<feed xmlns='http://www.w3.org/2005/Atom'>
<title>blaster4385/linux-IllusionX/arch/x86/kernel/cpu/sgx, branch v6.12.1</title>
<subtitle>Linux kernel with personal config changes for arch linux</subtitle>
<id>http://git.tablaster.dev/blaster4385/linux-IllusionX/atom?h=v6.12.1</id>
<link rel='self' href='http://git.tablaster.dev/blaster4385/linux-IllusionX/atom?h=v6.12.1'/>
<link rel='alternate' type='text/html' href='http://git.tablaster.dev/blaster4385/linux-IllusionX/'/>
<updated>2024-09-23T16:35:36Z</updated>
<entry>
<title>Merge tag 'pull-stable-struct_fd' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs</title>
<updated>2024-09-23T16:35:36Z</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2024-09-23T16:35:36Z</published>
<link rel='alternate' type='text/html' href='http://git.tablaster.dev/blaster4385/linux-IllusionX/commit/?id=f8ffbc365f703d74ecca8ca787318d05bbee2bf7'/>
<id>urn:sha1:f8ffbc365f703d74ecca8ca787318d05bbee2bf7</id>
<content type='text'>
Pull 'struct fd' updates from Al Viro:
 "Just the 'struct fd' layout change, with conversion to accessor
  helpers"

* tag 'pull-stable-struct_fd' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  add struct fd constructors, get rid of __to_fd()
  struct fd: representation change
  introduce fd_file(), convert all accessors to it.
</content>
</entry>
<entry>
<title>Merge tag 'x86-cleanups-2024-09-17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip</title>
<updated>2024-09-17T11:00:12Z</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2024-09-17T11:00:12Z</published>
<link rel='alternate' type='text/html' href='http://git.tablaster.dev/blaster4385/linux-IllusionX/commit/?id=0279aa780df4362f218b5645c07e5265859937f6'/>
<id>urn:sha1:0279aa780df4362f218b5645c07e5265859937f6</id>
<content type='text'>
Pull x86 cleanups from Thomas Gleixner:
 "A set of cleanups across x86:

   - Use memremap() for the EISA probe instead of ioremap(). EISA is
     strictly memory and not MMIO

   - Cleanups and enhancement all over the place"

* tag 'x86-cleanups-2024-09-17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/EISA: Dereference memory directly instead of using readl()
  x86/extable: Remove unused declaration fixup_bug()
  x86/boot/64: Strip percpu address space when setting up GDT descriptors
  x86/cpu: Clarify the error message when BIOS does not support SGX
  x86/kexec: Add comments around swap_pages() assembly to improve readability
  x86/kexec: Fix a comment of swap_pages() assembly
  x86/sgx: Fix a W=1 build warning in function comment
  x86/EISA: Use memremap() to probe for the EISA BIOS signature
  x86/mtrr: Remove obsolete declaration for mtrr_bp_restore()
  x86/cpu_entry_area: Annotate percpu_setup_exception_stacks() as __init
</content>
</entry>
<entry>
<title>x86/sgx: Log information when a node lacks an EPC section</title>
<updated>2024-09-05T22:20:47Z</updated>
<author>
<name>Aaron Lu</name>
<email>aaron.lu@intel.com</email>
</author>
<published>2024-09-05T08:08:55Z</published>
<link rel='alternate' type='text/html' href='http://git.tablaster.dev/blaster4385/linux-IllusionX/commit/?id=c8ddc99eeba5f00b65efeae920eec3990bfc34ca'/>
<id>urn:sha1:c8ddc99eeba5f00b65efeae920eec3990bfc34ca</id>
<content type='text'>
For optimized performance, firmware typically distributes EPC sections
evenly across different NUMA nodes. However, there are scenarios where
a node may have both CPUs and memory but no EPC section configured. For
example, in an 8-socket system with a Sub-Numa-Cluster=2 setup, there
are a total of 16 nodes. Given that the maximum number of supported EPC
sections is 8, it is simply not feasible to assign one EPC section to
each node. This configuration is not incorrect - SGX will still operate
correctly; it is just not optimized from a NUMA standpoint.

For this reason, log a message when a node with both CPUs and memory
lacks an EPC section. This will provide users with a hint as to why they
might be experiencing less-than-ideal performance when running SGX
enclaves.

