 2024 at 02:14:26PM +0000, Weizhao Ouyang wrote:

The 'rng list' command probes all RNG devices and list those devices that are successfully probed. Also update the help info.

Reviewed-by: Heinrich Schuchardt xypron.glpk@gmx.de Signed-off-by: Weizhao Ouyang o451686892@gmail.com

Reviewed-by: Matthias Brugger mbrugger@suse.com

---

cmd/rng.c | 23 ++++++++++++++++++----- 1 file changed, 18 insertions(+), 5 deletions(-)

diff --git a/cmd/rng.c b/cmd/rng.c index 52f722c7af..b073a6c849 100644 --- a/cmd/rng.c +++ b/cmd/rng.c @@ -19,6 +19,22 @@ static int do_rng(struct cmd_tbl *cmdtp, int flag, int argc, char *const argv[]) struct udevice *dev; int ret = CMD_RET_SUCCESS;

• if (argc == 2 && !strcmp(argv[1], "list")) {

• int idx = 0;
  

• uclass_foreach_dev_probe(UCLASS_RNG, dev) {
  

• 	idx++;
  

• 	printf("RNG #%d - %s\n", dev->seq_, dev->name);
  

• }
  

• if (!idx) {
  

• 	log_err("No RNG device\n");
  

• 	return CMD_RET_FAILURE;
  

• }
  

• return CMD_RET_SUCCESS;
  

• }
• switch (argc) { case 1: devnum = 0;

@@ -56,12 +72,9 @@ static int do_rng(struct cmd_tbl *cmdtp, int flag, int argc, char *const argv[]) return ret; }

-U_BOOT_LONGHELP(rng,

• "[dev [n]]\n"
• " - print n random bytes(max 64) read from dev\n");

U_BOOT_CMD( rng, 3, 0, do_rng, "print bytes from the hardware random number generator",

• rng_help_text

• "list - list all the probed rng devices\n"
• "rng [dev] [n] - print n random bytes(max 64) read from dev\n"

);

2.39.2