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Date: Fri, 17 Dec 2021 11:58:58 +0100
From: Michał Winiarski <michal.winiarski@...el.com>
To: Christian König <christian.koenig@....com>,
<linux-pci@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
Bjorn Helgaas <bhelgaas@...gle.com>
CC: Ard Biesheuvel <ardb@...nel.org>,
"Michael J . Ruhl" <michael.j.ruhl@...el.com>,
Rodrigo Vivi <rodrigo.vivi@...el.com>
Subject: Re: [PATCH 1/2] PCI: Add support for VF Resizable Bar extended cap
On 16.12.2021 08:50, Christian König wrote:
>
>
> Am 15.12.21 um 15:16 schrieb Michał Winiarski:
>> 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@...el.com>
>> ---
>> drivers/pci/pci.c | 25 +++++++++++++++--
>> drivers/pci/setup-res.c | 53 ++++++++++++++++++++++++++++++++---
>> include/uapi/linux/pci_regs.h | 1 +
>> 3 files changed, 72 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
>> index 3d2fb394986a4..89448c5104e46 100644
>> --- a/drivers/pci/pci.c
>> +++ b/drivers/pci/pci.c
>> @@ -1682,12 +1682,15 @@ static void pci_restore_config_space(struct
>> pci_dev *pdev)
>> }
>> }
>> -static void pci_restore_rebar_state(struct pci_dev *pdev)
>> +static void __pci_restore_rebar_state(struct pci_dev *pdev, int cap)
>> {
>> unsigned int pos, nbars, i;
>> u32 ctrl;
>> - pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_REBAR);
>> + if (WARN_ON(cap != PCI_EXT_CAP_ID_REBAR && cap !=
>> PCI_EXT_CAP_ID_VF_REBAR))
>> + return;
>> +
>> + pos = pci_find_ext_capability(pdev, cap);
>> if (!pos)
>> return;
>> @@ -1709,6 +1712,14 @@ static void pci_restore_rebar_state(struct
>> pci_dev *pdev)
>> }
>> }
>> +static void pci_restore_rebar_state(struct pci_dev *pdev)
>> +{
>> + __pci_restore_rebar_state(pdev, PCI_EXT_CAP_ID_REBAR);
>> +#ifdef CONFIG_PCI_IOV
>> + __pci_restore_rebar_state(pdev, PCI_EXT_CAP_ID_VF_REBAR);
>> +#endif
>> +}
>> +
>
> It's probably cleaner to let the caller specify the capability to
> restore directly.
Ok - I'll go with:
pci_restore_rebar_state(dev);
pci_restore_vf_rebar_state(dev);
in pci_restore_state() (where pci_restore_vf_rebar_state() will be
"no-op" if there's no CONFIG_PCI_IOV).
>
>> /**
>> * pci_restore_state - Restore the saved state of a PCI device
>> * @dev: PCI device that we're dealing with
>> @@ -3639,10 +3650,18 @@ 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 (bar >= PCI_IOV_RESOURCES) {
>> + cap = PCI_EXT_CAP_ID_VF_REBAR;
>> + bar -= PCI_IOV_RESOURCES;
>> + }
>> +#endif
>> +
>> + pos = pci_find_ext_capability(pdev, cap);
>> if (!pos)
>> return -ENOTSUPP;
>> diff --git a/drivers/pci/setup-res.c b/drivers/pci/setup-res.c
>> index 7f1acb3918d0c..1946e52e7678a 100644
>> --- a/drivers/pci/setup-res.c
>> +++ b/drivers/pci/setup-res.c
>> @@ -407,13 +407,36 @@ void pci_release_resource(struct pci_dev *dev,
>> int resno)
>> }
>> EXPORT_SYMBOL(pci_release_resource);
>> +static int pci_memory_decoding(struct pci_dev *dev)
>> +{
>> + u16 cmd;
>> +
>> + pci_read_config_word(dev, PCI_COMMAND, &cmd);
>> + if (cmd & PCI_COMMAND_MEMORY)
>> + return -EBUSY;
>> +
>> + return 0;
>> +}
>> +
>> +#ifdef CONFIG_PCI_IOV
>> +static int pci_vf_memory_decoding(struct pci_dev *dev)
>> +{
>> + u16 cmd;
>> +
>> + pci_read_config_word(dev, dev->sriov->pos + PCI_SRIOV_CTRL, &cmd);
>> + if (cmd & PCI_SRIOV_CTRL_MSE)
>> + return -EBUSY;
>> +
>> + return 0;
>> +}
>> +#endif
>> +
>> 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);
>> @@ -424,9 +447,14 @@ 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)
>> - return -EBUSY;
>> +#ifdef CONFIG_PCI_IOV
>> + if (resno >= PCI_IOV_RESOURCES)
>> + ret = pci_vf_memory_decoding(dev);
>> + else
>> +#endif
>> + ret = pci_memory_decoding(dev);
>> + if (ret)
>> + return ret;
>
> Way to many #ifdef spread around inside the code, please restructure that.
