Re: [PATCH v3 3/5] PCI: Allow IOV resources to be resized in pci_resize_resource
From: Michał Winiarski
Date: Thu Oct 10 2024 - 07:43:09 EST
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@xxxxxxxxx>
> > ---
> > 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@xxxxxxxxxxxxxxx/
>
> --
> i.