Re: [PATCH 07/23] pci, dmar: Update dmar units devices list during hotplug

Bjorn Helgaas
2012-03-09T01:06:31Z

On Tue, Mar 6, 2012 at 12:13 AM, Yinghai Lu <yinghai@kernel.org> wrote:
> When do pci remove/rescan on system that have more iommus, got
>
> [  894.089745] Set context mapping for c4:00.0
> [  894.110890] mpt2sas3: Allocated physical memory: size(4293 kB)
> [  894.112556] mpt2sas3: Current Controller Queue Depth(1883), Max Controller Queue Depth(2144)
> [  894.127278] mpt2sas3: Scatter Gather Elements per IO(128)
> [  894.361295] DRHD: handling fault status reg 2
> [  894.364053] DMAR:[DMA Read] Request device [c4:00.0] fault addr fffbe000
> [  894.364056] DMAR:[fault reason 02] Present bit in context entry is cl
>
> it turns out when remove/rescan, pci dev will be freed and will get another new dev.
> but drhd units still keep old one... so dmar_find_matched_drhd_unit will
> return wrong drhd and iommu for the device that is not on first iommu.
>
> So need to update devices in drhd_units during pci remove/rescan.
>
> Could save domain/bus/device/function aside in the list and according that info
> restore new dev to drhd_units later.
> Then dmar_find_matched_drdh_unit and device_to_iommu could return right drhd and iommu.
>
> Add remove_dev_from_drhd/restore_dev_to_drhd functions to do the real work.
> call them in device ADD_DEVICE and UNBOUND_DRIVER
>
> Need to do the samething to atsr.  (expose dmar_atsr_units and add atsru->segment)
>
> After patch, will right iommu for the new dev and will not get DMAR error any more.
>
> -v2: add pci_dev_put/pci_dev_get to make refcount consistent.
>
> Signed-off-by: Yinghai Lu <yinghai@kernel.org>
> Cc: David Woodhouse <dwmw2@infradead.org>
> Cc: Vinod Koul <vinod.koul@intel.com>
> Cc: Dan Williams <dan.j.williams@intel.com>
> Cc: iommu@lists.linux-foundation.org
> ---
>  drivers/iommu/intel-iommu.c |  187 ++++++++++++++++++++++++++++++++++++++++---
>  include/linux/dmar.h        |    4 +
>  2 files changed, 181 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
> index c9c6053..39ef2ce 100644
> --- a/drivers/iommu/intel-iommu.c
> +++ b/drivers/iommu/intel-iommu.c
> @@ -665,6 +665,159 @@ static struct intel_iommu *device_to_iommu(int segment, u8 bus, u8 devfn)
>        return NULL;
>  }
>
> +#ifdef CONFIG_HOTPLUG
> +struct dev_dmaru {
> +       struct list_head list;
> +       void *dmaru;
> +       int index;
> +       int segment;
> +       unsigned char bus;
> +       unsigned int devfn;
> +};
> +
> +static int
> +save_dev_dmaru(int segment, unsigned char bus, unsigned int devfn,
> +                void *dmaru, int index, struct list_head *lh)

Follow the indentation style used elsewhere in the file: as much of
the declaration on one line as will fit (here and below).

I think the callers would read more naturally if you passed in the
struct pci_dev * to save_dev_dmaru() and extracted the
segment/bus/devfn here rather than in the callers.

