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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: Feng Wu <feng.wu@intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
This commit is contained in:
Feng Wu 2015-10-15 10:19:11 +08:00 committed by Joerg Roedel
parent dfddb969ed
commit 344cb4e0b6
1 changed files with 30 additions and 3 deletions
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33
drivers/iommu/intel_irq_remapping.c
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@ -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];
set_64bit(&irte->low, irte_modified->low);
set_64bit(&irte->high, irte_modified->high);
#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);
@ -727,7 +745,16 @@ static inline void set_irq_posting_cap(void)
struct intel_iommu *iommu;
if (!disable_irq_post) {
intel_irq_remap_ops.capability |= 1 << IRQ_POSTING_CAP;
/*
* 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)
if (!cap_pi_support(iommu->cap)) {