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Subject: Re: [PATCH 1/1] iommu/vt-d: Fix build error of pasid_enable_wpe()
 with !X86
To:     Lu Baolu <baolu.lu@linux.intel.com>,
        Joerg Roedel <joro@8bytes.org>, Will Deacon <will@kernel.org>
Cc:     iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org,
        Sanjay Kumar <sanjay.k.kumar@intel.com>,
        Jacob Pan <jacob.jun.pan@linux.intel.com>,
        kernel test robot <lkp@intel.com>
References: <20210411062312.3057579-1-baolu.lu@linux.intel.com>
From:   Randy Dunlap <rdunlap@infradead.org>
Message-ID: <6a36c635-5f88-6264-e9c8-62ea6c5d771e@infradead.org>
Date:   Sat, 10 Apr 2021 23:40:45 -0700
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On 4/10/21 11:23 PM, Lu Baolu wrote:
> Commit f68c7f539b6e9 ("iommu/vt-d: Enable write protect for supervisor
> SVM") added pasid_enable_wpe() which hit below compile error with !X86.
> 
> ../drivers/iommu/intel/pasid.c: In function 'pasid_enable_wpe':
> ../drivers/iommu/intel/pasid.c:554:22: error: implicit declaration of function 'read_cr0' [-Werror=implicit-function-declaration]
>   554 |  unsigned long cr0 = read_cr0();
>       |                      ^~~~~~~~
> In file included from ../include/linux/build_bug.h:5,
>                  from ../include/linux/bits.h:22,
>                  from ../include/linux/bitops.h:6,
>                  from ../drivers/iommu/intel/pasid.c:12:
> ../drivers/iommu/intel/pasid.c:557:23: error: 'X86_CR0_WP' undeclared (first use in this function)
>   557 |  if (unlikely(!(cr0 & X86_CR0_WP))) {
>       |                       ^~~~~~~~~~
> ../include/linux/compiler.h:78:42: note: in definition of macro 'unlikely'
>    78 | # define unlikely(x) __builtin_expect(!!(x), 0)
>       |                                          ^
> ../drivers/iommu/intel/pasid.c:557:23: note: each undeclared identifier is reported only once for each function it appears in
>   557 |  if (unlikely(!(cr0 & X86_CR0_WP))) {
>       |                       ^~~~~~~~~~
> ../include/linux/compiler.h:78:42: note: in definition of macro 'unlikely'
>    78 | # define unlikely(x) __builtin_expect(!!(x), 0)
>       |
> 
> Add the missing dependency.
> 
> Cc: Sanjay Kumar <sanjay.k.kumar@intel.com>
> Cc: Jacob Pan <jacob.jun.pan@linux.intel.com>
> Cc: Randy Dunlap <rdunlap@infradead.org>
> Reported-by: kernel test robot <lkp@intel.com>
> Reported-by: Randy Dunlap <rdunlap@infradead.org>
> Fixes: f68c7f539b6e9 ("iommu/vt-d: Enable write protect for supervisor SVM")
> Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>

Acked-by: Randy Dunlap <rdunlap@infradead.org> # build-tested


Thanks.

> ---
>  drivers/iommu/intel/pasid.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/iommu/intel/pasid.c b/drivers/iommu/intel/pasid.c
> index 477b2e1d303c..72646bafc52f 100644
> --- a/drivers/iommu/intel/pasid.c
> +++ b/drivers/iommu/intel/pasid.c
> @@ -551,6 +551,7 @@ static void pasid_flush_caches(struct intel_iommu *iommu,
>  
>  static inline int pasid_enable_wpe(struct pasid_entry *pte)
>  {
> +#ifdef CONFIG_X86
>  	unsigned long cr0 = read_cr0();
>  
>  	/* CR0.WP is normally set but just to be sure */
> @@ -558,6 +559,7 @@ static inline int pasid_enable_wpe(struct pasid_entry *pte)
>  		pr_err_ratelimited("No CPU write protect!\n");
>  		return -EINVAL;
>  	}
> +#endif
>  	pasid_set_wpe(pte);
>  
>  	return 0;
> 


-- 
~Randy