[v4,2/7] PCI/ATS: Initialize PRI in pci_ats_init()

Commit Message

Kuppuswamy Sathyanarayanan July 3, 2019, 8:46 p.m. UTC

From: Kuppuswamy Sathyanarayanan <[e-mail]>

Currently, PRI Capability checks are repeated across all PRI API's.
Instead, cache the capability check result in pci_pri_init() and use it
in other PRI API's. Also, since PRI is a shared resource between PF/VF,
initialize default values for common PRI features in pci_pri_init().

Signed-off-by: Kuppuswamy Sathyanarayanan <[e-mail]>
---
 drivers/pci/ats.c   | 83 +++++++++++++++++++++++++++++++--------------
 include/linux/pci.h |  1 +
 2 files changed, 59 insertions(+), 25 deletions(-)

Comments

Keith Busch Aug. 1, 2019, 9:09 p.m. UTC | #1

On Wed, Jul 03, 2019 at 01:46:19PM -0700, [e-mail] wrote:
> +#ifdef CONFIG_PCI_PRI
> +static void pci_pri_init(struct pci_dev *pdev)
> +{
> +	u32 max_requests;
> +	int pos;
> +
> +	/*
> +	 * As per PCIe r4.0, sec 9.3.7.11, only PF is permitted to
> +	 * implement PRI and all associated VFs can only use it.
> +	 * Since PF already initialized the PRI parameters there is
> +	 * no need to proceed further.
> +	 */
> +	if (pdev->is_virtfn)
> +		return;
> +
> +	pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PRI);
> +	if (!pos)
> +		return;
> +
> +	pci_read_config_dword(pdev, pos + PCI_PRI_MAX_REQ, &max_requests);
> +
> +	/*
> +	 * Since PRI is a shared resource between PF and VF, we must not
> +	 * configure Outstanding Page Allocation Quota as a per device
> +	 * resource in pci_enable_pri(). So use maximum value possible
> +	 * as default value.
> +	 */
> +	pci_write_config_dword(pdev, pos + PCI_PRI_ALLOC_REQ, max_requests);
> +
> +	pdev->pri_reqs_alloc = max_requests;
> +	pdev->pri_cap = pos;
> +}
> +#endif
> +
>  void pci_ats_init(struct pci_dev *dev)
>  {
>  	int pos;
> @@ -28,6 +62,10 @@ void pci_ats_init(struct pci_dev *dev)
>  		return;
>  
>  	dev->ats_cap = pos;
> +
> +#ifdef CONFIG_PCI_PRI
> +	pci_pri_init(dev);
> +#endif
>  }

Rather than surround the call to pci_pri_init() with the #ifdef, you
should provide an empty function implementation when CONFIG_PCI_PRI is
not defined. Same thing for the next patch adding PASID.

Kuppuswamy Sathyanarayanan Aug. 1, 2019, 9:21 p.m. UTC | #2

Hi Keith,

Thanks for the review.

On 8/1/19 2:09 PM, Keith Busch wrote:
> On Wed, Jul 03, 2019 at 01:46:19PM -0700, [e-mail] wrote:
>> +#ifdef CONFIG_PCI_PRI
>> +static void pci_pri_init(struct pci_dev *pdev)
>> +{
>> +	u32 max_requests;
>> +	int pos;
>> +
>> +	/*
>> +	 * As per PCIe r4.0, sec 9.3.7.11, only PF is permitted to
>> +	 * implement PRI and all associated VFs can only use it.
>> +	 * Since PF already initialized the PRI parameters there is
>> +	 * no need to proceed further.
>> +	 */
>> +	if (pdev->is_virtfn)
>> +		return;
>> +
>> +	pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PRI);
>> +	if (!pos)
>> +		return;
>> +
>> +	pci_read_config_dword(pdev, pos + PCI_PRI_MAX_REQ, &max_requests);
>> +
>> +	/*
>> +	 * Since PRI is a shared resource between PF and VF, we must not
>> +	 * configure Outstanding Page Allocation Quota as a per device
>> +	 * resource in pci_enable_pri(). So use maximum value possible
>> +	 * as default value.
>> +	 */
>> +	pci_write_config_dword(pdev, pos + PCI_PRI_ALLOC_REQ, max_requests);
>> +
>> +	pdev->pri_reqs_alloc = max_requests;
>> +	pdev->pri_cap = pos;
>> +}
>> +#endif
>> +
>>   void pci_ats_init(struct pci_dev *dev)
>>   {
>>   	int pos;
>> @@ -28,6 +62,10 @@ void pci_ats_init(struct pci_dev *dev)
>>   		return;
>>   
>>   	dev->ats_cap = pos;
>> +
>> +#ifdef CONFIG_PCI_PRI
>> +	pci_pri_init(dev);
>> +#endif
>>   }
> Rather than surround the call to pci_pri_init() with the #ifdef, you
> should provide an empty function implementation when CONFIG_PCI_PRI is
> not defined. Same thing for the next patch adding PASID.
This function is defined and used in the same file (ats.c). Is there any 
advantage in defining an empty function ? But if this is the recommended 
approach, I can make the necessary changes. Please confirm.
>

