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Message-Id: <20190529072124.GC3656@rapoport-lnx>
Date:   Wed, 29 May 2019 10:21:25 +0300
From:   Mike Rapoport <rppt@...ux.ibm.com>
To:     "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>, x86@...nel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, Borislav Petkov <bp@...en8.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Andy Lutomirski <luto@...capital.net>,
        David Howells <dhowells@...hat.com>,
        Kees Cook <keescook@...omium.org>,
        Dave Hansen <dave.hansen@...el.com>,
        Kai Huang <kai.huang@...ux.intel.com>,
        Jacob Pan <jacob.jun.pan@...ux.intel.com>,
        Alison Schofield <alison.schofield@...el.com>,
        linux-mm@...ck.org, kvm@...r.kernel.org, keyrings@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH, RFC 05/62] mm/page_alloc: Handle allocation for
 encrypted memory

On Wed, May 08, 2019 at 05:43:25PM +0300, Kirill A. Shutemov wrote:
> For encrypted memory, we need to allocate pages for a specific
> encryption KeyID.
> 
> There are two cases when we need to allocate a page for encryption:
> 
>  - Allocation for an encrypted VMA;
> 
>  - Allocation for migration of encrypted page;
> 
> The first case can be covered within alloc_page_vma(). We know KeyID
> from the VMA.
> 
> The second case requires few new page allocation routines that would
> allocate the page for a specific KeyID.
> 
> An encrypted page has to be cleared after KeyID set. This is handled
> in prep_encrypted_page() that will be provided by arch-specific code.
> 
> Any custom allocator that dials with encrypted pages has to call

Nit:                       ^ deals

> prep_encrypted_page() too. See compaction_alloc() for instance.
> 
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
> ---
>  include/linux/gfp.h     | 45 ++++++++++++++++++++++++++++++++-----
>  include/linux/migrate.h | 14 +++++++++---
>  mm/compaction.c         |  3 +++
>  mm/mempolicy.c          | 27 ++++++++++++++++------
>  mm/migrate.c            |  4 ++--
>  mm/page_alloc.c         | 50 +++++++++++++++++++++++++++++++++++++++++
>  6 files changed, 126 insertions(+), 17 deletions(-)
> 
> diff --git a/include/linux/gfp.h b/include/linux/gfp.h
> index b101aa294157..1716dbe587c9 100644
> --- a/include/linux/gfp.h
> +++ b/include/linux/gfp.h
> @@ -463,16 +463,43 @@ static inline void arch_free_page(struct page *page, int order) { }
>  static inline void arch_alloc_page(struct page *page, int order) { }
>  #endif
> 
> +#ifndef prep_encrypted_page

An explanation of what is expected from the architecture specific
implementation would be nice.

