Re: [PATCH v8 vfio 3/7] vfio/pds: register with the pds_core PF

[Brett Creeley <bcreeley@xxxxxxx>]

On 4/10/2023 1:41 PM, Alex Williamson wrote:
> Caution: This message originated from an External Source. Use proper caution when opening attachments, clicking links, or responding.
>
>
> On Tue, 4 Apr 2023 12:01:37 -0700
> Brett Creeley <brett.creeley@xxxxxxx> wrote:
>
> > The pds_core driver will supply adminq services, so find the PF
> > and register with the DSC services.
> >
> > Use the following commands to enable a VF:
> > echo 1 > /sys/bus/pci/drivers/pds_core/$PF_BDF/sriov_numvfs
> >
> > Signed-off-by: Brett Creeley <brett.creeley@xxxxxxx>
> > Signed-off-by: Shannon Nelson <shannon.nelson@xxxxxxx>
> > ---
> >   drivers/vfio/pci/pds/Makefile   |  1 +
> >   drivers/vfio/pci/pds/cmds.c     | 69 +++++++++++++++++++++++++++++++++
> >   drivers/vfio/pci/pds/cmds.h     | 10 +++++
> >   drivers/vfio/pci/pds/pci_drv.c  | 16 +++++++-
> >   drivers/vfio/pci/pds/pci_drv.h  |  9 +++++
> >   drivers/vfio/pci/pds/vfio_dev.c |  5 +++
> >   drivers/vfio/pci/pds/vfio_dev.h |  2 +
> >   include/linux/pds/pds_lm.h      | 12 ++++++
> >   8 files changed, 123 insertions(+), 1 deletion(-)
> >   create mode 100644 drivers/vfio/pci/pds/cmds.c
> >   create mode 100644 drivers/vfio/pci/pds/cmds.h
> >   create mode 100644 drivers/vfio/pci/pds/pci_drv.h
> >   create mode 100644 include/linux/pds/pds_lm.h
> >
> > diff --git a/drivers/vfio/pci/pds/Makefile b/drivers/vfio/pci/pds/Makefile
> > index e1a55ae0f079..87581111fa17 100644
> > --- a/drivers/vfio/pci/pds/Makefile
> > +++ b/drivers/vfio/pci/pds/Makefile
> > @@ -4,5 +4,6 @@
> >   obj-$(CONFIG_PDS_VFIO_PCI) += pds_vfio.o
> >
> >   pds_vfio-y := \
> > +     cmds.o          \
> >        pci_drv.o       \
> >        vfio_dev.o
> > diff --git a/drivers/vfio/pci/pds/cmds.c b/drivers/vfio/pci/pds/cmds.c
> > new file mode 100644
> > index 000000000000..7807dbb2c72c
> > --- /dev/null
> > +++ b/drivers/vfio/pci/pds/cmds.c
> > @@ -0,0 +1,69 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/* Copyright(c) 2023 Advanced Micro Devices, Inc. */
> > +
> > +#include <linux/io.h>
> > +#include <linux/types.h>
> > +
> > +#include <linux/pds/pds_common.h>
> > +#include <linux/pds/pds_core_if.h>
> > +#include <linux/pds/pds_adminq.h>
> > +#include <linux/pds/pds_lm.h>
> > +
> > +#include "vfio_dev.h"
> > +#include "cmds.h"
> > +
> > +int
> > +pds_vfio_register_client_cmd(struct pds_vfio_pci_device *pds_vfio)
> > +{
> > +     union pds_core_adminq_comp comp = { 0 };
> > +     union pds_core_adminq_cmd cmd = { 0 };
> > +     struct device *dev;
> > +     int err;
> > +     u32 id;
> > +     u16 ci;
> > +
> > +     id = PCI_DEVID(pds_vfio->pdev->bus->number,
> > +                    pci_iov_virtfn_devfn(pds_vfio->pdev, pds_vfio->vf_id));
>
> Does this actually work?
>
> pds_vfio_pci_probe() is presumably called with a VF pdev because it
> calls pdsc_get_pf_struct() -> pci_iov_get_pf_drvdata(), which returns
> an error if !dev->is_virtfn.  pds_vfio_init_device() also stores the
> vf_id from pci_iov_vf_id(), which requires that it's called on a VF,
> not PF.  This same pdev gets stored at pds_vfio->pdev.
>
> OTOH, pci_iov_virtfn_devfn() used here errors if !dev->is_physfn.  So I
> expect we're calling PCI_DEVID with the second arg as -EINVAL.  The
> first arg would also be suspicious if pds_vfio->pdev were the PF since
> then we'd be making a PCI_DEVID combining the PF bus number and the VF
> devfn.
>
> We've also already stored the VF PCI_DEVID at pds_vfio->pci_id, so
> creating it again seems entirely unnecessary.
>
> Also, since we never check the return of pdsc_get_pf_struct() I'd guess
> we take a segfault referencing off of pds_vfio->pdsc should the driver
> bind to something other than expected.  Validating the PF drvdata
> before anything else seems like a good first stop in
> pds_vfio_pci_probe().
>
> It's also a little curious why we're storing the pdev at all  in the
> pds_vfio_pci_device when it's readily available from the embedded
> vfio_pci_core_device.  Thanks,
>
> Alex