Keith Busch Aug. 1, 2019, 9:26 p.m. UTC | #3

On Thu, Aug 01, 2019 at 02:21:07PM -0700, sathyanarayanan kuppuswamy wrote:
> On 8/1/19 2:09 PM, Keith Busch wrote:
> > Rather than surround the call to pci_pri_init() with the #ifdef, you
> > should provide an empty function implementation when CONFIG_PCI_PRI is
> > not defined. Same thing for the next patch adding PASID.
>
> This function is defined and used in the same file (ats.c). Is there any
> advantage in defining an empty function ? But if this is the recommended
> approach, I can make the necessary changes. Please confirm.

That way is just the existing convention, so it's recommended for
kernel style consistency. See the "Conditional Compilation" section in
Documentation/process/coding-style.rst (currently section 21).

Patch

diff --git a/drivers/pci/ats.c b/drivers/pci/ats.c
index f9eeb7db0db3..a14ab20f1c28 100644
--- a/drivers/pci/ats.c
+++ b/drivers/pci/ats.c
@@ -16,6 +16,40 @@ 
 
 #include "pci.h"
 
+#ifdef CONFIG_PCI_PRI
+static void pci_pri_init(struct pci_dev *pdev)
+{
+	u32 max_requests;
+	int pos;
+
+	/*
+	 * As per PCIe r4.0, sec 9.3.7.11, only PF is permitted to
+	 * implement PRI and all associated VFs can only use it.
+	 * Since PF already initialized the PRI parameters there is
+	 * no need to proceed further.
+	 */
+	if (pdev->is_virtfn)
+		return;
+
+	pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PRI);
+	if (!pos)
+		return;
+
+	pci_read_config_dword(pdev, pos + PCI_PRI_MAX_REQ, &max_requests);
+
+	/*
+	 * Since PRI is a shared resource between PF and VF, we must not
+	 * configure Outstanding Page Allocation Quota as a per device
+	 * resource in pci_enable_pri(). So use maximum value possible
+	 * as default value.
+	 */
+	pci_write_config_dword(pdev, pos + PCI_PRI_ALLOC_REQ, max_requests);
+
+	pdev->pri_reqs_alloc = max_requests;
+	pdev->pri_cap = pos;
+}
+#endif
+
 void pci_ats_init(struct pci_dev *dev)
 {
 	int pos;
@@ -28,6 +62,10 @@  void pci_ats_init(struct pci_dev *dev)
 		return;
 
 	dev->ats_cap = pos;
+
+#ifdef CONFIG_PCI_PRI
+	pci_pri_init(dev);
+#endif
 }
 
 /**
@@ -175,31 +213,34 @@  EXPORT_SYMBOL_GPL(pci_ats_page_aligned);
  * @ pdev: PCI device structure
  *
  * Returns 0 on success, negative value on error
+ *
+ * TODO: Since PRI is a shared resource between PF/VF, don't update
+ * Outstanding Page Allocation Quota in the same API as a per device
+ * feature.
  */
 int pci_enable_pri(struct pci_dev *pdev, u32 reqs)
 {
 	u16 control, status;
 	u32 max_requests;
-	int pos;
 
 	if (WARN_ON(pdev->pri_enabled))
 		return -EBUSY;
 
-	pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PRI);
-	if (!pos)
+	if (!pdev->pri_cap)
 		return -EINVAL;
 
-	pci_read_config_word(pdev, pos + PCI_PRI_STATUS, &status);
+	pci_read_config_word(pdev, pdev->pri_cap + PCI_PRI_STATUS, &status);
 	if (!(status & PCI_PRI_STATUS_STOPPED))
 		return -EBUSY;
 