> +static inline void prep_encrypted_page(struct page *page, int order,
> +		int keyid, bool zero)
> +{
> +}
> +#endif
> +
> +/*
> + * Encrypted page has to be cleared once keyid is set, not on allocation.
> + */
> +static inline bool deferred_page_zero(int keyid, gfp_t *gfp_mask)
> +{
> +	if (keyid && (*gfp_mask & __GFP_ZERO)) {
> +		*gfp_mask &= ~__GFP_ZERO;
> +		return true;
> +	}
> +
> +	return false;
> +}
> +
>  struct page *
>  __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order, int preferred_nid,
>  							nodemask_t *nodemask);
> 
> +struct page *
> +__alloc_pages_nodemask_keyid(gfp_t gfp_mask, unsigned int order,
> +		int preferred_nid, nodemask_t *nodemask, int keyid);
> +
>  static inline struct page *
>  __alloc_pages(gfp_t gfp_mask, unsigned int order, int preferred_nid)
>  {
>  	return __alloc_pages_nodemask(gfp_mask, order, preferred_nid, NULL);
>  }
> 
> +struct page *__alloc_pages_node_keyid(int nid, int keyid,
> +		gfp_t gfp_mask, unsigned int order);
> +
>  /*
>   * Allocate pages, preferring the node given as nid. The node must be valid and
>   * online. For more general interface, see alloc_pages_node().
> @@ -500,6 +527,19 @@ static inline struct page *alloc_pages_node(int nid, gfp_t gfp_mask,
>  	return __alloc_pages_node(nid, gfp_mask, order);
>  }
> 
> +static inline struct page *alloc_pages_node_keyid(int nid, int keyid,
> +		gfp_t gfp_mask, unsigned int order)
> +{
> +	if (nid == NUMA_NO_NODE)
> +		nid = numa_mem_id();
> +
> +	return __alloc_pages_node_keyid(nid, keyid, gfp_mask, order);
> +}
> +
> +extern struct page *alloc_pages_vma(gfp_t gfp_mask, int order,
> +			struct vm_area_struct *vma, unsigned long addr,
> +			int node, bool hugepage);
> +
>  #ifdef CONFIG_NUMA
>  extern struct page *alloc_pages_current(gfp_t gfp_mask, unsigned order);
> 
> @@ -508,14 +548,9 @@ alloc_pages(gfp_t gfp_mask, unsigned int order)
>  {
>  	return alloc_pages_current(gfp_mask, order);
>  }
> -extern struct page *alloc_pages_vma(gfp_t gfp_mask, int order,
> -			struct vm_area_struct *vma, unsigned long addr,
> -			int node, bool hugepage);
>  #else
>  #define alloc_pages(gfp_mask, order) \
>  		alloc_pages_node(numa_node_id(), gfp_mask, order)
> -#define alloc_pages_vma(gfp_mask, order, vma, addr, node, false)\
> -	alloc_pages(gfp_mask, order)
>  #endif
>  #define alloc_page(gfp_mask) alloc_pages(gfp_mask, 0)
>  #define alloc_page_vma(gfp_mask, vma, addr)			\
> diff --git a/include/linux/migrate.h b/include/linux/migrate.h
> index e13d9bf2f9a5..a6e068762d08 100644
> --- a/include/linux/migrate.h
> +++ b/include/linux/migrate.h
> @@ -38,9 +38,16 @@ static inline struct page *new_page_nodemask(struct page *page,
>  	unsigned int order = 0;
>  	struct page *new_page = NULL;
> 
> -	if (PageHuge(page))
> +	if (PageHuge(page)) {
> +		/*
> +		 * HugeTLB doesn't support encryption. We shouldn't see
> +		 * such pages.
> +		 */
> +		if (WARN_ON_ONCE(page_keyid(page)))
> +			return NULL;
>  		return alloc_huge_page_nodemask(page_hstate(compound_head(page)),
>  				preferred_nid, nodemask);
> +	}
> 
>  	if (PageTransHuge(page)) {
>  		gfp_mask |= GFP_TRANSHUGE;
> @@ -50,8 +57,9 @@ static inline struct page *new_page_nodemask(struct page *page,
>  	if (PageHighMem(page) || (zone_idx(page_zone(page)) == ZONE_MOVABLE))
>  		gfp_mask |= __GFP_HIGHMEM;
> 
> -	new_page = __alloc_pages_nodemask(gfp_mask, order,
> -				preferred_nid, nodemask);
> +	/* Allocate a page with the same KeyID as the source page */
> +	new_page = __alloc_pages_nodemask_keyid(gfp_mask, order,
> +				preferred_nid, nodemask, page_keyid(page));
> 
>  	if (new_page && PageTransHuge(new_page))
>  		prep_transhuge_page(new_page);
> diff --git a/mm/compaction.c b/mm/compaction.c
> index 3319e0872d01..559b8bd6d245 100644
> --- a/mm/compaction.c
> +++ b/mm/compaction.c
> @@ -1557,6 +1557,9 @@ static struct page *compaction_alloc(struct page *migratepage,
>  	list_del(&freepage->lru);
>  	cc->nr_freepages--;
> 
> +	/* Prepare the page using the same KeyID as the source page */
> +	if (freepage)
> +		prep_encrypted_page(freepage, 0, page_keyid(migratepage), false);
>  	return freepage;
>  }
> 
> diff --git a/mm/mempolicy.c b/mm/mempolicy.c
> index 14b18449c623..5cad39fb7b35 100644
> --- a/mm/mempolicy.c
> +++ b/mm/mempolicy.c
> @@ -961,22 +961,29 @@ static void migrate_page_add(struct page *page, struct list_head *pagelist,
>  /* page allocation callback for NUMA node migration */
>  struct page *alloc_new_node_page(struct page *page, unsigned long node)
>  {
> -	if (PageHuge(page))
> +	if (PageHuge(page)) {
> +		/*
> +		 * HugeTLB doesn't support encryption. We shouldn't see
> +		 * such pages.
> +		 */
> +		if (WARN_ON_ONCE(page_keyid(page)))
> +			return NULL;
>  		return alloc_huge_page_node(page_hstate(compound_head(page)),
>  					node);
> -	else if (PageTransHuge(page)) {
> +	} else if (PageTransHuge(page)) {
>  		struct page *thp;
> 
> -		thp = alloc_pages_node(node,
> +		thp = alloc_pages_node_keyid(node, page_keyid(page),
>  			(GFP_TRANSHUGE | __GFP_THISNODE),
>  			HPAGE_PMD_ORDER);
>  		if (!thp)
>  			return NULL;
>  		prep_transhuge_page(thp);
>  		return thp;
> -	} else
> -		return __alloc_pages_node(node, GFP_HIGHUSER_MOVABLE |
> -						    __GFP_THISNODE, 0);
> +	} else {
> +		return __alloc_pages_node_keyid(node, page_keyid(page),
> +				GFP_HIGHUSER_MOVABLE | __GFP_THISNODE, 0);
> +	}
>  }
> 
>  /*
> @@ -2053,9 +2060,13 @@ alloc_pages_vma(gfp_t gfp, int order, struct vm_area_struct *vma,
>  {
>  	struct mempolicy *pol;
>  	struct page *page;
> -	int preferred_nid;
> +	bool deferred_zero;
> +	int keyid, preferred_nid;
>  	nodemask_t *nmask;
> 
> +	keyid = vma_keyid(vma);
> +	deferred_zero = deferred_page_zero(keyid, &gfp);
> +
>  	pol = get_vma_policy(vma, addr);
> 
>  	if (pol->mode == MPOL_INTERLEAVE) {
> @@ -2097,6 +2108,8 @@ alloc_pages_vma(gfp_t gfp, int order, struct vm_area_struct *vma,
>  	page = __alloc_pages_nodemask(gfp, order, preferred_nid, nmask);
>  	mpol_cond_put(pol);
>  out:
> +	if (page)
> +		prep_encrypted_page(page, order, keyid, deferred_zero);
>  	return page;
>  }
> 
> diff --git a/mm/migrate.c b/mm/migrate.c
> index 663a5449367a..04b36a56865d 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -1880,7 +1880,7 @@ static struct page *alloc_misplaced_dst_page(struct page *page,
>  	int nid = (int) data;
>  	struct page *newpage;
> 
> -	newpage = __alloc_pages_node(nid,
> +	newpage = __alloc_pages_node_keyid(nid, page_keyid(page),
>  					 (GFP_HIGHUSER_MOVABLE |
>  					  __GFP_THISNODE | __GFP_NOMEMALLOC |
>  					  __GFP_NORETRY | __GFP_NOWARN) &
> @@ -2006,7 +2006,7 @@ int migrate_misplaced_transhuge_page(struct mm_struct *mm,
>  	int page_lru = page_is_file_cache(page);
>  	unsigned long start = address & HPAGE_PMD_MASK;
> 
> -	new_page = alloc_pages_node(node,
> +	new_page = alloc_pages_node_keyid(node, page_keyid(page),
>  		(GFP_TRANSHUGE_LIGHT | __GFP_THISNODE),
>  		HPAGE_PMD_ORDER);
>  	if (!new_page)
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index c02cff1ed56e..ab1d8661aa87 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -3930,6 +3930,41 @@ should_compact_retry(struct alloc_context *ac, unsigned int order, int alloc_fla
>  }
>  #endif /* CONFIG_COMPACTION */
> 
> +#ifndef CONFIG_NUMA
> +struct page *alloc_pages_vma(gfp_t gfp_mask, int order,
> +		struct vm_area_struct *vma, unsigned long addr,
> +		int node, bool hugepage)
> +{

