linux-kernel - Re: [PATCH] iommu/amd: Set translation valid bit only when IO page tables are in used

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Message-ID: <015d68dc-aa38-1823-68ab-f66d78124d13@amd.com>
Date:   Fri, 29 Apr 2022 00:16:24 +0700
From:   Suravee Suthikulpanit <suravee.suthikulpanit@....com>
To:     linux-kernel@...r.kernel.org, iommu@...ts.linux-foundation.org
Cc:     joro@...tes.org, vasant.hegde@....com, jon.grimm@....com
Subject: Re: [PATCH] iommu/amd: Set translation valid bit only when IO page
 tables are in used



On 4/20/22 6:29 PM, Suravee Suthikulpanit wrote:
> On AMD system with SNP enabled, IOMMU hardware checks the host translation
> valid (TV) and guest translation valid (GV) bits in the device
> table entry (DTE) before accessing the corresponded page tables.
> 
> However, current IOMMU driver sets the TV bit for all devices
> regardless of whether the host page table is in used.
> This results in ILLEGAL_DEV_TABLE_ENTRY event for devices, which
> do not the host page table root pointer set up.
> 
> Thefore, only set TV bit when host or guest page tables are in used.
> 
> Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@....com>
>

I found a bug in this patch. I will send out v2 with the fix.

Regards,
Suravee