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From: Joerg Roedel <joro@8bytes.org>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org,
	tglx@linutronix.de
Subject: Re: [PATCH 05/10] iommu/amd: remove the special case from get_irq_table()
Date: Thu, 15 Mar 2018 14:07:23 +0100	[thread overview]
Message-ID: <20180315130723.dunmpmbkswwvq54g@8bytes.org> (raw)
In-Reply-To: <20180315130153.3ba2loj5oplogdew@linutronix.de>

On Thu, Mar 15, 2018 at 02:01:53PM +0100, Sebastian Andrzej Siewior wrote:
> On 2018-03-15 13:53:42 [+0100], Joerg Roedel wrote:
> > On Fri, Feb 23, 2018 at 11:27:31PM +0100, Sebastian Andrzej Siewior wrote:
> > > @@ -4103,10 +4093,26 @@ static int irq_remapping_alloc(struct irq_domain *domain, unsigned int virq,
> > >  		return ret;
> > >  
> > >  	if (info->type == X86_IRQ_ALLOC_TYPE_IOAPIC) {
> > > -		if (get_irq_table(devid, true))
> > > +		struct irq_remap_table *table;
> > > +		struct amd_iommu *iommu;
> > > +
> > > +		table = get_irq_table(devid);
> > > +		if (table) {
> > > +			if (!table->min_index) {
> > > +				/*
> > > +				 * Keep the first 32 indexes free for IOAPIC
> > > +				 * interrupts.
> > > +				 */
> > > +				table->min_index = 32;
> > > +				iommu = amd_iommu_rlookup_table[devid];
> > > +				for (i = 0; i < 32; ++i)
> > > +					iommu->irte_ops->set_allocated(table, i);
> > > +			}
> > 
> > I think this needs to be protected by the table->lock.
> 
> Which part any why? The !->min_index part plus extending(setting to 32)?

In particular the set_allocated part, when get_irq_table() returns the
table is visible to other users as well. I have not checked the
irq-layer locking to be sure that can happen, though.

WARNING: multiple messages have this Message-ID (diff)
From: Joerg Roedel <joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
To: Sebastian Andrzej Siewior
	<bigeasy-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>
Cc: iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org,
	tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org,
	linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [PATCH 05/10] iommu/amd: remove the special case from get_irq_table()
Date: Thu, 15 Mar 2018 14:07:23 +0100	[thread overview]
Message-ID: <20180315130723.dunmpmbkswwvq54g@8bytes.org> (raw)
In-Reply-To: <20180315130153.3ba2loj5oplogdew-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>

On Thu, Mar 15, 2018 at 02:01:53PM +0100, Sebastian Andrzej Siewior wrote:
> On 2018-03-15 13:53:42 [+0100], Joerg Roedel wrote:
> > On Fri, Feb 23, 2018 at 11:27:31PM +0100, Sebastian Andrzej Siewior wrote:
> > > @@ -4103,10 +4093,26 @@ static int irq_remapping_alloc(struct irq_domain *domain, unsigned int virq,
> > >  		return ret;
> > >  
> > >  	if (info->type == X86_IRQ_ALLOC_TYPE_IOAPIC) {
> > > -		if (get_irq_table(devid, true))
> > > +		struct irq_remap_table *table;
> > > +		struct amd_iommu *iommu;
> > > +
> > > +		table = get_irq_table(devid);
> > > +		if (table) {
> > > +			if (!table->min_index) {
> > > +				/*
> > > +				 * Keep the first 32 indexes free for IOAPIC
> > > +				 * interrupts.
> > > +				 */
> > > +				table->min_index = 32;
> > > +				iommu = amd_iommu_rlookup_table[devid];
> > > +				for (i = 0; i < 32; ++i)
> > > +					iommu->irte_ops->set_allocated(table, i);
> > > +			}
> > 
> > I think this needs to be protected by the table->lock.
> 
> Which part any why? The !->min_index part plus extending(setting to 32)?

