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Date: Wed, 28 Feb 2018 15:30:26 -0600
From: Bjorn Helgaas <helgaas@...nel.org>
To: KarimAllah Ahmed <karahmed@...zon.de>
Cc: linux-pci@...r.kernel.org, Bjorn Helgaas <bhelgaas@...gle.com>,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH] pci: Store more data about VFs into the SRIOV struct
On Wed, Jan 17, 2018 at 06:44:23PM +0100, KarimAllah Ahmed wrote:
> ... to avoid reading them from the config space of all the PCI VFs. This is
> specially a useful optimization when bringing up thousands of VFs.
>
> Cc: Bjorn Helgaas <bhelgaas@...gle.com>
> Cc: linux-pci@...r.kernel.org
> Cc: linux-kernel@...r.kernel.org
> Signed-off-by: KarimAllah Ahmed <karahmed@...zon.de>
What does this patch apply to? It doesn't apply to v4.16-rc1 (my
"master" branch). I don't see anything in the history of
drivers/pci/iov.c about pci_iov_wq_fn().
> ---
> drivers/pci/iov.c | 20 ++++++++++++++++++--
> drivers/pci/pci.h | 6 +++++-
> drivers/pci/probe.c | 42 ++++++++++++++++++++++++++++++++----------
> 3 files changed, 55 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
> index 168328a..78e9595 100644
> --- a/drivers/pci/iov.c
> +++ b/drivers/pci/iov.c
> @@ -129,7 +129,7 @@ resource_size_t pci_iov_resource_size(struct pci_dev *dev, int resno)
> if (!dev->is_physfn)
> return 0;
>
> - return dev->sriov->barsz[resno - PCI_IOV_RESOURCES];
> + return dev->sriov->vf_barsz[resno - PCI_IOV_RESOURCES];
> }
>
> int batch_pci_iov_add_virtfn(struct pci_dev *dev, struct pci_bus **bus,
> @@ -325,6 +325,20 @@ static void pci_iov_wq_fn(struct work_struct *work)
> kfree(req);
> }
>
> +static void pci_read_vf_config_common(struct pci_bus *bus,
> + struct pci_dev *dev)
> +{
> + int devfn = pci_iov_virtfn_devfn(dev, 0);
> +
> + pci_bus_read_config_dword(bus, devfn, PCI_CLASS_REVISION,
> + &dev->sriov->vf_class);
> + pci_bus_read_config_word(bus, devfn, PCI_SUBSYSTEM_ID,
> + &dev->sriov->vf_subsystem_device);
> + pci_bus_read_config_word(bus, devfn, PCI_SUBSYSTEM_VENDOR_ID,
> + &dev->sriov->vf_subsystem_vendor);
> + pci_bus_read_config_byte(bus, devfn, PCI_HEADER_TYPE, &dev->sriov->vf_hdr_type);
> +}
> +
> static struct workqueue_struct *pci_iov_wq;
>
> static int __init init_pci_iov_wq(void)
> @@ -361,6 +375,8 @@ static int enable_vfs(struct pci_dev *dev, int nr_vfs)
> goto add_bus_fail;
> }
>
> + pci_read_vf_config_common(bus[0], dev);
> +
> while (remaining_vfs > 0) {
> bool ret;
> struct pci_iov_wq_item *req;
> @@ -617,7 +633,7 @@ static int sriov_init(struct pci_dev *dev, int pos)
> rc = -EIO;
> goto failed;
> }
> - iov->barsz[i] = resource_size(res);
> + iov->vf_barsz[i] = resource_size(res);
> res->end = res->start + resource_size(res) * total - 1;
> dev_info(&dev->dev, "VF(n) BAR%d space: %pR (contains BAR%d for %d VFs)\n",
> i, res, i, total);
> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> index f6b58b3..3264c9e 100644
> --- a/drivers/pci/pci.h
> +++ b/drivers/pci/pci.h
> @@ -271,7 +271,11 @@ 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 */
> - resource_size_t barsz[PCI_SRIOV_NUM_BARS]; /* VF BAR size */
> + u8 vf_hdr_type; /* VF header type */
> + u32 vf_class; /* VF device */
> + u16 vf_subsystem_vendor; /* VF subsystem vendor */
