| Message ID | 20210313160119.1318533-4-jarkko@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | x86/sgx: NUMA | expand |
On Sat, Mar 13, 2021 at 06:01:19PM +0200, Jarkko Sakkinen wrote: > Background > ========== > > EPC section is covered by one or more SRAT entries that are associated with > one and only one PXM (NUMA node). The motivation behind this patch is to > provide basic elements of building allocation scheme based on this premise. > > Just like normal RAM, enclave memory (EPC) should be covered by entries > in the ACPI SRAT table. These entries allow each EPC section to be > associated with a NUMA node. > > Use this information to implement a simple NUMA-aware allocator for > enclave memory. > > Solution > ======== > > Use phys_to_target_node() to associate each NUMA node with the EPC > sections contained within its range. In sgx_alloc_epc_page(), first try > to allocate from the NUMA node, where the CPU is executing. If that > fails, allocate from other nodes, iterating them from the current node > in order. > > Other > ===== > > NUMA_KEEP_MEMINFO dependency is required for phys_to_target_node(). > > Link: https://lore.kernel.org/lkml/158188326978.894464.217282995221175417.stgit@dwillia2-desk3.amr.corp.intel.com/ > Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org> We *can* have also epc_page->node by: - Considering the first section as the EPC of that node. - Printing a warning if more sections hit the same node, and ignoring them. - Merging sgx_numa_node and sgx_epc_section I think this would be a decent idea. I think it's a sane assumption that a node has a single EPC section, but it's good to have that warning just in case. I did not want to do this into this version because it's faster for me to refactor into this assumption than revert back. /Jarkko > --- > > v4: > * Cycle nodes instead of a global page list, starting from the node > of the current thread. > * Documented NUMA_KEEP_MEMINFO dependency to the commit message. > * Added NUMA node pointer to struct sgx_epc_section. EPC page should > reference to a section, since potentially a node could have multiple > sections (Intel SDM does not say anything explicit about this). > This the safest play. > * Remove nodes_clear(sgx_numa_node_mask). > * Appended Dave's additions to the commit message for the background > section. > > arch/x86/Kconfig | 1 + > arch/x86/kernel/cpu/sgx/main.c | 117 ++++++++++++++++++++------------- > arch/x86/kernel/cpu/sgx/sgx.h | 16 +++-- > 3 files changed, 84 insertions(+), 50 deletions(-) > > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > index 513895af8ee7..3e6152a8dd2b 100644 > --- a/arch/x86/Kconfig > +++ b/arch/x86/Kconfig > @@ -1930,6 +1930,7 @@ config X86_SGX > depends on CRYPTO_SHA256=y > select SRCU > select MMU_NOTIFIER > + select NUMA_KEEP_MEMINFO if NUMA > help > Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions > that can be used by applications to set aside private regions of code > diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c > index cb4561444b96..3b524a1361d6 100644 > --- a/arch/x86/kernel/cpu/sgx/main.c > +++ b/arch/x86/kernel/cpu/sgx/main.c > @@ -18,14 +18,23 @@ static int sgx_nr_epc_sections; > static struct task_struct *ksgxd_tsk; > static DECLARE_WAIT_QUEUE_HEAD(ksgxd_waitq); > > -/* > - * These variables are part of the state of the reclaimer, and must be accessed > - * with sgx_reclaimer_lock acquired. > - */ > +/* The reclaimer lock protected variables prepend the lock. */ > static LIST_HEAD(sgx_active_page_list); > - > static DEFINE_SPINLOCK(sgx_reclaimer_lock); > > +/* The free page list lock protected variables prepend the lock. */ > +static unsigned long sgx_nr_free_pages; > + > +/* Nodes with one or more EPC sections. */ > +static nodemask_t sgx_numa_mask; > + > +/* > + * Array with one list_head for each possible NUMA node. Each > + * list contains all the sgx_epc_section's which are on that > + * node. > + */ > +static struct sgx_numa_node *sgx_numa_nodes; > + > /* > * When the driver initialized, EPC pages go first here, as they could be > * initialized to an active enclave, on kexec entry. > @@ -352,21 +361,9 @@ static void sgx_reclaim_pages(void) > } > } > > -static unsigned long sgx_nr_free_pages(void) > -{ > - unsigned long cnt = 0; > - int i; > - > - for (i = 0; i < sgx_nr_epc_sections; i++) > - cnt += sgx_epc_sections[i].free_cnt; > - > - return cnt; > -} > - > static bool sgx_should_reclaim(unsigned long watermark) > { > - return sgx_nr_free_pages() < watermark && > - !list_empty(&sgx_active_page_list); > + return sgx_nr_free_pages < watermark && !list_empty(&sgx_active_page_list); > } > > static int ksgxd(void *p) > @@ -443,50 +440,63 @@ static bool __init sgx_page_reclaimer_init(void) > return true; > } > > -static struct sgx_epc_page *__sgx_alloc_epc_page_from_section(struct sgx_epc_section *section) > +static struct sgx_epc_page *__sgx_alloc_epc_page_from_node(int nid) > { > - struct sgx_epc_page *page; > + struct sgx_numa_node *node = &sgx_numa_nodes[nid]; > + struct sgx_epc_page *page = NULL; > + > + if (!node_isset(nid, sgx_numa_mask)) > + return NULL; > > - spin_lock(§ion->lock); > + spin_lock(&node->lock); > > - if (list_empty(§ion->page_list)) { > - spin_unlock(§ion->lock); > + if (list_empty(&node->free_page_list)) { > + spin_unlock(&node->lock); > return NULL; > } > > - page = list_first_entry(§ion->page_list, struct sgx_epc_page, list); > + page = list_first_entry(&node->free_page_list, struct sgx_epc_page, list); > list_del_init(&page->list); > - section->free_cnt--; > + sgx_nr_free_pages--; > + > + spin_unlock(&node->lock); > > - spin_unlock(§ion->lock); > return page; > } > > /** > * __sgx_alloc_epc_page() - Allocate an EPC page > * > - * Iterate through EPC sections and borrow a free EPC page to the caller. When a > - * page is no longer needed it must be released with sgx_free_epc_page(). > + * Iterate through NUMA nodes and borrow a free EPC page to the caller. When a > + * page is no longer needed it must be released with sgx_free_epc_page(). Start > + * from the NUMA node, where the caller is executing. > * > * Return: > - * an EPC page, > - * -errno on error > + * - an EPC page: Free EPC pages were available. > + * - ERR_PTR(-ENOMEM): Run out of EPC pages. > */ > struct sgx_epc_page *__sgx_alloc_epc_page(void) > { > - struct sgx_epc_section *section; > struct sgx_epc_page *page; > - int i; > + int nid = numa_node_id(); > > - for (i = 0; i < sgx_nr_epc_sections; i++) { > - section = &sgx_epc_sections[i]; > + /* Try to allocate EPC from the current node, first: */ > + page = __sgx_alloc_epc_page_from_node(nid); > + if (page) > + return page; > > - page = __sgx_alloc_epc_page_from_section(section); > + /* Then, go through the other nodes: */ > + while (true) { > + nid = next_node_in(nid, sgx_numa_mask); > + if (nid == numa_node_id()) > + break; > + > + page = __sgx_alloc_epc_page_from_node(nid); > if (page) > - return page; > + break; > } > > - return ERR_PTR(-ENOMEM); > + return page; > } > > /** > @@ -592,6 +602,7 @@ struct sgx_epc_page *sgx_alloc_epc_page(void *owner, bool reclaim) > void sgx_free_epc_page(struct sgx_epc_page *page) > { > struct sgx_epc_section *section = &sgx_epc_sections[page->section]; > + struct sgx_numa_node *node = section->node; > int ret; > > WARN_ON_ONCE(page->flags & SGX_EPC_PAGE_RECLAIMER_TRACKED); > @@ -600,10 +611,12 @@ void sgx_free_epc_page(struct sgx_epc_page *page) > if (WARN_ONCE(ret, "EREMOVE returned %d (0x%x)", ret, ret)) > return; > > - spin_lock(§ion->lock); > - list_add_tail(&page->list, §ion->page_list); > - section->free_cnt++; > - spin_unlock(§ion->lock); > + spin_lock(&node->lock); > + > + list_add_tail(&page->list, &node->free_page_list); > + sgx_nr_free_pages++; > + > + spin_unlock(&node->lock); > } > > static bool __init sgx_setup_epc_section(u64 phys_addr, u64 size, > @@ -624,8 +637,6 @@ static bool __init sgx_setup_epc_section(u64 phys_addr, u64 size, > } > > section->phys_addr = phys_addr; > - spin_lock_init(§ion->lock); > - INIT_LIST_HEAD(§ion->page_list); > > for (i = 0; i < nr_pages; i++) { > section->pages[i].section = index; > @@ -634,7 +645,7 @@ static bool __init sgx_setup_epc_section(u64 phys_addr, u64 size, > list_add_tail(§ion->pages[i].list, &sgx_dirty_page_list); > } > > - section->free_cnt = nr_pages; > + sgx_nr_free_pages += nr_pages; > return true; > } > > @@ -653,8 +664,11 @@ static bool __init sgx_page_cache_init(void) > { > u32 eax, ebx, ecx, edx, type; > u64 pa, size; > + int nid; > int i; > > + sgx_numa_nodes = kmalloc_array(num_possible_nodes(), sizeof(*sgx_numa_nodes), GFP_KERNEL); > + > for (i = 0; i < ARRAY_SIZE(sgx_epc_sections); i++) { > cpuid_count(SGX_CPUID, i + SGX_CPUID_EPC, &eax, &ebx, &ecx, &edx); > > @@ -677,6 +691,21 @@ static bool __init sgx_page_cache_init(void) > break; > } > > + nid = numa_map_to_online_node(phys_to_target_node(pa)); > + if (nid == NUMA_NO_NODE) { > + /* The physical address is already printed above. */ > + pr_warn(FW_BUG "Unable to map EPC section to online node. Fallback to the NUMA node 0.\n"); > + nid = 0; > + } > + > + if (!node_isset(nid, sgx_numa_mask)) { > + spin_lock_init(&sgx_numa_nodes[nid].lock); > + INIT_LIST_HEAD(&sgx_numa_nodes[nid].free_page_list); > + node_set(nid, sgx_numa_mask); > + } > + > + sgx_epc_sections[i].node = &sgx_numa_nodes[nid]; > + > sgx_nr_epc_sections++; > } > > diff --git a/arch/x86/kernel/cpu/sgx/sgx.h b/arch/x86/kernel/cpu/sgx/sgx.h > index bc8af0428640..653af8ca1a25 100644 > --- a/arch/x86/kernel/cpu/sgx/sgx.h > +++ b/arch/x86/kernel/cpu/sgx/sgx.h > @@ -29,22 +29,26 @@ struct sgx_epc_page { > struct list_head list; > }; > > +/* > + * Contains the tracking data for NUMA nodes having EPC pages. Most importantly, > + * the free page list local to the node is stored here. > + */ > +struct sgx_numa_node { > + struct list_head free_page_list; > + spinlock_t lock; > +}; > + > /* > * The firmware can define multiple chunks of EPC to the different areas of the > * physical memory e.g. for memory areas of the each node. This structure is > * used to store EPC pages for one EPC section and virtual memory area where > * the pages have been mapped. > - * > - * 'lock' must be held before accessing 'page_list' or 'free_cnt'. > */ > struct sgx_epc_section { > unsigned long phys_addr; > void *virt_addr; > struct sgx_epc_page *pages; > - > - spinlock_t lock; > - struct list_head page_list; > - unsigned long free_cnt; > + struct sgx_numa_node *node; > }; > > extern struct sgx_epc_section sgx_epc_sections[SGX_MAX_EPC_SECTIONS]; > -- > 2.30.2 >