Suggested-by: Dave Hansen &lt;dave.hansen@intel.com&gt;
Signed-off-by: Aaron Lu &lt;aaron.lu@intel.com&gt;
Signed-off-by: Dave Hansen &lt;dave.hansen@linux.intel.com&gt;
Reviewed-by: Jarkko Sakkinen &lt;jarkko@kernel.org&gt;
Acked-by: Kai Huang &lt;kai.huang@intel.com&gt;
Link: https://lore.kernel.org/all/20240905080855.1699814-3-aaron.lu%40intel.com
</content>
</entry>
<entry>
<title>x86/sgx: Fix deadlock in SGX NUMA node search</title>
<updated>2024-09-05T22:20:47Z</updated>
<author>
<name>Aaron Lu</name>
<email>aaron.lu@intel.com</email>
</author>
<published>2024-09-05T08:08:54Z</published>
<link rel='alternate' type='text/html' href='http://git.tablaster.dev/blaster4385/linux-IllusionX/commit/?id=9c936844010466535bd46ea4ce4656ef17653644'/>
<id>urn:sha1:9c936844010466535bd46ea4ce4656ef17653644</id>
<content type='text'>
When the current node doesn't have an EPC section configured by firmware
and all other EPC sections are used up, CPU can get stuck inside the
while loop that looks for an available EPC page from remote nodes
indefinitely, leading to a soft lockup. Note how nid_of_current will
never be equal to nid in that while loop because nid_of_current is not
set in sgx_numa_mask.

Also worth mentioning is that it's perfectly fine for the firmware not
to setup an EPC section on a node. While setting up an EPC section on
each node can enhance performance, it is not a requirement for
functionality.

Rework the loop to start and end on *a* node that has SGX memory. This
avoids the deadlock looking for the current SGX-lacking node to show up
in the loop when it never will.

Fixes: 901ddbb9ecf5 ("x86/sgx: Add a basic NUMA allocation scheme to sgx_alloc_epc_page()")
Reported-by: "Molina Sabido, Gerardo" &lt;gerardo.molina.sabido@intel.com&gt;
Signed-off-by: Aaron Lu &lt;aaron.lu@intel.com&gt;
Signed-off-by: Dave Hansen &lt;dave.hansen@linux.intel.com&gt;
Reviewed-by: Kai Huang &lt;kai.huang@intel.com&gt;
Reviewed-by: Jarkko Sakkinen &lt;jarkko@kernel.org&gt;
Acked-by: Dave Hansen &lt;dave.hansen@linux.intel.com&gt;
Tested-by: Zhimin Luo &lt;zhimin.luo@intel.com&gt;
Link: https://lore.kernel.org/all/20240905080855.1699814-2-aaron.lu%40intel.com
</content>
</entry>
<entry>
<title>x86/sgx: Fix a W=1 build warning in function comment</title>
<updated>2024-08-25T12:29:38Z</updated>
<author>
<name>Kai Huang</name>
<email>kai.huang@intel.com</email>
</author>
<published>2024-08-25T08:06:49Z</published>
<link rel='alternate' type='text/html' href='http://git.tablaster.dev/blaster4385/linux-IllusionX/commit/?id=c6e6a3c1698a86bacf7eac256b0f1215a3616dc7'/>
<id>urn:sha1:c6e6a3c1698a86bacf7eac256b0f1215a3616dc7</id>
<content type='text'>
Building the SGX code with W=1 generates below warning:

  arch/x86/kernel/cpu/sgx/main.c:741: warning: Function parameter or
  struct member 'low' not described in 'sgx_calc_section_metric'
  arch/x86/kernel/cpu/sgx/main.c:741: warning: Function parameter or
  struct member 'high' not described in 'sgx_calc_section_metric'
  ...

The function sgx_calc_section_metric() is a simple helper which is only
used in sgx/main.c.  There's no need to use kernel-doc style comment for
it.

Downgrade to a normal comment.

