diff mbox series

[RFC,2/2] ata: ahci: Protect users from setting policies their drives don't support

Message ID 20220225181030.980223-2-mario.limonciello@amd.com
State New
Headers show
Series [RFC,1/2] ata: ahci: Drop low power policy board type | expand

Commit Message

Mario Limonciello Feb. 25, 2022, 6:10 p.m. UTC 
As the default low power policy applies to more chipsets and drives, it's
important to make sure that drives actually support the policy that a user
selected in their kernel configuration.

If the drive doesn't support slumber, don't let the default policy for the
ATA port be `min_power` or `min_power_with_partial`.

Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
---
 drivers/ata/ahci.c | 8 ++++++++
 1 file changed, 8 insertions(+)

Comments

Hans de Goede Feb. 25, 2022, 9:20 p.m. UTC | #1 
Hi,

On 2/25/22 19:10, Mario Limonciello wrote:
> As the default low power policy applies to more chipsets and drives, it's
> important to make sure that drives actually support the policy that a user
> selected in their kernel configuration.
> 
> If the drive doesn't support slumber, don't let the default policy for the
> ATA port be `min_power` or `min_power_with_partial`.
> 
> Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
> ---
>  drivers/ata/ahci.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
> index 17d757ad7111..af8999453084 100644
> --- a/drivers/ata/ahci.c
> +++ b/drivers/ata/ahci.c
> @@ -1584,8 +1584,16 @@ static int ahci_init_msi(struct pci_dev *pdev, unsigned int n_ports,
>  static void ahci_update_initial_lpm_policy(struct ata_port *ap,
>  					   struct ahci_host_priv *hpriv)
>  {
> +	struct pci_dev *pdev = to_pci_dev(ap->host->dev);
>  	int policy = CONFIG_SATA_LPM_POLICY;
>  
> +	if (policy >= ATA_LPM_MIN_POWER_WITH_PARTIAL &&
> +	   !(hpriv->cap & HOST_CAP_SSC)) {
> +		dev_warn(&pdev->dev,
> +			 "This drive doesn't support slumber; ignoring default SATA policy\n");
> +		return;
> +	}
> +

Don't the capabilties get checked later when the policy gets applied ?

At least I think they do get checked later, but I have not looked
at this code for years  ...  ?

Regards,

Hans


>  	/* user modified policy via module param */
>  	if (mobile_lpm_policy != -1) {
>  		policy = mobile_lpm_policy;
Mario Limonciello Feb. 25, 2022, 9:24 p.m. UTC | #2 
[AMD Official Use Only]



> -----Original Message-----
> From: Hans de Goede <hdegoede@redhat.com>
> Sent: Friday, February 25, 2022 15:20
> To: Limonciello, Mario <Mario.Limonciello@amd.com>; Damien Le Moal
> <damien.lemoal@opensource.wdc.com>
> Cc: open list:LIBATA SUBSYSTEM (Serial and Parallel ATA drivers) <linux-
> ide@vger.kernel.org>; open list <linux-kernel@vger.kernel.org>
> Subject: Re: [RFC 2/2] ata: ahci: Protect users from setting policies their
> drives don't support
> 
> Hi,
> 
> On 2/25/22 19:10, Mario Limonciello wrote:
> > As the default low power policy applies to more chipsets and drives, it's
> > important to make sure that drives actually support the policy that a user
> > selected in their kernel configuration.
> >
> > If the drive doesn't support slumber, don't let the default policy for the
> > ATA port be `min_power` or `min_power_with_partial`.
> >
> > Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
> > ---
> >  drivers/ata/ahci.c | 8 ++++++++
> >  1 file changed, 8 insertions(+)
> >
> > diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
> > index 17d757ad7111..af8999453084 100644
> > --- a/drivers/ata/ahci.c
> > +++ b/drivers/ata/ahci.c
> > @@ -1584,8 +1584,16 @@ static int ahci_init_msi(struct pci_dev *pdev,
> unsigned int n_ports,
> >  static void ahci_update_initial_lpm_policy(struct ata_port *ap,
> >  					   struct ahci_host_priv *hpriv)
> >  {
> > +	struct pci_dev *pdev = to_pci_dev(ap->host->dev);
> >  	int policy = CONFIG_SATA_LPM_POLICY;
> >
> > +	if (policy >= ATA_LPM_MIN_POWER_WITH_PARTIAL &&
> > +	   !(hpriv->cap & HOST_CAP_SSC)) {
> > +		dev_warn(&pdev->dev,
> > +			 "This drive doesn't support slumber; ignoring default
> SATA policy\n");
> > +		return;
> > +	}
> > +
> 
> Don't the capabilties get checked later when the policy gets applied ?
> 
> At least I think they do get checked later, but I have not looked
> at this code for years  ...  ?

