linux-kernel - Re: [PATCH 1/2] agp/intel: Use per device iommu check

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Date:   Tue, 8 Mar 2022 14:42:24 +0800
From:   Lu Baolu <baolu.lu@...ux.intel.com>
To:     David Airlie <airlied@...ux.ie>, Joerg Roedel <joro@...tes.org>,
        Will Deacon <will@...nel.org>,
        Chris Wilson <chris@...is-wilson.co.uk>,
        Nathan Myers <ncm@...trip.org>
Cc:     baolu.lu@...ux.intel.com,
        Tvrtko Ursulin <tvrtko.ursulin@...el.com>,
        Lucas De Marchi <lucas.demarchi@...el.com>,
        Robin Murphy <robin.murphy@....com>,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] agp/intel: Use per device iommu check

On 2022/2/11 11:05, Lu Baolu wrote:
> The IOMMU subsystem has already provided an interface to query whether
> the IOMMU hardware is enabled for a specific device. This changes the
> check from Intel specific intel_iommu_gfx_mapped (globally exported by
> the Intel IOMMU driver) to probing the presence of IOMMU on a specific
> device using the generic device_iommu_mapped().
> 
> This follows commit cca084692394a ("drm/i915: Use per device iommu check")
> which converted drm/i915 driver to use device_iommu_mapped().
> 
> Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
> ---
>   drivers/char/agp/intel-gtt.c | 17 +++++++----------
>   1 file changed, 7 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/char/agp/intel-gtt.c b/drivers/char/agp/intel-gtt.c
> index c53cc9868cd8..9631cbc7002e 100644
> --- a/drivers/char/agp/intel-gtt.c
> +++ b/drivers/char/agp/intel-gtt.c
> @@ -20,7 +20,7 @@
>   #include <linux/kernel.h>
>   #include <linux/pagemap.h>
>   #include <linux/agp_backend.h>
> -#include <linux/intel-iommu.h>
> +#include <linux/iommu.h>
>   #include <linux/delay.h>
>   #include <asm/smp.h>
>   #include "agp.h"
> @@ -573,18 +573,15 @@ static void intel_gtt_cleanup(void)
>    */
>   static inline int needs_ilk_vtd_wa(void)
>   {
> -#ifdef CONFIG_INTEL_IOMMU
>   	const unsigned short gpu_devid = intel_private.pcidev->device;
>   
> -	/* Query intel_iommu to see if we need the workaround. Presumably that
> -	 * was loaded first.
> +	/*
> +	 * Query iommu subsystem to see if we need the workaround. Presumably
> +	 * that was loaded first.
>   	 */
> -	if ((gpu_devid == PCI_DEVICE_ID_INTEL_IRONLAKE_D_IG ||
> -	     gpu_devid == PCI_DEVICE_ID_INTEL_IRONLAKE_M_IG) &&
> -	     intel_iommu_gfx_mapped)
> -		return 1;
> -#endif
> -	return 0;
> +	return ((gpu_devid == PCI_DEVICE_ID_INTEL_IRONLAKE_D_IG ||
> +		 gpu_devid == PCI_DEVICE_ID_INTEL_IRONLAKE_M_IG) &&
> +		device_iommu_mapped(&intel_private.pcidev->dev));
>   }
>   
>   static bool intel_gtt_can_wc(void)

A gentle ping ...:-)

Best regards,
baolu