[PATCH v4 1/2] PCI/IOV: Use VF0 cached config registers for other VFs

[PATCH v4 1/2] PCI/IOV: Use VF0 cached config registers for other VFs

[KarimAllah Ahmed]

Cache some config data from VF0 and use it for all other VFs instead of
reading it from the config space of each VF.  We assume these items are the
same across all associated VFs:

   Revision ID
   Class Code
   Subsystem Vendor ID
   Subsystem ID

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>
[bhelgaas: changelog, simplify comments, remove unused "device"]
Signed-off-by: Bjorn Helgaas <helgaas@kernel.org>
---
v3->v4:
- Restructure the code to handle CONFIG_PCI_ATS

 drivers/pci/iov.c   | 42 +++++++++++++++++++++++++++++++++++-------
 drivers/pci/pci.h   |  4 ++++
 drivers/pci/probe.c | 47 ++++++++++++++++++++++++++++++++++++++++++-----
 3 files changed, 81 insertions(+), 12 deletions(-)

diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
index 677924a..30bf8f7 100644
--- a/drivers/pci/iov.c
+++ b/drivers/pci/iov.c
@@ -114,6 +114,29 @@ resource_size_t pci_iov_resource_size(struct pci_dev *dev, int resno)
 	return dev->sriov->barsz[resno - PCI_IOV_RESOURCES];
 }
 
+static void pci_read_vf_config_common(struct pci_dev *virtfn)
+{
+	struct pci_dev *physfn = virtfn->physfn;
+
+	/*
+	 * Some config registers are the same across all associated VFs.
+	 * Read them once from VF0 so we can skip reading them from the
+	 * other VFs.
+	 *
+	 * PCIe r4.0, sec 9.3.4.1, technically doesn't require all VFs to
+	 * have the same Revision ID and Subsystem ID, but we assume they
+	 * do.
+	 */
+	pci_read_config_dword(virtfn, PCI_CLASS_REVISION,
+			      &physfn->sriov->class);
+	pci_read_config_byte(virtfn, PCI_HEADER_TYPE,
+			     &physfn->sriov->hdr_type);
+	pci_read_config_word(virtfn, PCI_SUBSYSTEM_VENDOR_ID,
+			     &physfn->sriov->subsystem_vendor);
+	pci_read_config_word(virtfn, PCI_SUBSYSTEM_ID,
+			     &physfn->sriov->subsystem_device);
+}
+
 int pci_iov_add_virtfn(struct pci_dev *dev, int id)
 {
 	int i;
@@ -136,13 +159,17 @@ int pci_iov_add_virtfn(struct pci_dev *dev, int id)
 	virtfn->devfn = pci_iov_virtfn_devfn(dev, id);
 	virtfn->vendor = dev->vendor;
 	virtfn->device = iov->vf_device;
+	virtfn->is_virtfn = 1;
+	virtfn->physfn = pci_dev_get(dev);
+
+	if (id == 0)
+		pci_read_vf_config_common(virtfn);
+
 	rc = pci_setup_device(virtfn);
 	if (rc)
-		goto failed0;
+		goto failed1;
 
 	virtfn->dev.parent = dev->dev.parent;
-	virtfn->physfn = pci_dev_get(dev);
-	virtfn->is_virtfn = 1;
 	virtfn->multifunction = 0;
 
 	for (i = 0; i < PCI_SRIOV_NUM_BARS; i++) {
@@ -163,10 +190,10 @@ int pci_iov_add_virtfn(struct pci_dev *dev, int id)
 	sprintf(buf, "virtfn%u", id);
 	rc = sysfs_create_link(&dev->dev.kobj, &virtfn->dev.kobj, buf);
 	if (rc)
-		goto failed1;
+		goto failed2;
 	rc = sysfs_create_link(&virtfn->dev.kobj, &dev->dev.kobj, "physfn");
 	if (rc)
-		goto failed2;
+		goto failed3;
 
 	kobject_uevent(&virtfn->dev.kobj, KOBJ_CHANGE);
 
@@ -174,11 +201,12 @@ int pci_iov_add_virtfn(struct pci_dev *dev, int id)
 
 	return 0;
 