On 3/13/21 8:01 AM, Jarkko Sakkinen wrote: > Background > ========== > > EPC section is covered by one or more SRAT entries that are associated with > one and only one PXM (NUMA node). The motivation behind this patch is to > provide basic elements of building allocation scheme based on this premise. A better set of background information here would also remind folks what an 'EPC section' is. > Just like normal RAM, enclave memory (EPC) should be covered by entries > in the ACPI SRAT table. These entries allow each EPC section to be > associated with a NUMA node. > > Use this information to implement a simple NUMA-aware allocator for > enclave memory. SGX enclave memory is enumerated by the processor in contiguous physical ranges called "EPC sections". Currently, there is a free list per section, but allocations simply target the lowest-numbered sections. This is functional, but has no NUMA awareness. Fortunately, EPC sections are covered by entries in the ACPI SRAT table. These entries allow each EPC section to be associated with a NUMA node, just like normal RAM. > Solution > ======== > > Use phys_to_target_node() to associate each NUMA node with the EPC > sections contained within its range. In sgx_alloc_epc_page(), first try > to allocate from the NUMA node, where the CPU is executing. If that > fails, allocate from other nodes, iterating them from the current node > in order. To me, this is just telling us what the code does. It's not very useful. I'd say: Implement a NUMA-aware enclave page allocator. Mirror the buddy allocator and maintain a list of enclave pages for each NUMA node. Attempt to allocate enclave memory first from local nodes, then fall back to other nodes. Note that the fallback is not as sophisticated as the buddy allocator and is itself not aware of NUMA distances. When a node's free list is empty, it searches for the next-highest node with enclave pages (and will wrap if necessary). This could be improved in the future. > Other > ===== > > NUMA_KEEP_MEMINFO dependency is required for phys_to_target_node(). Reading the changelog, it's not obvious that you're talking about a Kconfig variable here. I was also thinking, this says: # Keep arch NUMA mapping infrastructure post-init. config NUMA_KEEP_MEMINFO bool But we only need it during SGX init. Could you explain a bit why it's needed here specifically? Superficially it seems like we only need this info *during* init. > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > index 513895af8ee7..3e6152a8dd2b 100644 > --- a/arch/x86/Kconfig > +++ b/arch/x86/Kconfig > @@ -1930,6 +1930,7 @@ config X86_SGX > depends on CRYPTO_SHA256=y > select SRCU > select MMU_NOTIFIER > + select NUMA_KEEP_MEMINFO if NUMA > help > Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions > that can be used by applications to set aside private regions of code > diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c > index cb4561444b96..3b524a1361d6 100644 > --- a/arch/x86/kernel/cpu/sgx/main.c > +++ b/arch/x86/kernel/cpu/sgx/main.c > @@ -18,14 +18,23 @@ static int sgx_nr_epc_sections; > static struct task_struct *ksgxd_tsk; > static DECLARE_WAIT_QUEUE_HEAD(ksgxd_waitq); > > -/* > - * These variables are part of the state of the reclaimer, and must be accessed > - * with sgx_reclaimer_lock acquired. > - */ > +/* The reclaimer lock protected variables prepend the lock. */ > static LIST_HEAD(sgx_active_page_list); > - > static DEFINE_SPINLOCK(sgx_reclaimer_lock); > > +/* The free page list lock protected variables prepend the lock. */ > +static unsigned long sgx_nr_free_pages; > + > +/* Nodes with one or more EPC sections. */ > +static nodemask_t sgx_numa_mask; > + > +/* > + * Array with one list_head for each possible NUMA node. Each > + * list contains all the sgx_epc_section's which are on that > + * node. > + */ > +static struct sgx_numa_node *sgx_numa_nodes; > + > /* > * When the driver initialized, EPC pages go first here, as they could be > * initialized to an active enclave, on kexec entry. > @@ -352,21 +361,9 @@ static void sgx_reclaim_pages(void) > } > } > > -static unsigned long sgx_nr_free_pages(void) > -{ > - unsigned long cnt = 0; > - int i; > - > - for (i = 0; i < sgx_nr_epc_sections; i++) > - cnt += sgx_epc_sections[i].free_cnt; > - > - return cnt; > -} > - > static bool sgx_should_reclaim(unsigned long watermark) > { > - return sgx_nr_free_pages() < watermark && > - !list_empty(&sgx_active_page_list); > + return sgx_nr_free_pages < watermark && !list_empty(&sgx_active_page_list); > } > > static int ksgxd(void *p) > @@ -443,50 +440,63 @@ static bool __init sgx_page_reclaimer_init(void) > return true; > } > > -static struct sgx_epc_page *__sgx_alloc_epc_page_from_section(struct sgx_epc_section *section) > +static struct sgx_epc_page *__sgx_alloc_epc_page_from_node(int nid) > { > - struct sgx_epc_page *page; > + struct sgx_numa_node *node = &sgx_numa_nodes[nid]; > + struct sgx_epc_page *page = NULL; > + > + if (!node_isset(nid, sgx_numa_mask)) > + return NULL; I don't think this mask check is super necessary. It won't ever trigger for the "fallback" path. For the node-local allocation, I guess it saves a cacheline (node->free_page_list). > - spin_lock(§ion->lock); > + spin_lock(&node->lock); > > - if (list_empty(§ion->page_list)) { > - spin_unlock(§ion->lock); > + if (list_empty(&node->free_page_list)) { > + spin_unlock(&node->lock); > return NULL; > } > > - page = list_first_entry(§ion->page_list, struct sgx_epc_page, list); > + page = list_first_entry(&node->free_page_list, struct sgx_epc_page, list); > list_del_init(&page->list); > - section->free_cnt--; > + sgx_nr_free_pages--; > + > + spin_unlock(&node->lock); > > - spin_unlock(§ion->lock); > return page; > } > > /** > * __sgx_alloc_epc_page() - Allocate an EPC page > * > - * Iterate through EPC sections and borrow a free EPC page to the caller. When a > - * page is no longer needed it must be released with sgx_free_epc_page(). > + * Iterate through NUMA nodes and borrow a free EPC page to the caller. When a "borrow" is a weird word to use here. > + * page is no longer needed it must be released with sgx_free_epc_page(). Start > + * from the NUMA node, where the caller is executing. I don't think we need to tell folks how allocators work: that "free" and "alloc" are opposites. > * Return: > - * an EPC page, > - * -errno on error > + * - an EPC page: Free EPC pages were available. > + * - ERR_PTR(-ENOMEM): Run out of EPC pages. > */ I think returning NULL from a allocator is probably OK. Folks understand that NULL means ENOMEM. > struct sgx_epc_page *__sgx_alloc_epc_page(void) > { > - struct sgx_epc_section *section; > struct sgx_epc_page *page; > - int i; > + int nid = numa_node_id(); > > - for (i = 0; i < sgx_nr_epc_sections; i++) { > - section = &sgx_epc_sections[i]; > + /* Try to allocate EPC from the current node, first: */ > + page = __sgx_alloc_epc_page_from_node(nid); > + if (page) > + return page; > > - page = __sgx_alloc_epc_page_from_section(section); > + /* Then, go through the other nodes: */ > + while (true) { > + nid = next_node_in(nid, sgx_numa_mask); > + if (nid == numa_node_id()) > + break; One nit: This can _theoretically_ livelock. Preemption is enabled here and numa_node_id() can change. It's theoretically possible that numa_node_id()!=nid forever. The way to prevent this is to read numa_node_id() once and then compare 'nid' against that single read. > + page = __sgx_alloc_epc_page_from_node(nid); > if (page) > - return page; > + break; > } > > - return ERR_PTR(-ENOMEM); > + return page; > } I guess you probably wrote it this way because you prefer it. But, this can be written with a single call to __sgx_alloc_epc_page_from_node(). > /** > @@ -592,6 +602,7 @@ struct sgx_epc_page *sgx_alloc_epc_page(void *owner, bool reclaim) > void sgx_free_epc_page(struct sgx_epc_page *page) > { > struct sgx_epc_section *section = &sgx_epc_sections[page->section]; > + struct sgx_numa_node *node = section->node; > int ret; > > WARN_ON_ONCE(page->flags & SGX_EPC_PAGE_RECLAIMER_TRACKED); > @@ -600,10 +611,12 @@ void sgx_free_epc_page(struct sgx_epc_page *page) > if (WARN_ONCE(ret, "EREMOVE returned %d (0x%x)", ret, ret)) > return; > > - spin_lock(§ion->lock); > - list_add_tail(&page->list, §ion->page_list); > - section->free_cnt++; > - spin_unlock(§ion->lock); > + spin_lock(&node->lock); > + > + list_add_tail(&page->list, &node->free_page_list); > + sgx_nr_free_pages++; > + > + spin_unlock(&node->lock); > } > > static bool __init sgx_setup_epc_section(u64 phys_addr, u64 size, > @@ -624,8 +637,6 @@ static bool __init sgx_setup_epc_section(u64 phys_addr, u64 size, > } > > section->phys_addr = phys_addr; > - spin_lock_init(§ion->lock); > - INIT_LIST_HEAD(§ion->page_list); > > for (i = 0; i < nr_pages; i++) { > section->pages[i].section = index; > @@ -634,7 +645,7 @@ static bool __init sgx_setup_epc_section(u64 phys_addr, u64 size, > list_add_tail(§ion->pages[i].list, &sgx_dirty_page_list); > } > > - section->free_cnt = nr_pages; > + sgx_nr_free_pages += nr_pages; > return true; > } > > @@ -653,8 +664,11 @@ static bool __init sgx_page_cache_init(void) > { > u32 eax, ebx, ecx, edx, type; > u64 pa, size; > + int nid; > int i; > > + sgx_numa_nodes = kmalloc_array(num_possible_nodes(), sizeof(*sgx_numa_nodes), GFP_KERNEL); Needs a NULL check. > for (i = 0; i < ARRAY_SIZE(sgx_epc_sections); i++) { > cpuid_count(SGX_CPUID, i + SGX_CPUID_EPC, &eax, &ebx, &ecx, &edx); > > @@ -677,6 +691,21 @@ static bool __init sgx_page_cache_init(void) > break; > } > > + nid = numa_map_to_online_node(phys_to_target_node(pa)); > + if (nid == NUMA_NO_NODE) { > + /* The physical address is already printed above. */ > + pr_warn(FW_BUG "Unable to map EPC section to online node. Fallback to the NUMA node 0.\n"); > + nid = 0; > + } > + > + if (!node_isset(nid, sgx_numa_mask)) { > + spin_lock_init(&sgx_numa_nodes[nid].lock); > + INIT_LIST_HEAD(&sgx_numa_nodes[nid].free_page_list); > + node_set(nid, sgx_numa_mask); > + } > + > + sgx_epc_sections[i].node = &sgx_numa_nodes[nid]; > + > sgx_nr_epc_sections++; > } The rest looks OK.
