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Message-ID: <rnysuzhc4qrw5g5nx7q7xc3jtxsydmm5ck5vcdptxipetxn6f5@vqajach4lzv3>
Date: Wed, 2 Apr 2025 12:25:41 +0200
From: Michał Winiarski <michal.winiarski@...el.com>
To: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
CC: <linux-pci@...r.kernel.org>, <intel-xe@...ts.freedesktop.org>,
<dri-devel@...ts.freedesktop.org>, LKML <linux-kernel@...r.kernel.org>,
"Bjorn Helgaas" <bhelgaas@...gle.com>, Christian König
<christian.koenig@....com>, Krzysztof Wilczyński
<kw@...ux.com>, Rodrigo Vivi <rodrigo.vivi@...el.com>, Michal Wajdeczko
<michal.wajdeczko@...el.com>, Lucas De Marchi <lucas.demarchi@...el.com>,
Thomas Hellström <thomas.hellstrom@...ux.intel.com>,
"Maarten Lankhorst" <maarten.lankhorst@...ux.intel.com>, Maxime Ripard
<mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, David Airlie
<airlied@...il.com>, Simona Vetter <simona@...ll.ch>, Matt Roper
<matthew.d.roper@...el.com>
Subject: Re: [PATCH v6 3/6] PCI: Allow IOV resources to be resized in
pci_resize_resource()
On Wed, Mar 26, 2025 at 04:58:14PM +0200, Ilpo Järvinen wrote:
> On Thu, 20 Mar 2025, 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.
>
> There are differences in resizing which should be described (size calc
> and mem decode check).
I'll change it to:
"The capability layout is the same as PCI_EXT_CAP_ID_REBAR, which means
we can reuse most of the implementation, the only differences being
resource size calculation (which is multiplied by total VFs) and memory
decoding (which is controlled by a separate VF MSE field in SR-IOV
cap)."
>
> > Extend the pci_resize_resource() function to accept IOV resources.
>
> > See PCIe r4.0, sec 9.3.7.4.
>
> Can you update this to r6* please.
Sure, r6.2, sec 7.8.7.
>
> > Signed-off-by: Michał Winiarski <michal.winiarski@...el.com>
> > ---
> > drivers/pci/iov.c | 21 +++++++++++++++++++++
> > drivers/pci/pci.c | 8 +++++++-
> > drivers/pci/pci.h | 9 +++++++++
> > drivers/pci/setup-res.c | 35 ++++++++++++++++++++++++++++++-----
> > 4 files changed, 67 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
> > index 985ea11339c45..cbf335725d4fb 100644
> > --- a/drivers/pci/iov.c
> > +++ b/drivers/pci/iov.c
> > @@ -154,6 +154,27 @@ resource_size_t pci_iov_resource_size(struct pci_dev *dev, int resno)
> > return dev->sriov->barsz[pci_resource_num_to_vf_bar(resno)];
> > }
> >
> > +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[pci_resource_num_to_vf_bar(resno)] = 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 ff69f3d653ced..1fad9f4c54977 100644
> > --- a/drivers/pci/pci.c
> > +++ b/drivers/pci/pci.c
> > @@ -3745,7 +3745,13 @@ static int pci_rebar_find_pos(struct pci_dev *pdev, int bar)
> > unsigned int pos, nbars, i;
> > u32 ctrl;
> >
> > - pos = pdev->rebar_cap;
> > + if (pci_resource_is_iov(bar)) {
> > + pos = pdev->physfn ? pdev->sriov->vf_rebar_cap : 0;
>
> I'd explicitly do:
>
> if (!pdev->physfn)
> return -ENOTSUPP;
>
> rather than relying pos = 0 triggering that return later on as the intent
> is more obvious that way.
Ok.
Thanks,
-Michał
>
> > + bar = pci_resource_num_to_vf_bar(bar);
> > + } else {
> > + pos = pdev->rebar_cap;
> > + }
> > +
> > if (!pos)
> > return -ENOTSUPP;
> >
> > diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> > index f44840ee3c327..643cd8c737f66 100644
> > --- a/drivers/pci/pci.h
> > +++ b/drivers/pci/pci.h
> > @@ -689,6 +689,9 @@ void pci_iov_update_resource(struct pci_dev *dev, int resno);
> > resource_size_t pci_sriov_resource_alignment(struct pci_dev *dev, int resno);
> > void pci_restore_iov_state(struct pci_dev *dev);
> > int pci_iov_bus_range(struct pci_bus *bus);
> > +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);
> > static inline bool pci_resource_is_iov(int resno)
> > {
> > return resno >= PCI_IOV_RESOURCES && resno <= PCI_IOV_RESOURCE_END;
> > @@ -722,6 +725,12 @@ static inline int pci_iov_bus_range(struct pci_bus *bus)
> > {
> > return 0;
> > }
> > +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;
> > +}
> > static inline bool pci_resource_is_iov(int resno)
> > {
> > return false;
> > diff --git a/drivers/pci/setup-res.c b/drivers/pci/setup-res.c
> > index c6657cdd06f67..d2b3ed51e8804 100644
> > --- a/drivers/pci/setup-res.c
> > +++ b/drivers/pci/setup-res.c
> > @@ -423,13 +423,39 @@ 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 = pci_resource_n(dev, resno);
> > +
> > + if (!pci_resource_is_iov(resno)) {
> > + resource_set_size(res, res_size);
> > + } else {
> > + resource_set_size(res, res_size * pci_sriov_get_totalvfs(dev));
> > + pci_iov_resource_set_size(dev, resno, res_size);
> > + }
> > +}
> > +
> > int pci_resize_resource(struct pci_dev *dev, int resno, int size)
> > {
> > struct resource *res = pci_resource_n(dev, 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);
> > @@ -440,8 +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);
> > @@ -459,7 +484,7 @@ int pci_resize_resource(struct pci_dev *dev, int resno, int size)
> > if (ret)
> > return ret;
> >
> > - resource_set_size(res, pci_rebar_size_to_bytes(size));
> > + pci_resize_resource_set_size(dev, resno, size);
> >
> > /* Check if the new config works by trying to assign everything. */
> > if (dev->bus->self) {
> > @@ -471,7 +496,7 @@ int pci_resize_resource(struct pci_dev *dev, int resno, int size)
> >
> > error_resize:
> > pci_rebar_set_size(dev, resno, old);
> > - resource_set_size(res, pci_rebar_size_to_bytes(old));
> > + pci_resize_resource_set_size(dev, resno, old);
> > return ret;
> > }
> > EXPORT_SYMBOL(pci_resize_resource);
> >
>
> --
> i.
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