[PATCH v3 3/5] PCI: Allow IOV resources to be resized in pci_resize_resource

Michał Winiarski michal.winiarski at intel.com
Thu Oct 10 11:42:51 UTC 2024


On Thu, Oct 10, 2024 at 02:17:11PM +0300, Ilpo Järvinen wrote:
> On Thu, 10 Oct 2024, Michał Winiarski wrote:
> 
> > Similar to regular resizable BAR, VF BAR can also be resized.
> > The structures are very similar, which means we can reuse most of the
> > implementation. See PCIe r4.0, sec 9.3.7.4.
> > 
> > Signed-off-by: Michał Winiarski <michal.winiarski at intel.com>
> > ---
> >  drivers/pci/iov.c       | 20 ++++++++++++++++++++
> >  drivers/pci/pci.c       |  9 ++++++++-
> >  drivers/pci/pci.h       |  8 ++++++++
> >  drivers/pci/setup-res.c | 33 ++++++++++++++++++++++++++++-----
> >  4 files changed, 64 insertions(+), 6 deletions(-)
> > 
> > diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
> > index fd5c059b29c13..591a3eae1618a 100644
> > --- a/drivers/pci/iov.c
> > +++ b/drivers/pci/iov.c
> > @@ -154,6 +154,26 @@ resource_size_t pci_iov_resource_size(struct pci_dev *dev, int resno)
> >  	return dev->sriov->barsz[resno - PCI_IOV_RESOURCES];
> >  }
> >  
> > +void pci_iov_resource_set_size(struct pci_dev *dev, int resno, resource_size_t size)
> > +{
> > +	if (!pci_resource_is_iov(resno)) {
> > +		pci_warn(dev, "%s is not an IOV resource\n",
> > +			 pci_resource_name(dev, resno));
> > +		return;
> > +	}
> > +
> > +	dev->sriov->barsz[resno - PCI_IOV_RESOURCES] = size;
> > +}
> > +
> > +bool pci_iov_is_memory_decoding_enabled(struct pci_dev *dev)
> > +{
> > +	u16 cmd;
> > +
> > +	pci_read_config_word(dev, dev->sriov->pos + PCI_SRIOV_CTRL, &cmd);
> > +
> > +	return cmd & PCI_SRIOV_CTRL_MSE;
> > +}
> > +
> >  static void pci_read_vf_config_common(struct pci_dev *virtfn)
> >  {
> >  	struct pci_dev *physfn = virtfn->physfn;
> > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> > index 7d85c04fbba2a..788ae61731213 100644
> > --- a/drivers/pci/pci.c
> > +++ b/drivers/pci/pci.c
> > @@ -3718,10 +3718,17 @@ void pci_acs_init(struct pci_dev *dev)
> >   */
> >  static int pci_rebar_find_pos(struct pci_dev *pdev, int bar)
> >  {
> > +	int cap = PCI_EXT_CAP_ID_REBAR;
> >  	unsigned int pos, nbars, i;
> >  	u32 ctrl;
> >  
> > -	pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_REBAR);
> > +#ifdef CONFIG_PCI_IOV
> > +	if (pci_resource_is_iov(bar)) {
> > +		cap = PCI_EXT_CAP_ID_VF_REBAR;
> > +		bar -= PCI_IOV_RESOURCES;
> > +	}
> > +#endif
> 
> Perhaps abstracting bar -= PCI_IOV_RESOURCES too into some static inline 
> function would be useful so you could drop the ifdefs. That calculation 
> seems to be done in few places besides this one.

I have a version of this series with helpers for conversion in both
ways:
pci_iov_resource_to_vf_bar (which is this one)
and pci_vf_bar_to_iov_resource (+= PCI_IOV_RESOURCES)

But decided to leave it out for now.
I can include it in v4 (or send it separately, depending on the
direction in which this revision goes).

