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SubjectRe: [PATCH v8 1/8] PCI: Add pcie_reset_flr to follow calling convention of other reset methods
On Tue, 29 Jun 2021 21:30:57 +0530
Amey Narkhede <ameynarkhede03@gmail.com> wrote:

> Add has_flr bitfield in struct pci_dev to indicate support for pcie flr
> to avoid reading PCI_EXP_DEVCAP multiple times and get rid of
> PCI_DEV_FLAGS_NO_FLR_RESET in quirk_no_flr().
>
> Currently there is separate function pcie_has_flr() to probe if pcie flr is
> supported by the device which does not match the calling convention
> followed by reset methods which use second function argument to decide
> whether to probe or not. Add new function pcie_reset_flr() that follows
> the calling convention of reset methods.
>
> Co-developed-by: Alex Williamson <alex.williamson@redhat.com>
> Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

There are some non-trivial changes here vs previous, should probably
drop this.

> Signed-off-by: Amey Narkhede <ameynarkhede03@gmail.com>
> ---
> drivers/crypto/cavium/nitrox/nitrox_main.c | 4 +-
> drivers/pci/pci.c | 62 +++++++++++-----------
> drivers/pci/pcie/aer.c | 12 ++---
> drivers/pci/probe.c | 6 ++-
> drivers/pci/quirks.c | 11 ++--
> include/linux/pci.h | 7 ++-
> 6 files changed, 47 insertions(+), 55 deletions(-)
>
> diff --git a/drivers/crypto/cavium/nitrox/nitrox_main.c b/drivers/crypto/cavium/nitrox/nitrox_main.c
> index facc8e6bc..15d6c8452 100644
> --- a/drivers/crypto/cavium/nitrox/nitrox_main.c
> +++ b/drivers/crypto/cavium/nitrox/nitrox_main.c
> @@ -306,9 +306,7 @@ static int nitrox_device_flr(struct pci_dev *pdev)
> return -ENOMEM;
> }
>
> - /* check flr support */
> - if (pcie_has_flr(pdev))
> - pcie_flr(pdev);
> + pcie_reset_flr(pdev, 0);
>
> pci_restore_state(pdev);
>
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 452351025..28f099a4f 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -4611,32 +4611,12 @@ int pci_wait_for_pending_transaction(struct pci_dev *dev)
> }
> EXPORT_SYMBOL(pci_wait_for_pending_transaction);
>
> -/**
> - * pcie_has_flr - check if a device supports function level resets
> - * @dev: device to check
> - *
> - * Returns true if the device advertises support for PCIe function level
> - * resets.
> - */
> -bool pcie_has_flr(struct pci_dev *dev)
> -{
> - u32 cap;
> -
> - if (dev->dev_flags & PCI_DEV_FLAGS_NO_FLR_RESET)
> - return false;
> -
> - pcie_capability_read_dword(dev, PCI_EXP_DEVCAP, &cap);
> - return cap & PCI_EXP_DEVCAP_FLR;
> -}
> -EXPORT_SYMBOL_GPL(pcie_has_flr);
> -
> /**
> * pcie_flr - initiate a PCIe function level reset
> * @dev: device to reset
> *
> - * Initiate a function level reset on @dev. The caller should ensure the
> - * device supports FLR before calling this function, e.g. by using the
> - * pcie_has_flr() helper.
> + * Initiate a function level reset unconditionally on @dev without
> + * checking any flags and DEVCAP
> */
> int pcie_flr(struct pci_dev *dev)
> {
> @@ -4659,16 +4639,35 @@ int pcie_flr(struct pci_dev *dev)
> }
> EXPORT_SYMBOL_GPL(pcie_flr);
>
> +/**
> + * pcie_reset_flr - initiate a PCIe function level reset
> + * @dev: device to reset
> + * @probe: If set, only check if the device can be reset this way.
> + *
> + * Initiate a function level reset on @dev.
> + */
> +int pcie_reset_flr(struct pci_dev *dev, int probe)
> +{
> + if (!dev->has_flr)
> + return -ENOTTY;
> +
> + if (probe)
> + return 0;
> +
> + return pcie_flr(dev);
> +}
> +EXPORT_SYMBOL_GPL(pcie_reset_flr);
> +
> static int pci_af_flr(struct pci_dev *dev, int probe)
> {
> int pos;
> u8 cap;
>
> - pos = pci_find_capability(dev, PCI_CAP_ID_AF);
> - if (!pos)
> + if (!dev->has_flr)
> return -ENOTTY;
>
> - if (dev->dev_flags & PCI_DEV_FLAGS_NO_FLR_RESET)
> + pos = pci_find_capability(dev, PCI_CAP_ID_AF);
> + if (!pos)
> return -ENOTTY;
>
> pci_read_config_byte(dev, pos + PCI_AF_CAP, &cap);


