Re: [PATCH v9 5/7] x86/sgx: Hook arch_memory_failure() into mainline code

[Jarkko Sakkinen <jarkko@kernel.org>]

On Mon, 2021-10-11 at 11:59 -0700, Tony Luck wrote:
> Add a call inside memory_failure() to call the arch specific code
> to check if the address is an SGX EPC page and handle it.
> 
> Note the SGX EPC pages do not have a "struct page" entry, so the hook
> goes in at the same point as the device mapping hook.
> 
> Pull the call to acquire the mutex earlier so the SGX errors are also
> protected.
> 
> Make set_mce_nospec() skip SGX pages when trying to adjust
> the 1:1 map.
> 
> Tested-by: Reinette Chatre <reinette.chatre@intel.com>
> Signed-off-by: Tony Luck <tony.luck@intel.com>
> ---
>  arch/x86/include/asm/processor.h  |  8 ++++++++
>  arch/x86/include/asm/set_memory.h |  4 ++++
>  include/linux/mm.h                | 14 ++++++++++++++
>  mm/memory-failure.c               | 19 +++++++++++++------
>  4 files changed, 39 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
> index 9ad2acaaae9b..4865f2860a4f 100644
> --- a/arch/x86/include/asm/processor.h
> +++ b/arch/x86/include/asm/processor.h
> @@ -853,4 +853,12 @@ enum mds_mitigations {
>         MDS_MITIGATION_VMWERV,
>  };
>  
> +#ifdef CONFIG_X86_SGX
> +int arch_memory_failure(unsigned long pfn, int flags);
> +#define arch_memory_failure arch_memory_failure
> +
> +bool arch_is_platform_page(u64 paddr);
> +#define arch_is_platform_page arch_is_platform_page
> +#endif
> +
>  #endif /* _ASM_X86_PROCESSOR_H */
> diff --git a/arch/x86/include/asm/set_memory.h b/arch/x86/include/asm/set_memory.h
> index 43fa081a1adb..ce8dd215f5b3 100644
> --- a/arch/x86/include/asm/set_memory.h
> +++ b/arch/x86/include/asm/set_memory.h
> @@ -2,6 +2,7 @@
>  #ifndef _ASM_X86_SET_MEMORY_H
>  #define _ASM_X86_SET_MEMORY_H
>  
> +#include <linux/mm.h>
>  #include <asm/page.h>
>  #include <asm-generic/set_memory.h>
>  
> @@ -98,6 +99,9 @@ static inline int set_mce_nospec(unsigned long pfn, bool unmap)
>         unsigned long decoy_addr;
>         int rc;
>  
> +       /* SGX pages are not in the 1:1 map */
> +       if (arch_is_platform_page(pfn << PAGE_SHIFT))
> +               return 0;
>         /*
>          * We would like to just call:
>          *      set_memory_XX((unsigned long)pfn_to_kaddr(pfn), 1);
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 73a52aba448f..62b199ed5ec6 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -3284,5 +3284,19 @@ static inline int seal_check_future_write(int seals, struct vm_area_struct *vma)
>         return 0;
>  }
>  
> +#ifndef arch_memory_failure
> +static inline int arch_memory_failure(unsigned long pfn, int flags)
> +{
> +       return -ENXIO;
> +}
> +#endif
> +
> +#ifndef arch_is_platform_page
> +static inline bool arch_is_platform_page(u64 paddr)
> +{
> +       return false;
> +}
> +#endif
> +
>  #endif /* __KERNEL__ */
>  #endif /* _LINUX_MM_H */
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index 3e6449f2102a..b1cbf9845c19 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -1632,21 +1632,28 @@ int memory_failure(unsigned long pfn, int flags)
>         if (!sysctl_memory_failure_recovery)
>                 panic("Memory failure on page %lx", pfn);
>  
> +       mutex_lock(&mf_mutex);
> +
>         p = pfn_to_online_page(pfn);
>         if (!p) {
> +               res = arch_memory_failure(pfn, flags);
> +               if (res == 0)
> +                       goto unlock_mutex;
> +
>                 if (pfn_valid(pfn)) {
>                         pgmap = get_dev_pagemap(pfn, NULL);
> -                       if (pgmap)
> -                               return memory_failure_dev_pagemap(pfn, flags,
> -                                                                 pgmap);
> +                       if (pgmap) {
> +                               res = memory_failure_dev_pagemap(pfn, flags,
> +                                                                pgmap);
> +                               goto unlock_mutex;
> +                       }
>                 }
>                 pr_err("Memory failure: %#lx: memory outside kernel control\n",
>                         pfn);
> -               return -ENXIO;
> +               res = -ENXIO;
> +               goto unlock_mutex;
>         }
>  
> -       mutex_lock(&mf_mutex);
> -
>  try_again:
>         if (PageHuge(p)) {
>                 res = memory_failure_hugetlb(pfn, flags);

Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>

/Jarkko