Having NUMA and !NUMA alloc_pages_vma() in different place is confusing,
but I don't have a better suggestion :(

> +	struct page *page;
> +	bool deferred_zero;
> +	int keyid = vma_keyid(vma);
> +
> +	deferred_zero = deferred_page_zero(keyid, &gfp_mask);
> +	page = alloc_pages(gfp_mask, order);
> +	if (page)
> +		prep_encrypted_page(page, order, keyid, deferred_zero);
> +
> +	return page;
> +}
> +#endif
> +
> +struct page * __alloc_pages_node_keyid(int nid, int keyid,
> +		gfp_t gfp_mask, unsigned int order)
> +{

A kerneldoc description would be appreciated

> +	struct page *page;
> +	bool deferred_zero;
> +
> +	VM_BUG_ON(nid < 0 || nid >= MAX_NUMNODES);
> +	VM_WARN_ON(!node_online(nid));
> +
> +	deferred_zero = deferred_page_zero(keyid, &gfp_mask);
> +	page = __alloc_pages(gfp_mask, order, nid);
> +	if (page)
> +		prep_encrypted_page(page, order, keyid, deferred_zero);
> +
> +	return page;
> +}

Shouldn't it be EXPORT_SYMBOL?

> +
>  #ifdef CONFIG_LOCKDEP
>  static struct lockdep_map __fs_reclaim_map =
>  	STATIC_LOCKDEP_MAP_INIT("fs_reclaim", &__fs_reclaim_map);
> @@ -4645,6 +4680,21 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order, int preferred_nid,
>  }
>  EXPORT_SYMBOL(__alloc_pages_nodemask);
>
> +struct page *
> +__alloc_pages_nodemask_keyid(gfp_t gfp_mask, unsigned int order,
> +		int preferred_nid, nodemask_t *nodemask, int keyid)
> +{

A kerneldoc description would be appreciated

> +	struct page *page;
> +	bool deferred_zero;
> +
> +	deferred_zero = deferred_page_zero(keyid, &gfp_mask);
> +	page = __alloc_pages_nodemask(gfp_mask, order, preferred_nid, nodemask);
> +	if (page)
> +		prep_encrypted_page(page, order, keyid, deferred_zero);
> +	return page;
> +}
> +EXPORT_SYMBOL(__alloc_pages_nodemask_keyid);
> +
>  /*
>   * Common helper functions. Never use with __GFP_HIGHMEM because the returned
>   * address cannot represent highmem pages. Use alloc_pages and then kmap if
> -- 
> 2.20.1
> 

-- 
Sincerely yours,
Mike.

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