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Reinette Chatre 5a90d2c3f5 x86/sgx: Support adding of pages to an initialized enclave
With SGX1 an enclave needs to be created with its maximum memory demands
allocated. Pages cannot be added to an enclave after it is initialized.
SGX2 introduces a new function, ENCLS[EAUG], that can be used to add
pages to an initialized enclave. With SGX2 the enclave still needs to
set aside address space for its maximum memory demands during enclave
creation, but all pages need not be added before enclave initialization.
Pages can be added during enclave runtime.

Add support for dynamically adding pages to an initialized enclave,
architecturally limited to RW permission at creation but allowed to
obtain RWX permissions after trusted enclave runs EMODPE. Add pages
via the page fault handler at the time an enclave address without a
backing enclave page is accessed, potentially directly reclaiming
pages if no free pages are available.

The enclave is still required to run ENCLU[EACCEPT] on the page before
it can be used. A useful flow is for the enclave to run ENCLU[EACCEPT]
on an uninitialized address. This will trigger the page fault handler
that will add the enclave page and return execution to the enclave to
repeat the ENCLU[EACCEPT] instruction, this time successful.

If the enclave accesses an uninitialized address in another way, for
example by expanding the enclave stack to a page that has not yet been
added, then the page fault handler would add the page on the first
write but upon returning to the enclave the instruction that triggered
the page fault would be repeated and since ENCLU[EACCEPT] was not run
yet it would trigger a second page fault, this time with the SGX flag
set in the page fault error code. This can only be recovered by entering
the enclave again and directly running the ENCLU[EACCEPT] instruction on
the now initialized address.

Accessing an uninitialized address from outside the enclave also
triggers this flow but the page will remain inaccessible (access will
result in #PF) until accepted from within the enclave via
ENCLU[EACCEPT].

Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Tested-by: Jarkko Sakkinen <jarkko@kernel.org>
Tested-by: Haitao Huang <haitao.huang@intel.com>
Tested-by: Vijay Dhanraj <vijay.dhanraj@intel.com>
Link: https://lkml.kernel.org/r/a254a58eabea053803277449b24b6e4963a3883b.1652137848.git.reinette.chatre@intel.com
2022-07-07 10:13:03 -07:00
arch x86/sgx: Support adding of pages to an initialized enclave 2022-07-07 10:13:03 -07:00
block Revert "block: release rq qos structures for queue without disk" 2022-05-02 10:06:40 -06:00
certs Kbuild updates for v5.18 2022-03-31 11:59:03 -07:00
crypto for-5.18/64bit-pi-2022-03-25 2022-03-26 12:01:35 -07:00
Documentation Driver core fixes for 5.18-rc7 2022-05-15 08:08:51 -07:00
drivers Driver core fixes for 5.18-rc7 2022-05-15 08:08:51 -07:00
fs gfs2 fixes 2022-05-13 14:32:53 -07:00
include The recent expansion of the sched switch tracepoint inserted a new argument 2022-05-15 06:40:11 -07:00
init Kbuild updates for v5.18 2022-03-31 11:59:03 -07:00
ipc fs: allocate inode by using alloc_inode_sb() 2022-03-22 15:57:03 -07:00
kernel The recent expansion of the sched switch tracepoint inserted a new argument 2022-05-15 06:40:11 -07:00
lib dim: initialize all struct fields 2022-05-09 17:20:37 -07:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm hotfixes for 5.18-rc7 2022-05-13 10:22:37 -07:00
net NFS client bugfixes for Linux 5.18 2022-05-13 11:04:37 -07:00
samples sched/tracing: Append prev_state to tp args instead 2022-05-12 00:37:11 +02:00
scripts objtool: Enable unreachable warnings for CLANG LTO 2022-04-19 21:58:48 +02:00
security hardening updates for v5.18-rc1-fix1 2022-03-31 11:43:01 -07:00
sound ASoC: Fixes for v5.18 2022-05-08 10:49:25 +02:00
tools perf tools fixes for v5.18: 5th batch 2022-05-14 11:43:47 -07:00
usr Kbuild updates for v5.18 2022-03-31 11:59:03 -07:00
virt Merge branch 'kvm-fixes-for-5.18-rc5' into HEAD 2022-04-29 12:39:34 -04:00
.clang-format genirq/msi: Make interrupt allocation less convoluted 2021-12-16 22:22:20 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap hotfixes for 5.18-rc7 2022-05-13 10:22:37 -07:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: replace a Microchip AT91 maintainer 2022-02-09 11:30:01 +01:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS perf tools fixes for v5.18: 5th batch 2022-05-14 11:43:47 -07:00
Makefile Linux 5.18-rc7 2022-05-15 18:08:58 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.