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From: Joerg Roedel <joro@8bytes.org>
To: Douglas Anderson <dianders@chromium.org>
Cc: will@kernel.org, robin.murphy@arm.com,
	bjorn.andersson@linaro.org, ulf.hansson@linaro.org,
	adrian.hunter@intel.com, bhelgaas@google.com,
	john.garry@huawei.com, robdclark@chromium.org,
	quic_c_gdjako@quicinc.com, saravanak@google.com,
	rajatja@google.com, saiprakash.ranjan@codeaurora.org,
	vbadigan@codeaurora.org, linux-mmc@vger.kernel.org,
	linux-arm-msm@vger.kernel.org, linux-pci@vger.kernel.org,
	iommu@lists.linux-foundation.org, sonnyrao@chromium.org,
	joel@joelfernandes.org, Andrew Morton <akpm@linux-foundation.org>,
	Jonathan Corbet <corbet@lwn.net>,
	Jordan Crouse <jordan@cosmicpenguin.net>,
	Konrad Dybcio <konrad.dybcio@somainline.org>,
	Krishna Reddy <vdumpa@nvidia.com>,
	"Maciej W. Rozycki" <macro@orcam.me.uk>,
	Nicolin Chen <nicoleotsuka@gmail.com>,
	"Paul E. McKenney" <paulmck@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Randy Dunlap <rdunlap@infradead.org>,
	Thierry Reding <thierry.reding@gmail.com>,
	Viresh Kumar <viresh.kumar@linaro.org>,
	Vlastimil Babka <vbabka@suse.cz>,
	linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 0/3] iommu: Enable non-strict DMA on QCom SD/MMC
Date: Fri, 25 Jun 2021 15:18:58 +0200	[thread overview]
Message-ID: <YNXXwvuErVnlHt+s@8bytes.org> (raw)
In-Reply-To: <20210624171759.4125094-1-dianders@chromium.org>

Hi Douglas,

On Thu, Jun 24, 2021 at 10:17:56AM -0700, Douglas Anderson wrote:
> The goal of this patch series is to get better SD/MMC performance on
> Qualcomm eMMC controllers and in generally nudge us forward on the
> path of allowing some devices to be in strict mode and others to be in
> non-strict mode.

So if I understand it right, this patch-set wants a per-device decision
about setting dma-mode to strict vs. non-strict.

I think we should get to the reason why strict mode is used by default
first. Is the default on ARM platforms to use iommu-strict mode by
default and if so, why?

The x86 IOMMUs use non-strict mode by default (yes, it is a security
trade-off).

Regards,

	Joerg

  parent reply	other threads:[~2021-06-25 13:19 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-24 17:17 Douglas Anderson
2021-06-24 17:17 ` [PATCH v2 1/3] iommu: Add per-domain strictness and combine with the global default Douglas Anderson
2021-06-24 17:17 ` [PATCH v2 2/3] iommu/arm-smmu: Check for strictness after calling impl->init_context() Douglas Anderson
2021-06-24 17:17 ` [PATCH v2 3/3] mmc: sdhci-msm: Request non-strict IOMMU mode Douglas Anderson
2021-06-24 23:05   ` Doug Anderson
2021-06-25 13:18 ` Joerg Roedel [this message]
2021-06-25 14:42   ` [PATCH v2 0/3] iommu: Enable non-strict DMA on QCom SD/MMC Doug Anderson
2021-07-07 20:00     ` Doug Anderson
2021-07-08  8:08       ` Joerg Roedel
2021-07-08 14:36         ` Doug Anderson
2021-07-13 18:07           ` Robin Murphy
2021-07-14 15:14             ` Doug Anderson
2021-08-03  0:09               ` Rajat Jain
2021-08-03  0:34                 ` Rajat Jain
2021-08-03  8:19                 ` Robin Murphy
2021-07-09 13:56         ` Robin Murphy
2021-07-14 10:15           ` Joerg Roedel
2021-07-14 10:29             ` Robin Murphy
2021-07-14 10:48               ` Joerg Roedel
2021-07-09 19:21         ` Robin Murphy

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