Messages in this thread | | | Date | Fri, 11 Jul 2014 10:29:12 +0800 | From | ethan zhao <> | Subject | Re: [PATCH 1/4] PCI: introduce VFs reference counter and simplify pci_vfs_assigned() implementation |
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On 2014/7/11 10:22, Alex Williamson wrote: > On Fri, 2014-07-11 at 10:10 +0800, ethan zhao wrote: >> Alex, >> Thanks for your reviewing, when I create the patch order, I thought >> about the question you concerned for >> quit a while, make every patch be independent to each other as possible >> as I could, so we can do bisect when hit >> problem. >> >> I manage to take more time to figure out better patch order. >> >> Thanks, >> Ethan >> >> On 2014/7/11 9:48, Alex Williamson wrote: >>> Since there's no 0th patch, I guess I'll comment here. This series is >>> not bisectable, patch 1 breaks the existing implementation. I'd >>> suggest: >>> >>> patch 1 - fix i40e >> i40e only could be fixed with new interface, so it couldn't >> be the first one. > It looks like i40e just has it's own copy of pci_vfs_assigned(), why > can't your current patch 4/4 be applied now? Yes, i40e has its local copy of pci_vfs_assigned(),it could be simplified . with new interface,in another word, its a user of new interface.
Thanks, Ethan > >>> patch 2 - create assign/deassign that uses dev_flags >> This will be the first ? >>> patch 3 - convert users to new interface >> Have to be the later step. >>> patch 4 - convert interface to use atomic_t >> Could it be standalone step ? >> >> Let me think about it. >> >>> IMHO, the assigned flag is a horrible hack and I don't know why drivers >>> like xenback need to use it. KVM needs to use it because it doesn't >>> actually have a driver to bind to when a device is assigned, it's happy >>> to assign devices without any driver. Thanks, >>> >>> Alex >>> >>> >>> On Fri, 2014-07-11 at 08:47 +0800, Ethan Zhao wrote: >>>> Current implementation of helper function pci_vfs_assigned() is a little complex, to >>>> get sum of VFs that assigned to VM, access low level configuration space register and >>>> then loop in traversing device tree. >>>> >>>> This patch introduce an atomic reference counter for VFs that assigned to VM in struct >>>> pci_sriov, and compose two more helper functions >>>> >>>> pci_sriov_assign_device(), >>>> pci_sriov_deassign_device() >>>> >>>> to replace manipulation to device flag and the meanwhile increase and decease the counter. >>>> >>>> Passed building on 3.15.5 >>>> >>>> Signed-off-by: Ethan Zhao <ethan.zhao@oracle.com> >>>> --- >>>> drivers/pci/iov.c | 65 ++++++++++++++++++++++++++++---------------------- >>>> drivers/pci/pci.h | 1 + >>>> include/linux/pci.h | 4 +++ >>>> 3 files changed, 41 insertions(+), 29 deletions(-) >>>> >>>> diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c >>>> index de7a747..72e267f 100644 >>>> --- a/drivers/pci/iov.c >>>> +++ b/drivers/pci/iov.c >>>> @@ -382,6 +382,7 @@ found: >>>> iov->nres = nres; >>>> iov->ctrl = ctrl; >>>> iov->total_VFs = total; >>>> + atomic_set(&iov->VFs_assigned_cnt, 0); >>>> iov->offset = offset; >>>> iov->stride = stride; >>>> iov->pgsz = pgsz; >>>> @@ -603,45 +604,51 @@ int pci_num_vf(struct pci_dev *dev) >>>> EXPORT_SYMBOL_GPL(pci_num_vf); >>>> >>>> /** >>>> - * pci_vfs_assigned - returns number of VFs are assigned to a guest >>>> - * @dev: the PCI device >>>> + * pci_vfs_assigned - returns number of VFs are assigned to VM >>>> + * @dev: the physical PCI device that contains the VFs. >>>> * >>>> - * Returns number of VFs belonging to this device that are assigned to a guest. >>>> + * Returns number of VFs belonging to this device that are assigned to VM. >>>> * If device is not a physical function returns 0. >>>> */ >>>> int pci_vfs_assigned(struct pci_dev *dev) >>>> { >>>> - struct pci_dev *vfdev; >>>> - unsigned int vfs_assigned = 0; >>>> - unsigned short