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X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 07 Jan 2025 13:36:48.4052 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: c64f3cce-e0cc-40b9-9e75-08dd2f205605 X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[SATLEXMB04.amd.com] X-MS-Exchange-CrossTenant-AuthSource: DS2PEPF00003443.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ0PR12MB6808 On 1/7/2025 5:45 PM, Vasant Hegde wrote: Hi vasant, > > On 1/7/2025 12:44 AM, Alejandro Jimenez wrote: >> When updating the page table root field on the DTE, avoid overwriting any >> bits that are already set. The earlier call to make_clear_dte() writes >> default values that all DTEs must have set (currently DTE[V]), and those >> must be preserved. >> >> Currently this doesn't cause problems since the page table root update is >> the first field that is set after make_clear_dte() is called, and >> DTE_FLAG_V is set again later along with the permission bits (IR/IW). >> Remove this redundant assignment too. > > Good catch! > >>> Fixes: fd5dff9de4be ("iommu/amd: Modify set_dte_entry() to use 256-bit DTE > helpers") >> Signed-off-by: Alejandro Jimenez >> --- >> drivers/iommu/amd/iommu.c | 4 ++-- >> 1 file changed, 2 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c >> index 20177e18eb0d..a8c17b602c95 100644 >> --- a/drivers/iommu/amd/iommu.c >> +++ b/drivers/iommu/amd/iommu.c >> @@ -2052,12 +2052,12 @@ static void set_dte_entry(struct amd_iommu *iommu, >> make_clear_dte(dev_data, dte, &new); > > This fix is fine. But with all changes we have done in this code does, do we > really need make_clear_dte()? > > How about removing `make_clear_dte()` and moving DTE_FLAG_V to > write_dte_lower128() ? > I dont think moving DTE_FLAG_V to write_dte_lower128() is a good idea, because the order in which the function update_dte256() assigns upper and lower 128 bits depends on this flag. Regards Sairaj Kodilkar > -Vasant > > >