From: Andre Przywara <andre.przywara@arm.com>
To: Julien Grall <julien.grall@arm.com>,
Stefano Stabellini <sstabellini@kernel.org>
Cc: xen-devel@lists.xenproject.org,
Vijaya Kumar K <Vijaya.Kumar@caviumnetworks.com>,
Vijay Kilari <vijay.kilari@gmail.com>,
Shanker Donthineni <shankerd@codeaurora.org>
Subject: [PATCH v10 01/32] ARM: vGIC: avoid rank lock when reading priority
Date: Fri, 26 May 2017 18:35:09 +0100 [thread overview]
Message-ID: <20170526173540.10066-2-andre.przywara@arm.com> (raw)
In-Reply-To: <20170526173540.10066-1-andre.przywara@arm.com>
When reading the priority value of a virtual interrupt, we were taking
the respective rank lock so far.
However for forwarded interrupts (Dom0 only so far) this may lead to a
deadlock with the following call chain:
- MMIO access to change the IRQ affinity, calling the ITARGETSR handler
- this handler takes the appropriate rank lock and calls vgic_store_itargetsr()
- vgic_store_itargetsr() will eventually call vgic_migrate_irq()
- if this IRQ is already in-flight, it will remove it from the old
VCPU and inject it into the new one, by calling vgic_vcpu_inject_irq()
- vgic_vcpu_inject_irq will call vgic_get_virq_priority()
- vgic_get_virq_priority() tries to take the rank lock - again!
It seems like this code path has never been exercised before.
Fix this by avoiding taking the lock in vgic_get_virq_priority() (like we
do in vgic_get_target_vcpu()).
Actually we are just reading one byte, and priority changes while
interrupts are handled are a benign race that can happen on real hardware
too. So it looks safe to just use read_atomic() instead.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
---
xen/arch/arm/vgic.c | 8 +-------
1 file changed, 1 insertion(+), 7 deletions(-)
diff --git a/xen/arch/arm/vgic.c b/xen/arch/arm/vgic.c
index 83569b0..54b2aad 100644
--- a/xen/arch/arm/vgic.c
+++ b/xen/arch/arm/vgic.c
@@ -227,14 +227,8 @@ struct vcpu *vgic_get_target_vcpu(struct vcpu *v, unsigned int virq)
static int vgic_get_virq_priority(struct vcpu *v, unsigned int virq)
{
struct vgic_irq_rank *rank = vgic_rank_irq(v, virq);
- unsigned long flags;
- int priority;
-
- vgic_lock_rank(v, rank, flags);
- priority = rank->priority[virq & INTERRUPT_RANK_MASK];
- vgic_unlock_rank(v, rank, flags);
- return priority;
+ return read_atomic(&rank->priority[virq & INTERRUPT_RANK_MASK]);
}
bool vgic_migrate_irq(struct vcpu *old, struct vcpu *new, unsigned int irq)
--
2.9.0
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next prev parent reply other threads:[~2017-05-26 17:35 UTC|newest]
Thread overview: 96+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-26 17:35 [PATCH v10 00/32] arm64: Dom0 ITS emulation Andre Przywara
2017-05-26 17:35 ` Andre Przywara [this message]
2017-05-30 10:47 ` [PATCH v10 01/32] ARM: vGIC: avoid rank lock when reading priority Julien Grall
2017-05-30 21:39 ` Stefano Stabellini
2017-05-31 10:42 ` Julien Grall
2017-06-02 17:44 ` Julien Grall
2017-06-06 17:06 ` Andre Przywara
2017-06-06 17:11 ` Julien Grall
2017-06-06 17:20 ` Andre Przywara
2017-06-06 17:21 ` Julien Grall
2017-06-06 18:39 ` Stefano Stabellini
2017-05-26 17:35 ` [PATCH v10 02/32] ARM: GICv3: setup number of LPI bits for a GICv3 guest Andre Przywara
2017-05-30 10:54 ` Julien Grall
2017-06-06 10:19 ` Andre Przywara
2017-05-26 17:35 ` [PATCH v10 03/32] ARM: vGIC: move irq_to_pending() calls under the VGIC VCPU lock Andre Przywara
2017-05-30 11:08 ` Julien Grall
2017-05-30 21:46 ` Stefano Stabellini
2017-05-31 10:44 ` Julien Grall
2017-06-06 17:24 ` Andre Przywara
2017-06-06 18:46 ` Stefano Stabellini
2017-06-07 10:49 ` Andre Przywara
2017-05-26 17:35 ` [PATCH v10 04/32] ARM: vGIC: rework gic_remove_from_queues() Andre Przywara
2017-05-30 11:15 ` Julien Grall
2017-05-26 17:35 ` [PATCH v10 05/32] ARM: vGIC: introduce gic_remove_irq() Andre Przywara
2017-05-30 11:31 ` Julien Grall
2017-06-06 10:19 ` Andre Przywara
2017-05-26 17:35 ` [PATCH v10 06/32] ARM: GIC: Add checks for NULL pointer pending_irq's Andre Przywara
