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SubjectRe: [RFC PATCH v2 02/10] iommu/vt-d: Add multiple domains per device query
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Hi,

On 09/06/2018 03:35 AM, Alex Williamson wrote:
> On Thu, 30 Aug 2018 12:09:14 +0800
> Lu Baolu <baolu.lu@linux.intel.com> wrote:
>
>> Add the response to IOMMU_CAP_AUX_DOMAIN capability query
>> through iommu_capable(). Return true if IOMMUs support the
>> scalable mode, return false otherwise.
>>
>> Cc: Ashok Raj <ashok.raj@intel.com>
>> Cc: Jacob Pan <jacob.jun.pan@linux.intel.com>
>> Cc: Kevin Tian <kevin.tian@intel.com>
>> Cc: Liu Yi L <yi.l.liu@intel.com>
>> Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
>> ---
>> drivers/iommu/intel-iommu.c | 31 +++++++++++++++++++++++++++++--
>> 1 file changed, 29 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
>> index 3e49d4029058..891ae70e7bf2 100644
>> --- a/drivers/iommu/intel-iommu.c
>> +++ b/drivers/iommu/intel-iommu.c
>> @@ -5193,12 +5193,39 @@ static phys_addr_t intel_iommu_iova_to_phys(struct iommu_domain *domain,
>> return phys;
>> }
>>
>> +static inline bool scalable_mode_support(void)
>> +{
>> + struct dmar_drhd_unit *drhd;
>> + struct intel_iommu *iommu;
>> + bool ret = true;
>> +
>> + rcu_read_lock();
>> + for_each_active_iommu(iommu, drhd) {
>> + if (!sm_supported(iommu)) {
>> + ret = false;
>> + break;
>> + }
>> + }
>> + rcu_read_unlock();
>> +
>> + return ret;
>> +}
>> +
>> static bool intel_iommu_capable(enum iommu_cap cap)
>> {
>> - if (cap == IOMMU_CAP_CACHE_COHERENCY)
>> + switch (cap) {
>> + case IOMMU_CAP_CACHE_COHERENCY:
>> return domain_update_iommu_snooping(NULL) == 1;
>> - if (cap == IOMMU_CAP_INTR_REMAP)
>> + case IOMMU_CAP_INTR_REMAP:
>> return irq_remapping_enabled == 1;
>> + case IOMMU_CAP_AUX_DOMAIN:
>> + return scalable_mode_support();
>> + case IOMMU_CAP_NOEXEC:
>> + /* PASSTHROUGH */
>> + default:
>> + pr_info("Unsupported capability query %d\n", cap);
>> + break;
>
> Please don't do this, there's no reason to be noisy about a query of a
> capability that VT-d doesn't know about. We implement capabilities
> exactly so that relevant drivers can expose a feature and others can
> happily (and quietly) ignore them. Thanks,

Fair enough. I will remove it in the next version.

Best regards,
Lu Baolu

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