> + u16 vf_subsystem_device; /* VF subsystem device */
> + resource_size_t vf_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 14e0ea1..65099d0 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -175,6 +175,7 @@ static inline unsigned long decode_bar(struct pci_dev *dev, u32 bar)
> int __pci_read_base(struct pci_dev *dev, enum pci_bar_type type,
> struct resource *res, unsigned int pos)
> {
> + int bar = res - dev->resource;
> u32 l = 0, sz = 0, mask;
> u64 l64, sz64, mask64;
> u16 orig_cmd;
> @@ -194,9 +195,13 @@ int __pci_read_base(struct pci_dev *dev, enum pci_bar_type type,
> res->name = pci_name(dev);
>
> pci_read_config_dword(dev, pos, &l);
> - pci_write_config_dword(dev, pos, l | mask);
> - pci_read_config_dword(dev, pos, &sz);
> - pci_write_config_dword(dev, pos, l);
> + if (dev->is_virtfn) {
> + sz = dev->physfn->sriov->vf_barsz[bar] & 0xffffffff;
> + } else {
> + pci_write_config_dword(dev, pos, l | mask);
> + pci_read_config_dword(dev, pos, &sz);
> + pci_write_config_dword(dev, pos, l);
> + }
>
> /*
> * All bits set in sz means the device isn't working properly.
> @@ -236,9 +241,14 @@ int __pci_read_base(struct pci_dev *dev, enum pci_bar_type type,
>
> if (res->flags & IORESOURCE_MEM_64) {
> pci_read_config_dword(dev, pos + 4, &l);
> - pci_write_config_dword(dev, pos + 4, ~0);
> - pci_read_config_dword(dev, pos + 4, &sz);
> - pci_write_config_dword(dev, pos + 4, l);
> +
> + if (dev->is_virtfn) {
> + sz = (dev->physfn->sriov->vf_barsz[bar] >> 32) & 0xffffffff;
> + } else {
> + pci_write_config_dword(dev, pos + 4, ~0);
> + pci_read_config_dword(dev, pos + 4, &sz);
> + pci_write_config_dword(dev, pos + 4, l);
> + }
>
> l64 |= ((u64)l << 32);
> sz64 |= ((u64)sz << 32);
> @@ -327,6 +337,8 @@ static void pci_read_bases(struct pci_dev *dev, unsigned int howmany, int rom)
> for (pos = 0; pos < howmany; pos++) {
> struct resource *res = &dev->resource[pos];
> reg = PCI_BASE_ADDRESS_0 + (pos << 2);
> + if (dev->is_virtfn && dev->physfn->sriov->vf_barsz[pos] == 0)
> + continue;
> pos += __pci_read_base(dev, pci_bar_unknown, res, reg);
> }
>
> @@ -1444,7 +1456,9 @@ 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))
> + if (dev->is_virtfn)
> + hdr_type = dev->physfn->sriov->vf_hdr_type;
> + else if (pci_read_config_byte(dev, PCI_HEADER_TYPE, &hdr_type))
> return -EIO;
>
> dev->sysdata = dev->bus->sysdata;
> @@ -1464,7 +1478,10 @@ 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);
> + if (dev->is_virtfn)
> + class = dev->physfn->sriov->vf_class;
> + else
> + pci_read_config_dword(dev, PCI_CLASS_REVISION, &class);
> dev->revision = class & 0xff;
> dev->class = class >> 8; /* upper 3 bytes */
>
> @@ -1503,8 +1520,13 @@ 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);
> + if (dev->is_virtfn) {
> + dev->subsystem_vendor = dev->physfn->sriov->vf_subsystem_vendor;
> + dev->subsystem_device = dev->physfn->sriov->vf_subsystem_device;
> + } else {
> + pci_read_config_word(dev, PCI_SUBSYSTEM_VENDOR_ID, &dev->subsystem_vendor);
> + pci_read_config_word(dev, PCI_SUBSYSTEM_ID, &dev->subsystem_device);
> + }
>
> /*
> * Do the ugly legacy mode stuff here rather than broken chip
> --
> 2.7.4
>
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