linux-kernel - Re: [PATCH 3/5] iommu/vt-d: Do deferred attachment in iommu_need

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Date:   Mon, 17 Feb 2020 12:51:36 -0700
From:   Jerry Snitselaar <jsnitsel@...hat.com>
To:     Joerg Roedel <joro@...tes.org>
Cc:     Lu Baolu <baolu.lu@...ux.intel.com>,
        David Woodhouse <dwmw2@...radead.org>, jroedel@...e.de,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/5] iommu/vt-d: Do deferred attachment in
 iommu_need_mapping()

On Mon Feb 17 20, Joerg Roedel wrote:
>From: Joerg Roedel <jroedel@...e.de>
>
>The attachment of deferred devices needs to happen before the check
>whether the device is identity mapped or not. Otherwise the check will
>return wrong results, cause warnings boot failures in kdump kernels, like
>
>	WARNING: CPU: 0 PID: 318 at ../drivers/iommu/intel-iommu.c:592 domain_get_iommu+0x61/0x70
>
>	[...]
>
>	 Call Trace:
>	  __intel_map_single+0x55/0x190
>	  intel_alloc_coherent+0xac/0x110
>	  dmam_alloc_attrs+0x50/0xa0
>	  ahci_port_start+0xfb/0x1f0 [libahci]
>	  ata_host_start.part.39+0x104/0x1e0 [libata]
>
>With the earlier check the kdump boot succeeds and a crashdump is written.
>
>Signed-off-by: Joerg Roedel <jroedel@...e.de>

Reviewed-by: Jerry Snitselaar <jsnitsel@...hat.com>