On Mon, Mar 15, 2021 at 09:35:03AM -0700, Dave Hansen wrote: > On 3/13/21 8:01 AM, Jarkko Sakkinen wrote: > > Background > > ========== > > > > EPC section is covered by one or more SRAT entries that are associated with > > one and only one PXM (NUMA node). The motivation behind this patch is to > > provide basic elements of building allocation scheme based on this premise. > > A better set of background information here would also remind folks what > an 'EPC section' is. I don't actually know what exactly they are, because SDM's definition is not very rigorous ;-) I.e. it is not too precise between NUMA node and section relationship. > > > Just like normal RAM, enclave memory (EPC) should be covered by entries > > in the ACPI SRAT table. These entries allow each EPC section to be > > associated with a NUMA node. > > > > Use this information to implement a simple NUMA-aware allocator for > > enclave memory. > > SGX enclave memory is enumerated by the processor in contiguous physical > ranges called "EPC sections". Currently, there is a free list per > section, but allocations simply target the lowest-numbered sections. > This is functional, but has no NUMA awareness. > > Fortunately, EPC sections are covered by entries in the ACPI SRAT table. > These entries allow each EPC section to be associated with a NUMA node, > just like normal RAM. Thanks! > > Solution > > ======== > > > > Use phys_to_target_node() to associate each NUMA node with the EPC > > sections contained within its range. In sgx_alloc_epc_page(), first try > > to allocate from the NUMA node, where the CPU is executing. If that > > fails, allocate from other nodes, iterating them from the current node > > in order. > > To me, this is just telling us what the code does. It's not very > useful. I'd say: > > Implement a NUMA-aware enclave page allocator. Mirror the buddy > allocator and maintain a list of enclave pages for each NUMA node. > Attempt to allocate enclave memory first from local nodes, then fall > back to other nodes. > > Note that the fallback is not as sophisticated as the buddy allocator > and is itself not aware of NUMA distances. When a node's free list is > empty, it searches for the next-highest node with enclave pages (and > will wrap if necessary). This could be improved in the future. Thanks. > > Other > > ===== > > > > NUMA_KEEP_MEMINFO dependency is required for phys_to_target_node(). > > Reading the changelog, it's not obvious that you're talking about a > Kconfig variable here. > > I was also thinking, this says: > > # Keep arch NUMA mapping infrastructure post-init. > config NUMA_KEEP_MEMINFO > bool > > But we only need it during SGX init. Could you explain a bit why it's > needed here specifically? Superficially it seems like we only need this > info *during* init. Well, numa_meminfo is a static variable of mm/numa.c, so we cannot directly access it. And phys_to_numa_node(), which accesses its data, does not exist, unless NUMA_KEEP_MEMINFO is defined. So, yes, theoretically we could pull the data withotu NUMA_KEEP_MEMINFO, but thise would require to numa_meminfo a global variable. We do not care about post-init part, in that sense you are right. > > > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > > index 513895af8ee7..3e6152a8dd2b 100644 > > --- a/arch/x86/Kconfig > > +++ b/arch/x86/Kconfig > > @@ -1930,6 +1930,7 @@ config X86_SGX > > depends on CRYPTO_SHA256=y > > select SRCU > > select MMU_NOTIFIER > > + select NUMA_KEEP_MEMINFO if NUMA > > help > > Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions > > that can be used by applications to set aside private regions of code > > diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c > > index cb4561444b96..3b524a1361d6 100644 > > --- a/arch/x86/kernel/cpu/sgx/main.c > > +++ b/arch/x86/kernel/cpu/sgx/main.c > > @@ -18,14 +18,23 @@ static int sgx_nr_epc_sections; > > static struct task_struct *ksgxd_tsk; > > static DECLARE_WAIT_QUEUE_HEAD(ksgxd_waitq); > > > > -/* > > - * These variables are part of the state of the reclaimer, and must be accessed > > - * with sgx_reclaimer_lock acquired. > > - */ > > +/* The reclaimer lock protected variables prepend the lock. */ > > static LIST_HEAD(sgx_active_page_list); > > - > > static DEFINE_SPINLOCK(sgx_reclaimer_lock); > > > > +/* The free page list lock protected variables prepend the lock. */ > > +static unsigned long sgx_nr_free_pages; > > + > > +/* Nodes with one or more EPC sections. */ > > +static nodemask_t sgx_numa_mask; > > + > > +/* > > + * Array with one list_head for each possible NUMA node. Each > > + * list contains all the sgx_epc_section's which are on that > > + * node. > > + */ > > +static struct sgx_numa_node *sgx_numa_nodes; > > + > > /* > > * When the driver initialized, EPC pages go first here, as they could be > > * initialized to an active enclave, on kexec entry. > > @@ -352,21 +361,9 @@ static void sgx_reclaim_pages(void) > > } > > } > > > > -static unsigned long sgx_nr_free_pages(void) > > -{ > > - unsigned long cnt = 0; > > - int i; > > - > > - for (i = 0; i < sgx_nr_epc_sections; i++) > > - cnt += sgx_epc_sections[i].free_cnt; > > - > > - return cnt; > > -} > > - > > static