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21 Jul 2021 07:18:11 -0700 To: Robin Murphy , Joerg Roedel , Sanjay Kumar , Kevin Tian , Ashok Raj , Jacob Pan , Dave Jiang , Liu Yi L References: <20210720013856.4143880-1-baolu.lu@linux.intel.com> <20210720013856.4143880-5-baolu.lu@linux.intel.com> <22302277-0470-db41-7a19-41b5f73bd2c5@arm.com> <4d3a2546-da21-605d-26a9-1f6f52123056@linux.intel.com> <5662caea-a974-e511-9509-010606fda251@arm.com> From: Lu Baolu Subject: Re: [PATCH 4/5] iommu/vt-d: Disallow SVA if devices don't support 64-bit address Message-ID: Date: Wed, 21 Jul 2021 22:17:18 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.12.0 MIME-Version: 1.0 In-Reply-To: <5662caea-a974-e511-9509-010606fda251@arm.com> Content-Language: en-US Cc: iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: base64 Content-Type: text/plain; charset="utf-8"; Format="flowed" Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" T24gMjAyMS83LzIxIDE5OjEyLCBSb2JpbiBNdXJwaHkgd3JvdGU6Cj4gT24gMjAyMS0wNy0yMSAw Mjo1MCwgTHUgQmFvbHUgd3JvdGU6Cj4+IEhpIFJvYmluLAo+Pgo+PiBUaGFua3MgYSBsb3QgZm9y IHJldmlld2luZyBteSBwYXRjaCEKPj4KPj4gT24gNy8yMC8yMSA1OjI3IFBNLCBSb2JpbiBNdXJw aHkgd3JvdGU6Cj4+PiBPbiAyMDIxLTA3LTIwIDAyOjM4LCBMdSBCYW9sdSB3cm90ZToKPj4+PiBX aGVuIHRoZSBkZXZpY2UgYW5kIENQVSBzaGFyZSBhbiBhZGRyZXNzIHNwYWNlIChzdWNoIGFzIFNW QSksIHRoZSAKPj4+PiBkZXZpY2UKPj4+PiBtdXN0IHN1cHBvcnQgdGhlIHNhbWUgYWRkcmVzc2lu ZyBjYXBhYmlsaXR5IGFzIHRoZSBDUFUuIFRoZSBDUFUgZG9lcyAKPj4+PiBub3QKPj4+PiBjb25z aWRlciB0aGUgYWRkcmVzc2luZyBhYmlsaXR5IG9mIGFueSBkZXZpY2Ugd2hlbiBtYW5hZ2luZyB0 aGUgcGFnZSAKPj4+PiB0YWJsZQo+Pj4+IG9mIGEgcHJvY2Vzcywgc28gdGhlIGRldmljZSBtdXN0 IGhhdmUgZW5vdWdoIGFkZHJlc3NpbmcgYWJpbGl0eSB0byBiaW5kCj4+Pj4gdGhlIHBhZ2UgdGFi bGUgb2YgdGhlIHByb2Nlc3MuCj4+Pj4KPj4+PiBTaWduZWQtb2ZmLWJ5OiBMdSBCYW9sdSA8YmFv bHUubHVAbGludXguaW50ZWwuY29tPgo+Pj4+IC0tLQo+Pj4+IMKgIGRyaXZlcnMvaW9tbXUvaW50 ZWwvaW9tbXUuYyB8IDMgKysrCj4+Pj4gwqAgMSBmaWxlIGNoYW5nZWQsIDMgaW5zZXJ0aW9ucygr KQo+Pj4+Cj4+Pj4gZGlmZiAtLWdpdCBhL2RyaXZlcnMvaW9tbXUvaW50ZWwvaW9tbXUuYyBiL2Ry aXZlcnMvaW9tbXUvaW50ZWwvaW9tbXUuYwo+Pj4+IGluZGV4IGY0NWM4MGNlMjM4MS4uZjNjY2Ex ZGQzODRkIDEwMDY0NAo+Pj4+IC0tLSBhL2RyaXZlcnMvaW9tbXUvaW50ZWwvaW9tbXUuYwo+Pj4+ ICsrKyBiL2RyaXZlcnMvaW9tbXUvaW50ZWwvaW9tbXUuYwo+Pj4+IEBAIC01MzcyLDYgKzUzNzIs OSBAQCBzdGF0aWMgaW50IGludGVsX2lvbW11X2VuYWJsZV9zdmEoc3RydWN0IAo+Pj4+IGRldmlj ZSAqZGV2KQo+Pj4+IMKgwqDCoMKgwqAgaWYgKCEoaW9tbXUtPmZsYWdzICYgVlREX0ZMQUdfU1ZN X0NBUEFCTEUpKQo+Pj4+IMKgwqDCoMKgwqDCoMKgwqDCoCByZXR1cm4gLUVOT0RFVjsKPj4+PiAr wqDCoMKgIGlmICghZGV2LT5kbWFfbWFzayB8fCAqZGV2LT5kbWFfbWFzayAhPSBETUFfQklUX01B U0soNjQpKQo+Pj4KPj4+IENhcmVmdWwgLSBWRklPIGRvZXNuJ3Qgc2V0IERNQSBtYXNrcyAoc2lu Y2UgaXQgZG9lc24ndCB1c2UgdGhlIERNQSBBUEkpLAo+Pgo+PiBTVkEgZG9lc24ndCB3b3JrIHRo cm91Z2ggdGhlIFZGSU8gZnJhbWV3b3JrLgo+IAo+IERpZCBhbnlvbmUgc2F5IGl0IGRvZXM/IE15 IHBvaW50IGlzIHRoYXQsIGFzIGZhciBhcyBJIHVuZGVyc3RhbmQsIHRoZSAKPiBTVkEgVUFQSSBp cyB2ZXJ5IG11Y2ggaW50ZW5kZWQgdG8gd29yayAqd2l0aCogVkZJTywgYW5kIGV2ZW4gaWYgdGhl IAo+IGZpbmVyIGRldGFpbHMgYXJlIHN0aWxsIG1pcmVkIGluIHRoZSAvZGV2L2lvYXNpZCBkaXNj