Use the xarray based sgx_va to maintain VA slots for an enclave. This effectively removes the need for any complex dynamic behaviour as the slots are assigned only in during the enclave construction.
Signed-off-by: Jarkko Sakkinen <[email protected]> --- arch/x86/kernel/cpu/sgx/driver.c | 3 +- arch/x86/kernel/cpu/sgx/encl.c | 60 ++--------------------------- arch/x86/kernel/cpu/sgx/encl.h | 12 ++---- arch/x86/kernel/cpu/sgx/ioctl.c | 65 ++++++++++++-------------------- arch/x86/kernel/cpu/sgx/main.c | 18 ++------- 5 files changed, 37 insertions(+), 121 deletions(-) diff --git a/arch/x86/kernel/cpu/sgx/driver.c b/arch/x86/kernel/cpu/sgx/driver.c index 8ce6d8371cfb..3fa52d962456 100644 --- a/arch/x86/kernel/cpu/sgx/driver.c +++ b/arch/x86/kernel/cpu/sgx/driver.c @@ -26,9 +26,10 @@ static int sgx_open(struct inode *inode, struct file *file) kref_init(&encl->refcount); xa_init(&encl->page_array); mutex_init(&encl->lock); - INIT_LIST_HEAD(&encl->va_pages); INIT_LIST_HEAD(&encl->mm_list); spin_lock_init(&encl->mm_lock); + ida_init(&encl->va_index); + sgx_va_init(&encl->va); ret = init_srcu_struct(&encl->srcu); if (ret) { diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c index c8ce3779eaa7..6aef00814afc 100644 --- a/arch/x86/kernel/cpu/sgx/encl.c +++ b/arch/x86/kernel/cpu/sgx/encl.c @@ -20,7 +20,7 @@ static int __sgx_encl_eldu(struct sgx_encl_page *encl_page, struct sgx_epc_page *epc_page, struct sgx_epc_page *secs_page) { - unsigned long va_offset = encl_page->desc & SGX_ENCL_PAGE_VA_OFFSET_MASK; + unsigned long va_offset = 8 * (encl_page->va_index & (SGX_VA_SLOT_COUNT - 1)); struct sgx_encl *encl = encl_page->encl; struct sgx_pageinfo pginfo; struct sgx_backing b; @@ -67,8 +67,6 @@ static struct sgx_epc_page *sgx_encl_eldu(struct sgx_encl_page *encl_page, struct sgx_epc_page *secs_page) { - unsigned long va_offset = encl_page->desc & SGX_ENCL_PAGE_VA_OFFSET_MASK; - struct sgx_encl *encl = encl_page->encl; struct sgx_epc_page *epc_page; int ret; @@ -82,9 +80,6 @@ static struct sgx_epc_page *sgx_encl_eldu(struct sgx_encl_page *encl_page, return ERR_PTR(ret); } - sgx_free_va_slot(encl_page->va_page, va_offset); - list_move(&encl_page->va_page->list, &encl->va_pages); - encl_page->desc &= ~SGX_ENCL_PAGE_VA_OFFSET_MASK; encl_page->epc_page = epc_page; return epc_page; @@ -391,7 +386,6 @@ const struct vm_operations_struct sgx_vm_ops = { void sgx_encl_release(struct kref *ref) { struct sgx_encl *encl = container_of(ref, struct sgx_encl, refcount); - struct sgx_va_page *va_page; struct sgx_encl_page *entry; unsigned long index; @@ -419,13 +413,8 @@ void sgx_encl_release(struct kref *ref) encl->secs.epc_page = NULL; } - while (!list_empty(&encl->va_pages)) { - va_page = list_first_entry(&encl->va_pages, struct sgx_va_page, - list); - list_del(&va_page->list); - sgx_free_epc_page(va_page->epc_page); - kfree(va_page); - } + sgx_va_destroy(&encl->va); + ida_destroy(&encl->va_index); if (encl->backing) fput(encl->backing); @@ -707,49 +696,6 @@ struct sgx_va_page *sgx_alloc_va_page(void) return ERR_PTR(ret); } -/** - * sgx_alloc_va_slot - allocate a VA slot - * @va_page: a &struct sgx_va_page instance - * - * Allocates a slot from a &struct sgx_va_page instance. - * - * Return: offset of the slot inside the VA page - */ -unsigned int sgx_alloc_va_slot(struct sgx_va_page *va_page) -{ - int slot = find_first_zero_bit(va_page->slots, SGX_VA_SLOT_COUNT); - - if (slot < SGX_VA_SLOT_COUNT) - set_bit(slot, va_page->slots); - - return slot << 