dev_id; >>>> - >>>> - /* only search if we are a PF */ >>>> if (!dev->is_physfn) >>>> return 0; >>>> + if (dev->sriov) >>>> + return atomic_read(&dev->sriov->VFs_assigned_cnt); >>>> + return 0; >>>> +} >>>> +EXPORT_SYMBOL_GPL(pci_vfs_assigned); >>>> >>>> - /* >>>> - * determine the device ID for the VFs, the vendor ID will be the >>>> - * same as the PF so there is no need to check for that one >>>> - */ >>>> - pci_read_config_word(dev, dev->sriov->pos + PCI_SRIOV_VF_DID, &dev_id); >>>> - >>>> - /* loop through all the VFs to see if we own any that are assigned */ >>>> - vfdev = pci_get_device(dev->vendor, dev_id, NULL); >>>> - while (vfdev) { >>>> - /* >>>> - * It is considered assigned if it is a virtual function with >>>> - * our dev as the physical function and the assigned bit is set >>>> - */ >>>> - if (vfdev->is_virtfn && (vfdev->physfn == dev) && >>>> - (vfdev->dev_flags & PCI_DEV_FLAGS_ASSIGNED)) >>>> - vfs_assigned++; >>>> - >>>> - vfdev = pci_get_device(dev->vendor, dev_id, vfdev); >>>> - } >>>> +/** >>>> + * pci_sriov_assign_device - assign device to VM >>>> + * @pdev: the device to be assigned. >>>> + */ >>>> +void pci_sriov_assign_device(struct pci_dev *pdev) >>>> +{ >>>> + pdev->dev_flags |= PCI_DEV_FLAGS_ASSIGNED; >>>> + if (pdev->is_virtfn && !pdev->is_physfn) >>>> + if (pdev->physfn) >>>> + if (pdev->physfn->sriov) >>>> + atomic_inc(&pdev->physfn->sriov-> >>>> + VFs_assigned_cnt); >>>> +} >>>> +EXPORT_SYMBOL_GPL(pci_sriov_assign_device); >>>> >>>> - return vfs_assigned; >>>> +/** >>>> + * pci_sriov_deassign_device - deasign device from VM >>>> + * @pdev: the device to be deassigned. >>>> + */ >>>> +void pci_sriov_deassign_device(struct pci_dev *pdev) >>>> +{ >>>> + pdev->dev_flags &= ~PCI_DEV_FLAGS_ASSIGNED; >>>> + if (pdev->is_virtfn && !pdev->is_physfn) >>>> + if (pdev->physfn) >>>> + if (pdev->physfn->sriov) >>>> + atomic_dec(&pdev->physfn->sriov-> >>>> + VFs_assigned_cnt); >>>> } >>>> -EXPORT_SYMBOL_GPL(pci_vfs_assigned); >>>> +EXPORT_SYMBOL_GPL(pci_sriov_deassign_device); >>>> >>>> /** >>>> * pci_sriov_set_totalvfs -- reduce the TotalVFs available >>>> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h >>>> index 6bd0822..d17bda2 100644 >>>> --- a/drivers/pci/pci.h >>>> +++ b/drivers/pci/pci.h >>>> @@ -235,6 +235,7 @@ struct pci_sriov { >>>> u32 pgsz; /* page size for BAR alignment */ >>>> u8 link; /* Function Dependency Link */ >>>> u16 driver_max_VFs; /* max num VFs driver supports */ >>>> + atomic_t VFs_assigned_cnt; /* counter of VFs assigned to VM */ >>>> struct pci_dev *dev; /* lowest numbered PF */ >>>> struct pci_dev *self; /* this PF */ >>>> struct mutex lock; /* lock for VF bus */ >>>> diff --git a/include/linux/pci.h b/include/linux/pci.h >>>> index aab57b4..5cf6833 100644 >>>> --- a/include/linux/pci.h >>>> +++ b/include/linux/pci.h >>>> @@ -1601,6 +1601,8 @@ int pci_enable_sriov(struct pci_dev *dev, int nr_virtfn); >>>> void pci_disable_sriov(struct pci_dev *dev); >>>> int pci_num_vf(struct pci_dev *dev); >>>> int pci_vfs_assigned(struct pci_dev *dev); >>>> +void pci_sriov_assign_device(struct pci_dev *dev); >>>> +void pci_sriov_deassign_device(struct pci_dev *dev); >>>> int pci_sriov_set_totalvfs(struct pci_dev *dev, u16 numvfs); >>>> int pci_sriov_get_totalvfs(struct pci_dev *dev); >>>> #else >>>> @@ -1610,6 +1612,8 @@ static inline void pci_disable_sriov(struct pci_dev *dev) { } >>>> static inline int pci_num_vf(struct pci_dev *dev) { return 0; } >>>> static inline int pci_vfs_assigned(struct pci_dev *dev) >>>> { return 0; } >>>> +static inline void pci_sriov_assign_device(struct pci_dev *dev) { } >>>> +static inline void pci_sriov_deassign_device(struct pci_dev *dev) { } >>>> static inline int pci_sriov_set_totalvfs(struct pci_dev *dev, u16 numvfs) >>>> { return 0; } >>>> static inline int pci_sriov_get_totalvfs(struct pci_dev *dev) >>> > >
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