From: Jason Gunthorpe <jgg@nvidia.com>
To: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Cc: linux-kernel@vger.kernel.org, iommu@lists.linux.dev,
joro@8bytes.org, yi.l.liu@intel.com, kevin.tian@intel.com,
nicolinc@nvidia.com, eric.auger@redhat.com, vasant.hegde@amd.com,
jon.grimm@amd.com, santosh.shukla@amd.com, Dhaval.Giani@amd.com,
pandoh@google.com, loganodell@google.com
Subject: Re: [RFCv2 PATCH 2/7] iommu/amd: Refactor set_dte_entry
Date: Fri, 8 Mar 2024 09:51:38 -0400 [thread overview]
Message-ID: <20240308135138.GJ9179@nvidia.com> (raw)
In-Reply-To: <20240112000646.98001-3-suravee.suthikulpanit@amd.com>
On Thu, Jan 11, 2024 at 06:06:41PM -0600, Suravee Suthikulpanit wrote:
> - old_domid = dev_table[devid].data[1] & DEV_DOMID_MASK;
> - dev_table[devid].data[1] = flags;
> - dev_table[devid].data[0] = pte_root;
> + dev_table[devid].data[0] = target.data[0];
> + dev_table[devid].data[1] = target.data[1];
> + dev_table[devid].data[2] = target.data[2];
Maybe you could have convinced me this doesn't have bugs today with 2
qword updates, but no way this is OK.
The multi qword update needs to be sequenced correctly so the HW
doesn't have tearing. The manual talks about this and it talks about
128 bit updates too.
This needs to follow the design ARM has where it uses the special
update logic to reliably sequence the change. Since nesting is making
the update more complex it becomes important.
Jason
next prev parent reply other threads:[~2024-03-08 13:51 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-12 0:06 [RFCv2 PATCH 0/7] iommu/amd: Introduce hardware info reporting and nested translation support Suravee Suthikulpanit
2024-01-12 0:06 ` [RFCv2 PATCH 1/7] iommu/amd: Introduce struct gcr3_tbl_info.giov Suravee Suthikulpanit
2024-03-08 13:48 ` Jason Gunthorpe
2024-01-12 0:06 ` [RFCv2 PATCH 2/7] iommu/amd: Refactor set_dte_entry Suravee Suthikulpanit
2024-01-22 8:39 ` Tian, Kevin
2024-03-08 13:51 ` Jason Gunthorpe [this message]
2024-01-12 0:06 ` [RFCv2 PATCH 3/7] iommu/amd: Update PASID, GATS, and GLX feature related macros Suravee Suthikulpanit
2024-03-08 13:55 ` Jason Gunthorpe
2024-01-12 0:06 ` [RFCv2 PATCH 4/7] iommu/amd: Add support for hw_info for iommu capability query Suravee Suthikulpanit
2024-03-08 13:57 ` Jason Gunthorpe
2024-01-12 0:06 ` [RFCv2 PATCH 5/7] iommufd: Introduce data struct for AMD nested domain allocation Suravee Suthikulpanit
2024-01-22 8:46 ` Tian, Kevin
2024-03-08 13:58 ` Jason Gunthorpe
2024-01-12 0:06 ` [RFCv2 PATCH 6/7] iommu/amd: Add nested domain allocation support Suravee Suthikulpanit
2024-01-22 8:52 ` Tian, Kevin
2024-03-08 14:04 ` Jason Gunthorpe
2024-01-12 0:06 ` [RFCv2 PATCH 7/7] iommu/amd: Add nested domain attach/detach support Suravee Suthikulpanit
2024-01-22 8:56 ` Tian, Kevin
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