linux-kernel - Re: [PATCH 05/10] iommu/amd: remove the special case from get_irq

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20180315151917.pgheszruqnnjbqb4@8bytes.org>
Date:   Thu, 15 Mar 2018 16:19:17 +0100
From:   Joerg Roedel <joro@...tes.org>
To:     Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc:     iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        tglx@...utronix.de
Subject: Re: [PATCH 05/10] iommu/amd: remove the special case from
 get_irq_table()

On Thu, Mar 15, 2018 at 03:15:41PM +0100, Sebastian Andrzej Siewior wrote:
> ->set_allocated() operates only on 0…31 and other could be used at the
> same time. However 0…31 should be accessed by other user before they are
> ready.
> 
> irq_remapping_alloc() is that ->alloc() callback invoked via
> irq_domain_alloc_irqs_hierarchy() and each caller has to hold the
> &irq_domain_mutex mutex. So we should not have those in parallel.
> 
> Is it possible to have those entries accessed before the setup is
> complete? My understanding is that this setup is performed once during
> boot (especially that ioapic part) and not again.
> 
> From looking at that hunk, it should not hurt to add that lock, just
> wanted to check it is really needed.

Okay, if the irq-layer does the needed locking, then we don't need
another lock here. There is the modify_irte_ga() path for the
virtualized irq routing into KVM guests, but there should be no KVM
guests running when setup the ioapic routing entries.



	Joerg