[PATCH] ata: libata: disallow dev-initiated LPM transitions to unsupported states

[PATCH] ata: libata: disallow dev-initiated LPM transitions to unsupported states

[Niklas Cassel]

From: Niklas Cassel <niklas.cassel@wdc.com>

In AHCI 1.3.1, the register description for CAP.SSC:
"When cleared to ‘0’, software must not allow the HBA to initiate
transitions to the Slumber state via agressive link power management nor
the PxCMD.ICC field in each port, and the PxSCTL.IPM field in each port
must be programmed to disallow device initiated Slumber requests."

In AHCI 1.3.1, the register description for CAP.PSC:
"When cleared to ‘0’, software must not allow the HBA to initiate
transitions to the Partial state via agressive link power management nor
the PxCMD.ICC field in each port, and the PxSCTL.IPM field in each port
must be programmed to disallow device initiated Partial requests."

Ensure that we always set the corresponding bits in PxSCTL.IPM, such that
a device is not allowed to initiate transitions to power states which are
unsupported by the HBA.

DevSleep is always initiated by the HBA, however, for completeness, set the
corresponding bit in PxSCTL.IPM such that agressive link power management
cannot transition to DevSleep if DevSleep is not supported.

sata_link_scr_lpm() is used by libahci, ata_piix and libata-pmp.
However, only libahci has the ability to read the CAP/CAP2 register to see
if these features are supported. Therefore, in order to not introduce any
regressions on ata_piix or libata-pmp, create flags that indicate that the
respective feature is NOT supported. This way, the behavior for ata_piix
and libata-pmp should remain unchanged.

This change is based on a patch originally submitted by Runa Guo-oc.

Signed-off-by: Niklas Cassel <niklas.cassel@wdc.com>
---
 drivers/ata/ahci.c        |  9 +++++++++
 drivers/ata/libata-sata.c | 19 ++++++++++++++++---
 include/linux/libata.h    |  4 ++++
 3 files changed, 29 insertions(+), 3 deletions(-)

diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
index abb5911c9d09..08745e7db820 100644
--- a/drivers/ata/ahci.c
+++ b/drivers/ata/ahci.c
@@ -1883,6 +1883,15 @@ static int ahci_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
 	else
 		dev_info(&pdev->dev, "SSS flag set, parallel bus scan disabled\n");
 
+	if (!(hpriv->cap & HOST_CAP_PART))
+		host->flags |= ATA_HOST_NO_PART;
+
+	if (!(hpriv->cap & HOST_CAP_SSC))
+		host->flags |= ATA_HOST_NO_SSC;
+
+	if (!(hpriv->cap2 & HOST_CAP2_SDS))
+		host->flags |= ATA_HOST_NO_DEVSLP;
+
 	if (pi.flags & ATA_FLAG_EM)
 		ahci_reset_em(host);
 
diff --git a/drivers/ata/libata-sata.c b/drivers/ata/libata-sata.c
index 5d31c08be013..a701e1538482 100644
--- a/drivers/ata/libata-sata.c
+++ b/drivers/ata/libata-sata.c
@@ -396,10 +396,23 @@ int sata_link_scr_lpm(struct ata_link *link, enum ata_lpm_policy policy,
 	case ATA_LPM_MED_POWER_WITH_DIPM:
 	case ATA_LPM_MIN_POWER_WITH_PARTIAL:
 	case ATA_LPM_MIN_POWER:
-		if (ata_link_nr_enabled(link) > 0)
-			/* no restrictions on LPM transitions */
+		if (ata_link_nr_enabled(link) > 0) {
+			/* assume no restrictions on LPM transitions */
 			scontrol &= ~(0x7 << 8);
-		else {
+
+			/*
+			 * If the controller does not support partial, slumber,
+			 * or devsleep, then disallow these transitions.
+			 */
+			if (link->ap->host->flags & ATA_HOST_NO_PART)
+				scontrol |= (0x1 << 8);
+
+			if (link->ap->host->flags & ATA_HOST_NO_SSC)
+				scontrol |= (0x2 << 8);
+
+			if (link->ap->host->flags & ATA_HOST_NO_DEVSLP)
+				scontrol |= (0x4 << 8);
+		} else {
 			/* empty port, power off */
 			scontrol &= ~0xf;
 			scontrol |= (0x1 << 2);
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 52d58b13e5ee..bf4913f4d7ac 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -222,6 +222,10 @@ enum {
 	ATA_HOST_PARALLEL_SCAN	= (1 << 2),	/* Ports on this host can be scanned in parallel */
 	ATA_HOST_IGNORE_ATA	= (1 << 3),	/* Ignore ATA devices on this host. */
 
