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Commit 344cb4e0 authored by Feng Wu's avatar Feng Wu Committed by Joerg Roedel
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iommu/vt-d: Use cmpxchg16b to update posted format IRTE atomically 



If IRTE is in posted format, the 'pda' field goes across the 64-bit
boundary, we need use cmpxchg16b to atomically update it. We only
expose posted-interrupt when X86_FEATURE_CX16 is supported and use
to update it atomically.

Signed-off-by: default avatarFeng Wu <feng.wu@intel.com>
Signed-off-by: default avatarJoerg Roedel <jroedel@suse.de>
parent dfddb969

drivers/iommu/intel_irq_remapping.c

+30 −3
Original line number Diff line number Diff line
@@ -169,8 +169,26 @@ static int modify_irte(struct irq_2_iommu *irq_iommu, 
	index = irq_iommu->irte_index + irq_iommu->sub_handle;

	irte = &iommu->ir_table->base[index];



#if defined(CONFIG_HAVE_CMPXCHG_DOUBLE)

	if ((irte->pst == 1) || (irte_modified->pst == 1)) {

		bool ret;



		ret = cmpxchg_double(&irte->low, &irte->high,

				     irte->low, irte->high,

				     irte_modified->low, irte_modified->high);

		/*

		 * We use cmpxchg16 to atomically update the 128-bit IRTE,

		 * and it cannot be updated by the hardware or other processors

		 * behind us, so the return value of cmpxchg16 should be the

		 * same as the old value.

		 */

		WARN_ON(!ret);

	} else

#endif

	{

		set_64bit(&irte->low, irte_modified->low);

		set_64bit(&irte->high, irte_modified->high);

	}

	__iommu_flush_cache(iommu, irte, sizeof(*irte));



	rc = qi_flush_iec(iommu, index, 0);
@@ -727,6 +745,15 @@ static inline void set_irq_posting_cap(void) 
	struct intel_iommu *iommu;



	if (!disable_irq_post) {

		/*

		 * If IRTE is in posted format, the 'pda' field goes across the

		 * 64-bit boundary, we need use cmpxchg16b to atomically update

		 * it. We only expose posted-interrupt when X86_FEATURE_CX16

		 * is supported. Actually, hardware platforms supporting PI

		 * should have X86_FEATURE_CX16 support, this has been confirmed

		 * with Intel hardware guys.

		 */

		if ( cpu_has_cx16 )

			intel_irq_remap_ops.capability |= 1 << IRQ_POSTING_CAP;



		for_each_iommu(iommu, drhd)