-failed2:
+failed3:
 	sysfs_remove_link(&dev->dev.kobj, buf);
+failed2:
+	pci_stop_and_remove_bus_device(virtfn);
 failed1:
 	pci_dev_put(dev);
-	pci_stop_and_remove_bus_device(virtfn);
 failed0:
 	virtfn_remove_bus(dev->bus, bus);
 failed:
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index fcd8191..bdb4ba2 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -271,6 +271,10 @@ 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		class;		/* VF device */
+	u8		hdr_type;	/* VF header type */
+	u16		subsystem_vendor; /* VF subsystem vendor */
+	u16		subsystem_device; /* VF subsystem device */
 	resource_size_t	barsz[PCI_SRIOV_NUM_BARS];	/* VF BAR size */
 	bool		drivers_autoprobe; /* Auto probing of VFs by driver */
 };
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index ef53774..21ee1c3 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1389,6 +1389,43 @@ int pci_cfg_space_size(struct pci_dev *dev)
 	return PCI_CFG_SPACE_SIZE;
 }
 
+static int pci_cfg_space_class(struct pci_dev *dev)
+{
+	int class;
+
+#ifdef CONFIG_PCI_ATS
+	if (dev->is_virtfn)
+		return dev->physfn->sriov->class;
+#endif
+	pci_read_config_dword(dev, PCI_CLASS_REVISION, &class);
+	return class;
+}
+
+static void pci_cfg_space_subsystem(struct pci_dev *dev, u16 *vendor, u16 *device)
+{
+#ifdef CONFIG_PCI_ATS
+	if (dev->is_virtfn) {
+		*vendor = dev->physfn->sriov->subsystem_vendor;
+		*device = dev->physfn->sriov->subsystem_device;
+		return;
+	}
+#endif
+	pci_read_config_word(dev, PCI_SUBSYSTEM_VENDOR_ID, vendor);
+	pci_read_config_word(dev, PCI_SUBSYSTEM_ID, device);
+}
+
+static u8 pci_cfg_space_hdr_type(struct pci_dev *dev)
+{
+	u8 hdr_type;
+
+#ifdef CONFIG_PCI_ATS
+	if (dev->is_virtfn)
+		return dev->physfn->sriov->hdr_type;
+#endif
+	pci_read_config_byte(dev, PCI_HEADER_TYPE, &hdr_type);
+	return hdr_type;
+}
+
 #define LEGACY_IO_RESOURCE	(IORESOURCE_IO | IORESOURCE_PCI_FIXED)
 
 static void pci_msi_setup_pci_dev(struct pci_dev *dev)
@@ -1454,8 +1491,7 @@ int pci_setup_device(struct pci_dev *dev)
 	struct pci_bus_region region;
 	struct resource *res;
 
-	if (pci_read_config_byte(dev, PCI_HEADER_TYPE, &hdr_type))
-		return -EIO;
+	hdr_type = pci_cfg_space_hdr_type(dev);
 
 	dev->sysdata = dev->bus->sysdata;
 	dev->dev.parent = dev->bus->bridge;
@@ -1477,7 +1513,8 @@ int pci_setup_device(struct pci_dev *dev)
 		     dev->bus->number, PCI_SLOT(dev->devfn),
 		     PCI_FUNC(dev->devfn));
 
-	pci_read_config_dword(dev, PCI_CLASS_REVISION, &class);
+	class = pci_cfg_space_class(dev);
+
 	dev->revision = class & 0xff;
 	dev->class = class >> 8;		    /* upper 3 bytes */
 
@@ -1517,8 +1554,8 @@ int pci_setup_device(struct pci_dev *dev)
 			goto bad;
 		pci_read_irq(dev);
 		pci_read_bases(dev, 6, PCI_ROM_ADDRESS);
-		pci_read_config_word(dev, PCI_SUBSYSTEM_VENDOR_ID, &dev->subsystem_vendor);
-		pci_read_config_word(dev, PCI_SUBSYSTEM_ID, &dev->subsystem_device);
+
+		pci_cfg_space_subsystem(dev, &dev->subsystem_vendor, &dev->subsystem_device);
 
 		/*
 		 * Do the ugly legacy mode stuff here rather than broken chip
-- 
2.7.4

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

[KarimAllah Ahmed]

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(-)

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);
-- 
2.7.4

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

[Bjorn Helgaas]

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
> 

Re: [PATCH v4 1/2] PCI/IOV: Use VF0 cached config registers for other VFs

[Bjorn Helgaas]

On Mon, Mar 19, 2018 at 09:06:00PM +0100, KarimAllah Ahmed wrote:
> Cache some config data from VF0 and use it for all other VFs instead of
> reading it from the config space of each VF.  We assume these items are the
> same across all associated VFs:
> 
>    Revision ID
>    Class Code
>    Subsystem Vendor ID
>    Subsystem ID
> 
> 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>
> [bhelgaas: changelog, simplify comments, remove unused "device"]
> Signed-off-by: Bjorn Helgaas <helgaas@kernel.org>

I applied this one to pci/virtualization for v4.17, thanks!