dXNzaW9uIHRvZGF5IHdlIAo+IHNob3VsZCBkZWZpbml0ZWx5IGV4cGVjdCB0byBzZWUgVkZJTy1s aWtlIHVzZS1jYXNlcyBhdCBzb21lIHBvaW50LiBJIAo+IGNlcnRhaW5seSBkb24ndCBzZWUgd2h5 IGFueSBvZiB0aGUgZ3Vlc3QgU1ZBIHN0dWZmIGV4aXN0cyBhbHJlYWR5IGlmIG5vdCAKPiBmb3Ig VkZJTy1hc3NpZ25lZCBkZXZpY2VzPwoKQWdyZWVkLiBGcm9tIC9kZXYvaW9hc2lkIGRlc2lnbiBw b2ludCBvZiB2aWV3LCBpdCdzIHBvc3NpYmxlIHRvIGhhdmUKVkZJTy1saWtlIHVzZSBjYXNlIG9m IFNWQS4gUGVyaGFwcyB0aGUgZGV2aWNlIGFkZHJlc3NpbmcgY2FwYWJpbGl0eQpjb3VsZCBiZSBp bmNsdWRlZCBpbiBHRVRfREVWX0lORk8gb2YgL2Rldi9pb2FzaWQgVUFQSS4KCj4gCj4+PiBzbyB0 aGlzIGFwcGVhcnMgdG8gYmUgcmVseWluZyBvbiBhbm90aGVyIGRyaXZlciBoYXZpbmcgYm91bmQg cHJldmlvdXNseSwKPj4KPj4gWWVzLiBZb3UgYXJlIHJpZ2h0Lgo+Pgo+Pj4gb3RoZXJ3aXNlIHRo ZSBtYXNrIHdvdWxkIHN0aWxsIGJlIHRoZSBkZWZhdWx0IDMyLWJpdCBvbmUgZnJvbSAKPj4+IHBj aV9zZXR1cF9kZXZpY2UoKS4gSSdtIG5vdCBzdXJlIHRoYXQncyBhbiBlbnRpcmVseSByb2J1c3Qg YXNzdW1wdGlvbi4KPj4KPj4gQ3VycmVudGx5IFNWQSBpbXBsZW1lbnRhdGlvbiBhbHdheXMgcmVx dWlyZXMgYSBuYXRpdmUga2VybmVsIGRyaXZlci4gVGhlCj4+IGFzc3VtcHRpb24gaXMgdGhhdCB0 aGUgZHJpdmVycyBzaG91bGQgY2hlY2sgYW5kIHNldCA2NC1iaXQgYWRkcmVzc2luZwo+PiBjYXBh YmlsaXR5IGJlZm9yZSBjYWxsaW5nIGlvbW11X3N2YV94eHgoKSBBUElzLgo+IAo+IC4uLmFuZCBn aXZlbiB0aGF0IHRoYXQgaXMgbm90IGEgZG9jdW1lbnRlZCByZXF1aXJlbWVudCwgYW5kIGNlcnRh aW5seSAKPiBub3QgYSB0ZWNobmljYWwgb25lIChldmVuIGEgc2VsZi1jb250YWluZWQga2VybmVs IGRyaXZlciBjb3VsZCBjaG9vc2UgdG8gCj4gb25seSB1c2UgU1ZBIGNvbnRleHRzIGFuZCBub3Qg dG91Y2ggdGhlIERNQSBBUEkpLCBpdCdzIGFuIGluaGVyZW50bHkgCj4gZnJhZ2lsZSBhc3N1bXB0 aW9uIHdoaWNoIEknbSBjb25maWRlbnQgKndpbGwqIGJlIGJyb2tlbiBldmVudHVhbGx5IDopCj4g CgpGYWlyIGVub3VnaC4gSSB3aWxsIGRyb3AgdGhpcyBwYXRjaC4KClRoYW5rcyBhIGxvdCBmb3Ig dGhlIGNvbW1lbnRzLgoKQmVzdCByZWdhcmRzLApiYW9sdQoKPiBSb2Jpbi4KPiAKPj4+PiArwqDC oMKgwqDCoMKgwqAgcmV0dXJuIC1FTk9ERVY7Cj4+Pj4gKwo+Pj4+IMKgwqDCoMKgwqAgaWYgKGlu dGVsX2lvbW11X2VuYWJsZV9wYXNpZChpb21tdSwgZGV2KSkKPj4+PiDCoMKgwqDCoMKgwqDCoMKg wqAgcmV0dXJuIC1FTk9ERVY7Cj4+Pj4KPj4KPj4gQmVzdCByZWdhcmRzLAo+PiBiYW9sdQpfX19f X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fXwppb21tdSBtYWlsaW5n IGxpc3QKaW9tbXVAbGlzdHMubGludXgtZm91bmRhdGlvbi5vcmcKaHR0cHM6Ly9saXN0cy5saW51 eGZvdW5kYXRpb24ub3JnL21haWxtYW4vbGlzdGluZm8vaW9tbXU= From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.4 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1A957C12002 for ; 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21 Jul 2021 07:18:11 -0700 Cc: baolu.lu@linux.intel.com, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org To: Robin Murphy , Joerg Roedel , Sanjay Kumar , Kevin Tian , Ashok Raj , Jacob Pan , Dave Jiang , Liu Yi L References: <20210720013856.4143880-1-baolu.lu@linux.intel.com> <20210720013856.4143880-5-baolu.lu@linux.intel.com> <22302277-0470-db41-7a19-41b5f73bd2c5@arm.com> <4d3a2546-da21-605d-26a9-1f6f52123056@linux.intel.com> <5662caea-a974-e511-9509-010606fda251@arm.com> From: Lu Baolu Subject: Re: [PATCH 4/5] iommu/vt-d: Disallow SVA if devices don't support 64-bit address Message-ID: Date: Wed, 21 Jul 2021 22:17:18 