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[v4,2/2] PCI/IOV: Use VF0 cached config space size for other VFs

Message ID 1521489961-18291-2-git-send-email-karahmed@amazon.de (mailing list archive)
State New, archived
Headers show

Commit Message

KarimAllah Ahmed March 19, 2018, 8:06 p.m. UTC
Cache the config space size from VF0 and use it for all other VFs instead
of reading it from the config space of each VF.  We assume that it will be
the same across all associated VFs.

This is an optimization when enabling SR-IOV on a device with many VFs.

Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: linux-pci@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de>
---
 drivers/pci/iov.c   |  3 +++
 drivers/pci/pci.h   |  1 +
 drivers/pci/probe.c | 11 ++++++++++-
 include/linux/pci.h |  1 +
 4 files changed, 15 insertions(+), 1 deletion(-)

Comments

Bjorn Helgaas March 30, 2018, 11:22 p.m. UTC | #1
On Mon, Mar 19, 2018 at 09:06:01PM +0100, KarimAllah Ahmed wrote:
> Cache the config space size from VF0 and use it for all other VFs instead
> of reading it from the config space of each VF.  We assume that it will be
> the same across all associated VFs.
> 
> This is an optimization when enabling SR-IOV on a device with many VFs.
> 
> Cc: Bjorn Helgaas <bhelgaas@google.com>
> Cc: linux-pci@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de>

I didn't apply this one because:

  - I don't like the "add two leading underscores to the name"
    disease.  I'd really like pci_cfg_space_size() to be able to
    figure out whether this is VF0 and do the right thing.  But I
    don't know if we can tell from the pci_dev whether it is VF0.  We
    do know that every VF is a PCIe device; maybe that's useful
    somehow.

  - Whatever the name ends up being, it should be declared in
    drivers/pci/pci.h, not include/linux/pci.h, because it shouldn't
    be used outside the PCI core.

> ---
>  drivers/pci/iov.c   |  3 +++
>  drivers/pci/pci.h   |  1 +
>  drivers/pci/probe.c | 11 ++++++++++-
>  include/linux/pci.h |  1 +
>  4 files changed, 15 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
> index 30bf8f7..046e0d3 100644
> --- a/drivers/pci/iov.c
> +++ b/drivers/pci/iov.c
> @@ -135,6 +135,9 @@ static void pci_read_vf_config_common(struct pci_dev *virtfn)
>  			     &physfn->sriov->subsystem_vendor);
>  	pci_read_config_word(virtfn, PCI_SUBSYSTEM_ID,
>  			     &physfn->sriov->subsystem_device);
> +
> +	virtfn->class = physfn->sriov->class;

Oops, where did this come from?  It looks like this belongs in a
different patch because this patch doesn't do anything else with
virtfn->class.