I changed the ifdefs from CONFIG_PCI_ATS to CONFIG_PCI_IOV.  I know we
use CONFIG_PCI_ATS in linux/pci.h, but I think that's a mistake.

> ---
> v3->v4:
> - Restructure the code to handle CONFIG_PCI_ATS
> 
>  drivers/pci/iov.c   | 42 +++++++++++++++++++++++++++++++++++-------
>  drivers/pci/pci.h   |  4 ++++
>  drivers/pci/probe.c | 47 ++++++++++++++++++++++++++++++++++++++++++-----
>  3 files changed, 81 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
> index 677924a..30bf8f7 100644
> --- a/drivers/pci/iov.c
> +++ b/drivers/pci/iov.c
> @@ -114,6 +114,29 @@ resource_size_t pci_iov_resource_size(struct pci_dev *dev, int resno)
>  	return dev->sriov->barsz[resno - PCI_IOV_RESOURCES];
>  }
>  
> +static void pci_read_vf_config_common(struct pci_dev *virtfn)
> +{
> +	struct pci_dev *physfn = virtfn->physfn;
> +
> +	/*
> +	 * Some config registers are the same across all associated VFs.
> +	 * Read them once from VF0 so we can skip reading them from the
> +	 * other VFs.
> +	 *
> +	 * PCIe r4.0, sec 9.3.4.1, technically doesn't require all VFs to
> +	 * have the same Revision ID and Subsystem ID, but we assume they
> +	 * do.
> +	 */
> +	pci_read_config_dword(virtfn, PCI_CLASS_REVISION,
> +			      &physfn->sriov->class);
> +	pci_read_config_byte(virtfn, PCI_HEADER_TYPE,
> +			     &physfn->sriov->hdr_type);
> +	pci_read_config_word(virtfn, PCI_SUBSYSTEM_VENDOR_ID,
> +			     &physfn->sriov->subsystem_vendor);
> +	pci_read_config_word(virtfn, PCI_SUBSYSTEM_ID,
> +			     &physfn->sriov->subsystem_device);
> +}
> +
>  int pci_iov_add_virtfn(struct pci_dev *dev, int id)
>  {
>  	int i;
> @@ -136,13 +159,17 @@ int pci_iov_add_virtfn(struct pci_dev *dev, int id)
>  	virtfn->devfn = pci_iov_virtfn_devfn(dev, id);
>  	virtfn->vendor = dev->vendor;
>  	virtfn->device = iov->vf_device;
> +	virtfn->is_virtfn = 1;
> +	virtfn->physfn = pci_dev_get(dev);
> +
> +	if (id == 0)
> +		pci_read_vf_config_common(virtfn);
> +
>  	rc = pci_setup_device(virtfn);
>  	if (rc)
> -		goto failed0;
> +		goto failed1;
>  
>  	virtfn->dev.parent = dev->dev.parent;
> -	virtfn->physfn = pci_dev_get(dev);
> -	virtfn->is_virtfn = 1;
>  	virtfn->multifunction = 0;
>  
>  	for (i = 0; i < PCI_SRIOV_NUM_BARS; i++) {
> @@ -163,10 +190,10 @@ int pci_iov_add_virtfn(struct pci_dev *dev, int id)
>  	sprintf(buf, "virtfn%u", id);
>  	rc = sysfs_create_link(&dev->dev.kobj, &virtfn->dev.kobj, buf);
>  	if (rc)
> -		goto failed1;
> +		goto failed2;
>  	rc = sysfs_create_link(&virtfn->dev.kobj, &dev->dev.kobj, "physfn");
>  	if (rc)
> -		goto failed2;
> +		goto failed3;
>  
>  	kobject_uevent(&virtfn->dev.kobj, KOBJ_CHANGE);
>  
> @@ -174,11 +201,12 @@ int pci_iov_add_virtfn(struct pci_dev *dev, int id)
>  
>  	return 0;
>  
> -failed2:
> +failed3:
>  	sysfs_remove_link(&dev->dev.kobj, buf);
> +failed2:
> +	pci_stop_and_remove_bus_device(virtfn);
>  failed1:
>  	pci_dev_put(dev);
> -	pci_stop_and_remove_bus_device(virtfn);
>  failed0:
>  	virtfn_remove_bus(dev->bus, bus);
>  failed:
> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> index fcd8191..bdb4ba2 100644
> --- a/drivers/pci/pci.h
> +++ b/drivers/pci/pci.h
> @@ -271,6 +271,10 @@ 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		class;		/* VF device */
> +	u8		hdr_type;	/* VF header type */
> +	u16		subsystem_vendor; /* VF subsystem vendor */
> +	u16		subsystem_device; /* VF subsystem device */
>  	resource_size_t	barsz[PCI_SRIOV_NUM_BARS];	/* VF BAR size */
>  	bool		drivers_autoprobe; /* Auto probing of VFs by driver */
>  };
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index ef53774..21ee1c3 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -1389,6 +1389,43 @@ int pci_cfg_space_size(struct pci_dev *dev)
>  	return PCI_CFG_SPACE_SIZE;
>  }
>  
> +static int pci_cfg_space_class(struct pci_dev *dev)
> +{
> +	int class;
> +
> +#ifdef CONFIG_PCI_ATS
> +	if (dev->is_virtfn)
> +		return dev->physfn->sriov->class;
> +#endif
> +	pci_read_config_dword(dev, PCI_CLASS_REVISION, &class);
> +	return class;
> +}
> +
> +static void pci_cfg_space_subsystem(struct pci_dev *dev, u16 *vendor, u16 *device)
> +{
> +#ifdef CONFIG_PCI_ATS
> +	if (dev->is_virtfn) {
> +		*vendor = dev->physfn->sriov->subsystem_vendor;
> +		*device = dev->physfn->sriov->subsystem_device;
> +		return;
> +	}
> +#endif
> +	pci_read_config_word(dev, PCI_SUBSYSTEM_VENDOR_ID, vendor);
> +	pci_read_config_word(dev, PCI_SUBSYSTEM_ID, device);
> +}
> +
> +static u8 pci_cfg_space_hdr_type(struct pci_dev *dev)
> +{
> +	u8 hdr_type;
> +
> +#ifdef CONFIG_PCI_ATS
> +	if (dev->is_virtfn)
> +		return dev->physfn->sriov->hdr_type;
> +#endif
> +	pci_read_config_byte(dev, PCI_HEADER_TYPE, &hdr_type);
> +	return hdr_type;
> +}
> +
>  #define LEGACY_IO_RESOURCE	(IORESOURCE_IO | IORESOURCE_PCI_FIXED)
>  
>  static void pci_msi_setup_pci_dev(struct pci_dev *dev)
> @@ -1454,8 +1491,7 @@ int pci_setup_device(struct pci_dev *dev)
>  	struct pci_bus_region region;
>  	struct resource *res;
>  
> -	if (pci_read_config_byte(dev, PCI_HEADER_TYPE, &hdr_type))
> -		return -EIO;
> +	hdr_type = pci_cfg_space_hdr_type(dev);
>  
>  	dev->sysdata = dev->bus->sysdata;
>  	dev->dev.parent = dev->bus->bridge;
> @@ -1477,7 +1513,8 @@ int pci_setup_device(struct pci_dev *dev)
>  		     dev->bus->number, PCI_SLOT(dev->devfn),
>  		     PCI_FUNC(dev->devfn));
>  
> -	pci_read_config_dword(dev, PCI_CLASS_REVISION, &class);
> +	class = pci_cfg_space_class(dev);
> +
>  	dev->revision = class & 0xff;
>  	dev->class = class >> 8;		    /* upper 3 bytes */
>  
> @@ -1517,8 +1554,8 @@ int pci_setup_device(struct pci_dev *dev)
>  			goto bad;
>  		pci_read_irq(dev);
>  		pci_read_bases(dev, 6, PCI_ROM_ADDRESS);
> -		pci_read_config_word(dev, PCI_SUBSYSTEM_VENDOR_ID, &dev->subsystem_vendor);
> -		pci_read_config_word(dev, PCI_SUBSYSTEM_ID, &dev->subsystem_device);
> +
> +		pci_cfg_space_subsystem(dev, &dev->subsystem_vendor, &dev->subsystem_device);
>  
>  		/*
>  		 * Do the ugly legacy mode stuff here rather than broken chip
> -- 
> 2.7.4
>