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    Subject[PATCH v5 1/7] x86/sgx: Provide indication of life-cycle of EPC pages
    Date
    SGX EPC pages go through the following life cycle:

    DIRTY ---> FREE ---> IN-USE --\
    ^ |
    \-----------------/

    Recovery action for poison for a DIRTY or FREE page is simple. Just
    make sure never to allocate the page. IN-USE pages need some extra
    handling.

    It would be good to use the sgx_epc_page->owner field as an indicator
    of where an EPC page is currently in that cycle (owner != NULL means
    the EPC page is IN-USE). But there is one caller, sgx_alloc_va_page(),
    that calls with NULL.

    Since there are multiple uses of the "owner" field with different types
    change the sgx_epc_page structure to define an anonymous union with
    each of the uses explicitly called out.

    Start epc_pages out with a non-NULL owner while they are in DIRTY state.

    Fix up the one holdout to provide a non-NULL owner.

    Refactor the allocation sequence so that changes to/from NULL
    value happen together with adding/removing the epc_page from
    a free list while the node->lock is held.

    Signed-off-by: Tony Luck <tony.luck@intel.com>
    ---
    arch/x86/kernel/cpu/sgx/encl.c | 5 +++--
    arch/x86/kernel/cpu/sgx/encl.h | 2 +-
    arch/x86/kernel/cpu/sgx/ioctl.c | 2 +-
    arch/x86/kernel/cpu/sgx/main.c | 23 ++++++++++++-----------
    arch/x86/kernel/cpu/sgx/sgx.h | 12 ++++++++----
    5 files changed, 25 insertions(+), 19 deletions(-)

    diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c
    index 001808e3901c..ad8c61933b0a 100644
    --- a/arch/x86/kernel/cpu/sgx/encl.c
    +++ b/arch/x86/kernel/cpu/sgx/encl.c
    @@ -667,6 +667,7 @@ int sgx_encl_test_and_clear_young(struct mm_struct *mm,

    /**
    * sgx_alloc_va_page() - Allocate a Version Array (VA) page
    + * @va_page: struct sgx_va_page connected to this VA page
    *
    * Allocate a free EPC page and convert it to a Version Array (VA) page.
    *
    @@ -674,12 +675,12 @@ int sgx_encl_test_and_clear_young(struct mm_struct *mm,
    * a VA page,
    * -errno otherwise
    */
    -struct sgx_epc_page *sgx_alloc_va_page(void)
    +struct sgx_epc_page *sgx_alloc_va_page(struct sgx_va_page *va_page)
    {
    struct sgx_epc_page *epc_page;
    int ret;

    - epc_page = sgx_alloc_epc_page(NULL, true);
    + epc_page = sgx_alloc_epc_page(va_page, true);
    if (IS_ERR(epc_page))
    return ERR_CAST(epc_page);

    diff --git a/arch/x86/kernel/cpu/sgx/encl.h b/arch/x86/kernel/cpu/sgx/encl.h
    index fec43ca65065..3d12dbeae14a 100644
    --- a/arch/x86/kernel/cpu/sgx/encl.h
    +++ b/arch/x86/kernel/cpu/sgx/encl.h
    @@ -111,7 +111,7 @@ void sgx_encl_put_backing(struct sgx_backing *backing, bool do_write);
    int sgx_encl_test_and_clear_young(struct mm_struct *mm,
    struct sgx_encl_page *page);

    -struct sgx_epc_page *sgx_alloc_va_page(void);
    +struct sgx_epc_page *sgx_alloc_va_page(struct sgx_va_page *va_page);
    unsigned int sgx_alloc_va_slot(struct sgx_va_page *va_page);
    void sgx_free_va_slot(struct sgx_va_page *va_page, unsigned int offset);
    bool sgx_va_page_full(struct sgx_va_page *va_page);
    diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c
    index 83df20e3e633..655ce0bb069d 100644
    --- a/arch/x86/kernel/cpu/sgx/ioctl.c
    +++ b/arch/x86/kernel/cpu/sgx/ioctl.c
    @@ -30,7 +30,7 @@ static struct sgx_va_page *sgx_encl_grow(struct sgx_encl *encl)
    if (!va_page)
    return ERR_PTR(-ENOMEM);

    - va_page->epc_page = sgx_alloc_va_page();
    + va_page->epc_page = sgx_alloc_va_page(va_page);
    if (IS_ERR(va_page->epc_page)) {
    err = ERR_CAST(va_page->epc_page);
    kfree(va_page);
    diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
    index 63d3de02bbcc..4a5b51d16133 100644
    --- a/arch/x86/kernel/cpu/sgx/main.c
    +++ b/arch/x86/kernel/cpu/sgx/main.c
    @@ -457,7 +457,7 @@ static bool __init sgx_page_reclaimer_init(void)
    return true;
    }

