[Xen-changelog] [xen master] AMD IOMMU: fix an init time spinlock flaw

[patchbot@xxxxxxx]

commit bf55ead25c5e9a7fbd8fa47c64ec8d1557478efb
Author:     Quan Xu <quan.xu@xxxxxxxxx>
AuthorDate: Mon Mar 14 12:59:39 2016 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Mon Mar 14 12:59:39 2016 +0100

    AMD IOMMU: fix an init time spinlock flaw
    
    pcidevs_lock doesn't require interrupts to be disabled while being acquired.
    However there remains an exception in AMD IOMMU code, where the lock is
    acquired with interrupt disabled. This inconsistency might lead to deadlock.
    
    The fix is straightforward to use spin_lock instead. Also interrupt has been
    enabled when this function is invoked, so we're sure consistency around
    pcidevs_lock can be guaranteed after this fix.
    
    Signed-off-by: Quan Xu <quan.xu@xxxxxxxxx>
    Reviewed-by: Dario Faggioli <dario.faggioli@xxxxxxxxxx>
    Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
    Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
---
 xen/drivers/passthrough/amd/iommu_init.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/xen/drivers/passthrough/amd/iommu_init.c 
b/xen/drivers/passthrough/amd/iommu_init.c
index d90a2d2..a400497 100644
--- a/xen/drivers/passthrough/amd/iommu_init.c
+++ b/xen/drivers/passthrough/amd/iommu_init.c
@@ -778,7 +778,6 @@ static bool_t __init set_iommu_interrupt_handler(struct 
amd_iommu *iommu)
 {
     int irq, ret;
     hw_irq_controller *handler;
-    unsigned long flags;
     u16 control;
 
     irq = create_irq(NUMA_NO_NODE);
@@ -788,10 +787,10 @@ static bool_t __init set_iommu_interrupt_handler(struct 
amd_iommu *iommu)
         return 0;
     }
 
-    spin_lock_irqsave(&pcidevs_lock, flags);
+    spin_lock(&pcidevs_lock);
     iommu->msi.dev = pci_get_pdev(iommu->seg, PCI_BUS(iommu->bdf),
                                   PCI_DEVFN2(iommu->bdf));
-    spin_unlock_irqrestore(&pcidevs_lock, flags);
+    spin_unlock(&pcidevs_lock);
     if ( !iommu->msi.dev )
     {
         AMD_IOMMU_DEBUG("IOMMU: no pdev for %04x:%02x:%02x.%u\n",
--
generated by git-patchbot for /home/xen/git/xen.git#master

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