2022-07-14 23:17:44

by rjingar

Subject: [PATCH v2 2/2] PCI/PTM: fix to maintain pci_dev->ptm_enabled

pci_dev->ptm_enabled needs to be maintained to reflect the current PTM
state of the device. In pci_ptm_disable(), clear ptm_enabled from
'struct pci_dev' on disabling PTM state for the device.
In pci_restore_ptm_state(), set dev->ptm_enabled based on the restored
PTM state of the device.

Also, perform ptm_enabled check in pci_ptm_disable() to avoid config
space access in case if PTM is already disabled for the device.

Signed-off-by: Rajvi Jingar <[email protected]>
---
v1->v2:
- add ptm_enabled check in pci_ptm_disable().
- set the dev->ptm_enabled value in pci_restore_ptm_state().
---
drivers/pci/pcie/ptm.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/drivers/pci/pcie/ptm.c b/drivers/pci/pcie/ptm.c
index 368a254e3124..8dc7d2285a0d 100644
--- a/drivers/pci/pcie/ptm.c
+++ b/drivers/pci/pcie/ptm.c
@@ -34,6 +34,9 @@ void pci_disable_ptm(struct pci_dev *dev)
int ptm;
u16 ctrl;

+ if (!dev->ptm_enabled)
+ return;
+
if (!pci_is_pcie(dev))
return;

@@ -44,6 +47,7 @@ void pci_disable_ptm(struct pci_dev *dev)
pci_read_config_word(dev, ptm + PCI_PTM_CTRL, &ctrl);
ctrl &= ~(PCI_PTM_CTRL_ENABLE | PCI_PTM_CTRL_ROOT);
pci_write_config_word(dev, ptm + PCI_PTM_CTRL, ctrl);
+ dev->ptm_enabled = 0;
}

void pci_save_ptm_state(struct pci_dev *dev)
@@ -83,6 +87,7 @@ void pci_restore_ptm_state(struct pci_dev *dev)

cap = (u16 *)&save_state->cap.data[0];
pci_write_config_word(dev, ptm + PCI_PTM_CTRL, *cap);
+ dev->ptm_enabled = !!(*cap & PCI_PTM_CTRL_ENABLE);
}

void pci_ptm_init(struct pci_dev *dev)
--
2.25.1

2022-07-15 12:28:58

by Rafael J. Wysocki

Subject: Re: [PATCH v2 2/2] PCI/PTM: fix to maintain pci_dev->ptm_enabled

On Fri, Jul 15, 2022 at 1:16 AM Rajvi Jingar
<[email protected]> wrote:
>
> pci_dev->ptm_enabled needs to be maintained to reflect the current PTM
> state of the device. In pci_ptm_disable(), clear ptm_enabled from
> 'struct pci_dev' on disabling PTM state for the device.
> In pci_restore_ptm_state(), set dev->ptm_enabled based on the restored
> PTM state of the device.
>
> Also, perform ptm_enabled check in pci_ptm_disable() to avoid config
> space access in case if PTM is already disabled for the device.
>
> Signed-off-by: Rajvi Jingar <[email protected]>
> ---
> v1->v2:
> - add ptm_enabled check in pci_ptm_disable().
> - set the dev->ptm_enabled value in pci_restore_ptm_state().
> ---
> drivers/pci/pcie/ptm.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/drivers/pci/pcie/ptm.c b/drivers/pci/pcie/ptm.c
> index 368a254e3124..8dc7d2285a0d 100644
> --- a/drivers/pci/pcie/ptm.c
> +++ b/drivers/pci/pcie/ptm.c
> @@ -34,6 +34,9 @@ void pci_disable_ptm(struct pci_dev *dev)
> int ptm;
> u16 ctrl;
>
> + if (!dev->ptm_enabled)
> + return;
> +
> if (!pci_is_pcie(dev))
> return;

After the check you've added this doesn't need to be checked any more,
because ptm_enabled will not be set if pci_is_pcie(dev) is not true
AFAICS.

Otherwise the patch looks good to me, so with the above addressed,
please feel free to add

Reviewed-by: Rafael J. Wysocki <[email protected]>

to it.

Thanks!

>
> @@ -44,6 +47,7 @@ void pci_disable_ptm(struct pci_dev *dev)
> pci_read_config_word(dev, ptm + PCI_PTM_CTRL, &ctrl);
> ctrl &= ~(PCI_PTM_CTRL_ENABLE | PCI_PTM_CTRL_ROOT);
> pci_write_config_word(dev, ptm + PCI_PTM_CTRL, ctrl);
> + dev->ptm_enabled = 0;
> }
>
> void pci_save_ptm_state(struct pci_dev *dev)
> @@ -83,6 +87,7 @@ void pci_restore_ptm_state(struct pci_dev *dev)
>
> cap = (u16 *)&save_state->cap.data[0];
> pci_write_config_word(dev, ptm + PCI_PTM_CTRL, *cap);
> + dev->ptm_enabled = !!(*cap & PCI_PTM_CTRL_ENABLE);
> }
>
> void pci_ptm_init(struct pci_dev *dev)
> --
> 2.25.1
>