How can has_flr encompass both methods of invoking FLR? PCIe FLR is
not a prerequisite to AF FLR.


> @@ -5139,11 +5138,9 @@ int __pci_reset_function_locked(struct pci_dev *dev)
> rc = pci_dev_specific_reset(dev, 0);
> if (rc != -ENOTTY)
> return rc;
> - if (pcie_has_flr(dev)) {
> - rc = pcie_flr(dev);
> - if (rc != -ENOTTY)
> - return rc;
> - }
> + rc = pcie_reset_flr(dev, 0);
> + if (rc != -ENOTTY)
> + return rc;
> rc = pci_af_flr(dev, 0);
> if (rc != -ENOTTY)
> return rc;
> @@ -5174,8 +5171,9 @@ int pci_probe_reset_function(struct pci_dev *dev)
> rc = pci_dev_specific_reset(dev, 1);
> if (rc != -ENOTTY)
> return rc;
> - if (pcie_has_flr(dev))
> - return 0;
> + rc = pcie_reset_flr(dev, 1);
> + if (rc != -ENOTTY)
> + return rc;
> rc = pci_af_flr(dev, 1);
> if (rc != -ENOTTY)
> return rc;
> diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
> index ec943cee5..98077595a 100644
> --- a/drivers/pci/pcie/aer.c
> +++ b/drivers/pci/pcie/aer.c
> @@ -1405,13 +1405,11 @@ static pci_ers_result_t aer_root_reset(struct pci_dev *dev)
> }
>
> if (type == PCI_EXP_TYPE_RC_EC || type == PCI_EXP_TYPE_RC_END) {
> - if (pcie_has_flr(dev)) {
> - rc = pcie_flr(dev);
> - pci_info(dev, "has been reset (%d)\n", rc);
> - } else {
> - pci_info(dev, "not reset (no FLR support)\n");
> - rc = -ENOTTY;
> - }
> + rc = pcie_reset_flr(dev, 0);
> + if (!rc)
> + pci_info(dev, "has been reset\n");
> + else
> + pci_info(dev, "not reset (no FLR support: %d)\n", rc);
> } else {
> rc = pci_bus_error_reset(dev);
> pci_info(dev, "%s Port link has been reset (%d)\n",
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index 3a62d09b8..862d91615 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -1487,6 +1487,7 @@ void set_pcie_port_type(struct pci_dev *pdev)
> {
> int pos;
> u16 reg16;
> + u32 reg32;
> int type;
> struct pci_dev *parent;
>
> @@ -1497,8 +1498,9 @@ void set_pcie_port_type(struct pci_dev *pdev)
> pdev->pcie_cap = pos;
> pci_read_config_word(pdev, pos + PCI_EXP_FLAGS, &reg16);
> pdev->pcie_flags_reg = reg16;
> - pci_read_config_word(pdev, pos + PCI_EXP_DEVCAP, &reg16);
> - pdev->pcie_mpss = reg16 & PCI_EXP_DEVCAP_PAYLOAD;
> + pci_read_config_dword(pdev, pos + PCI_EXP_DEVCAP, &reg32);
> + pdev->pcie_mpss = reg32 & PCI_EXP_DEVCAP_PAYLOAD;
> + pdev->has_flr = reg32 & PCI_EXP_DEVCAP_FLR ? 1 : 0;

We only set has_flr for PCIe FLR, so I think this effectively kills AF
FLR. The ternary should be unnecessary here.

