Re: [Xen-devel] [PATCH v7 1/2] VT-d: Reduce spin timeout to 1ms, which can be boot-time changed

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

> From: Xu, Quan
> Sent: Thursday, March 17, 2016 3:13 PM
> diff --git a/xen/drivers/passthrough/vtd/qinval.c 
> b/xen/drivers/passthrough/vtd/qinval.c
> index b81b0bd..37a15fb 100644
> --- a/xen/drivers/passthrough/vtd/qinval.c
> +++ b/xen/drivers/passthrough/vtd/qinval.c
> @@ -28,6 +28,11 @@
>  #include "vtd.h"
>  #include "extern.h"
> 
> +static unsigned int __read_mostly vtd_qi_timeout = 1;
> +integer_param("vtd_qi_timeout", vtd_qi_timeout);
> +
> +#define IOMMU_QI_TIMEOUT (vtd_qi_timeout * MILLISECS(1))
> +
>  static void print_qi_regs(struct iommu *iommu)
>  {
>      u64 val;
> @@ -130,10 +135,14 @@ static void queue_invalidate_iotlb(struct iommu *iommu,
>      spin_unlock_irqrestore(&iommu->register_lock, flags);
>  }
> 
> +/*
> + * NB. We must check all kinds of error and all the way up the
> + * call trees.
> + */

This comment is meaningless put in the code. It just reflects what
you need do to push the whole patch series, but it's obvious
a straightforward requirement.

>  static int queue_invalidate_wait(struct iommu *iommu,
>      u8 iflag, u8 sw, u8 fn)
>  {

Thanks
Kevin

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