From: "Roger Pau Monné" <roger.pau@citrix.com>
To: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>,
"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>
Cc: Jan Beulich <jbeulich@suse.com>, Xiantao Zhang <xiantao.zhang@intel.com>
Subject: Re: [PATCH v4 3/4] amd-iommu: disable iommu_hap_pt_share with AMD IOMMUs
Date: Tue, 22 Jul 2014 19:39:57 +0200 [thread overview]
Message-ID: <53CEA1ED.1050604@citrix.com> (raw)
In-Reply-To: <53CE9FAC.8070008@amd.com>
On 22/07/14 19:30, Suravee Suthikulpanit wrote:
> Roger,
>
> I am not quite sure why you would disable "iommu_hap_pt_share" for AMD
> IOMMU. The current implementation assumes that the p2m can be shared.
>
> Also, I feel that simply just set iommu_hap_pt_share = 0 (while still
> having several places in the AMD iommu drivers and p2m-pt.c assuming
> that it can be shared) seems a bit messy.
According to the comment in p2m.h, AMD IOMMU only supports bit 52 to bit
58 in the pte to be 0, otherwise the hw generates page faults.
If we want to support doing IO to devices behind an IOMMU from page
types different than p2m_ram_rw the p2m tables cannot be shared, because
the bits from 52 to 58 will indeed be different than 0, and will
generate page faults.
Roger.
next prev parent reply other threads:[~2014-07-22 17:40 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-04 10:06 [PATCH v4 0/4] Fix grant/foreign mappings with auto-translated guests Roger Pau Monne
2014-06-04 10:06 ` [PATCH v4 1/4] xen: make logdirty and iommu mutually exclusive Roger Pau Monne
2014-06-05 11:33 ` Tim Deegan
2014-06-04 10:06 ` [PATCH v4 2/4] iommu: set correct IOMMU entries when iommu_hap_pt_share == 0 Roger Pau Monne
2014-06-04 10:06 ` [PATCH v4 3/4] amd-iommu: disable iommu_hap_pt_share with AMD IOMMUs Roger Pau Monne
2014-06-04 12:52 ` Jan Beulich
2014-07-04 9:44 ` Jan Beulich
2014-07-22 17:30 ` Suravee Suthikulpanit
2014-07-22 17:39 ` Roger Pau Monné [this message]
2014-08-08 15:36 ` Suravee Suthikulanit
2014-08-18 9:22 ` Roger Pau Monné
2014-08-07 8:12 ` Ping: " Jan Beulich
2014-06-04 10:06 ` [PATCH v4 4/4] xen: expose that grant table mappings update the IOMMU Roger Pau Monne
2014-06-04 13:07 ` Jan Beulich
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