Signed-off-by: Kai Huang &lt;kai.huang@intel.com&gt;
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Link: https://lore.kernel.org/all/20240825080649.145250-1-kai.huang@intel.com

</content>
</entry>
<entry>
<title>introduce fd_file(), convert all accessors to it.</title>
<updated>2024-08-13T02:00:43Z</updated>
<author>
<name>Al Viro</name>
<email>viro@zeniv.linux.org.uk</email>
</author>
<published>2024-05-31T18:12:01Z</published>
<link rel='alternate' type='text/html' href='http://git.tablaster.dev/blaster4385/linux-IllusionX/commit/?id=1da91ea87aefe2c25b68c9f96947a9271ba6325d'/>
<id>urn:sha1:1da91ea87aefe2c25b68c9f96947a9271ba6325d</id>
<content type='text'>
	For any changes of struct fd representation we need to
turn existing accesses to fields into calls of wrappers.
Accesses to struct fd::flags are very few (3 in linux/file.h,
1 in net/socket.c, 3 in fs/overlayfs/file.c and 3 more in
explicit initializers).
	Those can be dealt with in the commit converting to
new layout; accesses to struct fd::file are too many for that.
	This commit converts (almost) all of f.file to
fd_file(f).  It's not entirely mechanical ('file' is used as
a member name more than just in struct fd) and it does not
even attempt to distinguish the uses in pointer context from
those in boolean context; the latter will be eventually turned
into a separate helper (fd_empty()).

	NOTE: mass conversion to fd_empty(), tempting as it
might be, is a bad idea; better do that piecewise in commit
that convert from fdget...() to CLASS(...).

[conflicts in fs/fhandle.c, kernel/bpf/syscall.c, mm/memcontrol.c
caught by git; fs/stat.c one got caught by git grep]
[fs/xattr.c conflict]

Reviewed-by: Christian Brauner &lt;brauner@kernel.org&gt;
Signed-off-by: Al Viro &lt;viro@zeniv.linux.org.uk&gt;
</content>
</entry>
<entry>
<title>mm: switch mm-&gt;get_unmapped_area() to a flag</title>
<updated>2024-04-26T03:56:25Z</updated>
<author>
<name>Rick Edgecombe</name>
<email>rick.p.edgecombe@intel.com</email>
</author>
<published>2024-03-26T02:16:44Z</published>
<link rel='alternate' type='text/html' href='http://git.tablaster.dev/blaster4385/linux-IllusionX/commit/?id=529ce23a764f25d172198b4c6ba90f1e2ad17f93'/>
<id>urn:sha1:529ce23a764f25d172198b4c6ba90f1e2ad17f93</id>
<content type='text'>
The mm_struct contains a function pointer *get_unmapped_area(), which is
set to either arch_get_unmapped_area() or arch_get_unmapped_area_topdown()
during the initialization of the mm.

Since the function pointer only ever points to two functions that are
named the same across all arch's, a function pointer is not really
required.  In addition future changes will want to add versions of the
functions that take additional arguments.  So to save a pointers worth of
bytes in mm_struct, and prevent adding additional function pointers to
mm_struct in future changes, remove it and keep the information about
which get_unmapped_area() to use in a flag.

Add the new flag to MMF_INIT_MASK so it doesn't get clobbered on fork by
mmf_init_flags().  Most MM flags get clobbered on fork.  In the
pre-existing behavior mm-&gt;get_unmapped_area() would get copied to the new
mm in dup_mm(), so not clobbering the flag preserves the existing behavior
around inheriting the topdown-ness.

Introduce a helper, mm_get_unmapped_area(), to easily convert code that
refers to the old function pointer to instead select and call either
arch_get_unmapped_area() or arch_get_unmapped_area_topdown() based on the
flag.  Then drop the mm-&gt;get_unmapped_area() function pointer.  Leave the
get_unmapped_area() pointer in struct file_operations alone.  The main
purpose of this change is to reorganize in preparation for future changes,
but it also converts the calls of mm-&gt;get_unmapped_area() from indirect
branches into a direct ones.

The stress-ng bigheap benchmark calls realloc a lot, which calls through
get_unmapped_area() in the kernel.  On x86, the change yielded a ~1%
improvement there on a retpoline config.

In testing a few x86 configs, removing the pointer unfortunately didn't
result in any actual size reductions in the compiled layout of mm_struct. 
But depending on compiler or arch alignment requirements, the change could
shrink the size of mm_struct.