>
> For example concentrating the logic in a single function should help:
>
> static int pci_check_decoding_disabled(..., inr resno)
> {
>
> #ifdef CONFIG_PCI_IOV
> if (resno...
> return -EBUSY;
> else
> return 0;
> #endif
>
> if (...)
> return -EBUSY;
> return 0;
>
> }
>
Ok.
>> sizes = pci_rebar_get_possible_sizes(dev, resno);
>> if (!sizes)
>> @@ -445,6 +473,14 @@ int pci_resize_resource(struct pci_dev *dev, int
>> resno, int size)
>> res->end = res->start + pci_rebar_size_to_bytes(size) - 1;
>> +#ifdef CONFIG_PCI_IOV
>> + if (resno >= PCI_IOV_RESOURCES) {
>> + dev->sriov->barsz[resno - PCI_IOV_RESOURCES] =
>> pci_rebar_size_to_bytes(size);
>> + res->end = res->start +
>> + resource_size(res) * pci_sriov_get_totalvfs(dev) - 1;
>> + }
>> +#endif
>> +
>> /* Check if the new config works by trying to assign everything. */
>> if (dev->bus->self) {
>> ret = pci_reassign_bridge_resources(dev->bus->self,
>> res->flags);
>> @@ -456,6 +492,15 @@ 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;
>> +
>> +#ifdef CONFIG_PCI_IOV
>> + if (resno >= PCI_IOV_RESOURCES) {
>> + dev->sriov->barsz[resno - PCI_IOV_RESOURCES] =
>> pci_rebar_size_to_bytes(old);
>> + res->end = res->start +
>> + pci_rebar_size_to_bytes(old) *
>> pci_sriov_get_totalvfs(dev) - 1;
>> + }
>> +#endif
>> +
>
> Looks like this deserves it's own function.
I'll extract the whole "restore after failed resize" to separate
function (for both native and IOV).
Thanks!
-Michał
>
> Regards,
> Christian.
>
>> return ret;
>> }
>> EXPORT_SYMBOL(pci_resize_resource);
>> diff --git a/include/uapi/linux/pci_regs.h
>> b/include/uapi/linux/pci_regs.h
>> index ff6ccbc6efe96..7f5726d23b038 100644
>> --- a/include/uapi/linux/pci_regs.h
>> +++ b/include/uapi/linux/pci_regs.h
>> @@ -734,6 +734,7 @@
>> #define PCI_EXT_CAP_ID_L1SS 0x1E /* L1 PM Substates */
>> #define PCI_EXT_CAP_ID_PTM 0x1F /* Precision Time Measurement */
>> #define PCI_EXT_CAP_ID_DVSEC 0x23 /* Designated
>> Vendor-Specific */
>> +#define PCI_EXT_CAP_ID_VF_REBAR 0x24 /* VF Resizable BAR */
>> #define PCI_EXT_CAP_ID_DLF 0x25 /* Data Link Feature */
>> #define PCI_EXT_CAP_ID_PL_16GT 0x26 /* Physical Layer 16.0
>> GT/s */
>> #define PCI_EXT_CAP_ID_MAX PCI_EXT_CAP_ID_PL_16GT
>
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