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From: Sinan Kaya <Okaya@kernel.org>
To: "Raj, Ashok" <ashok.raj@intel.com>
Cc: sathyanarayanan.kuppuswamy@linux.intel.com, bhelgaas@google.com,
	joro@8bytes.org, dwmw2@infradead.org, linux-pci@vger.kernel.org,
	iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org,
	Jacob Pan <jacob.jun.pan@linux.intel.com>,
	Keith Busch <keith.busch@intel.com>
Subject: Re: [PATCH v1 1/2] PCI: ATS: Add function to check ATS page aligned request status.
Date: Mon, 11 Feb 2019 15:35:13 -0500	[thread overview]
Message-ID: <a2fcfb40-cc07-87fa-dc52-72c979d9900b@kernel.org> (raw)
In-Reply-To: <20190211191549.GA12090@otc-nc-03>

On 2/11/2019 2:15 PM, Raj, Ashok wrote:
> It seems rather odd we have to check for ATS version.
> 
> I always assumed unspecified bits (Reserved) must be 0. We only check
> this if ATS is enabled, and this particular bit wasn't given away for another
> feature.
> 
> Is it really required to check for ATS version before consuming this?

Reading again, it looks like version check is not necessary since it
is implied by the presence of this bit per this paragraph.

Page Aligned Request – If Set, indicates the Untranslated Address is 
always aligned to a 4096 byte boundary.  Setting this bit is 
recommended.  This bit permits software to distinguish between 
implementations compatible with earlier version of this specification 
that permitted a requester to supply anything in bits [11:2].

  parent reply	other threads:[~2019-02-11 20:35 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-07 18:41 [PATCH v1 0/2] Add page alignment check in Intel IOMMU sathyanarayanan.kuppuswamy
2019-02-07 18:41 ` [PATCH v1 1/2] PCI: ATS: Add function to check ATS page aligned request status sathyanarayanan.kuppuswamy
2019-02-07 20:07   ` Bjorn Helgaas
2019-02-07 20:39     ` sathyanarayanan kuppuswamy
2019-02-07 20:38   ` Sinan Kaya
2019-02-07 22:16     ` sathyanarayanan kuppuswamy
2019-02-08  1:58       ` Sinan Kaya
2019-02-09  1:02         ` sathyanarayanan kuppuswamy
2019-02-09  4:49           ` Sinan Kaya
2019-02-11 19:15             ` Raj, Ashok
2019-02-11 19:24               ` sathyanarayanan kuppuswamy
2019-02-11 20:35               ` Sinan Kaya [this message]
2019-02-07 18:41 ` [PATCH v1 2/2] iommu/vt-d: Enable ATS only if the device uses page aligned address sathyanarayanan.kuppuswamy

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