LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Auger Eric <eric.auger@redhat.com>
To: Lu Baolu <baolu.lu@linux.intel.com>,
	eric.auger.pro@gmail.com, joro@8bytes.org,
	iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org,
	dwmw2@infradead.org, robin.murphy@arm.com
Cc: alex.williamson@redhat.com, shameerali.kolothum.thodi@huawei.com,
	jean-philippe.brucker@arm.com
Subject: Re: [PATCH v5 2/7] iommu/vt-d: Duplicate iommu_resv_region objects per device list
Date: Wed, 29 May 2019 17:40:51 +0200	[thread overview]
Message-ID: <a4b991b1-53c8-bb72-a981-67d02763873e@redhat.com> (raw)
In-Reply-To: <e22ccc46-7c37-c8d2-784b-3d4168512772@linux.intel.com>

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@redhat.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@linux.intel.com>
Thanks!

Eric
> 
> Best regards,
> Baolu

  reply	other threads:[~2019-05-29 15:41 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-28 11:50 [PATCH v5 0/7] RMRR related fixes and enhancements Eric Auger
2019-05-28 11:50 ` [PATCH v5 1/7] iommu: Fix a leak in iommu_insert_resv_region Eric Auger
2019-05-29  6:17   ` Christoph Hellwig
2019-05-29 15:38     ` Auger Eric
2019-05-28 11:50 ` [PATCH v5 2/7] iommu/vt-d: Duplicate iommu_resv_region objects per device list Eric Auger
2019-05-29  2:04   ` Lu Baolu
2019-05-29 15:40     ` Auger Eric [this message]
2019-05-28 11:50 ` [PATCH v5 3/7] iommu/vt-d: Introduce is_downstream_to_pci_bridge helper Eric Auger
2019-05-29  2:11   ` Lu Baolu
2019-05-29  6:21   ` Christoph Hellwig
2019-05-29 15:43     ` Auger Eric
2019-05-28 11:50 ` [PATCH v5 4/7] iommu/vt-d: Handle RMRR with PCI bridge device scopes Eric Auger
2019-05-29  2:12   ` Lu Baolu
2019-05-28 11:50 ` [PATCH v5 5/7] iommu/vt-d: Handle PCI bridge RMRR device scopes in intel_iommu_get_resv_regions Eric Auger
2019-05-29  2:13   ` Lu Baolu
2019-05-28 11:50 ` [PATCH v5 6/7] iommu: Introduce IOMMU_RESV_DIRECT_RELAXABLE reserved memory regions Eric Auger
2019-05-28 11:50 ` [PATCH v5 7/7] iommu/vt-d: Differentiate relaxable and non relaxable RMRRs Eric Auger
2019-05-29  2:34   ` Lu Baolu
2019-05-29 15:43     ` Auger Eric

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=a4b991b1-53c8-bb72-a981-67d02763873e@redhat.com \
    --to=eric.auger@redhat.com \
    --cc=alex.williamson@redhat.com \
    --cc=baolu.lu@linux.intel.com \
    --cc=dwmw2@infradead.org \
    --cc=eric.auger.pro@gmail.com \
    --cc=iommu@lists.linux-foundation.org \
    --cc=jean-philippe.brucker@arm.com \
    --cc=joro@8bytes.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=robin.murphy@arm.com \
    --cc=shameerali.kolothum.thodi@huawei.com \
    --subject='Re: [PATCH v5 2/7] iommu/vt-d: Duplicate iommu_resv_region objects per device list' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).