From: Ian Campbell <ian.campbell@citrix.com>
To: Julien Grall <julien.grall@linaro.org>
Cc: xen-devel@lists.xenproject.org, stefano.stabellini@citrix.com,
tim@xen.org
Subject: Re: [PATCH v5] xen/iommu: smmu: Advertise when the SMMU support coherent table walk
Date: Mon, 2 Mar 2015 17:02:52 +0000 [thread overview]
Message-ID: <1425315772.24959.18.camel@citrix.com> (raw)
In-Reply-To: <1425310963-20948-1-git-send-email-julien.grall@linaro.org>
On Mon, 2015-03-02 at 15:42 +0000, Julien Grall wrote:
> When SMMU doesn't support coherent table walk, Xen may need to clean
> updated PT (see commit 4c5f4cb "xen/arm: p2m: Clean cache PT when the
> IOMMU doesn't support coherent walk").
>
> If one SMMU of the platform doesn't support coherent table walk, the
> feature is disabled for the whole platform. This is because device is
> assigned to a domain after the page table are populated.
>
> This could impact performance on domain which doesn't use device
> passthrough. But, as the spec strongly recommends the support of this
> feature for mainstream platform, I expect server will always have SMMUs
> supporting coherent table walk. If not, we may need to enable this feature
> per-domain.
>
> Signed-off-by: Julien Grall <julien.grall@linaro.org>
Acked + applied,thanks.
next prev parent reply other threads:[~2015-03-02 17:04 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-02 15:42 [PATCH v5] xen/iommu: smmu: Advertise when the SMMU support coherent table walk Julien Grall
2015-03-02 17:02 ` Ian Campbell [this message]
2015-03-02 17:04 ` Ian Campbell
2015-03-03 12:19 ` Julien Grall
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