Link: https://lkml.kernel.org/r/20240326021656.202649-3-rick.p.edgecombe@intel.com
Signed-off-by: Rick Edgecombe &lt;rick.p.edgecombe@intel.com&gt;
Acked-by: Dave Hansen &lt;dave.hansen@linux.intel.com&gt;
Acked-by: Liam R. Howlett &lt;Liam.Howlett@oracle.com&gt;
Reviewed-by: Kirill A. Shutemov &lt;kirill.shutemov@linux.intel.com&gt;
Acked-by: Alexei Starovoitov &lt;ast@kernel.org&gt;
Cc: Dan Williams &lt;dan.j.williams@intel.com&gt;
Cc: Andy Lutomirski &lt;luto@kernel.org&gt;
Cc: Aneesh Kumar K.V &lt;aneesh.kumar@kernel.org&gt;
Cc: Borislav Petkov (AMD) &lt;bp@alien8.de&gt;
Cc: Christophe Leroy &lt;christophe.leroy@csgroup.eu&gt;
Cc: Deepak Gupta &lt;debug@rivosinc.com&gt;
Cc: Guo Ren &lt;guoren@kernel.org&gt;
Cc: Helge Deller &lt;deller@gmx.de&gt;
Cc: H. Peter Anvin (Intel) &lt;hpa@zytor.com&gt;
Cc: Ingo Molnar &lt;mingo@redhat.com&gt;
Cc: "James E.J. Bottomley" &lt;James.Bottomley@HansenPartnership.com&gt;
Cc: Kees Cook &lt;keescook@chromium.org&gt;
Cc: Mark Brown &lt;broonie@kernel.org&gt;
Cc: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Cc: Naveen N. Rao &lt;naveen.n.rao@linux.ibm.com&gt;
Cc: Nicholas Piggin &lt;npiggin@gmail.com&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</content>
</entry>
<entry>
<title>fix missing vmalloc.h includes</title>
<updated>2024-04-26T03:55:49Z</updated>
<author>
<name>Kent Overstreet</name>
<email>kent.overstreet@linux.dev</email>
</author>
<published>2024-03-21T16:36:23Z</published>
<link rel='alternate' type='text/html' href='http://git.tablaster.dev/blaster4385/linux-IllusionX/commit/?id=0069455bcbf9ea73ffe4553ed6d2b4e4cad703de'/>
<id>urn:sha1:0069455bcbf9ea73ffe4553ed6d2b4e4cad703de</id>
<content type='text'>
Patch series "Memory allocation profiling", v6.

Overview:
Low overhead [1] per-callsite memory allocation profiling. Not just for
debug kernels, overhead low enough to be deployed in production.

Example output:
  root@moria-kvm:~# sort -rn /proc/allocinfo
   127664128    31168 mm/page_ext.c:270 func:alloc_page_ext
    56373248     4737 mm/slub.c:2259 func:alloc_slab_page
    14880768     3633 mm/readahead.c:247 func:page_cache_ra_unbounded
    14417920     3520 mm/mm_init.c:2530 func:alloc_large_system_hash
    13377536      234 block/blk-mq.c:3421 func:blk_mq_alloc_rqs
    11718656     2861 mm/filemap.c:1919 func:__filemap_get_folio
     9192960     2800 kernel/fork.c:307 func:alloc_thread_stack_node
     4206592        4 net/netfilter/nf_conntrack_core.c:2567 func:nf_ct_alloc_hashtable
     4136960     1010 drivers/staging/ctagmod/ctagmod.c:20 [ctagmod] func:ctagmod_start
     3940352      962 mm/memory.c:4214 func:alloc_anon_folio
     2894464    22613 fs/kernfs/dir.c:615 func:__kernfs_new_node
     ...

Usage:
kconfig options:
 - CONFIG_MEM_ALLOC_PROFILING
 - CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT
 - CONFIG_MEM_ALLOC_PROFILING_DEBUG
   adds warnings for allocations that weren't accounted because of a
   missing annotation

sysctl:
  /proc/sys/vm/mem_profiling

Runtime info:
  /proc/allocinfo

Notes:

[1]: Overhead
To measure the overhead we are comparing the following configurations:
(1) Baseline with CONFIG_MEMCG_KMEM=n
(2) Disabled by default (CONFIG_MEM_ALLOC_PROFILING=y &amp;&amp;
    CONFIG_MEM_ALLOC_PROFILING_BY_DEFAULT=n)
(3) Enabled by default (CONFIG_MEM_ALLOC_PROFILING=y &amp;&amp;
    CONFIG_MEM_ALLOC_PROFILING_BY_DEFAULT=y)
(4) Enabled at runtime (CONFIG_MEM_ALLOC_PROFILING=y &amp;&amp;
    CONFIG_MEM_ALLOC_PROFILING_BY_DEFAULT=n &amp;&amp; /proc/sys/vm/mem_profiling=1)
(5) Baseline with CONFIG_MEMCG_KMEM=y &amp;&amp; allocating with __GFP_ACCOUNT
(6) Disabled by default (CONFIG_MEM_ALLOC_PROFILING=y &amp;&amp;
    CONFIG_MEM_ALLOC_PROFILING_BY_DEFAULT=n)  &amp;&amp; CONFIG_MEMCG_KMEM=y
(7) Enabled by default (CONFIG_MEM_ALLOC_PROFILING=y &amp;&amp;
    CONFIG_MEM_ALLOC_PROFILING_BY_DEFAULT=y) &amp;&amp; CONFIG_MEMCG_KMEM=y