Yeah, these are all good catches and I'm not sure how I didn't notice 
them before. I will rework these bits based on your feedback.

Thanks,

Brett

> > +
> > +     dev = &pds_vfio->pdev->dev;
> > +     cmd.client_reg.opcode = PDS_AQ_CMD_CLIENT_REG;
> > +     snprintf(cmd.client_reg.devname, sizeof(cmd.client_reg.devname),
> > +              "%s.%d-%u", PDS_LM_DEV_NAME,
> > +              pci_domain_nr(pds_vfio->pdev->bus), id);
> > +
> > +     err = pdsc_adminq_post(pds_vfio->pdsc, &cmd, &comp, false);
> > +     if (err) {
> > +             dev_info(dev, "register with DSC failed, status %d: %pe\n",
> > +                      comp.status, ERR_PTR(err));
> > +             return err;
> > +     }
> > +
> > +     ci = le16_to_cpu(comp.client_reg.client_id);
> > +     if (!ci) {
> > +             dev_err(dev, "%s: device returned null client_id\n", __func__);
> > +             return -EIO;
> > +     }
> > +     pds_vfio->client_id = ci;
> > +
> > +     return 0;
> > +}
> > +
> > +void
> > +pds_vfio_unregister_client_cmd(struct pds_vfio_pci_device *pds_vfio)
> > +{
> > +     union pds_core_adminq_comp comp = { 0 };
> > +     union pds_core_adminq_cmd cmd = { 0 };
> > +     struct device *dev;
> > +     int err;
> > +
> > +     dev = &pds_vfio->pdev->dev;
> > +     cmd.client_unreg.opcode = PDS_AQ_CMD_CLIENT_UNREG;
> > +     cmd.client_unreg.client_id = cpu_to_le16(pds_vfio->client_id);
> > +
> > +     err = pdsc_adminq_post(pds_vfio->pdsc, &cmd, &comp, false);
> > +     if (err)
> > +             dev_info(dev, "unregister from DSC failed, status %d: %pe\n",
> > +                      comp.status, ERR_PTR(err));
> > +
> > +     pds_vfio->client_id = 0;
> > +}
> > diff --git a/drivers/vfio/pci/pds/cmds.h b/drivers/vfio/pci/pds/cmds.h
> > new file mode 100644
> > index 000000000000..4c592afccf89
> > --- /dev/null
> > +++ b/drivers/vfio/pci/pds/cmds.h
> > @@ -0,0 +1,10 @@
> > +/* SPDX-License-Identifier: GPL-2.0 */
> > +/* Copyright(c) 2023 Advanced Micro Devices, Inc. */
> > +
> > +#ifndef _CMDS_H_
> > +#define _CMDS_H_
> > +
> > +int pds_vfio_register_client_cmd(struct pds_vfio_pci_device *pds_vfio);
> > +void pds_vfio_unregister_client_cmd(struct pds_vfio_pci_device *pds_vfio);
> > +
> > +#endif /* _CMDS_H_ */
> > diff --git a/drivers/vfio/pci/pds/pci_drv.c b/drivers/vfio/pci/pds/pci_drv.c
> > index 5e554420792e..46537afdee2d 100644
> > --- a/drivers/vfio/pci/pds/pci_drv.c
> > +++ b/drivers/vfio/pci/pds/pci_drv.c
> > @@ -8,9 +8,13 @@
> >   #include <linux/types.h>
> >   #include <linux/vfio.h>
> >
> > +#include <linux/pds/pds_common.h>
> >   #include <linux/pds/pds_core_if.h>
> > +#include <linux/pds/pds_adminq.h>
> >
> >   #include "vfio_dev.h"
> > +#include "pci_drv.h"
> > +#include "cmds.h"
> >
> >   #define PDS_VFIO_DRV_NAME            "pds_vfio"
> >   #define PDS_VFIO_DRV_DESCRIPTION     "AMD/Pensando VFIO Device Driver"
> > @@ -30,13 +34,23 @@ pds_vfio_pci_probe(struct pci_dev *pdev,
> >
> >        dev_set_drvdata(&pdev->dev, &pds_vfio->vfio_coredev);
