On Thu, Oct 15, 2015 at 10:19:11AM +0800, Feng Wu wrote:
> 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...@intel.com>
> ---
> drivers/iommu/intel_irq_remapping.c | 33 ++++++++++++++++++++++++++++++---
> 1 file changed, 30 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/iommu/intel_irq_remapping.c
> b/drivers/iommu/intel_irq_remapping.c
> index f15692a..b4f7569 100644
> --- a/drivers/iommu/intel_irq_remapping.c
> +++ b/drivers/iommu/intel_irq_remapping.c
> @@ -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.
> + */
> + BUG_ON(!ret);
Changed this to a WARN_ON, otherwise applied.
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