linux-kernel - Re: [PATCH next] iommu: intel: don't dereference iommu_device if IOMMU

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Date:   Wed, 14 Oct 2020 08:42:57 +0800
From:   Lu Baolu <baolu.lu@...ux.intel.com>
To:     Bartosz Golaszewski <brgl@...ev.pl>,
        David Woodhouse <dwmw2@...radead.org>,
        Joerg Roedel <joro@...tes.org>
Cc:     baolu.lu@...ux.intel.com, iommu@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org,
        Bartosz Golaszewski <bgolaszewski@...libre.com>
Subject: Re: [PATCH next] iommu: intel: don't dereference iommu_device if
 IOMMU_API is not built

On 10/13/20 3:30 PM, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bgolaszewski@...libre.com>
> 
> Since commit c40aaaac1018 ("iommu/vt-d: Gracefully handle DMAR units
> with no supported address widths") dmar.c needs struct iommu_device to
> be selected. We can drop this dependency by not dereferencing struct
> iommu_device if IOMMU_API is not selected and by reusing the information
> stored in iommu->drhd->ignored instead.
> 
> This fixes the following build error when IOMMU_API is not selected:
> 
> drivers/iommu/intel/dmar.c: In function ‘free_iommu’:
> drivers/iommu/intel/dmar.c:1139:41: error: ‘struct iommu_device’ has no member named ‘ops’
>   1139 |  if (intel_iommu_enabled && iommu->iommu.ops) {
>                                                  ^
> 
> Fixes: c40aaaac1018 ("iommu/vt-d: Gracefully handle DMAR units with no supported address widths")
> Signed-off-by: Bartosz Golaszewski <bgolaszewski@...libre.com>

With commit title adjusted to "iommu/vt-d: Don't dereference
iommu_device if IOMMU_API is not built",

Acked-by: Lu Baolu <baolu.lu@...ux.intel.com>

Best regards,
baolu

> ---
>   drivers/iommu/intel/dmar.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/iommu/intel/dmar.c b/drivers/iommu/intel/dmar.c
> index 2d70d56d8e0d..404b40af31cb 100644
> --- a/drivers/iommu/intel/dmar.c
> +++ b/drivers/iommu/intel/dmar.c
> @@ -1136,7 +1136,7 @@ static int alloc_iommu(struct dmar_drhd_unit *drhd)
>   
>   static void free_iommu(struct intel_iommu *iommu)
>   {
> -	if (intel_iommu_enabled && iommu->iommu.ops) {
> +	if (intel_iommu_enabled && !iommu->drhd->ignored) {
>   		iommu_device_unregister(&iommu->iommu);
>   		iommu_device_sysfs_remove(&iommu->iommu);
>   	}
>