3; -} - -/** - * sgx_free_va_slot - free a VA slot - * @va_page: a &struct sgx_va_page instance - * @offset: offset of the slot inside the VA page - * - * Frees a slot from a &struct sgx_va_page instance. - */ -void sgx_free_va_slot(struct sgx_va_page *va_page, unsigned int offset) -{ - clear_bit(offset >> 3, va_page->slots); -} - -/** - * sgx_va_page_full - is the VA page full? - * @va_page: a &struct sgx_va_page instance - * - * Return: true if all slots have been taken - */ -bool sgx_va_page_full(struct sgx_va_page *va_page) -{ - int slot = find_first_zero_bit(va_page->slots, SGX_VA_SLOT_COUNT); - - return slot == SGX_VA_SLOT_COUNT; -} - /** * sgx_va_init() - Initialize a version array (VA) * @va: A version array. diff --git a/arch/x86/kernel/cpu/sgx/encl.h b/arch/x86/kernel/cpu/sgx/encl.h index 806cf3ff7391..a1d6280029f0 100644 --- a/arch/x86/kernel/cpu/sgx/encl.h +++ b/arch/x86/kernel/cpu/sgx/encl.h @@ -8,6 +8,7 @@ #define _X86_ENCL_H #include <linux/cpumask.h> +#include <linux/idr.h> #include <linux/kref.h> #include <linux/list.h> #include <linux/mm_types.h> @@ -24,7 +25,6 @@ struct sgx_va_page { struct sgx_epc_page *epc_page; DECLARE_BITMAP(slots, SGX_VA_SLOT_COUNT); - struct list_head list; }; struct sgx_va { @@ -32,9 +32,6 @@ struct sgx_va { struct mutex lock; }; -/* 'desc' bits holding the offset in the VA (version array) page. */ -#define SGX_ENCL_PAGE_VA_OFFSET_MASK GENMASK_ULL(11, 3) - /* 'desc' bit marking that the page is being reclaimed. */ #define SGX_ENCL_PAGE_BEING_RECLAIMED BIT(3) @@ -44,6 +41,7 @@ struct sgx_encl_page { struct sgx_epc_page *epc_page; struct sgx_encl *encl; struct sgx_va_page *va_page; + int va_index; }; enum sgx_encl_flags { @@ -75,7 +73,8 @@ struct sgx_encl { cpumask_t cpumask; struct file *backing; struct kref refcount; - struct list_head va_pages; + struct ida va_index; + struct sgx_va va; unsigned long mm_list_version; struct list_head mm_list; spinlock_t mm_lock; @@ -117,9 +116,6 @@ int sgx_encl_test_and_clear_young(struct mm_struct *mm, struct sgx_encl_page *page); struct sgx_va_page *sgx_alloc_va_page(void); -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); void sgx_va_init(struct sgx_va *va); void sgx_va_destroy(struct sgx_va *va); diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c index db6e2c6ad42d..4a5393b25edd 100644 --- a/arch/x86/kernel/cpu/sgx/ioctl.c +++ b/arch/x86/kernel/cpu/sgx/ioctl.c @@ -16,47 +16,38 @@ #include "encl.h" #include "encls.h" -static struct sgx_va_page *sgx_encl_grow(struct sgx_encl *encl) +static int sgx_encl_alloc_va_slot(struct sgx_encl *encl, struct sgx_encl_page *encl_page) { - struct sgx_va_page *va_page = NULL; - - BUILD_BUG_ON(SGX_VA_SLOT_COUNT != (SGX_ENCL_PAGE_VA_OFFSET_MASK >> 3) + 1); - - if (!(encl->page_cnt % SGX_VA_SLOT_COUNT)) - va_page = sgx_alloc_va_page(); + struct sgx_va_page *va_page; + int ret; - encl->page_cnt++; + ret = ida_alloc(&encl->va_index, GFP_KERNEL); + if (ret < 0) + return ret; - return va_page; -} + va_page = sgx_va_get(&encl->va, ret); + if (IS_ERR(va_page)) { + ida_free(&encl->va_index, ret); + return PTR_ERR(va_page); + } -static void sgx_encl_shrink(struct sgx_encl *encl, struct sgx_va_page *va_page) -{ - encl->page_cnt--; + encl_page->va_page = va_page; + encl_page->va_index = ret; - if (va_page) { - sgx_free_epc_page(va_page->epc_page); - list_del(&va_page->list); - kfree(va_page); - } + return 0; } static int sgx_encl_create(struct sgx_encl *encl, struct sgx_secs *secs) { struct sgx_epc_page *secs_epc; - struct