In particular the set_allocated part, when get_irq_table() returns the
table is visible to other users as well. I have not checked the
irq-layer locking to be sure that can happen, though.

  reply	other threads:[~2018-03-15 13:07 UTC|newest]

Thread overview: 39+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-02-23 22:27 iommu/amd: lock splitting & GFP_KERNEL allocation Sebastian Andrzej Siewior
2018-02-23 22:27 ` Sebastian Andrzej Siewior
2018-02-23 22:27 ` [PATCH 01/10] iommu/amd: take into account that alloc_dev_data() may return NULL Sebastian Andrzej Siewior
2018-02-23 22:27   ` Sebastian Andrzej Siewior
2018-02-23 22:27 ` [PATCH 02/10] iommu/amd: turn dev_data_list into a lock less list Sebastian Andrzej Siewior
2018-02-23 22:27   ` Sebastian Andrzej Siewior
2018-02-23 22:27 ` [PATCH 03/10] iommu/amd: split domain id out of amd_iommu_devtable_lock Sebastian Andrzej Siewior
2018-02-23 22:27   ` Sebastian Andrzej Siewior
2018-02-23 22:27 ` [PATCH 04/10] iommu/amd: split irq_lookup_table out of the amd_iommu_devtable_lock Sebastian Andrzej Siewior
2018-02-23 22:27   ` Sebastian Andrzej Siewior
2018-03-15 12:54   ` Joerg Roedel
2018-03-15 12:54     ` Joerg Roedel
2018-02-23 22:27 ` [PATCH 05/10] iommu/amd: remove the special case from get_irq_table() Sebastian Andrzej Siewior
2018-02-23 22:27   ` Sebastian Andrzej Siewior
2018-03-15 12:53   ` Joerg Roedel
2018-03-15 13:01     ` Sebastian Andrzej Siewior
2018-03-15 13:01       ` Sebastian Andrzej Siewior
2018-03-15 13:07       ` Joerg Roedel [this message]
2018-03-15 13:07         ` Joerg Roedel
2018-03-15 14:15         ` Sebastian Andrzej Siewior
2018-03-15 14:15           ` Sebastian Andrzej Siewior
2018-03-15 15:19           ` Joerg Roedel
2018-03-15 15:19             ` Joerg Roedel
2018-03-15 15:25             ` Sebastian Andrzej Siewior
2018-03-15 15:25               ` Sebastian Andrzej Siewior
2018-02-23 22:27 ` [PATCH 06/10] iommu/amd: use `table' instead `irt' as variable name in amd_iommu_update_ga() Sebastian Andrzej Siewior
2018-02-23 22:27   ` Sebastian Andrzej Siewior
2018-02-23 22:27 ` [PATCH 07/10] iommu/amd: factor out setting the remap table for a devid Sebastian Andrzej Siewior
2018-02-23 22:27   ` Sebastian Andrzej Siewior
2018-02-23 22:27 ` [PATCH 08/10] iommu/amd: drop the lock while allocating new irq remap table Sebastian Andrzej Siewior
2018-02-23 22:27   ` Sebastian Andrzej Siewior
2018-03-15 12:58   ` Joerg Roedel
2018-03-15 12:58     ` Joerg Roedel
2018-02-23 22:27 ` [PATCH 09/10] iommu/amd: declare irq_remap_table's and amd_iommu's lock as a raw_spin_lock Sebastian Andrzej Siewior
2018-02-23 22:27   ` Sebastian Andrzej Siewior
2018-02-23 22:27 ` [PATCH 10/10] iommu/amd: make amd_iommu_devtable_lock a spin_lock Sebastian Andrzej Siewior
2018-02-23 22:27   ` Sebastian Andrzej Siewior
2018-03-15 13:01 ` iommu/amd: lock splitting & GFP_KERNEL allocation Joerg Roedel
2018-03-15 13:01   ` Joerg Roedel

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