-	pci_read_config_dword(pdev, pos + PCI_PRI_MAX_REQ, &max_requests);
+	pci_read_config_dword(pdev, pdev->pri_cap + PCI_PRI_MAX_REQ,
+			      &max_requests);
 	reqs = min(max_requests, reqs);
 	pdev->pri_reqs_alloc = reqs;
-	pci_write_config_dword(pdev, pos + PCI_PRI_ALLOC_REQ, reqs);
+	pci_write_config_dword(pdev, pdev->pri_cap + PCI_PRI_ALLOC_REQ, reqs);
 
 	control = PCI_PRI_CTRL_ENABLE;
-	pci_write_config_word(pdev, pos + PCI_PRI_CTRL, control);
+	pci_write_config_word(pdev, pdev->pri_cap + PCI_PRI_CTRL, control);
 
 	pdev->pri_enabled = 1;
 
@@ -216,18 +257,16 @@  EXPORT_SYMBOL_GPL(pci_enable_pri);
 void pci_disable_pri(struct pci_dev *pdev)
 {
 	u16 control;
-	int pos;
 
 	if (WARN_ON(!pdev->pri_enabled))
 		return;
 
-	pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PRI);
-	if (!pos)
+	if (!pdev->pri_cap)
 		return;
 
-	pci_read_config_word(pdev, pos + PCI_PRI_CTRL, &control);
+	pci_read_config_word(pdev, pdev->pri_cap + PCI_PRI_CTRL, &control);
 	control &= ~PCI_PRI_CTRL_ENABLE;
-	pci_write_config_word(pdev, pos + PCI_PRI_CTRL, control);
+	pci_write_config_word(pdev, pdev->pri_cap + PCI_PRI_CTRL, control);
 
 	pdev->pri_enabled = 0;
 }
@@ -241,17 +280,15 @@  void pci_restore_pri_state(struct pci_dev *pdev)
 {
 	u16 control = PCI_PRI_CTRL_ENABLE;
 	u32 reqs = pdev->pri_reqs_alloc;
-	int pos;
 
 	if (!pdev->pri_enabled)
 		return;
 
-	pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PRI);
-	if (!pos)
+	if (!pdev->pri_cap)
 		return;
 
-	pci_write_config_dword(pdev, pos + PCI_PRI_ALLOC_REQ, reqs);
-	pci_write_config_word(pdev, pos + PCI_PRI_CTRL, control);
+	pci_write_config_dword(pdev, pdev->pri_cap + PCI_PRI_ALLOC_REQ, reqs);
+	pci_write_config_word(pdev, pdev->pri_cap + PCI_PRI_CTRL, control);
 }
 EXPORT_SYMBOL_GPL(pci_restore_pri_state);
 
@@ -265,17 +302,15 @@  EXPORT_SYMBOL_GPL(pci_restore_pri_state);
 int pci_reset_pri(struct pci_dev *pdev)
 {
 	u16 control;
-	int pos;
 
 	if (WARN_ON(pdev->pri_enabled))
 		return -EBUSY;
 
-	pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PRI);
-	if (!pos)
+	if (!pdev->pri_cap)
 		return -EINVAL;
 
 	control = PCI_PRI_CTRL_RESET;
-	pci_write_config_word(pdev, pos + PCI_PRI_CTRL, control);
+	pci_write_config_word(pdev, pdev->pri_cap + PCI_PRI_CTRL, control);
 
 	return 0;
 }
@@ -410,13 +445,11 @@  EXPORT_SYMBOL_GPL(pci_pasid_features);
 int pci_prg_resp_pasid_required(struct pci_dev *pdev)
 {
 	u16 status;
-	int pos;
 
-	pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PRI);
-	if (!pos)
+	if (!pdev->pri_cap)
 		return 0;
 
-	pci_read_config_word(pdev, pos + PCI_PRI_STATUS, &status);
+	pci_read_config_word(pdev, pdev->pri_cap + PCI_PRI_STATUS, &status);
 
 	if (status & PCI_PRI_STATUS_PASID)
 		return 1;
diff --git a/include/linux/pci.h b/include/linux/pci.h
index dd436da7eccc..f3fe625bc8bb 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -452,6 +452,7 @@  struct pci_dev {
 	atomic_t	ats_ref_cnt;	/* Number of VFs with ATS enabled */
 #endif
 #ifdef CONFIG_PCI_PRI
+	u16		pri_cap;	/* PRI Capability offset */
 	u32		pri_reqs_alloc; /* Number of PRI requests allocated */
 #endif
 #ifdef CONFIG_PCI_PASID