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.12.0 MIME-Version: 1.0 In-Reply-To: <5662caea-a974-e511-9509-010606fda251@arm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/7/21 19:12, Robin Murphy wrote: > On 2021-07-21 02:50, Lu Baolu wrote: >> Hi Robin, >> >> Thanks a lot for reviewing my patch! >> >> On 7/20/21 5:27 PM, Robin Murphy wrote: >>> On 2021-07-20 02:38, Lu Baolu wrote: >>>> When the device and CPU share an address space (such as SVA), the >>>> device >>>> must support the same addressing capability as the CPU. The CPU does >>>> not >>>> consider the addressing ability of any device when managing the page >>>> table >>>> of a process, so the device must have enough addressing ability to bind >>>> the page table of the process. >>>> >>>> Signed-off-by: Lu Baolu >>>> --- >>>>   drivers/iommu/intel/iommu.c | 3 +++ >>>>   1 file changed, 3 insertions(+) >>>> >>>> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c >>>> index f45c80ce2381..f3cca1dd384d 100644 >>>> --- a/drivers/iommu/intel/iommu.c >>>> +++ b/drivers/iommu/intel/iommu.c >>>> @@ -5372,6 +5372,9 @@ static int intel_iommu_enable_sva(struct >>>> device *dev) >>>>       if (!(iommu->flags & VTD_FLAG_SVM_CAPABLE)) >>>>           return -ENODEV; >>>> +    if (!dev->dma_mask || *dev->dma_mask != DMA_BIT_MASK(64)) >>> >>> Careful - VFIO doesn't set DMA masks (since it doesn't use the DMA API), >> >> SVA doesn't work through the VFIO framework. > > Did anyone say it does? My point is that, as far as I understand, the > SVA UAPI is very much intended to work *with* VFIO, and even if the > finer details are still mired in the /dev/ioasid discussion today we > should definitely expect to see VFIO-like use-cases at some point. I > certainly don't see why any of the guest SVA stuff exists already if not > for VFIO-assigned devices? Agreed. From /dev/ioasid design point of view, it's possible to have VFIO-like use case of SVA. Perhaps the device addressing capability could be included in GET_DEV_INFO of /dev/ioasid UAPI. > >>> so this appears to be relying on another driver having bound previously, >> >> Yes. You are right. >> >>> otherwise the mask would still be the default 32-bit one from >>> pci_setup_device(). I'm not sure that's an entirely robust assumption. >> >> Currently SVA implementation always requires a native kernel driver. The >> assumption is that the drivers should check and set 64-bit addressing >> capability before calling iommu_sva_xxx() APIs. > > ...and given that that is not a documented requirement, and certainly > not a technical one (even a self-contained kernel driver could choose to > only use SVA contexts and not touch the DMA API), it's an inherently > fragile assumption which I'm confident *will* be broken eventually :) > Fair enough. I will drop this patch. Thanks a lot for the comments. Best regards, baolu > Robin. > >>>> +        return -ENODEV; >>>> + >>>>       if (intel_iommu_enable_pasid(iommu, dev)) >>>>           return -ENODEV; >>>> >> >> Best regards, >> baolu