Message ID | 20201104145430.300542-10-jarkko.sakkinen@linux.intel.com (mailing list archive) |
---|---|
State | New, archived |
Headers | show |
Series | Intel SGX foundations | expand |
On Wed, Nov 04, 2020 at 04:54:15PM +0200, Jarkko Sakkinen wrote: > The previous patch initialized a simple SGX page allocator. 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. > > Acked-by: Jethro Beekman <jethro@fortanix.com> > Reviewed-by: Darren Kenny <darren.kenny@oracle.com> > Co-developed-by: Sean Christopherson <sean.j.christopherson@intel.com> > Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com> > Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> > --- > arch/x86/kernel/cpu/sgx/main.c | 62 ++++++++++++++++++++++++++++++++++ > arch/x86/kernel/cpu/sgx/sgx.h | 3 ++ > 2 files changed, 65 insertions(+) > > diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c > index 956055a0eff6..b9ac438a13a4 100644 > --- a/arch/x86/kernel/cpu/sgx/main.c > +++ b/arch/x86/kernel/cpu/sgx/main.c > @@ -85,6 +85,68 @@ 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; > + > + if (list_empty(§ion->page_list)) > + return NULL; > + > + page = list_first_entry(§ion->page_list, struct sgx_epc_page, list); > + list_del_init(&page->list); > + > + 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]; > + spin_lock(§ion->lock); > + page = __sgx_alloc_epc_page_from_section(section); > + spin_unlock(§ion->lock); Something for a future cleanup: you can put that logic into __sgx_alloc_epc_page_from_section() and simplify this one call site. But not now - you can do that later or if v41 needs to be sent out... Thx.
diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c index 956055a0eff6..b9ac438a13a4 100644 --- a/arch/x86/kernel/cpu/sgx/main.c +++ b/arch/x86/kernel/cpu/sgx/main.c @@ -85,6 +85,68 @@ 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; + + if (list_empty(§ion->page_list)) + return NULL; + + page = list_first_entry(§ion->page_list, struct sgx_epc_page, list); + list_del_init(&page->list); + + 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]; + spin_lock(§ion->lock); + page = __sgx_alloc_epc_page_from_section(section); + spin_unlock(§ion->lock); + + 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 02afa84dd8fd..bd9dcb1ffcfa 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 */