+	ATA_HOST_NO_PART	= (1 << 4), /* Host does not support partial */
+	ATA_HOST_NO_SSC		= (1 << 5), /* Host does not support slumber */
+	ATA_HOST_NO_DEVSLP	= (1 << 6), /* Host does not support devslp */
+
 	/* bits 24:31 of host->flags are reserved for LLD specific flags */
 
 	/* various lengths of time */
-- 
2.41.0

Re: [PATCH] ata: libata: disallow dev-initiated LPM transitions to unsupported states

[Damien Le Moal]

On 9/5/23 05:42, Niklas Cassel wrote:
> From: Niklas Cassel <niklas.cassel@wdc.com>
> 
> In AHCI 1.3.1, the register description for CAP.SSC:
> "When cleared to ‘0’, software must not allow the HBA to initiate
> transitions to the Slumber state via agressive link power management nor
> the PxCMD.ICC field in each port, and the PxSCTL.IPM field in each port
> must be programmed to disallow device initiated Slumber requests."
> 
> In AHCI 1.3.1, the register description for CAP.PSC:
> "When cleared to ‘0’, software must not allow the HBA to initiate
> transitions to the Partial state via agressive link power management nor
> the PxCMD.ICC field in each port, and the PxSCTL.IPM field in each port
> must be programmed to disallow device initiated Partial requests."
> 
> Ensure that we always set the corresponding bits in PxSCTL.IPM, such that
> a device is not allowed to initiate transitions to power states which are
> unsupported by the HBA.
> 
> DevSleep is always initiated by the HBA, however, for completeness, set the
> corresponding bit in PxSCTL.IPM such that agressive link power management
> cannot transition to DevSleep if DevSleep is not supported.
> 
> sata_link_scr_lpm() is used by libahci, ata_piix and libata-pmp.
> However, only libahci has the ability to read the CAP/CAP2 register to see
> if these features are supported. Therefore, in order to not introduce any
> regressions on ata_piix or libata-pmp, create flags that indicate that the
> respective feature is NOT supported. This way, the behavior for ata_piix
> and libata-pmp should remain unchanged.
> 
> This change is based on a patch originally submitted by Runa Guo-oc.
> 
> Signed-off-by: Niklas Cassel <niklas.cassel@wdc.com>

Looks good, but don't we need a Fixes tag for this ?

