The following commit has been merged into the x86/sgx branch of tip: Commit-ID: d2285493bef310b66b56dfe4eb75c1e2f431ea5c Gitweb: https://git.kernel.org/tip/d2285493bef310b66b56dfe4eb75c1e2f431ea5c Author: Jarkko Sakkinen <[email protected]> AuthorDate: Fri, 13 Nov 2020 00:01:20 +02:00 Committer: Borislav Petkov <[email protected]> CommitterDate: Tue, 17 Nov 2020 14:36:13 +01:00
x86/sgx: Add SGX page allocator functions Add functions for runtime allocation and free. This allocator and its algorithms are as simple as it gets. They do a linear search across all EPC sections and find the first free page. They are not NUMA-aware and only hand out individual pages. The SGX hardware does not support large pages, so something more complicated like a buddy allocator is unwarranted. The free function (sgx_free_epc_page()) implicitly calls ENCLS[EREMOVE], which returns the page to the uninitialized state. This ensures that the page is ready for use at the next allocation. Co-developed-by: Sean Christopherson <[email protected]> Signed-off-by: Sean Christopherson <[email protected]> Signed-off-by: Jarkko Sakkinen <[email protected]> Signed-off-by: Borislav Petkov <[email protected]> Acked-by: Jethro Beekman <[email protected]> Link: https://lkml.kernel.org/r/[email protected] --- arch/x86/kernel/cpu/sgx/main.c | 65 +++++++++++++++++++++++++++++++++- arch/x86/kernel/cpu/sgx/sgx.h | 3 ++- 2 files changed, 68 insertions(+) diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c index 187a237..2e53afc 100644 --- a/arch/x86/kernel/cpu/sgx/main.c +++ b/arch/x86/kernel/cpu/sgx/main.c @@ -85,6 +85,71 @@ 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) +{ + struct sgx_epc_page *page; + + spin_lock(§ion->lock); + + if (list_empty(§ion->page_list)) { + spin_unlock(§ion->lock); + return NULL; + } + + page = list_first_entry(§ion->page_list, struct sgx_epc_page, list); + list_del_init(&page->list); + + 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(). + * + * Return: + * an EPC page, + * -errno on error + */ +struct sgx_epc_page *__sgx_alloc_epc_page(void) +{ + struct sgx_epc_section *section; + struct sgx_epc_page *page; + int i; + + for (i = 0; i < sgx_nr_epc_sections; i++) { + section = &sgx_epc_sections[i]; + + page = __sgx_alloc_epc_page_from_section(section); + if (page) + return page; + } + + return ERR_PTR(-ENOMEM); +} + +/** + * sgx_free_epc_page() - Free an EPC page + * @page: an EPC page + * + * Call EREMOVE for an EPC page and insert it back to the list of free pages. + */ +void sgx_free_epc_page(struct sgx_epc_page *page) +{ + struct sgx_epc_section *section = &sgx_epc_sections[page->section]; + int ret; + + ret = __eremove(sgx_get_epc_virt_addr(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); + spin_unlock(§ion->lock); +} + static bool __init sgx_setup_epc_section(u64 phys_addr, u64 size, unsigned long index, struct sgx_epc_section *section) diff --git a/arch/x86/kernel/cpu/sgx/sgx.h b/arch/x86/kernel/cpu/sgx/sgx.h index 02afa84..bd9dcb1 100644 --- a/arch/x86/kernel/cpu/sgx/sgx.h +++ b/arch/x86/kernel/cpu/sgx/sgx.h @@ -57,4 +57,7 @@ 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); +void sgx_free_epc_page(struct sgx_epc_page *page); + #endif /* _X86_SGX_H */