> >        pds_vfio->pdev = pdev;
> > +     pds_vfio->pdsc = pdsc_get_pf_struct(pdev);
> > +
> > +     err = pds_vfio_register_client_cmd(pds_vfio);
> > +     if (err) {
> > +             dev_err(&pdev->dev, "failed to register as client: %pe\n",
> > +                     ERR_PTR(err));
> > +             goto out_put_vdev;
> > +     }
> >
> >        err = vfio_pci_core_register_device(&pds_vfio->vfio_coredev);
> >        if (err)
> > -             goto out_put_vdev;
> > +             goto out_unreg_client;
> >
> >        return 0;
> >
> > +out_unreg_client:
> > +     pds_vfio_unregister_client_cmd(pds_vfio);
> >   out_put_vdev:
> >        vfio_put_device(&pds_vfio->vfio_coredev.vdev);
> >        return err;
> > diff --git a/drivers/vfio/pci/pds/pci_drv.h b/drivers/vfio/pci/pds/pci_drv.h
> > new file mode 100644
> > index 000000000000..e79bed12ed14
> > --- /dev/null
> > +++ b/drivers/vfio/pci/pds/pci_drv.h
> > @@ -0,0 +1,9 @@
> > +/* SPDX-License-Identifier: GPL-2.0 */
> > +/* Copyright(c) 2023 Advanced Micro Devices, Inc. */
> > +
> > +#ifndef _PCI_DRV_H
> > +#define _PCI_DRV_H
> > +
> > +#include <linux/pci.h>
> > +
> > +#endif /* _PCI_DRV_H */
> > diff --git a/drivers/vfio/pci/pds/vfio_dev.c b/drivers/vfio/pci/pds/vfio_dev.c
> > index 0f70efec01e1..056715dea512 100644
> > --- a/drivers/vfio/pci/pds/vfio_dev.c
> > +++ b/drivers/vfio/pci/pds/vfio_dev.c
> > @@ -31,6 +31,11 @@ pds_vfio_init_device(struct vfio_device *vdev)
> >        pds_vfio->vf_id = pci_iov_vf_id(pdev);
> >        pds_vfio->pci_id = PCI_DEVID(pdev->bus->number, pdev->devfn);
> >
> > +     dev_dbg(&pdev->dev, "%s: PF %#04x VF %#04x (%d) vf_id %d domain %d pds_vfio %p\n",
> > +             __func__, pci_dev_id(pdev->physfn),
> > +             pds_vfio->pci_id, pds_vfio->pci_id, pds_vfio->vf_id,
> > +             pci_domain_nr(pdev->bus), pds_vfio);
> > +
> >        return 0;
> >   }
> >
> > diff --git a/drivers/vfio/pci/pds/vfio_dev.h b/drivers/vfio/pci/pds/vfio_dev.h
> > index a66f8069b88c..10557e8dc829 100644
> > --- a/drivers/vfio/pci/pds/vfio_dev.h
> > +++ b/drivers/vfio/pci/pds/vfio_dev.h
> > @@ -10,9 +10,11 @@
> >   struct pds_vfio_pci_device {
> >        struct vfio_pci_core_device vfio_coredev;
> >        struct pci_dev *pdev;
> > +     void *pdsc;
> >
> >        int vf_id;
> >        int pci_id;
> > +     u16 client_id;
> >   };
> >
> >   const struct vfio_device_ops *pds_vfio_ops_info(void);
> > diff --git a/include/linux/pds/pds_lm.h b/include/linux/pds/pds_lm.h
> > new file mode 100644
> > index 000000000000..2bc2bf79426e
> > --- /dev/null
> > +++ b/include/linux/pds/pds_lm.h
> > @@ -0,0 +1,12 @@
> > +/* SPDX-License-Identifier: GPL-2.0 */
> > +/* Copyright(c) 2022 Pensando Systems, Inc */
> > +
> > +#ifndef _PDS_LM_H_
> > +#define _PDS_LM_H_
> > +
> > +#include "pds_common.h"
> > +
> > +#define PDS_DEV_TYPE_LM_STR  "LM"
> > +#define PDS_LM_DEV_NAME              PDS_CORE_DRV_NAME "." PDS_DEV_TYPE_LM_STR
> > +
> > +#endif /* _PDS_LM_H_ */