> ---
>  drivers/ata/ahci.c        |  9 +++++++++
>  drivers/ata/libata-sata.c | 19 ++++++++++++++++---
>  include/linux/libata.h    |  4 ++++
>  3 files changed, 29 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
> index abb5911c9d09..08745e7db820 100644
> --- a/drivers/ata/ahci.c
> +++ b/drivers/ata/ahci.c
> @@ -1883,6 +1883,15 @@ static int ahci_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
>  	else
>  		dev_info(&pdev->dev, "SSS flag set, parallel bus scan disabled\n");
>  
> +	if (!(hpriv->cap & HOST_CAP_PART))
> +		host->flags |= ATA_HOST_NO_PART;
> +
> +	if (!(hpriv->cap & HOST_CAP_SSC))
> +		host->flags |= ATA_HOST_NO_SSC;
> +
> +	if (!(hpriv->cap2 & HOST_CAP2_SDS))
> +		host->flags |= ATA_HOST_NO_DEVSLP;
> +
>  	if (pi.flags & ATA_FLAG_EM)
>  		ahci_reset_em(host);
>  
> diff --git a/drivers/ata/libata-sata.c b/drivers/ata/libata-sata.c
> index 5d31c08be013..a701e1538482 100644
> --- a/drivers/ata/libata-sata.c
> +++ b/drivers/ata/libata-sata.c
> @@ -396,10 +396,23 @@ int sata_link_scr_lpm(struct ata_link *link, enum ata_lpm_policy policy,
>  	case ATA_LPM_MED_POWER_WITH_DIPM:
>  	case ATA_LPM_MIN_POWER_WITH_PARTIAL:
>  	case ATA_LPM_MIN_POWER:
> -		if (ata_link_nr_enabled(link) > 0)
> -			/* no restrictions on LPM transitions */
> +		if (ata_link_nr_enabled(link) > 0) {
> +			/* assume no restrictions on LPM transitions */
>  			scontrol &= ~(0x7 << 8);
> -		else {
> +
> +			/*
> +			 * If the controller does not support partial, slumber,
> +			 * or devsleep, then disallow these transitions.
> +			 */
> +			if (link->ap->host->flags & ATA_HOST_NO_PART)
> +				scontrol |= (0x1 << 8);
> +
> +			if (link->ap->host->flags & ATA_HOST_NO_SSC)
> +				scontrol |= (0x2 << 8);
> +
> +			if (link->ap->host->flags & ATA_HOST_NO_DEVSLP)
> +				scontrol |= (0x4 << 8);
> +		} else {
>  			/* empty port, power off */
>  			scontrol &= ~0xf;
>  			scontrol |= (0x1 << 2);
> diff --git a/include/linux/libata.h b/include/linux/libata.h
> index 52d58b13e5ee..bf4913f4d7ac 100644
> --- a/include/linux/libata.h
> +++ b/include/linux/libata.h
> @@ -222,6 +222,10 @@ enum {
>  	ATA_HOST_PARALLEL_SCAN	= (1 << 2),	/* Ports on this host can be scanned in parallel */
>  	ATA_HOST_IGNORE_ATA	= (1 << 3),	/* Ignore ATA devices on this host. */
>  
> +	ATA_HOST_NO_PART	= (1 << 4), /* Host does not support partial */
> +	ATA_HOST_NO_SSC		= (1 << 5), /* Host does not support slumber */
> +	ATA_HOST_NO_DEVSLP	= (1 << 6), /* Host does not support devslp */
> +
>  	/* bits 24:31 of host->flags are reserved for LLD specific flags */
>  
>  	/* various lengths of time */

-- 
Damien Le Moal
Western Digital Research

Re: [PATCH] ata: libata: disallow dev-initiated LPM transitions to unsupported states

[Niklas Cassel]

On Tue, Sep 05, 2023 at 11:29:13AM +0900, Damien Le Moal wrote:
> On 9/5/23 05:42, Niklas Cassel wrote:
> > From: Niklas Cassel <niklas.cassel@wdc.com>
> > 
> > In AHCI 1.3.1, the register description for CAP.SSC:
> > "When cleared to ‘0’, software must not allow the HBA to initiate
> > transitions to the Slumber state via agressive link power management nor
> > the PxCMD.ICC field in each port, and the PxSCTL.IPM field in each port
> > must be programmed to disallow device initiated Slumber requests."
> > 
> > In AHCI 1.3.1, the register description for CAP.PSC:
> > "When cleared to ‘0’, software must not allow the HBA to initiate
> > transitions to the Partial state via agressive link power management nor
> > the PxCMD.ICC field in each port, and the PxSCTL.IPM field in each port
> > must be programmed to disallow device initiated Partial requests."
> > 
> > Ensure that we always set the corresponding bits in PxSCTL.IPM, such that
> > a device is not allowed to initiate transitions to power states which are
> > unsupported by the HBA.
> > 
> > DevSleep is always initiated by the HBA, however, for completeness, set the
> > corresponding bit in PxSCTL.IPM such that agressive link power management
> > cannot transition to DevSleep if DevSleep is not supported.
> > 
> > sata_link_scr_lpm() is used by libahci, ata_piix and libata-pmp.
> > However, only libahci has the ability to read the CAP/CAP2 register to see
> > if these features are supported. Therefore, in order to not introduce any
> > regressions on ata_piix or libata-pmp, create flags that indicate that the
> > respective feature is NOT supported. This way, the behavior for ata_piix
> > and libata-pmp should remain unchanged.
> > 
> > This change is based on a patch originally submitted by Runa Guo-oc.
> > 
> > Signed-off-by: Niklas Cassel <niklas.cassel@wdc.com>
> 
> Looks good, but don't we need a Fixes tag for this ?

Sure

Fixes: 1152b2617a6e ("libata: implement sata_link_scr_lpm() and make ata_dev_set_feature() global")

Can you add when applying, or do you want me to resend?


