From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sean Christopherson Subject: Re: [intel-sgx-kernel-dev] [PATCH RFC v3 07/12] intel_sgx: driver for Intel Software Guard Extensions Date: Thu, 02 Nov 2017 13:10:29 -0700 Message-ID: <1509653429.17230.20.camel@intel.com> References: <20171010143258.21623-1-jarkko.sakkinen@linux.intel.com> <20171010143258.21623-8-jarkko.sakkinen@linux.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit Return-path: Received: from mga06.intel.com ([134.134.136.31]:19941 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934342AbdKBUNQ (ORCPT ); Thu, 2 Nov 2017 16:13:16 -0400 In-Reply-To: <20171010143258.21623-8-jarkko.sakkinen@linux.intel.com> Sender: platform-driver-x86-owner@vger.kernel.org List-ID: To: Jarkko Sakkinen , intel-sgx-kernel-dev@lists.01.org Cc: platform-driver-x86@vger.kernel.org On Tue, 2017-10-10 at 17:32 +0300, Jarkko Sakkinen wrote: > +static int sgx_dev_init(struct device *parent, bool locked_msrs) > +{ > + struct sgx_context *sgx_dev; > + unsigned int eax, ebx, ecx, edx; > + unsigned long pa; > + unsigned long size; > + int ret; > + int i; > + > + pr_info("intel_sgx: " DRV_DESCRIPTION " v" DRV_VERSION "\n"); > + > + sgx_dev = sgxm_ctx_alloc(parent); > + > + sgx_locked_msrs = locked_msrs; > + > + cpuid_count(SGX_CPUID, SGX_CPUID_CAPABILITIES, &eax, &ebx, &ecx, > &edx); > + /* Only allow misc bits supported by the driver. */ > + sgx_misc_reserved = ~ebx | SGX_MISC_RESERVED_MASK; > +#ifdef CONFIG_X86_64 > + sgx_encl_size_max_64 = 1ULL << ((edx >> 8) & 0xFF); > +#endif > + sgx_encl_size_max_32 = 1ULL << (edx & 0xFF); > + > + if (boot_cpu_has(X86_FEATURE_OSXSAVE)) { > + cpuid_count(SGX_CPUID, SGX_CPUID_ATTRIBUTES, &eax, &ebx, > &ecx, > +     &edx); > + sgx_xfrm_mask = (((u64)edx) << 32) + (u64)ecx; > + > + for (i = 2; i < 64; i++) { > + cpuid_count(0x0D, i, &eax, &ebx, &ecx, &edx); > + if ((1 << i) & sgx_xfrm_mask) > + sgx_xsave_size_tbl[i] = eax + ebx; > + } > + } > + > + for (i = 0; i < SGX_MAX_EPC_BANKS; i++) { > + cpuid_count(SGX_CPUID, i + SGX_CPUID_EPC_BANKS, &eax, &ebx, > +     &ecx, &edx); > + if (!(eax & 0xf)) > + break; > + > + pa = ((u64)(ebx & 0xfffff) << 32) + (u64)(eax & 0xfffff000); > + size = ((u64)(edx & 0xfffff) << 32) + (u64)(ecx & > 0xfffff000); > + > + dev_info(parent, "EPC bank 0x%lx-0x%lx\n", pa, pa + size); > + > + sgx_epc_banks[i].pa = pa; > + sgx_epc_banks[i].size = size; > + } > + > + sgx_nr_epc_banks = i; > + > + for (i = 0; i < sgx_nr_epc_banks; i++) { > +#ifdef CONFIG_X86_64 > + sgx_epc_banks[i].va = (unsigned long) > + ioremap_cache(sgx_epc_banks[i].pa, > +       sgx_epc_banks[i].size); > + if (!sgx_epc_banks[i].va) { > + sgx_nr_epc_banks = i; > + ret = -ENOMEM; > + goto out_iounmap; > + } > +#endif > + ret = sgx_add_epc_bank(sgx_epc_banks[i].pa, > +        sgx_epc_banks[i].size, i); > + if (ret) { > + sgx_nr_epc_banks = i + 1; > + goto out_iounmap; > + } > + } > + > + ret = sgx_page_cache_init(); > + if (ret) > + goto out_iounmap; > + > + sgx_add_page_wq = alloc_workqueue("intel_sgx-add-page-wq", > +   WQ_UNBOUND | WQ_FREEZABLE, 1); > + if (!sgx_add_page_wq) { > + pr_err("intel_sgx: alloc_workqueue() failed\n"); > + ret = -ENOMEM; > + goto out_iounmap; > + } > + > + ret = cdev_device_add(&sgx_dev->cdev, &sgx_dev->dev); > + if (ret) > + goto out_workqueue; > + > + return 0; > +out_workqueue: > + destroy_workqueue(sgx_add_page_wq); > +out_iounmap: sgx_page_cache_teardown() should be called here, else ksgxswapd and the list of EPC pages will leak. > +#ifdef CONFIG_X86_64 > + for (i = 0; i < sgx_nr_epc_banks; i++) > + iounmap((void *)sgx_epc_banks[i].va); > +#endif > + return ret; > +} ...  > +int sgx_add_epc_bank(resource_size_t start, unsigned long size, int bank) > +{ > + unsigned long i; > + struct sgx_epc_page *new_epc_page, *entry; > + struct list_head *parser, *temp; > + > + for (i = 0; i < size; i += PAGE_SIZE) { > + new_epc_page = kzalloc(sizeof(*new_epc_page), GFP_KERNEL); > + if (!new_epc_page) > + goto err_freelist; > + new_epc_page->pa = (start + i) | bank; > + > + spin_lock(&sgx_free_list_lock); > + list_add_tail(&new_epc_page->list, &sgx_free_list); > + sgx_nr_total_epc_pages++; > + sgx_nr_free_pages++; > + spin_unlock(&sgx_free_list_lock); > + } > + > + return 0; > +err_freelist: > + list_for_each_safe(parser, temp, &sgx_free_list) { > + spin_lock(&sgx_free_list_lock); > + entry = list_entry(parser, struct sgx_epc_page, list); > + list_del(&entry->list); > + spin_unlock(&sgx_free_list_lock); > + kfree(entry); > + } > + return -ENOMEM; > +} Freeing the entire list on failure does not seem like the appropriate behavior for this helper func, e.g. the list should be purged by sgx_page_cache_teardown. Buffering the new pages into a local list and only splicing said list into the global list upon success is more inline with what I would expect from a helper func, and also only requires a single lock/unlock. diff --git drivers/platform/x86/intel_sgx/sgx_page_cache.c drivers/platform/x86/intel_sgx/sgx_page_cache.c index f8883d24692a..38496e6296f1 100644 --- drivers/platform/x86/intel_sgx/sgx_page_cache.c +++ drivers/platform/x86/intel_sgx/sgx_page_cache.c @@ -397,7 +397,8 @@ int sgx_add_epc_bank(resource_size_t start, unsigned long size, int bank)  {         unsigned long i;         struct sgx_epc_page *new_epc_page, *entry; -       struct list_head *parser, *temp; +       unsigned int nr_pages = 0; +       LIST_HEAD(epc_pages);           for (i = 0; i < size; i += PAGE_SIZE) {                 new_epc_page = kzalloc(sizeof(*new_epc_page), GFP_KERNEL); @@ -405,22 +406,19 @@ int sgx_add_epc_bank(resource_size_t start, unsigned long size, int bank)                         goto err_freelist;                 new_epc_page->pa = (start + i) | bank;   -               spin_lock(&sgx_free_list_lock); -               list_add_tail(&new_epc_page->list, &sgx_free_list); -               sgx_nr_total_epc_pages++; -               sgx_nr_free_pages++; -               spin_unlock(&sgx_free_list_lock); +               list_add_tail(&new_epc_page->list, &epc_pages); +               nr_pages++;         }   +       spin_lock(&sgx_free_list_lock); +       list_splice_tail(&epc_pages, &sgx_free_list); +       sgx_nr_total_epc_pages += nr_pages; +       sgx_nr_free_pages += nr_pages; +       spin_unlock(&sgx_free_list_lock);         return 0;  err_freelist: -       list_for_each_safe(parser, temp, &sgx_free_list) { -               spin_lock(&sgx_free_list_lock); -               entry = list_entry(parser, struct sgx_epc_page, list); -               list_del(&entry->list); -               spin_unlock(&sgx_free_list_lock); +       list_for_each_entry(entry, &sgx_free_list, list)                 kfree(entry); -       }         return -ENOMEM;  }