> +	physfn->sriov->cfg_size = __pci_cfg_space_size(virtfn);
>  }
>  
>  int pci_iov_add_virtfn(struct pci_dev *dev, int id)
> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> index bdb4ba2..69da57b 100644
> --- a/drivers/pci/pci.h
> +++ b/drivers/pci/pci.h
> @@ -271,6 +271,7 @@ struct pci_sriov {
>  	u16		driver_max_VFs;	/* Max num VFs driver supports */
>  	struct pci_dev	*dev;		/* Lowest numbered PF */
>  	struct pci_dev	*self;		/* This PF */
> +	u32		cfg_size;	/* VF config space size */
>  	u32		class;		/* VF device */
>  	u8		hdr_type;	/* VF header type */
>  	u16		subsystem_vendor; /* VF subsystem vendor */
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index 21ee1c3..fd21e2b 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -1365,7 +1365,7 @@ static int pci_cfg_space_size_ext(struct pci_dev *dev)
>  	return PCI_CFG_SPACE_EXP_SIZE;
>  }
>  
> -int pci_cfg_space_size(struct pci_dev *dev)
> +int __pci_cfg_space_size(struct pci_dev *dev)
>  {
>  	int pos;
>  	u32 status;
> @@ -1389,6 +1389,15 @@ int pci_cfg_space_size(struct pci_dev *dev)
>  	return PCI_CFG_SPACE_SIZE;
>  }
>  
> +int pci_cfg_space_size(struct pci_dev *dev)
> +{
> +#ifdef CONFIG_PCI_ATS
> +	if (dev->is_virtfn)
> +		return dev->physfn->sriov->cfg_size;
> +#endif
> +	return __pci_cfg_space_size(dev);
> +}
> +
>  static int pci_cfg_space_class(struct pci_dev *dev)
>  {
>  	int class;
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 024a1be..fcd5d88 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -1290,6 +1290,7 @@ int pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max,
>  
>  void pci_walk_bus(struct pci_bus *top, int (*cb)(struct pci_dev *, void *),
>  		  void *userdata);
> +int __pci_cfg_space_size(struct pci_dev *dev);
>  int pci_cfg_space_size(struct pci_dev *dev);
>  unsigned char pci_bus_max_busnr(struct pci_bus *bus);
>  void pci_setup_bridge(struct pci_bus *bus);
> -- 
> 2.7.4
>
diff mbox

Patch

diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
index 30bf8f7..046e0d3 100644
--- a/drivers/pci/iov.c
+++ b/drivers/pci/iov.c
@@ -135,6 +135,9 @@  static void pci_read_vf_config_common(struct pci_dev *virtfn)
 			     &physfn->sriov->subsystem_vendor);
 	pci_read_config_word(virtfn, PCI_SUBSYSTEM_ID,
 			     &physfn->sriov->subsystem_device);
+
+	virtfn->class = physfn->sriov->class;
+	physfn->sriov->cfg_size = __pci_cfg_space_size(virtfn);
 }
 
 int pci_iov_add_virtfn(struct pci_dev *dev, int id)
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index bdb4ba2..69da57b 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -271,6 +271,7 @@  struct pci_sriov {
 	u16		driver_max_VFs;	/* Max num VFs driver supports */
 	struct pci_dev	*dev;		/* Lowest numbered PF */
 	struct pci_dev	*self;		/* This PF */
+	u32		cfg_size;	/* VF config space size */
 	u32		class;		/* VF device */
 	u8		hdr_type;	/* VF header type */
 	u16		subsystem_vendor; /* VF subsystem vendor */
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 21ee1c3..fd21e2b 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1365,7 +1365,7 @@  static int pci_cfg_space_size_ext(struct pci_dev *dev)
 	return PCI_CFG_SPACE_EXP_SIZE;
 }
 
-int pci_cfg_space_size(struct pci_dev *dev)
+int __pci_cfg_space_size(struct pci_dev *dev)
 {
 	int pos;
 	u32 status;
@@ -1389,6 +1389,15 @@  int pci_cfg_space_size(struct pci_dev *dev)
 	return PCI_CFG_SPACE_SIZE;
 }
 
+int pci_cfg_space_size(struct pci_dev *dev)
+{
+#ifdef CONFIG_PCI_ATS
+	if (dev->is_virtfn)
+		return dev->physfn->sriov->cfg_size;
+#endif
+	return __pci_cfg_space_size(dev);
+}
+
 static int pci_cfg_space_class(struct pci_dev *dev)
 {
 	int class;
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 024a1be..fcd5d88 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1290,6 +1290,7 @@  int pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max,
 
 void pci_walk_bus(struct pci_bus *top, int (*cb)(struct pci_dev *, void *),
 		  void *userdata);
+int __pci_cfg_space_size(struct pci_dev *dev);
 int pci_cfg_space_size(struct pci_dev *dev);
 unsigned char pci_bus_max_busnr(struct pci_bus *bus);
 void pci_setup_bridge(struct pci_bus *bus);