> +{
> +       struct dev_dmaru *m;
> +
> +       m = kzalloc(sizeof(*m), GFP_KERNEL);
> +       if (!m)
> +               return -ENOMEM;
> +
> +       m->segment = segment;
> +       m->bus     = bus;
> +       m->devfn   = devfn;
> +       m->dmaru   = dmaru;
> +       m->index   = index;
> +
> +       list_add(&m->list, lh);
> +
> +       return 0;
> +}
> +
> +static void
> +*get_dev_dmaru(int segment, unsigned char bus, unsigned int devfn,
> +               int *index, struct list_head *lh)
> +{
> +       struct dev_dmaru *m;
> +       void *dmaru = NULL;
> +
> +       list_for_each_entry(m, lh, list) {
> +               if (m->segment == segment &&
> +                   m->bus == bus && m->devfn == devfn) {
> +                       *index = m->index;
> +                       dmaru  = m->dmaru;
> +                       list_del(&m->list);
> +                       kfree(m);
> +                       break;
> +               }
> +       }
> +
> +       return dmaru;
> +}
> +
> +static LIST_HEAD(saved_dev_drhd_list);
> +
> +static void remove_dev_from_drhd(struct pci_dev *dev)
> +{
> +       struct dmar_drhd_unit *drhd = NULL;
> +       int segment = pci_domain_nr(dev->bus);
> +       int i;
> +
> +       for_each_drhd_unit(drhd) {
> +               if (drhd->ignored)
> +                       continue;
> +               if (segment != drhd->segment)
> +                       continue;
> +
> +               for (i = 0; i < drhd->devices_cnt; i++) {
> +                       if (drhd->devices[i] == dev) {
> +                               /* save it at first if it is in drhd */
> +                               save_dev_dmaru(segment, dev->bus->number,
> +                                               dev->devfn, drhd, i,
> +                                               &saved_dev_drhd_list);
> +                               /* always remove it */
> +                               pci_dev_put(dev);
> +                               drhd->devices[i] = NULL;
> +                               return;
> +                       }
> +               }
> +       }
> +}
> +
> +static void restore_dev_to_drhd(struct pci_dev *dev)
> +{
> +       struct dmar_drhd_unit *drhd = NULL;
> +       int i;
> +
> +       /* find the stored drhd */
> +       drhd = get_dev_dmaru(pci_domain_nr(dev->bus), dev->bus->number,
> +                                dev->devfn, &i, &saved_dev_drhd_list);
> +       /* restore that into drhd */
> +       if (drhd)
> +               drhd->devices[i] = pci_dev_get(dev);
> +}
> +#else
> +static void remove_dev_from_drhd(struct pci_dev *dev)
> +{
> +}
> +
> +static void restore_dev_to_drhd(struct pci_dev *dev)
> +{
> +}
> +#endif
> +
> +#if defined(CONFIG_DMAR) && defined(CONFIG_HOTPLUG)
> +static LIST_HEAD(saved_dev_atsr_list);
> +
> +static void remove_dev_from_atsr(struct pci_dev *dev)
> +{
> +       struct dmar_atsr_unit *atsr = NULL;
> +       int segment = pci_domain_nr(dev->bus);
> +       int i;
> +
> +       for_each_atsr_unit(atsr) {
> +               if (segment != atsr->segment)
> +                       continue;
> +
> +               for (i = 0; i < atsr->devices_cnt; i++) {
> +                       if (atsr->devices[i] == dev) {
> +                               /* save it at first if it is in drhd */
> +                               save_dev_dmaru(segment, dev->bus->number,
> +                                               dev->devfn, atsr, i,
> +                                               &saved_dev_atsr_list);
> +                               /* always remove it */
> +                               pci_dev_put(dev);
> +                               atsr->devices[i] = NULL;
> +                               return;
> +                       }
> +               }
> +       }
> +}
> +
> +static void restore_dev_to_atsr(struct pci_dev *dev)