> 
> > +	pos = pci_find_ext_capability(pdev, cap);
> >  	if (!pos)
> >  		return -ENOTSUPP;
> >  
> > diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> > index c55f2d7a4f37e..e15fd8fe0f81f 100644
> > --- a/drivers/pci/pci.h
> > +++ b/drivers/pci/pci.h
> > @@ -584,6 +584,8 @@ static inline bool pci_resource_is_iov(int resno)
> >  {
> >  	return resno >= PCI_IOV_RESOURCES && resno <= PCI_IOV_RESOURCE_END;
> >  }
> > +void pci_iov_resource_set_size(struct pci_dev *dev, int resno, resource_size_t size);
> > +bool pci_iov_is_memory_decoding_enabled(struct pci_dev *dev);
> >  extern const struct attribute_group sriov_pf_dev_attr_group;
> >  extern const struct attribute_group sriov_vf_dev_attr_group;
> >  #else
> > @@ -607,6 +609,12 @@ static inline bool pci_resource_is_iov(int resno)
> >  {
> >  	return false;
> >  }
> > +static inline void pci_iov_resource_set_size(struct pci_dev *dev, int resno,
> > +					     resource_size_t size) { }
> > +static inline bool pci_iov_is_memory_decoding_enabled(struct pci_dev *dev)
> > +{
> > +	return false;
> > +}
> >  #endif /* CONFIG_PCI_IOV */
> >  
> >  #ifdef CONFIG_PCIE_PTM
> > diff --git a/drivers/pci/setup-res.c b/drivers/pci/setup-res.c
> > index e2cf79253ebda..95a13a5fa379c 100644
> > --- a/drivers/pci/setup-res.c
> > +++ b/drivers/pci/setup-res.c
> > @@ -425,13 +425,37 @@ void pci_release_resource(struct pci_dev *dev, int resno)
> >  }
> >  EXPORT_SYMBOL(pci_release_resource);
> >  
> > +static bool pci_resize_is_memory_decoding_enabled(struct pci_dev *dev, int resno)
> > +{
> > +	u16 cmd;
> > +
> > +	if (pci_resource_is_iov(resno))
> > +		return pci_iov_is_memory_decoding_enabled(dev);
> > +
> > +	pci_read_config_word(dev, PCI_COMMAND, &cmd);
> > +
> > +	return cmd & PCI_COMMAND_MEMORY;
> > +}
> > +
> > +static void pci_resize_resource_set_size(struct pci_dev *dev, int resno, int size)
> > +{
> > +	resource_size_t res_size = pci_rebar_size_to_bytes(size);
> > +	struct resource *res = dev->resource + resno;
> > +
> > +	if (!pci_resource_is_iov(resno)) {
> > +		res->end = res->start + res_size - 1;
> > +	} else {
> > +		res->end = res->start + res_size * pci_sriov_get_totalvfs(dev) - 1;
> 
> I wish Bjorn would pick up my resource_set_{range,size}() series [1] so we 
> wouldn't need to open-code this resource size calculation everywhere.

Yeah - that looks useful indeed.

Thanks,
-Michał

> 
> > +		pci_iov_resource_set_size(dev, resno, res_size);
> > +	}
> > +}
> > +
> >  int pci_resize_resource(struct pci_dev *dev, int resno, int size)
> >  {
> >  	struct resource *res = dev->resource + resno;
> >  	struct pci_host_bridge *host;
> >  	int old, ret;
> >  	u32 sizes;
> > -	u16 cmd;
> >  
> >  	/* Check if we must preserve the firmware's resource assignment */
> >  	host = pci_find_host_bridge(dev->bus);
> > @@ -442,8 +466,7 @@ int pci_resize_resource(struct pci_dev *dev, int resno, int size)
> >  	if (!(res->flags & IORESOURCE_UNSET))
> >  		return -EBUSY;
> >  
> > -	pci_read_config_word(dev, PCI_COMMAND, &cmd);
> > -	if (cmd & PCI_COMMAND_MEMORY)
> > +	if (pci_resize_is_memory_decoding_enabled(dev, resno))
> >  		return -EBUSY;
> >  
> >  	sizes = pci_rebar_get_possible_sizes(dev, resno);
> > @@ -461,7 +484,7 @@ int pci_resize_resource(struct pci_dev *dev, int resno, int size)
> >  	if (ret)
> >  		return ret;
> >  
> > -	res->end = res->start + pci_rebar_size_to_bytes(size) - 1;
> > +	pci_resize_resource_set_size(dev, resno, size);
> >  
> >  	/* Check if the new config works by trying to assign everything. */
> >  	if (dev->bus->self) {
> > @@ -473,7 +496,7 @@ int pci_resize_resource(struct pci_dev *dev, int resno, int size)
> >  
> >  error_resize:
> >  	pci_rebar_set_size(dev, resno, old);
> > -	res->end = res->start + pci_rebar_size_to_bytes(old) - 1;
> > +	pci_resize_resource_set_size(dev, resno, old);
> >  	return ret;
> >  }
> >  EXPORT_SYMBOL(pci_resize_resource);
> > 
> 
> [1] https://patchwork.kernel.org/project/linux-pci/patch/20240614100606.15830-2-ilpo.jarvinen@linux.intel.com/
> 
> -- 
>  i.



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