Messages in this thread | | | Date | Thu, 5 Nov 2020 16:08:39 +0100 | From | Borislav Petkov <> | Subject | Re: [PATCH v40 09/24] x86/sgx: Add SGX page allocator functions |
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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.
-- Regards/Gruss, Boris.
https://people.kernel.org/tglx/notes-about-netiquette
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