There's a bunch of layers of indirection so I might have missed something,
but I didn't see anything in sata_link_scr_lpm or anywhere else for that
matter that actually checked HOST_CAP_SSC.

> 
> Regards,
> 
> Hans
> 
> 
> >  	/* user modified policy via module param */
> >  	if (mobile_lpm_policy != -1) {
> >  		policy = mobile_lpm_policy;
Hans de Goede Feb. 26, 2022, 11:23 a.m. UTC | #3 
Hi,

On 2/25/22 22:24, Limonciello, Mario wrote:
> [AMD Official Use Only]
> 
> 
> 
>> -----Original Message-----
>> From: Hans de Goede <hdegoede@redhat.com>
>> Sent: Friday, February 25, 2022 15:20
>> To: Limonciello, Mario <Mario.Limonciello@amd.com>; Damien Le Moal
>> <damien.lemoal@opensource.wdc.com>
>> Cc: open list:LIBATA SUBSYSTEM (Serial and Parallel ATA drivers) <linux-
>> ide@vger.kernel.org>; open list <linux-kernel@vger.kernel.org>
>> Subject: Re: [RFC 2/2] ata: ahci: Protect users from setting policies their
>> drives don't support
>>
>> Hi,
>>
>> On 2/25/22 19:10, Mario Limonciello wrote:
>>> As the default low power policy applies to more chipsets and drives, it's
>>> important to make sure that drives actually support the policy that a user
>>> selected in their kernel configuration.
>>>
>>> If the drive doesn't support slumber, don't let the default policy for the
>>> ATA port be `min_power` or `min_power_with_partial`.
>>>
>>> Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
>>> ---
>>>  drivers/ata/ahci.c | 8 ++++++++
>>>  1 file changed, 8 insertions(+)
>>>
>>> diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
>>> index 17d757ad7111..af8999453084 100644
>>> --- a/drivers/ata/ahci.c
>>> +++ b/drivers/ata/ahci.c
>>> @@ -1584,8 +1584,16 @@ static int ahci_init_msi(struct pci_dev *pdev,
>> unsigned int n_ports,
>>>  static void ahci_update_initial_lpm_policy(struct ata_port *ap,
>>>  					   struct ahci_host_priv *hpriv)
>>>  {
>>> +	struct pci_dev *pdev = to_pci_dev(ap->host->dev);
>>>  	int policy = CONFIG_SATA_LPM_POLICY;
>>>
>>> +	if (policy >= ATA_LPM_MIN_POWER_WITH_PARTIAL &&
>>> +	   !(hpriv->cap & HOST_CAP_SSC)) {
>>> +		dev_warn(&pdev->dev,
>>> +			 "This drive doesn't support slumber; ignoring default
>> SATA policy\n");
>>> +		return;
>>> +	}
>>> +
>>
>> Don't the capabilties get checked later when the policy gets applied ?
>>
>> At least I think they do get checked later, but I have not looked
>> at this code for years  ...  ?
> 
> There's a bunch of layers of indirection so I might have missed something,
> but I didn't see anything in sata_link_scr_lpm or anywhere else for that
> matter that actually checked HOST_CAP_SSC.

Hmm, ok. Note that the user can still change the policy with an echo
to sysfs. So I think it would be better to do a fix where HOST_CAP_SSC
gets checked when the features are actually being enabled. Or at least
also at a HOST_CAP_SSC check to the sysfs write functions.

Regards,

Hans


>>>  	/* user modified policy via module param */
>>>  	if (mobile_lpm_policy != -1) {
>>>  		policy = mobile_lpm_policy;
diff mbox series

Patch

diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
index 17d757ad7111..af8999453084 100644
--- a/drivers/ata/ahci.c
+++ b/drivers/ata/ahci.c
@@ -1584,8 +1584,16 @@  static int ahci_init_msi(struct pci_dev *pdev, unsigned int n_ports,
 static void ahci_update_initial_lpm_policy(struct ata_port *ap,
 					   struct ahci_host_priv *hpriv)
 {
+	struct pci_dev *pdev = to_pci_dev(ap->host->dev);
 	int policy = CONFIG_SATA_LPM_POLICY;
 
+	if (policy >= ATA_LPM_MIN_POWER_WITH_PARTIAL &&
+	   !(hpriv->cap & HOST_CAP_SSC)) {
+		dev_warn(&pdev->dev,
+			 "This drive doesn't support slumber; ignoring default SATA policy\n");
+		return;
+	}
+
 	/* user modified policy via module param */
 	if (mobile_lpm_policy != -1) {
 		policy = mobile_lpm_policy;