sgx_va_page *va_page; struct sgx_pageinfo pginfo; struct sgx_secinfo secinfo; unsigned long encl_size; struct file *backing; long ret; - va_page = sgx_encl_grow(encl); - if (IS_ERR(va_page)) - return PTR_ERR(va_page); - else if (va_page) - list_add(&va_page->list, &encl->va_pages); - /* else the tail page of the VA page list had free slots. */ + /* Get a VA slot for swapping the SECS. */ + ret = sgx_encl_alloc_va_slot(encl, &encl->secs); /* The extra page goes to SECS. */ encl_size = secs->size + PAGE_SIZE; @@ -65,7 +56,7 @@ static int sgx_encl_create(struct sgx_encl *encl, struct sgx_secs *secs) VM_NORESERVE); if (IS_ERR(backing)) { ret = PTR_ERR(backing); - goto err_out_shrink; + goto err_out_va; } encl->backing = backing; @@ -112,8 +103,9 @@ static int sgx_encl_create(struct sgx_encl *encl, struct sgx_secs *secs) fput(encl->backing); encl->backing = NULL; -err_out_shrink: - sgx_encl_shrink(encl, va_page); +err_out_va: + sgx_va_put(&encl->va, encl->secs.va_index); + ida_free(&encl->va_index, encl->secs.va_index); return ret; } @@ -280,7 +272,6 @@ static int sgx_encl_add_page(struct sgx_encl *encl, unsigned long src, { struct sgx_encl_page *encl_page; struct sgx_epc_page *epc_page; - struct sgx_va_page *va_page; int ret; encl_page = sgx_encl_page_alloc(encl, offset, secinfo->flags); @@ -293,22 +284,13 @@ static int sgx_encl_add_page(struct sgx_encl *encl, unsigned long src, return PTR_ERR(epc_page); } - va_page = sgx_encl_grow(encl); - if (IS_ERR(va_page)) { - ret = PTR_ERR(va_page); + ret = sgx_encl_alloc_va_slot(encl, encl_page); + if (ret) goto err_out_free; - } mmap_read_lock(current->mm); mutex_lock(&encl->lock); - /* - * Adding to encl->va_pages must be done under encl->lock. Ditto for - * deleting (via sgx_encl_shrink()) in the error path. - */ - if (va_page) - list_add(&va_page->list, &encl->va_pages); - /* * Insert prior to EADD in case of OOM. EADD modifies MRENCLAVE, i.e. * can't be gracefully unwound, while failure on EADD/EXTEND is limited @@ -348,7 +330,8 @@ static int sgx_encl_add_page(struct sgx_encl *encl, unsigned long src, xa_erase(&encl->page_array, PFN_DOWN(encl_page->desc)); err_out_unlock: - sgx_encl_shrink(encl, va_page); + sgx_va_put(&encl->va, encl_page->va_index); + ida_free(&encl->va_index, encl_page->va_index); mutex_unlock(&encl->lock); mmap_read_unlock(current->mm); diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c index 26dfe6aecd72..5b2e5767419c 100644 --- a/arch/x86/kernel/cpu/sgx/main.c +++ b/arch/x86/kernel/cpu/sgx/main.c @@ -215,12 +215,9 @@ static void sgx_encl_ewb(struct sgx_epc_page *epc_page, encl_page->desc &= ~SGX_ENCL_PAGE_BEING_RECLAIMED; - va_page = list_first_entry(&encl->va_pages, struct sgx_va_page, - list); - va_offset = sgx_alloc_va_slot(va_page); + va_page = encl_page->va_page; + va_offset = 8 * (encl_page->va_index & (SGX_VA_SLOT_COUNT - 1)); va_slot = sgx_get_epc_virt_addr(va_page->epc_page) + va_offset; - if (sgx_va_page_full(va_page)) - list_move_tail(&va_page->list, &encl->va_pages); ret = __sgx_encl_ewb(epc_page, va_slot, backing); if (ret == SGX_NOT_TRACKED) { @@ -245,15 +242,8 @@ static void sgx_encl_ewb(struct sgx_epc_page *epc_page, } } - if (ret) { - if (encls_failed(ret)) - ENCLS_WARN(ret, "EWB"); - - sgx_free_va_slot(va_page, va_offset); - } else { - encl_page->desc |= va_offset; - encl_page->va_page = va_page; - } + if (ret && encls_failed(ret)) + ENCLS_WARN(ret, "EWB"); } static void sgx_reclaimer_write(struct sgx_epc_page *epc_page, -- 2.30.1
