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Date: Wed, 08 Jan 2014 14:01:49 +0800
From: Jiang Liu <jiang.liu@...ux.intel.com>
To: Kai Huang <dev.kai.huang@...il.com>
CC: Joerg Roedel <joro@...tes.org>,
David Woodhouse <dwmw2@...radead.org>,
Yinghai Lu <yinghai@...nel.org>,
Bjorn Helgaas <bhelgaas@...gle.com>,
Dan Williams <dan.j.williams@...el.com>,
Vinod Koul <vinod.koul@...el.com>,
Tony Luck <tony.luck@...el.com>, linux-pci@...r.kernel.org,
linux-kernel@...r.kernel.org, dmaengine@...r.kernel.org,
iommu@...ts.linux-foundation.org
Subject: Re: [RFC Patch Part2 V1 14/14] iommu/vt-d: update IOMMU state when
memory hotplug happens
On 2014/1/8 13:07, Kai Huang wrote:
> On Tue, Jan 7, 2014 at 5:00 PM, Jiang Liu <jiang.liu@...ux.intel.com> wrote:
>> If static identity domain is created, IOMMU driver needs to update
>> si_domain page table when memory hotplug event happens. Otherwise
>> PCI device DMA operations can't access the hot-added memory regions.
>>
>> Signed-off-by: Jiang Liu <jiang.liu@...ux.intel.com>
>> ---
>> drivers/iommu/intel-iommu.c | 52 ++++++++++++++++++++++++++++++++++++++++++-
>> 1 file changed, 51 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
>> index 83e3ed4..35a987d 100644
>> --- a/drivers/iommu/intel-iommu.c
>> +++ b/drivers/iommu/intel-iommu.c
>> @@ -33,6 +33,7 @@
>> #include <linux/dmar.h>
>> #include <linux/dma-mapping.h>
>> #include <linux/mempool.h>
>> +#include <linux/memory.h>
>> #include <linux/timer.h>
>> #include <linux/iova.h>
>> #include <linux/iommu.h>
>> @@ -3689,6 +3690,54 @@ static struct notifier_block device_nb = {
>> .notifier_call = device_notifier,
>> };
>>
>> +static int intel_iommu_memory_notifier(struct notifier_block *nb,
>> + unsigned long val, void *v)
>> +{
>> + struct memory_notify *mhp = v;
>> + unsigned long long start, end;
>> + struct iova *iova;
>> +
>> + switch (val) {
>> + case MEM_GOING_ONLINE:
>> + start = mhp->start_pfn << PAGE_SHIFT;
>> + end = ((mhp->start_pfn + mhp->nr_pages) << PAGE_SHIFT) - 1;
>> + if (iommu_domain_identity_map(si_domain, start, end)) {
>> + pr_warn("dmar: failed to build identity map for [%llx-%llx]\n",
>> + start, end);
>> + return NOTIFY_BAD;
>> + }
>
> Better to use iommu_prepare_identity_map? For si_domain, if
> hw_pass_through is used, there's no page table.
Hi Kai,
Good catch!
Seems function iommu_prepare_identity_map() is designed to handle
RMRRs. So how about avoiding of registering memory hotplug notifier
if hw_pass_through is true?
Thanks!
Gerry
>
>> + break;
>> + case MEM_OFFLINE:
>> + case MEM_CANCEL_ONLINE:
>> + /* TODO: enhance RB-tree and IOVA code to support of splitting iova */
>> + iova = find_iova(&si_domain->iovad, mhp->start_pfn);
>> + if (iova) {
>> + unsigned long start_pfn, last_pfn;
>> + struct dmar_drhd_unit *drhd;
>> + struct intel_iommu *iommu;
>> +
>> + start_pfn = mm_to_dma_pfn(iova->pfn_lo);
>> + last_pfn = mm_to_dma_pfn(iova->pfn_hi + 1) - 1;
>> + dma_pte_clear_range(si_domain, start_pfn, last_pfn);
>> + dma_pte_free_pagetable(si_domain, start_pfn, last_pfn);
>> + rcu_read_lock();
>> + for_each_active_iommu(iommu, drhd)
>> + iommu_flush_iotlb_psi(iommu, si_domain->id,
>> + start_pfn, last_pfn - start_pfn + 1, 0);
>> + rcu_read_unlock();
>> + __free_iova(&si_domain->iovad, iova);
>> + }
>
> The same as above. Looks we need to consider hw_pass_through for the si_domain.
>
> -Kai
>
>> + break;
>> + }
>> +
>> + return NOTIFY_OK;
>> +}
>> +
>> +static struct notifier_block intel_iommu_memory_nb = {
>> + .notifier_call = intel_iommu_memory_notifier,
>> + .priority = 0
>> +};
>> +
>> int __init intel_iommu_init(void)
>> {
>> int ret = -ENODEV;
>> @@ -3761,8 +3810,9 @@ int __init intel_iommu_init(void)
>> init_iommu_pm_ops();
>>
>> bus_set_iommu(&pci_bus_type, &intel_iommu_ops);
>> -
>> bus_register_notifier(&pci_bus_type, &device_nb);
>> + if (si_domain)
>> + register_memory_notifier(&intel_iommu_memory_nb);
>>
>> intel_iommu_enabled = 1;
>>
>> --
>> 1.7.10.4
>>
>> _______________________________________________
>> iommu mailing list
>> iommu@...ts.linux-foundation.org
>> https://lists.linuxfoundation.org/mailman/listinfo/iommu
--
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