On 09/18/13 at 03:09pm, Takao Indoh wrote: > This patch quiesces devices before disabling IOMMU on boot to stop > ongoing DMA. In intel_iommu_init(), check context entries and if there > is entry whose present bit is set then reset corresponding device. > > When IOMMU is already enabled on boot, it is disabled and new DMAR table > is created and then re-enabled in intel_iommu_init(). This causes DMAR > faults if there are in-flight DMAs. > > This causes problem on kdump. Devices are working in first kernel, and > after switching to second kernel and initializing IOMMU, many DMAR > faults occur and it causes problems like driver error or PCI SERR, at > last kdump fails. This patch fixes this problem. > > Changelog: > v2: > - Add CONTEXT_ENTRY_NR > > v1: > https://lkml.org/lkml/2013/8/21/71 > > Signed-off-by: Takao Indoh <indou.takao at jp.fujitsu.com> > --- > drivers/iommu/intel-iommu.c | 56 ++++++++++++++++++++++++++++++++++++++++++- > 1 files changed, 55 insertions(+), 1 deletions(-) > > diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c > index eec0d3e..d0e8aff 100644 > --- a/drivers/iommu/intel-iommu.c > +++ b/drivers/iommu/intel-iommu.c > @@ -224,6 +224,7 @@ struct context_entry { > u64 lo; > u64 hi; > }; > +#define CONTEXT_ENTRY_NR (VTD_PAGE_SIZE/sizeof(struct context_entry)) > > static inline bool context_present(struct context_entry *context) > { > @@ -3663,6 +3664,56 @@ static struct notifier_block device_nb = { > .notifier_call = device_notifier, > }; > > +/* Reset PCI devices if its entry exists in DMAR table */ > +static void __init iommu_reset_devices(struct intel_iommu *iommu, u16 segment) > +{ > + u64 addr; > + struct root_entry *root; > + struct context_entry *context; > + int bus, devfn; > + struct pci_dev *dev; > + > + addr = dmar_readq(iommu->reg + DMAR_RTADDR_REG); > + if (!addr) > + return; > + > + /* > + * In the case of kdump, ioremap is needed because root-entry table > + * exists in first kernel's memory area which is not mapped in second > + * kernel > + */ > + root = (struct root_entry *)ioremap(addr, PAGE_SIZE); > + if (!root) > + return; > + > + for (bus = 0; bus < ROOT_ENTRY_NR; bus++) { > + if (!root_present(&root[bus])) > + continue; > + > + context = (struct context_entry *)ioremap( > + root[bus].val & VTD_PAGE_MASK, PAGE_SIZE); > + if (!context) > + continue; > + > + for (devfn = 0; devfn < CONTEXT_ENTRY_NR; devfn++) { > + if (!context_present(&context[devfn])) > + continue; > + > + dev = pci_get_domain_bus_and_slot(segment, bus, devfn); > + if (!dev) > + continue; > + > + if (!pci_reset_bus(dev->bus)) /* go to next bus */ > + break; > + else /* Try per-function reset */ > + pci_reset_function(dev); > + > + } > + iounmap(context); > + } > + iounmap(root); > +} > + > int __init intel_iommu_init(void) > { > int ret = 0; > @@ -3687,8 +3738,11 @@ int __init intel_iommu_init(void) > continue; > > iommu = drhd->iommu; > - if (iommu->gcmd & DMA_GCMD_TE) > + if (iommu->gcmd & DMA_GCMD_TE) { > + if (reset_devices) > + iommu_reset_devices(iommu, drhd->segment); > iommu_disable_translation(iommu); > + } > } > > if (dmar_dev_scope_init() < 0) { Looks good to me, thanks! Acked-by: Baoquan He <bhe at redhat.com> > -- > 1.7.1 > >
