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Message-ID: <28ade99a-13ad-4b01-aff2-711c006856fd@linux.intel.com>
Date: Tue, 2 Jul 2024 12:43:41 +0800
From: Baolu Lu <baolu.lu@...ux.intel.com>
To: Jacob Pan <jacob.jun.pan@...ux.intel.com>
Cc: baolu.lu@...ux.intel.com, Joerg Roedel <joro@...tes.org>,
Will Deacon <will@...nel.org>, Robin Murphy <robin.murphy@....com>,
Jason Gunthorpe <jgg@...pe.ca>, Kevin Tian <kevin.tian@...el.com>,
iommu@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 1/2] iommu/vt-d: Add helper to flush caches for context
change
On 2024/7/2 12:41, Jacob Pan wrote:
> On Mon, 1 Jul 2024 19:23:16 +0800, Lu Baolu<baolu.lu@...ux.intel.com>
> wrote:
>
>> + if (flush_domains) {
>> + /*
>> + * If the IOMMU is running in scalable mode and there
>> might
>> + * be potential PASID translations, the caller should
>> hold
>> + * the lock to ensure that context changes and cache
>> flushes
>> + * are atomic.
>> + */
>> + assert_spin_locked(&iommu->lock);
>> + for (i = 0; i < info->pasid_table->max_pasid; i++) {
>> + pte = intel_pasid_get_entry(info->dev, i);
>> + if (!pte || !pasid_pte_is_present(pte))
>> + continue;
> Is it worth going through 1M PASIDs just to skip the PASID cache
> invalidation? Or just do the flush on all used DIDs unconditionally.
Currently we don't track all domains attached to a device. If such
optimization is necessary, perhaps we can add it later.
Best regards,
baolu
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