2017-05-30 11:38 ` Julien Grall
2017-06-06 10:19 ` Andre Przywara
2017-06-07 11:19 ` Julien Grall
2017-05-26 17:35 ` [PATCH v10 07/32] ARM: GICv3: introduce separate pending_irq structs for LPIs Andre Przywara
2017-05-26 17:35 ` [PATCH v10 08/32] ARM: GIC: export and extend vgic_init_pending_irq() Andre Przywara
2017-05-26 17:35 ` [PATCH v10 09/32] ARM: vGIC: cache virtual LPI priority in struct pending_irq Andre Przywara
2017-05-26 17:35 ` [PATCH v10 10/32] ARM: vGIC: add LPI VCPU ID to " Andre Przywara
2017-05-26 17:35 ` [PATCH v10 11/32] ARM: GICv3: forward pending LPIs to guests Andre Przywara
2017-05-30 11:56 ` Julien Grall
2017-05-30 22:07 ` Stefano Stabellini
2017-05-31 11:09 ` Julien Grall
2017-05-31 17:56 ` Stefano Stabellini
2017-05-31 18:39 ` Julien Grall
2017-05-26 17:35 ` [PATCH v10 12/32] ARM: GICv3: enable ITS and LPIs on the host Andre Przywara
2017-05-30 11:58 ` Julien Grall
2017-05-26 17:35 ` [PATCH v10 13/32] ARM: vGICv3: handle virtual LPI pending and property tables Andre Przywara
2017-05-26 17:35 ` [PATCH v10 14/32] ARM: introduce vgic_access_guest_memory() Andre Przywara
2017-05-26 17:35 ` [PATCH v10 15/32] ARM: vGICv3: re-use vgic_reg64_check_access Andre Przywara
2017-05-26 17:35 ` [PATCH v10 16/32] ARM: vGIC: advertise LPI support Andre Przywara
2017-05-30 12:59 ` Julien Grall
2017-05-26 17:35 ` [PATCH v10 17/32] ARM: vITS: add command handling stub and MMIO emulation Andre Przywara
2017-06-01 18:13 ` Julien Grall
2017-06-08 9:57 ` Julien Grall
2017-05-26 17:35 ` [PATCH v10 18/32] ARM: vITS: introduce translation table walks Andre Przywara
2017-06-02 16:25 ` Julien Grall
2017-06-08 9:35 ` Julien Grall
2017-06-08 9:45 ` Andre Przywara
2017-05-26 17:35 ` [PATCH v10 19/32] ARM: vITS: provide access to struct pending_irq Andre Przywara
2017-06-02 16:32 ` Julien Grall
2017-06-02 16:45 ` Julien Grall
2017-06-06 10:19 ` Andre Przywara
2017-06-06 11:13 ` Julien Grall
2017-05-26 17:35 ` [PATCH v10 20/32] ARM: vITS: handle INT command Andre Przywara
2017-06-02 16:37 ` Julien Grall
2017-05-26 17:35 ` [PATCH v10 21/32] ARM: vITS: handle MAPC command Andre Przywara
2017-05-26 17:35 ` [PATCH v10 22/32] ARM: vITS: handle CLEAR command Andre Przywara
2017-06-02 16:40 ` Julien Grall
2017-05-26 17:35 ` [PATCH v10 23/32] ARM: vITS: handle MAPD command Andre Przywara
2017-06-02 16:46 ` Julien Grall
2017-05-26 17:35 ` [PATCH v10 24/32] ARM: GICv3: handle unmapped LPIs Andre Przywara
2017-06-02 16:55 ` Julien Grall
2017-06-02 20:45 ` Stefano Stabellini
2017-06-08 9:45 ` Julien Grall
2017-06-08 13:51 ` Andre Przywara
2017-05-26 17:35 ` [PATCH v10 25/32] ARM: vITS: handle MAPTI/MAPI command Andre Przywara
2017-06-02 17:12 ` Julien Grall
2017-06-07 17:49 ` Andre Przywara
2017-06-12 16:33 ` Julien Grall
2017-06-09 11:17 ` Andre Przywara
2017-06-09 19:14 ` Stefano Stabellini
2017-06-12 16:10 ` Andre Przywara
2017-05-26 17:35 ` [PATCH v10 26/32] ARM: vITS: handle MOVI command Andre Przywara
2017-05-30 22:35 ` Stefano Stabellini
2017-05-31 11:23 ` Julien Grall
2017-05-31 17:53 ` Stefano Stabellini
2017-05-31 18:49 ` Julien Grall
2017-06-02 17:17 ` Julien Grall
2017-06-02 20:36 ` Stefano Stabellini
2017-05-26 17:35 ` [PATCH v10 27/32] ARM: vITS: handle DISCARD command Andre Przywara
2017-06-02 17:21 ` Julien Grall
2017-05-26 17:35 ` [PATCH v10 28/32] ARM: vITS: handle INV command Andre Przywara
2017-05-30 22:23 ` Stefano Stabellini
2017-05-26 17:35 ` [PATCH v10 29/32] ARM: vITS: handle INVALL command Andre Przywara
2017-06-02 17:27 ` Julien Grall
2017-05-26 17:35 ` [PATCH v10 30/32] ARM: vITS: increase mmio_count for each ITS Andre Przywara
2017-05-26 17:35 ` [PATCH v10 31/32] ARM: vITS: create and initialize virtual ITSes for Dom0 Andre Przywara
2017-06-02 17:31 ` Julien Grall
2017-05-26 17:35 ` [PATCH v10 32/32] ARM: vITS: create ITS subnodes for Dom0 DT Andre Przywara
2017-06-02 17:33 ` Julien Grall
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