Performance overhead:
To evaluate performance we implemented an in-kernel test executing
multiple get_free_page/free_page and kmalloc/kfree calls with allocation
sizes growing from 8 to 240 bytes with CPU frequency set to max and CPU
affinity set to a specific CPU to minimize the noise. Below are results
from running the test on Ubuntu 22.04.2 LTS with 6.8.0-rc1 kernel on
56 core Intel Xeon:

                        kmalloc                 pgalloc
(1 baseline)            6.764s                  16.902s
(2 default disabled)    6.793s  (+0.43%)        17.007s (+0.62%)
(3 default enabled)     7.197s  (+6.40%)        23.666s (+40.02%)
(4 runtime enabled)     7.405s  (+9.48%)        23.901s (+41.41%)
(5 memcg)               13.388s (+97.94%)       48.460s (+186.71%)
(6 def disabled+memcg)  13.332s (+97.10%)       48.105s (+184.61%)
(7 def enabled+memcg)   13.446s (+98.78%)       54.963s (+225.18%)

Memory overhead:
Kernel size:

   text           data        bss         dec         diff
(1) 26515311	      18890222    17018880    62424413
(2) 26524728	      19423818    16740352    62688898    264485
(3) 26524724	      19423818    16740352    62688894    264481
(4) 26524728	      19423818    16740352    62688898    264485
(5) 26541782	      18964374    16957440    62463596    39183

Memory consumption on a 56 core Intel CPU with 125GB of memory:
Code tags:           192 kB
PageExts:         262144 kB (256MB)
SlabExts:           9876 kB (9.6MB)
PcpuExts:            512 kB (0.5MB)

Total overhead is 0.2% of total memory.

Benchmarks:

Hackbench tests run 100 times:
hackbench -s 512 -l 200 -g 15 -f 25 -P
      baseline       disabled profiling           enabled profiling
avg   0.3543         0.3559 (+0.0016)             0.3566 (+0.0023)
stdev 0.0137         0.0188                       0.0077


hackbench -l 10000
      baseline       disabled profiling           enabled profiling
avg   6.4218         6.4306 (+0.0088)             6.5077 (+0.0859)
stdev 0.0933         0.0286                       0.0489

stress-ng tests:
stress-ng --class memory --seq 4 -t 60
stress-ng --class cpu --seq 4 -t 60
Results posted at: https://evilpiepirate.org/~kent/memalloc_prof_v4_stress-ng/

[2] https://lore.kernel.org/all/20240306182440.2003814-1-surenb@google.com/


This patch (of 37):

The next patch drops vmalloc.h from a system header in order to fix a
circular dependency; this adds it to all the files that were pulling it in
implicitly.