    -static struct sgx_epc_page *__sgx_alloc_epc_page_from_node(int nid)
    +static struct sgx_epc_page *__sgx_alloc_epc_page_from_node(void *private, int nid)
    {
    struct sgx_numa_node *node = &sgx_numa_nodes[nid];
    struct sgx_epc_page *page = NULL;
    @@ -471,6 +471,7 @@ static struct sgx_epc_page *__sgx_alloc_epc_page_from_node(int nid)

    page = list_first_entry(&node->free_page_list, struct sgx_epc_page, list);
    list_del_init(&page->list);
    + page->private = private;
    sgx_nr_free_pages--;

    spin_unlock(&node->lock);
    @@ -480,6 +481,7 @@ static struct sgx_epc_page *__sgx_alloc_epc_page_from_node(int nid)

    /**
    * __sgx_alloc_epc_page() - Allocate an EPC page
    + * @owner: the owner of the EPC page
    *
    * Iterate through NUMA nodes and reserve ia free EPC page to the caller. Start
    * from the NUMA node, where the caller is executing.
    @@ -488,14 +490,14 @@ static struct sgx_epc_page *__sgx_alloc_epc_page_from_node(int nid)
    * - an EPC page: A borrowed EPC pages were available.
    * - NULL: Out of EPC pages.
    */
    -struct sgx_epc_page *__sgx_alloc_epc_page(void)
    +struct sgx_epc_page *__sgx_alloc_epc_page(void *private)
    {
    struct sgx_epc_page *page;
    int nid_of_current = numa_node_id();
    int nid = nid_of_current;

    if (node_isset(nid_of_current, sgx_numa_mask)) {
    - page = __sgx_alloc_epc_page_from_node(nid_of_current);
    + page = __sgx_alloc_epc_page_from_node(private, nid_of_current);
    if (page)
    return page;
    }
    @@ -506,7 +508,7 @@ struct sgx_epc_page *__sgx_alloc_epc_page(void)
    if (nid == nid_of_current)
    break;

    - page = __sgx_alloc_epc_page_from_node(nid);
    + page = __sgx_alloc_epc_page_from_node(private, nid);
    if (page)
    return page;
    }
    @@ -559,7 +561,7 @@ int sgx_unmark_page_reclaimable(struct sgx_epc_page *page)

    /**
    * sgx_alloc_epc_page() - Allocate an EPC page
    - * @owner: the owner of the EPC page
    + * @private: per-caller private data
    * @reclaim: reclaim pages if necessary
    *
    * Iterate through EPC sections and borrow a free EPC page to the caller. When a
    @@ -574,16 +576,14 @@ int sgx_unmark_page_reclaimable(struct sgx_epc_page *page)
    * an EPC page,
    * -errno on error
    */
    -struct sgx_epc_page *sgx_alloc_epc_page(void *owner, bool reclaim)
    +struct sgx_epc_page *sgx_alloc_epc_page(void *private, bool reclaim)
    {
    struct sgx_epc_page *page;

    for ( ; ; ) {
    - page = __sgx_alloc_epc_page();
    - if (!IS_ERR(page)) {
    - page->owner = owner;
    + page = __sgx_alloc_epc_page(private);
    + if (!IS_ERR(page))
    break;
    - }

    if (list_empty(&sgx_active_page_list))
    return ERR_PTR(-ENOMEM);
    @@ -624,6 +624,7 @@ void sgx_free_epc_page(struct sgx_epc_page *page)

    spin_lock(&node->lock);

    + page->private = NULL;
    list_add_tail(&page->list, &node->free_page_list);
    sgx_nr_free_pages++;

    @@ -652,7 +653,7 @@ static bool __init sgx_setup_epc_section(u64 phys_addr, u64 size,
    for (i = 0; i < nr_pages; i++) {
    section->pages[i].section = index;
    section->pages[i].flags = 0;
    - section->pages[i].owner = NULL;
    + section->pages[i].private = "dirty";
    list_add_tail(&section->pages[i].list, &sgx_dirty_page_list);
    }

    diff --git a/arch/x86/kernel/cpu/sgx/sgx.h b/arch/x86/kernel/cpu/sgx/sgx.h
    index 4628acec0009..8b1be10a46f6 100644
    --- a/arch/x86/kernel/cpu/sgx/sgx.h
    +++ b/arch/x86/kernel/cpu/sgx/sgx.h
    @@ -28,8 +28,12 @@

    struct sgx_epc_page {
    unsigned int section;
    - unsigned int flags;
    - struct sgx_encl_page *owner;
    + int flags;
    + union {
    + void *private;
    + struct sgx_encl_page *owner;
    + struct sgx_encl_page *vepc;
    + };
    struct list_head list;
    };

    @@ -77,12 +81,12 @@ static inline void *sgx_get_epc_virt_addr(struct sgx_epc_page *page)
    return section->virt_addr + index * PAGE_SIZE;
    }

    -struct sgx_epc_page *__sgx_alloc_epc_page(void);
    +struct sgx_epc_page *__sgx_alloc_epc_page(void *private);
    void sgx_free_epc_page(struct sgx_epc_page *page);

    void sgx_mark_page_reclaimable(struct sgx_epc_page *page);
    int sgx_unmark_page_reclaimable(struct sgx_epc_page *page);
    -struct sgx_epc_page *sgx_alloc_epc_page(void *owner, bool reclaim);
    +struct sgx_epc_page *sgx_alloc_epc_page(void *private, bool reclaim);

    #ifdef CONFIG_X86_SGX_KVM
    int __init sgx_vepc_init(void);
    --
    2.31.1
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