linux-kernel - Re: [RFT][PATCH v2 4/9] vfio: Pass in starting IOVA to vfio_pin/unpin

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Message-ID: <20220706174923.GL693670@nvidia.com>
Date:   Wed, 6 Jul 2022 14:49:23 -0300
From:   Jason Gunthorpe <jgg@...dia.com>
To:     Nicolin Chen <nicolinc@...dia.com>
Cc:     kwankhede@...dia.com, corbet@....net, hca@...ux.ibm.com,
        gor@...ux.ibm.com, agordeev@...ux.ibm.com,
        borntraeger@...ux.ibm.com, svens@...ux.ibm.com,
        zhenyuw@...ux.intel.com, zhi.a.wang@...el.com,
        jani.nikula@...ux.intel.com, joonas.lahtinen@...ux.intel.com,
        rodrigo.vivi@...el.com, tvrtko.ursulin@...ux.intel.com,
        airlied@...ux.ie, daniel@...ll.ch, farman@...ux.ibm.com,
        mjrosato@...ux.ibm.com, pasic@...ux.ibm.com, vneethv@...ux.ibm.com,
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        kevin.tian@...el.com, hch@...radead.org, jchrist@...ux.ibm.com,
        kvm@...r.kernel.org, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-s390@...r.kernel.org,
        intel-gvt-dev@...ts.freedesktop.org,
        intel-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org
Subject: Re: [RFT][PATCH v2 4/9] vfio: Pass in starting IOVA to
 vfio_pin/unpin_pages API

On Tue, Jul 05, 2022 at 11:27:54PM -0700, Nicolin Chen wrote:

>  These functions call back into the back-end IOMMU module by using the pin_pages
> diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c
> index 8c67c9aba82d..ea6041fa48ac 100644
> --- a/drivers/gpu/drm/i915/gvt/kvmgt.c
> +++ b/drivers/gpu/drm/i915/gvt/kvmgt.c
> @@ -231,16 +231,8 @@ static void intel_gvt_cleanup_vgpu_type_groups(struct intel_gvt *gvt)
>  static void gvt_unpin_guest_page(struct intel_vgpu *vgpu, unsigned long gfn,
>  		unsigned long size)
>  {
> -	int total_pages;
> -	int npage;
> -
> -	total_pages = roundup(size, PAGE_SIZE) / PAGE_SIZE;
> -
> -	for (npage = 0; npage < total_pages; npage++) {
> -		unsigned long cur_gfn = gfn + npage;
> -
> -		vfio_unpin_pages(&vgpu->vfio_device, &cur_gfn, 1);
> -	}
> +	vfio_unpin_pages(&vgpu->vfio_device, gfn << PAGE_SHIFT,
> +			 roundup(size, PAGE_SIZE) / PAGE_SIZE);

These maths are DIV_ROUND_UP()

Otherwise,

Reviewed-by: Jason Gunthorpe <jgg@...dia.com>

Jason