From: Dave Hansen <dave.hansen@intel.com>
To: Hillf Danton <hdanton@sina.com>, Jarkko Sakkinen <jarkko@kernel.org>
Cc: x86@kernel.org, linux-sgx@vger.kernel.org,
linux-kernel@vger.kernel.org,
Sean Christopherson <sean.j.christopherson@intel.com>,
Jethro Beekman <jethro@fortanix.com>,
Serge Ayoun <serge.ayoun@intel.com>,
akpm@linux-foundation.org
Subject: Re: [PATCH v41 05/24] x86/sgx: Initialize metadata for Enclave Page Cache (EPC) sections
Date: Mon, 16 Nov 2020 10:33:24 -0800 [thread overview]
Message-ID: <0a96ecb7-50cc-634d-2f94-09e547be7b44@intel.com> (raw)
In-Reply-To: <20201114084211.5284-1-hdanton@sina.com>
On 11/14/20 12:42 AM, Hillf Danton wrote:
> On Fri, 13 Nov 2020 00:01:16 +0200 Jarkko Sakkinen wrote:
>> + */
>> +static void sgx_sanitize_section(struct sgx_epc_section *section)
>> +{
>> + struct sgx_epc_page *page;
>> + LIST_HEAD(dirty);
>> + int ret;
>> +
>> + while (!list_empty(§ion->laundry_list)) {
>> + if (kthread_should_stop())
>> + return;
>> +
>> + spin_lock(§ion->lock);
>> +
>> + page = list_first_entry(§ion->laundry_list,
>> + struct sgx_epc_page, list);
>> +
>> + ret = __eremove(sgx_get_epc_virt_addr(page));
>> + if (!ret)
>> + list_move(&page->list, §ion->page_list);
>> + else
>> + list_move_tail(&page->list, &dirty);
>> +
>> + spin_unlock(§ion->lock);
>> +
>> + cond_resched();
>> + }
>> +
>> + list_splice(&dirty, §ion->laundry_list);
>
> Move list splice into the section under section->lock.
The naming, commenting and changelogs could be better here. But, I
think the code is correct.
section->lock actually only protects ->page_list.
->laundry_list is initialized in core code, but after that is only used
by ksgxd and is effectively a thread-local structure.
I can think of a few other ways of doing this so that, for instance,
laundry_list was a thread-local structure in ksgxd that is freed after
initialization and sanitizing. But, this is pretty simple, although
under-documented, and wastes a list_head worth of space per section at
runtime.
>> +}
> [...]
>
>> +struct sgx_epc_page {
>> + unsigned int section;
>
> To make the sgx page naturally packed, add a small pad to match both
> sizeof(struct list_head) and X86_64. Feel free to turn back on the
> pad OTOH to save memory.
You make a good point: it's pretty obvious that the current code is
space-optimized. That doesn't seem like a bad thing to me, though.
next prev parent reply other threads:[~2020-11-16 18:33 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-12 22:01 [PATCH v41 00/24] Intel SGX foundations Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 01/24] x86/sgx: Add SGX architectural data structures Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 02/24] x86/sgx: Add wrappers for ENCLS functions Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 03/24] x86/cpufeatures: x86/msr: Add Intel SGX hardware bits Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 04/24] x86/cpufeatures: x86/msr: Add Intel SGX Launch Control " Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 05/24] x86/sgx: Initialize metadata for Enclave Page Cache (EPC) sections Jarkko Sakkinen
2020-11-16 22:25 ` [PATCH] x86/sgx: clarify 'laundry_list' locking Dave Hansen
2020-11-17 19:29 ` Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 06/24] x86/mm: x86/sgx: Signal SIGSEGV with PF_SGX Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 07/24] x86/cpu/intel: Detect SGX support Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 08/24] x86/cpu/intel: Add nosgx kernel parameter Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 09/24] x86/sgx: Add SGX page allocator functions Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 10/24] mm: Add 'mprotect' hook to struct vm_operations_struct Jarkko Sakkinen
2020-11-13 10:25 ` Mel Gorman
2020-11-17 18:16 ` Jarkko Sakkinen
2020-11-15 17:08 ` Dr. Greg
2020-11-15 17:32 ` Matthew Wilcox
2020-11-15 18:36 ` Dave Hansen
2020-11-16 10:09 ` Mel Gorman
2020-11-17 19:15 ` Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 11/24] x86/sgx: Add SGX misc driver interface Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 12/24] x86/sgx: Add SGX_IOC_ENCLAVE_CREATE Jarkko Sakkinen
[not found] ` <20201115044044.11040-1-hdanton@sina.com>
2020-11-17 17:35 ` Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 13/24] x86/sgx: Add SGX_IOC_ENCLAVE_ADD_PAGES Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 14/24] x86/sgx: Add SGX_IOC_ENCLAVE_INIT Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 15/24] x86/sgx: Add SGX_IOC_ENCLAVE_PROVISION Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 16/24] x86/vdso: Add support for exception fixup in vDSO functions Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 17/24] x86/fault: Add helper function to sanitize error code Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 18/24] x86/traps: Attempt to fixup exceptions in vDSO before signaling Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 19/24] x86/vdso: Implement a vDSO for Intel SGX enclave call Jarkko Sakkinen
2020-11-17 13:14 ` Borislav Petkov
2020-11-17 19:41 ` Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 20/24] selftests/x86: Add a selftest for SGX Jarkko Sakkinen
2020-11-16 18:19 ` Shuah Khan
2020-11-17 13:22 ` Borislav Petkov
2020-11-17 19:42 ` Jarkko Sakkinen
2020-11-17 17:26 ` Borislav Petkov
2020-11-17 21:27 ` Jarkko Sakkinen
2020-11-17 21:38 ` Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 21/24] x86/sgx: Add a page reclaimer Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 22/24] x86/sgx: Add ptrace() support for the SGX driver Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 23/24] docs: x86/sgx: Document SGX kernel architecture Jarkko Sakkinen
2020-11-12 22:01 ` [PATCH v41 24/24] x86/sgx: Update MAINTAINERS Jarkko Sakkinen
2020-11-16 16:55 ` [PATCH v41 00/24] Intel SGX foundations Borislav Petkov
2020-11-16 17:21 ` Dave Hansen
2020-11-16 17:28 ` Borislav Petkov
2020-11-17 19:20 ` Jarkko Sakkinen
[not found] ` <20201114084211.5284-1-hdanton@sina.com>
2020-11-16 18:33 ` Dave Hansen [this message]
[not found] ` <20201115040127.7804-1-hdanton@sina.com>
2020-11-16 21:11 ` [PATCH v41 11/24] x86/sgx: Add SGX misc driver interface Dave Hansen
[not found] ` <20201114090708.8684-1-hdanton@sina.com>
2020-11-17 18:12 ` [PATCH v41 06/24] x86/mm: x86/sgx: Signal SIGSEGV with PF_SGX Jarkko Sakkinen
[not found] ` <20201114093256.7800-1-hdanton@sina.com>
2020-11-17 18:14 ` [PATCH v41 09/24] x86/sgx: Add SGX page allocator functions Jarkko Sakkinen
[not found] ` <20201115030548.1572-1-hdanton@sina.com>
2020-11-17 18:22 ` [PATCH v41 10/24] mm: Add 'mprotect' hook to struct vm_operations_struct Jarkko Sakkinen
2020-12-15 5:38 ` [PATCH v41 00/24] Intel SGX foundations Hui, Chunyang
2020-12-15 5:43 ` Hui, Chunyang
2020-12-15 15:58 ` Jarkko Sakkinen
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