bool sgx_should_reclaim(unsigned long watermark) > > { > > - return sgx_nr_free_pages() < watermark && > > - !list_empty(&sgx_active_page_list); > > + return sgx_nr_free_pages < watermark && !list_empty(&sgx_active_page_list); > > } > > > > static int ksgxd(void *p) > > @@ -443,50 +440,63 @@ static bool __init sgx_page_reclaimer_init(void) > > return true; > > } > > > > -static struct sgx_epc_page *__sgx_alloc_epc_page_from_section(struct sgx_epc_section *section) > > +static struct sgx_epc_page *__sgx_alloc_epc_page_from_node(int nid) > > { > > - struct sgx_epc_page *page; > > + struct sgx_numa_node *node = &sgx_numa_nodes[nid]; > > + struct sgx_epc_page *page = NULL; > > + > > + if (!node_isset(nid, sgx_numa_mask)) > > + return NULL; > > I don't think this mask check is super necessary. It won't ever trigger > for the "fallback" path. For the node-local allocation, I guess it > saves a cacheline (node->free_page_list). > > > - spin_lock(§ion->lock); > > + spin_lock(&node->lock); > > > > - if (list_empty(§ion->page_list)) { > > - spin_unlock(§ion->lock); > > + if (list_empty(&node->free_page_list)) { > > + spin_unlock(&node->lock); > > return NULL; > > } > > > > - page = list_first_entry(§ion->page_list, struct sgx_epc_page, list); > > + page = list_first_entry(&node->free_page_list, struct sgx_epc_page, list); > > list_del_init(&page->list); > > - section->free_cnt--; > > + sgx_nr_free_pages--; > > + > > + spin_unlock(&node->lock); > > > > - spin_unlock(§ion->lock); > > return page; > > } > > > > /** > > * __sgx_alloc_epc_page() - Allocate an EPC page > > * > > - * Iterate through EPC sections and borrow a free EPC page to the caller. When a > > - * page is no longer needed it must be released with sgx_free_epc_page(). > > + * Iterate through NUMA nodes and borrow a free EPC page to the caller. When a > > "borrow" is a weird word to use here. > > > + * page is no longer needed it must be released with sgx_free_epc_page(). Start > > + * from the NUMA node, where the caller is executing. > > I don't think we need to tell folks how allocators work: that "free" and > "alloc" are opposites. > > > * Return: > > - * an EPC page, > > - * -errno on error > > + * - an EPC page: Free EPC pages were available. > > + * - ERR_PTR(-ENOMEM): Run out of EPC pages. > > */ > > I think returning NULL from a allocator is probably OK. Folks > understand that NULL means ENOMEM. > > > struct sgx_epc_page *__sgx_alloc_epc_page(void) > > { > > - struct sgx_epc_section *section; > > struct sgx_epc_page *page; > > - int i; > > + int nid = numa_node_id(); > > > > - for (i = 0; i < sgx_nr_epc_sections; i++) { > > - section = &sgx_epc_sections[i]; > > + /* Try to allocate EPC from the current node, first: */ > > + page = __sgx_alloc_epc_page_from_node(nid); > > + if (page) > > + return page; > > > > - page = __sgx_alloc_epc_page_from_section(section); > > + /* Then, go through the other nodes: */ > > + while (true) { > > + nid = next_node_in(nid, sgx_numa_mask); > > + if (nid == numa_node_id()) > > + break; > > One nit: This can _theoretically_ livelock. Preemption is enabled here > and numa_node_id() can change. It's theoretically possible that > numa_node_id()!=nid forever. > > The way to prevent this is to read numa_node_id() once and then compare > 'nid' against that single read. > > > + page = __sgx_alloc_epc_page_from_node(nid); > > if (page) > > - return page; > > + break; > > } > > > > - return ERR_PTR(-ENOMEM); > > + return page; > > } > > I guess you probably wrote it this way because you prefer it. But, this > can be written with a single call to __sgx_alloc_epc_page_from_node(). > > > /** > > @@ -592,6 +602,7 @@ struct sgx_epc_page *sgx_alloc_epc_page(void *owner, bool reclaim) > > void sgx_free_epc_page(struct sgx_epc_page *page) > > { > > struct sgx_epc_section *section = &sgx_epc_sections[page->section]; > > + struct sgx_numa_node *node = section->node; > > int ret; > > > > WARN_ON_ONCE(page->flags & SGX_EPC_PAGE_RECLAIMER_TRACKED); > > @@ -600,10 +611,12 @@ void sgx_free_epc_page(struct sgx_epc_page *page) > > if (WARN_ONCE(ret, "EREMOVE returned %d (0x%x)", ret, ret)) > > return; > > > > - spin_lock(§ion->lock); > > - list_add_tail(&page->list, §ion->page_list); > > - section->free_cnt++; > > - spin_unlock(§ion->lock); > > + spin_lock(&node->lock); > > + > > + list_add_tail(&page->list, &node->free_page_list); > > + sgx_nr_free_pages++; > > + > > + spin_unlock(&node->lock); > > } > > > > static bool __init sgx_setup_epc_section(u64 phys_addr, u64 size, > > @@ -624,8 +637,6 @@ static bool __init sgx_setup_epc_section(u64 phys_addr, u64 size, > > } > > > > section->phys_addr = phys_addr; > > - spin_lock_init(§ion->lock); > > - INIT_LIST_HEAD(§ion->page_list); > > > > for (i = 0; i < nr_pages; i++) { > > section->pages[i].section = index; > > @@ -634,7 +645,7 @@ static bool __init sgx_setup_epc_section(u64 phys_addr, u64 size, > > list_add_tail(§ion->pages[i].list, &sgx_dirty_page_list); > > } > > > > - section->free_cnt = nr_pages; > > + sgx_nr_free_pages += nr_pages; > > return true; > > } > > > > @@ -653,8 +664,11 @@ static bool __init sgx_page_cache_init(void) > > { > > u32 eax, ebx, ecx, edx, type; > > u64 pa, size; > > + int nid; > > int i; > > > > + sgx_numa_nodes = kmalloc_array(num_possible_nodes(), sizeof(*sgx_numa_nodes), GFP_KERNEL); > > Needs a NULL check. Ugh, lol, I did spot this but forgot to fix it. Darn, well, I'll fix it for the next version :-) > > > for (i = 0; i < ARRAY_SIZE(sgx_epc_sections); i++) { > > cpuid_count(SGX_CPUID, i + SGX_CPUID_EPC, &eax, &ebx, &ecx, &edx); > > > > @@ -677,6 +691,21 @@ static bool __init sgx_page_cache_init(void) > > break; > > } > > > > + nid = numa_map_to_online_node(phys_to_target_node(pa)); > > + if (nid == NUMA_NO_NODE) { > > + /* The physical address is already printed above. */ > > + pr_warn(FW_BUG "Unable to map EPC section to online node. Fallback to the NUMA node 0.