iommu, x86: Properly handle posted interrupts for IOMMU hotplug

Return error when inserting a new IOMMU which doesn't support posted
interrupts if posted interrupts are already enabled.

Signed-off-by: Feng Wu <feng.wu@intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Joerg Roedel <joro@8bytes.org>
Cc: jiang.liu@linux.intel.com
Cc: iommu@lists.linux-foundation.org
Cc: dwmw2@infradead.org
Link: http://lkml.kernel.org/r/1433827237-3382-11-git-send-email-feng.wu@intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/drivers/iommu/intel_irq_remapping.c b/drivers/iommu/intel_irq_remapping.c
index 0f57af72d8f84fc2645b8ff0921aa7988337e19c..80f1d1486247f97959d0a8bc58dda6f54d8fb202 100644 (file)
--- a/drivers/iommu/intel_irq_remapping.c
+++ b/drivers/iommu/intel_irq_remapping.c
@@ -1355,6 +1355,9 @@ int dmar_ir_hotplug(struct dmar_drhd_unit *dmaru, bool insert)
                return -EINVAL;
        if (!ecap_ir_support(iommu->ecap))
                return 0;
+       if (irq_remapping_cap(IRQ_POSTING_CAP) &&
+           !cap_pi_support(iommu->cap))
+               return -EBUSY;
 
        if (insert) {
                if (!iommu->ir_table)