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Message-ID: <1c9204d9-d9da-4785-b375-368b5ba9ec78@linux.intel.com>
Date: Tue, 2 Jul 2024 12:51:12 +0800
From: Baolu Lu <baolu.lu@...ux.intel.com>
To: "Tian, Kevin" <kevin.tian@...el.com>, Joerg Roedel <joro@...tes.org>,
Will Deacon <will@...nel.org>, Robin Murphy <robin.murphy@....com>,
Jason Gunthorpe <jgg@...pe.ca>
Cc: baolu.lu@...ux.intel.com, "iommu@...ts.linux.dev"
<iommu@...ts.linux.dev>,
"linux-kernel@...r.kernel.org" <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 10:43, Baolu Lu wrote:
> On 7/2/24 9:47 AM, Baolu Lu wrote:
>> On 7/2/24 9:11 AM, Tian, Kevin wrote:
>>>> From: Lu Baolu<baolu.lu@...ux.intel.com>
>>>> Sent: Monday, July 1, 2024 7:23 PM
>>>> +
>>>> + /*
>>>> + * For scalable mode:
>>>> + * - Domain-selective PASID-cache invalidation to affected domains
>>>> + * - Domain-selective IOTLB invalidation to affected domains
>>>> + * - Global Device-TLB invalidation to affected functions
>>>> + */
>>>> + 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;
>>>> +
>>>> + did = pasid_get_domain_id(pte);
>>>> + qi_flush_pasid_cache(iommu, did,
>>>> QI_PC_ALL_PASIDS, 0);
>>>> + iommu->flush.flush_iotlb(iommu, did, 0, 0,
>>>> DMA_TLB_DSI_FLUSH);
>>>> + }
>>>> + }
>>>> +
>>>> + __context_flush_dev_iotlb(info);
>>>> +}
>>> this only invalidates devtlb w/o PASID. We miss a pasid devtlb
>>> invalidation
>>> with global bit set.
>>
>> I am not sure about this. The spec says "Global Device-TLB invalidation
>> to affected functions", I am not sure whether this implies any PASID-
>> based-Device-TLB invalidation.
>
> I just revisited the spec, Device-TLB invalidation only covers caches
> for requests-without-PASID. If pasid translation is affected while
> updating the context entry, we should also take care of the caches for
> requests-with-pasid.
>
> I will add below line to address this.
>
> diff --git a/drivers/iommu/intel/pasid.c b/drivers/iommu/intel/pasid.c
> index 9a7b5668c723..91db0876682e 100644
> --- a/drivers/iommu/intel/pasid.c
> +++ b/drivers/iommu/intel/pasid.c
> @@ -932,6 +932,7 @@ void intel_context_flush_present(struct
> device_domain_info *info,
> did = pasid_get_domain_id(pte);
> qi_flush_pasid_cache(iommu, did,
> QI_PC_ALL_PASIDS, 0);
> iommu->flush.flush_iotlb(iommu, did, 0, 0,
> DMA_TLB_DSI_FLUSH);
> + pasid_cache_invalidation_with_pasid(iommu, did, i);
Should be
devtlb_invalidation_with_pasid(iommu, info->dev, i);
Sorry for the typo.
Best regards,
baolu
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