> +{
> +       struct dmar_atsr_unit *atsr = NULL;
> +       int i;
> +
> +       /* find the stored atsr */
> +       atsr = get_dev_dmaru(pci_domain_nr(dev->bus), dev->bus->number,
> +                                dev->devfn, &i, &saved_dev_atsr_list);
> +       /* restore that into atsr */
> +       if (atsr)
> +               atsr->devices[i] = pci_dev_get(dev);
> +}
> +#else
> +static void remove_dev_from_atsr(struct pci_dev *dev)
> +{
> +}
> +
> +static void restore_dev_to_atsr(struct pci_dev *dev)
> +{
> +}
> +#endif
> +
>  static void domain_flush_cache(struct dmar_domain *domain,
>                               void *addr, int size)
>  {
> @@ -3474,6 +3627,7 @@ int __init dmar_parse_one_atsr(struct acpi_dmar_header *hdr)
>
>        atsru->hdr = hdr;
>        atsru->include_all = atsr->flags & 0x1;
> +       atsru->segment = atsr->segment;
>
>        list_add(&atsru->list, &dmar_atsr_units);
>
> @@ -3505,16 +3659,13 @@ int dmar_find_matched_atsr_unit(struct pci_dev *dev)
>  {
>        int i;
>        struct pci_bus *bus;
> -       struct acpi_dmar_atsr *atsr;
>        struct dmar_atsr_unit *atsru;
>
>        dev = pci_physfn(dev);
>
> -       list_for_each_entry(atsru, &dmar_atsr_units, list) {
> -               atsr = container_of(atsru->hdr, struct acpi_dmar_atsr, header);
> -               if (atsr->segment == pci_domain_nr(dev->bus))
> +       list_for_each_entry(atsru, &dmar_atsr_units, list)
> +               if (atsru->segment == pci_domain_nr(dev->bus))
>                        goto found;
> -       }
>
>        return 0;
>
> @@ -3574,20 +3725,36 @@ static int device_notifier(struct notifier_block *nb,
>        struct pci_dev *pdev = to_pci_dev(dev);
>        struct dmar_domain *domain;
>
> -       if (iommu_no_mapping(dev))
> +       if (unlikely(dev->bus != &pci_bus_type))
>                return 0;
>
> -       domain = find_domain(pdev);
> -       if (!domain)
> -               return 0;
> +       switch (action) {
> +       case BUS_NOTIFY_UNBOUND_DRIVER:
> +               if (iommu_no_mapping(dev))
> +                       goto out;
> +
> +               if (iommu_pass_through)
> +                       goto out;
> +
> +               domain = find_domain(pdev);
> +               if (!domain)
> +                       goto out;
>
> -       if (action == BUS_NOTIFY_UNBOUND_DRIVER && !iommu_pass_through) {
>                domain_remove_one_dev_info(domain, pdev);
>
>                if (!(domain->flags & DOMAIN_FLAG_VIRTUAL_MACHINE) &&
>                    !(domain->flags & DOMAIN_FLAG_STATIC_IDENTITY) &&
>                    list_empty(&domain->devices))
>                        domain_exit(domain);
> +out:
> +               remove_dev_from_drhd(pdev);
> +               remove_dev_from_atsr(pdev);
> +
> +               break;
> +       case BUS_NOTIFY_ADD_DEVICE:
> +               restore_dev_to_drhd(pdev);
> +               restore_dev_to_atsr(pdev);
> +               break;
>        }
>
>        return 0;
> diff --git a/include/linux/dmar.h b/include/linux/dmar.h
> index 731a609..57e1375 100644
> --- a/include/linux/dmar.h
> +++ b/include/linux/dmar.h
> @@ -236,9 +236,13 @@ struct dmar_atsr_unit {
>        struct acpi_dmar_header *hdr;   /* ACPI header */
>        struct pci_dev **devices;       /* target devices */
>        int devices_cnt;                /* target device count */
> +       u16 segment;                    /* PCI domain */
>        u8 include_all:1;               /* include all ports */
>  };
>
> +#define for_each_atsr_unit(atsr) \
> +       list_for_each_entry(atsr, &dmar_atsr_units, list)
> +
>  int dmar_parse_rmrr_atsr_dev(void);
>  extern int dmar_parse_one_rmrr(struct acpi_dmar_header *header);
>  extern int dmar_parse_one_atsr(struct acpi_dmar_header *header);
> --
> 1.7.7
>
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