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Date: Wed, 29 May 2019 17:40:51 +0200
From: Auger Eric <eric.auger@...hat.com>
To: Lu Baolu <baolu.lu@...ux.intel.com>, eric.auger.pro@...il.com,
joro@...tes.org, iommu@...ts.linux-foundation.org,
linux-kernel@...r.kernel.org, dwmw2@...radead.org,
robin.murphy@....com
Cc: alex.williamson@...hat.com, shameerali.kolothum.thodi@...wei.com,
jean-philippe.brucker@....com
Subject: Re: [PATCH v5 2/7] iommu/vt-d: Duplicate iommu_resv_region objects
per device list
Hi Lu,
On 5/29/19 4:04 AM, Lu Baolu wrote:
> Hi Eric,
>
> On 5/28/19 7:50 PM, Eric Auger wrote:
>> intel_iommu_get_resv_regions() aims to return the list of
>> reserved regions accessible by a given @device. However several
>> devices can access the same reserved memory region and when
>> building the list it is not safe to use a single iommu_resv_region
>> object, whose container is the RMRR. This iommu_resv_region must
>> be duplicated per device reserved region list.
>>
>> Let's remove the struct iommu_resv_region from the RMRR unit
>> and allocate the iommu_resv_region directly in
>> intel_iommu_get_resv_regions(). We hold the dmar_global_lock instead
>> of the rcu-lock to allow sleeping.
>>
>> Fixes: 0659b8dc45a6 ("iommu/vt-d: Implement reserved region get/put
>> callbacks")
>> Signed-off-by: Eric Auger <eric.auger@...hat.com>
>>
>> ---
>>
>> v4 -> v5
>> - replace rcu-lock by the dmar_global_lock
>> ---
>> drivers/iommu/intel-iommu.c | 34 +++++++++++++++++-----------------
>> 1 file changed, 17 insertions(+), 17 deletions(-)
>>
>> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
>> index a209199f3af6..5ec8b5bd308f 100644
>> --- a/drivers/iommu/intel-iommu.c
>> +++ b/drivers/iommu/intel-iommu.c
>> @@ -322,7 +322,6 @@ struct dmar_rmrr_unit {
>> u64 end_address; /* reserved end address */
>> struct dmar_dev_scope *devices; /* target devices */
>> int devices_cnt; /* target device count */
>> - struct iommu_resv_region *resv; /* reserved region handle */
>> };
>> struct dmar_atsr_unit {
>> @@ -4205,7 +4204,6 @@ static inline void init_iommu_pm_ops(void) {}
>> int __init dmar_parse_one_rmrr(struct acpi_dmar_header *header, void
>> *arg)
>> {
>> struct acpi_dmar_reserved_memory *rmrr;
>> - int prot = DMA_PTE_READ|DMA_PTE_WRITE;
>> struct dmar_rmrr_unit *rmrru;
>> size_t length;
>> @@ -4219,22 +4217,16 @@ int __init dmar_parse_one_rmrr(struct
>> acpi_dmar_header *header, void *arg)
>> rmrru->end_address = rmrr->end_address;
>> length = rmrr->end_address - rmrr->base_address + 1;
>> - rmrru->resv = iommu_alloc_resv_region(rmrr->base_address, length,
>> prot,
>> - IOMMU_RESV_DIRECT);
>> - if (!rmrru->resv)
>> - goto free_rmrru;
>> rmrru->devices = dmar_alloc_dev_scope((void *)(rmrr + 1),
>> ((void *)rmrr) + rmrr->header.length,
>> &rmrru->devices_cnt);
>> if (rmrru->devices_cnt && rmrru->devices == NULL)
>> - goto free_all;
>> + goto free_rmrru;
>> list_add(&rmrru->list, &dmar_rmrr_units);
>> return 0;
>> -free_all:
>> - kfree(rmrru->resv);
>> free_rmrru:
>> kfree(rmrru);
>> out:
>> @@ -4452,7 +4444,6 @@ static void intel_iommu_free_dmars(void)
>> list_for_each_entry_safe(rmrru, rmrr_n, &dmar_rmrr_units, list) {
>> list_del(&rmrru->list);
>> dmar_free_dev_scope(&rmrru->devices, &rmrru->devices_cnt);
>> - kfree(rmrru->resv);
>> kfree(rmrru);
>> }
>> @@ -5470,22 +5461,33 @@ static void intel_iommu_remove_device(struct
>> device *dev)
>> static void intel_iommu_get_resv_regions(struct device *device,
>> struct list_head *head)
>> {
>> + int prot = DMA_PTE_READ|DMA_PTE_WRITE;
>
> I know this is moved from above. How about adding spaces around the '|'?
sure
>
>> struct iommu_resv_region *reg;
>> struct dmar_rmrr_unit *rmrr;
>> struct device *i_dev;
>> int i;
>> - rcu_read_lock();
>> + down_write(&dmar_global_lock);
>
> Just out of curiosity, why not down_read()? We don't change the rmrr
> list here, right?
you're right, my mistake.
>
>> for_each_rmrr_units(rmrr) {
>> for_each_active_dev_scope(rmrr->devices, rmrr->devices_cnt,
>> i, i_dev) {
>> + struct iommu_resv_region *resv;
>> + size_t length;
>> +
>> if (i_dev != device)
>> continue;
>> - list_add_tail(&rmrr->resv->list, head);
>> + length = rmrr->end_address - rmrr->base_address + 1;
>> + resv = iommu_alloc_resv_region(rmrr->base_address,
>> + length, prot,
>> + IOMMU_RESV_DIRECT);
>> + if (!resv)
>> + break;
>> +
>> + list_add_tail(&resv->list, head);
>> }
>> }
>> - rcu_read_unlock();
>> + up_write(&dmar_global_lock);
>> reg = iommu_alloc_resv_region(IOAPIC_RANGE_START,
>> IOAPIC_RANGE_END - IOAPIC_RANGE_START + 1,
>> @@ -5500,10 +5502,8 @@ static void intel_iommu_put_resv_regions(struct
>> device *dev,
>> {
>> struct iommu_resv_region *entry, *next;
>> - list_for_each_entry_safe(entry, next, head, list) {
>> - if (entry->type == IOMMU_RESV_MSI)
>> - kfree(entry);
>> - }
>> + list_for_each_entry_safe(entry, next, head, list)
>> + kfree(entry);
>> }
>> int intel_iommu_enable_pasid(struct intel_iommu *iommu, struct
>> device *dev)
>>
>
> Other looks good to me.
>
> Reviewed-by: Lu Baolu <baolu.lu@...ux.intel.com>
Thanks!
Eric
>
> Best regards,
> Baolu
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