>
> parent = pci_upstream_bridge(pdev);
> if (!parent)
> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
> index d85914afe..1efdc4e5a 100644
> --- a/drivers/pci/quirks.c
> +++ b/drivers/pci/quirks.c
> @@ -3819,7 +3819,7 @@ static int nvme_disable_and_flr(struct pci_dev *dev, int probe)
> u32 cfg;
>
> if (dev->class != PCI_CLASS_STORAGE_EXPRESS ||
> - !pcie_has_flr(dev) || !pci_resource_start(dev, 0))
> + pcie_reset_flr(dev, 1) || !pci_resource_start(dev, 0))
> return -ENOTTY;
>
> if (probe)
> @@ -3888,13 +3888,10 @@ static int nvme_disable_and_flr(struct pci_dev *dev, int probe)
> */
> static int delay_250ms_after_flr(struct pci_dev *dev, int probe)
> {
> - if (!pcie_has_flr(dev))
> - return -ENOTTY;
> + int ret = pcie_reset_flr(dev, probe);
>
> if (probe)
> - return 0;
> -
> - pcie_flr(dev);
> + return ret;
>
> msleep(250);
>
> @@ -5182,7 +5179,7 @@ DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x443, quirk_intel_qat_vf_cap);
> */
> static void quirk_no_flr(struct pci_dev *dev)
> {
> - dev->dev_flags |= PCI_DEV_FLAGS_NO_FLR_RESET;
> + dev->has_flr = 0;
> }
> DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_AMD, 0x1487, quirk_no_flr);
> DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_AMD, 0x148c, quirk_no_flr);
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index c20211e59..74f42a2cd 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -223,10 +223,8 @@ enum pci_dev_flags {
> PCI_DEV_FLAGS_VPD_REF_F0 = (__force pci_dev_flags_t) (1 << 8),
> /* A non-root bridge where translation occurs, stop alias search here */
> PCI_DEV_FLAGS_BRIDGE_XLATE_ROOT = (__force pci_dev_flags_t) (1 << 9),
> - /* Do not use FLR even if device advertises PCI_AF_CAP */
> - PCI_DEV_FLAGS_NO_FLR_RESET = (__force pci_dev_flags_t) (1 << 10),
> /* Don't use Relaxed Ordering for TLPs directed at this device */
> - PCI_DEV_FLAGS_NO_RELAXED_ORDERING = (__force pci_dev_flags_t) (1 << 11),
> + PCI_DEV_FLAGS_NO_RELAXED_ORDERING = (__force pci_dev_flags_t) (1 << 10),
> };
>
> enum pci_irq_reroute_variant {
> @@ -381,6 +379,7 @@ struct pci_dev {
> bit manually */
> unsigned int d3hot_delay; /* D3hot->D0 transition time in ms */
> unsigned int d3cold_delay; /* D3cold->D0 transition time in ms */
> + unsigned int has_flr:1;

There are more space efficient places to define this. Thanks,

Alex

>
> #ifdef CONFIG_PCIEASPM
> struct pcie_link_state *link_state; /* ASPM link state */
> @@ -1225,7 +1224,7 @@ u32 pcie_bandwidth_available(struct pci_dev *dev, struct pci_dev **limiting_dev,
> enum pci_bus_speed *speed,
> enum pcie_link_width *width);
> void pcie_print_link_status(struct pci_dev *dev);
> -bool pcie_has_flr(struct pci_dev *dev);
> +int pcie_reset_flr(struct pci_dev *dev, int probe);
> int pcie_flr(struct pci_dev *dev);
> int __pci_reset_function_locked(struct pci_dev *dev);
> int pci_reset_function(struct pci_dev *dev);

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