Messages in this thread | | | Subject | Re: [PATCH v4 1/6] x86/sgx: Provide indication of life-cycle of EPC pages | From | Jarkko Sakkinen <> | Date | Wed, 01 Sep 2021 06:55:54 +0300 |
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On Fri, 2021-08-27 at 12:55 -0700, Tony Luck wrote: > 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)
Why not just
struct sgx_epc_page *sgx_alloc_va_page(void *owner)
> { > 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);
epc_page = sgx_alloc_epc_page(owner, true);
> if (IS_ERR(epc_page)) > return ERR_CAST(epc_page);
This function does not do anything with the internals of struct sgx_va_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";
#define DIRTY ((void *)-1)
section->pages[i].owner = DIRTY;
> list_add_tail(§ion->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; > + };
Why not just keep it as void *owner, and cast it as seen appropriate?
> 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);
/Jarkko
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