From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755260AbeCVPXz (ORCPT ); Thu, 22 Mar 2018 11:23:55 -0400 Received: from Galois.linutronix.de ([146.0.238.70]:39552 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754727AbeCVPWy (ORCPT ); Thu, 22 Mar 2018 11:22:54 -0400 From: Sebastian Andrzej Siewior To: Joerg Roedel Cc: iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, Scott Wood , Sebastian Andrzej Siewior Subject: [PATCH 08/10] iommu/amd: drop the lock while allocating new irq remap table Date: Thu, 22 Mar 2018 16:22:40 +0100 Message-Id: <20180322152242.12705-9-bigeasy@linutronix.de> X-Mailer: git-send-email 2.16.2 In-Reply-To: <20180322152242.12705-1-bigeasy@linutronix.de> References: <20180322152242.12705-1-bigeasy@linutronix.de> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The irq_remap_table is allocated while the iommu_table_lock is held with interrupts disabled. >>From looking at the call sites, all callers are in the early device initialisation (apic_bsp_setup(), pci_enable_device(), pci_enable_msi()) so make sense to drop the lock which also enables interrupts and try to allocate that memory with GFP_KERNEL instead GFP_ATOMIC. Since during the allocation the iommu_table_lock is dropped, we need to recheck if table exists after the lock has been reacquired. I *think* that it is impossible that the "devid" entry appears in irq_lookup_table while the lock is dropped since the same device can only be probed once. However I check for both cases, just to be sure. Signed-off-by: Sebastian Andrzej Siewior --- drivers/iommu/amd_iommu.c | 65 +++++++++++++++++++++++++++++++++----------= ---- 1 file changed, 46 insertions(+), 19 deletions(-) diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c index 11ea2d656be8..c493d345b3ef 100644 --- a/drivers/iommu/amd_iommu.c +++ b/drivers/iommu/amd_iommu.c @@ -3617,6 +3617,30 @@ static struct irq_remap_table *get_irq_table(u16 dev= id) return table; } =20 +static struct irq_remap_table *__alloc_irq_table(void) +{ + struct irq_remap_table *table; + + table =3D kzalloc(sizeof(*table), GFP_KERNEL); + if (!table) + return NULL; + + table->table =3D kmem_cache_alloc(amd_iommu_irq_cache, GFP_KERNEL); + if (!table->table) { + kfree(table); + return NULL; + } + raw_spin_lock_init(&table->lock); + + if (!AMD_IOMMU_GUEST_IR_GA(amd_iommu_guest_ir)) + memset(table->table, 0, + MAX_IRQS_PER_TABLE * sizeof(u32)); + else + memset(table->table, 0, + (MAX_IRQS_PER_TABLE * (sizeof(u64) * 2))); + return table; +} + static void set_remap_table_entry(struct amd_iommu *iommu, u16 devid, struct irq_remap_table *table) { @@ -3628,6 +3652,7 @@ static void set_remap_table_entry(struct amd_iommu *i= ommu, u16 devid, static struct irq_remap_table *alloc_irq_table(u16 devid) { struct irq_remap_table *table =3D NULL; + struct irq_remap_table *new_table =3D NULL; struct amd_iommu *iommu; unsigned long flags; u16 alias; @@ -3646,42 +3671,44 @@ static struct irq_remap_table *alloc_irq_table(u16 = devid) table =3D irq_lookup_table[alias]; if (table) { set_remap_table_entry(iommu, devid, table); - goto out; + goto out_wait; } + spin_unlock_irqrestore(&iommu_table_lock, flags); =20 /* Nothing there yet, allocate new irq remapping table */ - table =3D kzalloc(sizeof(*table), GFP_ATOMIC); - if (!table) + new_table =3D __alloc_irq_table(); + if (!new_table) + return NULL; + + spin_lock_irqsave(&iommu_table_lock, flags); + + table =3D irq_lookup_table[devid]; + if (table) goto out_unlock; =20 - /* Initialize table spin-lock */ - raw_spin_lock_init(&table->lock); - - table->table =3D kmem_cache_alloc(amd_iommu_irq_cache, GFP_ATOMIC); - if (!table->table) { - kfree(table); - table =3D NULL; - goto out_unlock; + table =3D irq_lookup_table[alias]; + if (table) { + set_remap_table_entry(iommu, devid, table); + goto out_wait; } =20 - if (!AMD_IOMMU_GUEST_IR_GA(amd_iommu_guest_ir)) - memset(table->table, 0, - MAX_IRQS_PER_TABLE * sizeof(u32)); - else - memset(table->table, 0, - (MAX_IRQS_PER_TABLE * (sizeof(u64) * 2))); - + table =3D new_table; + new_table =3D NULL; =20 set_remap_table_entry(iommu, devid, table); if (devid !=3D alias) set_remap_table_entry(iommu, alias, table); =20 -out: +out_wait: iommu_completion_wait(iommu); =20 out_unlock: spin_unlock_irqrestore(&iommu_table_lock, flags); =20 + if (new_table) { + kmem_cache_free(amd_iommu_irq_cache, new_table->table); + kfree(new_table); + } return table; } =20 --=20 2.16.2