Kind regards,
Niklas

Re: [PATCH] ata: libata: disallow dev-initiated LPM transitions to unsupported states

[Damien Le Moal]

On 9/5/23 17:26, Niklas Cassel wrote:
> On Tue, Sep 05, 2023 at 11:29:13AM +0900, Damien Le Moal wrote:
>> On 9/5/23 05:42, Niklas Cassel wrote:
>>> From: Niklas Cassel <niklas.cassel@wdc.com>
>>>
>>> In AHCI 1.3.1, the register description for CAP.SSC:
>>> "When cleared to ‘0’, software must not allow the HBA to initiate
>>> transitions to the Slumber state via agressive link power management nor
>>> the PxCMD.ICC field in each port, and the PxSCTL.IPM field in each port
>>> must be programmed to disallow device initiated Slumber requests."
>>>
>>> In AHCI 1.3.1, the register description for CAP.PSC:
>>> "When cleared to ‘0’, software must not allow the HBA to initiate
>>> transitions to the Partial state via agressive link power management nor
>>> the PxCMD.ICC field in each port, and the PxSCTL.IPM field in each port
>>> must be programmed to disallow device initiated Partial requests."
>>>
>>> Ensure that we always set the corresponding bits in PxSCTL.IPM, such that
>>> a device is not allowed to initiate transitions to power states which are
>>> unsupported by the HBA.
>>>
>>> DevSleep is always initiated by the HBA, however, for completeness, set the
>>> corresponding bit in PxSCTL.IPM such that agressive link power management
>>> cannot transition to DevSleep if DevSleep is not supported.
>>>
>>> sata_link_scr_lpm() is used by libahci, ata_piix and libata-pmp.
>>> However, only libahci has the ability to read the CAP/CAP2 register to see
>>> if these features are supported. Therefore, in order to not introduce any
>>> regressions on ata_piix or libata-pmp, create flags that indicate that the
>>> respective feature is NOT supported. This way, the behavior for ata_piix
>>> and libata-pmp should remain unchanged.
>>>
>>> This change is based on a patch originally submitted by Runa Guo-oc.
>>>
>>> Signed-off-by: Niklas Cassel <niklas.cassel@wdc.com>
>>
>> Looks good, but don't we need a Fixes tag for this ?
> 
> Sure
> 
> Fixes: 1152b2617a6e ("libata: implement sata_link_scr_lpm() and make ata_dev_set_feature() global")
> 
> Can you add when applying, or do you want me to resend?

OK. Will add that. No need to resend.

> 
> 
> Kind regards,
> Niklas

-- 
Damien Le Moal
Western Digital Research

Re: [PATCH] ata: libata: disallow dev-initiated LPM transitions to unsupported states

[Damien Le Moal]

On 9/5/23 05:42, Niklas Cassel wrote:
> From: Niklas Cassel <niklas.cassel@wdc.com>
> 
> In AHCI 1.3.1, the register description for CAP.SSC:
> "When cleared to ‘0’, software must not allow the HBA to initiate
> transitions to the Slumber state via agressive link power management nor
> the PxCMD.ICC field in each port, and the PxSCTL.IPM field in each port
> must be programmed to disallow device initiated Slumber requests."
> 
> In AHCI 1.3.1, the register description for CAP.PSC:
> "When cleared to ‘0’, software must not allow the HBA to initiate
> transitions to the Partial state via agressive link power management nor
> the PxCMD.ICC field in each port, and the PxSCTL.IPM field in each port
> must be programmed to disallow device initiated Partial requests."
> 
> Ensure that we always set the corresponding bits in PxSCTL.IPM, such that
> a device is not allowed to initiate transitions to power states which are
> unsupported by the HBA.
> 
> DevSleep is always initiated by the HBA, however, for completeness, set the
> corresponding bit in PxSCTL.IPM such that agressive link power management
> cannot transition to DevSleep if DevSleep is not supported.
> 
> sata_link_scr_lpm() is used by libahci, ata_piix and libata-pmp.
> However, only libahci has the ability to read the CAP/CAP2 register to see
> if these features are supported. Therefore, in order to not introduce any
> regressions on ata_piix or libata-pmp, create flags that indicate that the
> respective feature is NOT supported. This way, the behavior for ata_piix
> and libata-pmp should remain unchanged.
> 
> This change is based on a patch originally submitted by Runa Guo-oc.
> 
> Signed-off-by: Niklas Cassel <niklas.cassel@wdc.com>

Applied to for-6.6-fixes. Thanks !


-- 
Damien Le Moal
Western Digital Research