linux-kernel - Re: [PATCH v4 17/22] iommu/vt-d: Avoid duplicated code for PASID setup

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Message-ID: <20190618170335.000078db@huawei.com>
Date:   Tue, 18 Jun 2019 17:03:35 +0100
From:   Jonathan Cameron <jonathan.cameron@...wei.com>
To:     Jacob Pan <jacob.jun.pan@...ux.intel.com>
CC:     <iommu@...ts.linux-foundation.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Joerg Roedel <joro@...tes.org>,
        David Woodhouse <dwmw2@...radead.org>,
        "Eric Auger" <eric.auger@...hat.com>,
        Alex Williamson <alex.williamson@...hat.com>,
        Jean-Philippe Brucker <jean-philippe.brucker@....com>,
        "Tian, Kevin" <kevin.tian@...el.com>,
        Raj Ashok <ashok.raj@...el.com>,
        Andriy Shevchenko <andriy.shevchenko@...ux.intel.com>
Subject: Re: [PATCH v4 17/22] iommu/vt-d: Avoid duplicated code for PASID
 setup

On Sun, 9 Jun 2019 06:44:17 -0700
Jacob Pan <jacob.jun.pan@...ux.intel.com> wrote:

> After each setup for PASID entry, related translation caches must be flushed.
> We can combine duplicated code into one function which is less error prone.
> 
> Signed-off-by: Jacob Pan <jacob.jun.pan@...ux.intel.com>
Formatting nitpick below ;)

Otherwise it's cut and paste
> ---
>  drivers/iommu/intel-pasid.c | 48 +++++++++++++++++----------------------------
>  1 file changed, 18 insertions(+), 30 deletions(-)
> 
> diff --git a/drivers/iommu/intel-pasid.c b/drivers/iommu/intel-pasid.c
> index 1e25539..1ff2ecc 100644
> --- a/drivers/iommu/intel-pasid.c
> +++ b/drivers/iommu/intel-pasid.c
> @@ -522,6 +522,21 @@ void intel_pasid_tear_down_entry(struct intel_iommu *iommu,
>  		devtlb_invalidation_with_pasid(iommu, dev, pasid);
>  }
>  
> +static inline void pasid_flush_caches(struct intel_iommu *iommu,
> +				struct pasid_entry *pte,
> +				int pasid, u16 did)
> +{
> +	if (!ecap_coherent(iommu->ecap))
> +		clflush_cache_range(pte, sizeof(*pte));
> +
> +	if (cap_caching_mode(iommu->cap)) {
> +		pasid_cache_invalidation_with_pasid(iommu, did, pasid);
> +		iotlb_invalidation_with_pasid(iommu, did, pasid);
> +	} else
> +		iommu_flush_write_buffer(iommu);

I have some vague recollection kernel style says use brackets around
single lines if other blocks in an if / else stack have multiple lines..

I checked, this case is specifically called out

https://www.kernel.org/doc/html/v5.1/process/coding-style.html
> +
This blank line doesn't add anything either ;)
> +}
> +
>  /*
>   * Set up the scalable mode pasid table entry for first only
>   * translation type.
> @@ -567,16 +582,7 @@ int intel_pasid_setup_first_level(struct intel_iommu *iommu,
>  	/* Setup Present and PASID Granular Transfer Type: */
>  	pasid_set_translation_type(pte, 1);
>  	pasid_set_present(pte);
> -
> -	if (!ecap_coherent(iommu->ecap))
> -		clflush_cache_range(pte, sizeof(*pte));
> -
> -	if (cap_caching_mode(iommu->cap)) {
> -		pasid_cache_invalidation_with_pasid(iommu, did, pasid);
> -		iotlb_invalidation_with_pasid(iommu, did, pasid);
> -	} else {
> -		iommu_flush_write_buffer(iommu);
> -	}
> +	pasid_flush_caches(iommu, pte, pasid, did);
>  
>  	return 0;
>  }
> @@ -640,16 +646,7 @@ int intel_pasid_setup_second_level(struct intel_iommu *iommu,
>  	 */
>  	pasid_set_sre(pte);
>  	pasid_set_present(pte);
> -
> -	if (!ecap_coherent(iommu->ecap))
> -		clflush_cache_range(pte, sizeof(*pte));
> -
> -	if (cap_caching_mode(iommu->cap)) {
> -		pasid_cache_invalidation_with_pasid(iommu, did, pasid);
> -		iotlb_invalidation_with_pasid(iommu, did, pasid);
> -	} else {
> -		iommu_flush_write_buffer(iommu);
> -	}
> +	pasid_flush_caches(iommu, pte, pasid, did);
>  
>  	return 0;
>  }
> @@ -683,16 +680,7 @@ int intel_pasid_setup_pass_through(struct intel_iommu *iommu,
>  	 */
>  	pasid_set_sre(pte);
>  	pasid_set_present(pte);
> -
> -	if (!ecap_coherent(iommu->ecap))
> -		clflush_cache_range(pte, sizeof(*pte));
> -
> -	if (cap_caching_mode(iommu->cap)) {
> -		pasid_cache_invalidation_with_pasid(iommu, did, pasid);
> -		iotlb_invalidation_with_pasid(iommu, did, pasid);
> -	} else {
> -		iommu_flush_write_buffer(iommu);
> -	}
> +	pasid_flush_caches(iommu, pte, pasid, did);
>  
>  	return 0;
>  }