\n"); > > + nid = 0; > > + } > > + > > + if (!node_isset(nid, sgx_numa_mask)) { > > + spin_lock_init(&sgx_numa_nodes[nid].lock); > > + INIT_LIST_HEAD(&sgx_numa_nodes[nid].free_page_list); > > + node_set(nid, sgx_numa_mask); > > + } > > + > > + sgx_epc_sections[i].node = &sgx_numa_nodes[nid]; > > + > > sgx_nr_epc_sections++; > > } > > The rest looks OK. > /Jarkko
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 513895af8ee7..3e6152a8dd2b 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -1930,6 +1930,7 @@ config X86_SGX depends on CRYPTO_SHA256=y select SRCU select MMU_NOTIFIER + select NUMA_KEEP_MEMINFO if NUMA help Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions that can be used by applications to set aside private regions of code diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c index cb4561444b96..3b524a1361d6 100644 --- a/arch/x86/kernel/cpu/sgx/main.c +++ b/arch/x86/kernel/cpu/sgx/main.c @@ -18,14 +18,23 @@ static int sgx_nr_epc_sections; static struct task_struct *ksgxd_tsk; static DECLARE_WAIT_QUEUE_HEAD(ksgxd_waitq); -/* - * These variables are part of the state of the reclaimer, and must be accessed - * with sgx_reclaimer_lock acquired. - */ +/* The reclaimer lock protected variables prepend the lock. */ static LIST_HEAD(sgx_active_page_list); - static DEFINE_SPINLOCK(sgx_reclaimer_lock); +/* The free page list lock protected variables prepend the lock. */ +static unsigned long sgx_nr_free_pages; + +/* Nodes with one or more EPC sections. */ +static nodemask_t sgx_numa_mask; + +/* + * Array with one list_head for each possible NUMA node. Each + * list contains all the sgx_epc_section's which are on that + * node. + */ +static struct sgx_numa_node *sgx_numa_nodes; + /* * When the driver initialized, EPC pages go first here, as they could be * initialized to an active enclave, on kexec entry. @@ -352,21 +361,9 @@ static void sgx_reclaim_pages(void) } } -static unsigned long sgx_nr_free_pages(void) -{ - unsigned long cnt = 0; - int i; - - for (i = 0; i < sgx_nr_epc_sections; i++) - cnt += sgx_epc_sections[i].free_cnt; - - return cnt; -} - static bool sgx_should_reclaim(unsigned long watermark) { - return sgx_nr_free_pages() < watermark && - !list_empty(&sgx_active_page_list); + return sgx_nr_free_pages < watermark && !list_empty(&sgx_active_page_list); } static int ksgxd(void *p) @@ -443,50 +440,63 @@ static bool __init sgx_page_reclaimer_init(void) return true; } -static struct sgx_epc_page *__sgx_alloc_epc_page_from_section(struct sgx_epc_section *section) +static struct sgx_epc_page *__sgx_alloc_epc_page_from_node(int nid) { - struct sgx_epc_page *page; + struct sgx_numa_node *node = &sgx_numa_nodes[nid]; + struct sgx_epc_page *page = NULL; + + if (!node_isset(nid, sgx_numa_mask)) + return NULL; - spin_lock(§ion->lock); + spin_lock(&node->lock); - if (list_empty(§ion->page_list)) { - spin_unlock(§ion->lock); + if (list_empty(&node->free_page_list)) { + spin_unlock(&node->lock); return NULL; } - page = list_first_entry(§ion->page_list, struct sgx_epc_page, list); + page = list_first_entry(&node->free_page_list, struct sgx_epc_page, list); list_del_init(&page->list); - section->free_cnt--; + sgx_nr_free_pages--; + + spin_unlock(&node->lock); - spin_unlock(§ion->lock); return page; } /** * __sgx_alloc_epc_page() - Allocate an EPC page * - * Iterate through EPC sections and borrow a free EPC page to the caller. When a - * page is no longer needed it must be released with sgx_free_epc_page(). + * Iterate through NUMA nodes and borrow a free EPC page to the caller. When a + * page is no longer needed it must be released with sgx_free_epc_page(). Start + * from the NUMA node, where the caller is executing. * * Return: - * an EPC page, - * -errno on error + * - an EPC page: Free EPC pages were available. + * - ERR_PTR(-ENOMEM): Run out of EPC pages. */ struct sgx_epc_page *__sgx_alloc_epc_page(void) { - struct sgx_epc_section *section; struct sgx_epc_page *page; - int i; + int nid = numa_node_id(); - for (i = 0; i < sgx_nr_epc_sections; i++) { - section = &sgx_epc_sections[i]; + /* Try to allocate EPC from the current node, first: */ + page = __sgx_alloc_epc_page_from_node(nid); + if (page) + return page; - page = __sgx_alloc_epc_page_from_section(section); + /* Then, go through the other nodes: */ + while (true) { + nid = next_node_in(nid, sgx_numa_mask); + if (nid == numa_node_id()) + break; + + page = __sgx_alloc_epc_page_from_node(nid); if (page) - return page; + break; } - return ERR_PTR(-ENOMEM); + return page; } /** @@ -592,6 +602,7 @@ struct sgx_epc_page *sgx_alloc_epc_page(void *owner, bool reclaim) void sgx_free_epc_page(struct sgx_epc_page *page) { struct sgx_epc_section *section = &sgx_epc_sections[page->section]; + struct sgx_numa_node *node = section->node; int ret; WARN_ON_ONCE(page->flags & SGX_EPC_PAGE_RECLAIMER_TRACKED); @@ -600,10 +611,12 @@ void sgx_free_epc_page(struct sgx_epc_page *page) if (WARN_ONCE(ret, "EREMOVE returned %d (0x%x)", ret, ret)) return; - spin_lock(§ion->lock); - list_add_tail(&page->list, §ion->page_list); - section->free_cnt++; - spin_unlock(§ion->lock); + spin_lock(&node->lock); + + list_add_tail(&page->list, &node->free_page_list); + sgx_nr_free_pages++; + + spin_unlock(&node->lock); } static bool __init sgx_setup_epc_section(u64 phys_addr, u64 size, @@ -624,8 +637,6 @@ static bool __init sgx_setup_epc_section(u64 phys_addr, u64 size, } section->phys_addr = phys_addr; - spin_lock_init(§ion->lock); - INIT_LIST_HEAD(§ion->page_list); for (i = 0; i < nr_pages; i++) { section->pages[i].section = index; @@ -634,7 +645,7 @@ static bool __init sgx_setup_epc_section(u64 phys_addr, u64 size, list_add_tail(§ion->pages[i].list, &sgx_dirty_page_list); } - section->free_cnt = nr_pages; + sgx_nr_free_pages += nr_pages; return true; } @@ -653,8 +664,11 @@ static bool __init sgx_page_cache_init(void) { u32 eax, ebx, ecx, edx, type; u64 pa, size; + int nid; int i; + sgx_numa_nodes = kmalloc_array(num_possible_nodes(), sizeof(*sgx_numa_nodes), GFP_KERNEL); + for (i = 0; i < ARRAY_SIZE(sgx_epc_sections); i++) { cpuid_count(SGX_CPUID, i + SGX_CPUID_EPC, &eax, &ebx, &ecx, &edx); @@ -677,6 +691,21 @@ static bool __init sgx_page_cache_init(void) break; } + nid = numa_map_to_online_node(phys_to_target_node(pa)); + if (nid == NUMA_NO_NODE) { + /* The physical address is already printed above. */ + pr_warn(FW_BUG "Unable to map EPC section to online node. Fallback to the NUMA node 0.\n"); + nid = 0; + } + + if (!node_isset(nid, sgx_numa_mask)) { + spin_lock_init(&sgx_numa_nodes[nid].lock); + INIT_LIST_HEAD(&sgx_numa_nodes[nid].free_page_list); + node_set(nid, sgx_numa_mask); + } + + sgx_epc_sections[i].node = &sgx_numa_nodes[nid]; + sgx_nr_epc_sections++; } diff --git a/arch/x86/kernel/cpu/sgx/sgx.h b/arch/x86/kernel/cpu/sgx/sgx.h index bc8af0428640..653af8ca1a25 100644 --- a/arch/x86/kernel/cpu/sgx/sgx.h +++ b/arch/x86/kernel/cpu/sgx/sgx.h @@ -29,22 +29,26 @@ struct sgx_epc_page { struct list_head list; }; +/* + * Contains the tracking data for NUMA nodes having EPC pages. Most importantly, + * the free page list local to the node is stored here. + */ +struct sgx_numa_node { + struct list_head free_page_list; + spinlock_t lock; +}; + /* * The firmware can define multiple chunks of EPC to the different areas of the * physical memory e.g. for memory areas of the each node. This structure is * used to store EPC pages for one EPC section and virtual memory area where * the pages have been mapped. - * - * 'lock' must be held before accessing 'page_list' or 'free_cnt'. */ struct sgx_epc_section { unsigned long phys_addr; void *virt_addr; struct sgx_epc_page *pages; - - spinlock_t lock; - struct list_head page_list; - unsigned long free_cnt; + struct sgx_numa_node *node; }; extern struct sgx_epc_section sgx_epc_sections[SGX_MAX_EPC_SECTIONS];
Background ========== EPC section is covered by one or more SRAT entries that are associated with one and only one PXM (NUMA node). The motivation behind this patch is to provide basic elements of building allocation scheme based on this premise. Just like normal RAM, enclave memory (EPC) should be covered by entries in the ACPI SRAT table. These entries allow each EPC section to be associated with a NUMA node. Use this information to implement a simple NUMA-aware allocator for enclave memory. Solution ======== Use phys_to_target_node() to associate each NUMA node with the EPC sections contained within its range. In sgx_alloc_epc_page(), first try to allocate from the NUMA node, where the CPU is executing. If that fails, allocate from other nodes, iterating them from the current node in order. Other ===== NUMA_KEEP_MEMINFO dependency is required for phys_to_target_node(). Link: https://lore.kernel.org/lkml/158188326978.894464.217282995221175417.stgit@dwillia2-desk3.amr.corp.intel.com/ Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org> --- v4: * Cycle nodes instead of a global page list, starting from the node of the current thread. * Documented NUMA_KEEP_MEMINFO dependency to the commit message. * Added NUMA node pointer to struct sgx_epc_section. EPC page should reference to a section, since potentially a node could have multiple sections (Intel SDM does not say anything explicit about this). This the safest play. * Remove nodes_clear(sgx_numa_node_mask). * Appended Dave's additions to the commit message for the background section. arch/x86/Kconfig | 1 + arch/x86/kernel/cpu/sgx/main.c | 117 ++++++++++++++++++++------------- arch/x86/kernel/cpu/sgx/sgx.h | 16 +++-- 3 files changed, 84 insertions(+), 50 deletions(-)