[kent.overstreet@linux.dev: fix arch/alpha/lib/memcpy.c]
  Link: https://lkml.kernel.org/r/20240327002152.3339937-1-kent.overstreet@linux.dev
[surenb@google.com: fix arch/x86/mm/numa_32.c]
  Link: https://lkml.kernel.org/r/20240402180933.1663992-1-surenb@google.com
[kent.overstreet@linux.dev: a few places were depending on sizes.h]
  Link: https://lkml.kernel.org/r/20240404034744.1664840-1-kent.overstreet@linux.dev
[arnd@arndb.de: fix mm/kasan/hw_tags.c]
  Link: https://lkml.kernel.org/r/20240404124435.3121534-1-arnd@kernel.org
[surenb@google.com: fix arc build]
  Link: https://lkml.kernel.org/r/20240405225115.431056-1-surenb@google.com
Link: https://lkml.kernel.org/r/20240321163705.3067592-1-surenb@google.com
Link: https://lkml.kernel.org/r/20240321163705.3067592-2-surenb@google.com
Signed-off-by: Kent Overstreet &lt;kent.overstreet@linux.dev&gt;
Signed-off-by: Suren Baghdasaryan &lt;surenb@google.com&gt;
Signed-off-by: Arnd Bergmann &lt;arnd@arndb.de&gt;
Reviewed-by: Pasha Tatashin &lt;pasha.tatashin@soleen.com&gt;
Tested-by: Kees Cook &lt;keescook@chromium.org&gt;
Cc: Alexander Viro &lt;viro@zeniv.linux.org.uk&gt;
Cc: Alex Gaynor &lt;alex.gaynor@gmail.com&gt;
Cc: Alice Ryhl &lt;aliceryhl@google.com&gt;
Cc: Andreas Hindborg &lt;a.hindborg@samsung.com&gt;
Cc: Benno Lossin &lt;benno.lossin@proton.me&gt;
Cc: "Björn Roy Baron" &lt;bjorn3_gh@protonmail.com&gt;
Cc: Boqun Feng &lt;boqun.feng@gmail.com&gt;
Cc: Christoph Lameter &lt;cl@linux.com&gt;
Cc: Dennis Zhou &lt;dennis@kernel.org&gt;
Cc: Gary Guo &lt;gary@garyguo.net&gt;
Cc: Miguel Ojeda &lt;ojeda@kernel.org&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Tejun Heo &lt;tj@kernel.org&gt;
Cc: Vlastimil Babka &lt;vbabka@suse.cz&gt;
Cc: Wedson Almeida Filho &lt;wedsonaf@gmail.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</content>
</entry>
<entry>
<title>arch/x86: Fix typos</title>
<updated>2024-01-03T10:46:22Z</updated>
<author>
<name>Bjorn Helgaas</name>
<email>bhelgaas@google.com</email>
</author>
<published>2024-01-03T00:40:11Z</published>
<link rel='alternate' type='text/html' href='http://git.tablaster.dev/blaster4385/linux-IllusionX/commit/?id=54aa699e8094efb7d7675fefbc03dfce24f98456'/>
<id>urn:sha1:54aa699e8094efb7d7675fefbc03dfce24f98456</id>
<content type='text'>
Fix typos, most reported by "codespell arch/x86".  Only touches comments,
no code changes.

Signed-off-by: Bjorn Helgaas &lt;bhelgaas@google.com&gt;
Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
Reviewed-by: Randy Dunlap &lt;rdunlap@infradead.org&gt;
Link: https://lore.kernel.org/r/20240103004011.1758650-1-helgaas@kernel.org
</content>
</entry>
<entry>
<title>x86/sgx: Resolves SECS reclaim vs. page fault for EAUG race</title>
<updated>2023-09-28T23:16:40Z</updated>
<author>
<name>Haitao Huang</name>
<email>haitao.huang@linux.intel.com</email>
</author>
<published>2023-07-28T05:10:24Z</published>
<link rel='alternate' type='text/html' href='http://git.tablaster.dev/blaster4385/linux-IllusionX/commit/?id=c6c2adcba50c2622ed25ba5d5e7f05f584711358'/>
<id>urn:sha1:c6c2adcba50c2622ed25ba5d5e7f05f584711358</id>
<content type='text'>
The SGX EPC reclaimer (ksgxd) may reclaim the SECS EPC page for an
enclave and set secs.epc_page to NULL. The SECS page is used for EAUG
and ELDU in the SGX page fault handler. However, the NULL check for
secs.epc_page is only done for ELDU, not EAUG before being used.

Fix this by doing the same NULL check and reloading of the SECS page as
needed for both EAUG and ELDU.

The SECS page holds global enclave metadata. It can only be reclaimed
when there are no other enclave pages remaining. At that point,
virtually nothing can be done with the enclave until the SECS page is
paged back in.

An enclave can not run nor generate page faults without a resident SECS
page. But it is still possible for a #PF for a non-SECS page to race
with paging out the SECS page: when the last resident non-SECS page A
triggers a #PF in a non-resident page B, and then page A and the SECS
both are paged out before the #PF on B is handled.

Hitting this bug requires that race triggered with a #PF for EAUG.
Following is a trace when it happens.

BUG: kernel NULL pointer dereference, address: 0000000000000000
RIP: 0010:sgx_encl_eaug_page+0xc7/0x210
Call Trace:
 ? __kmem_cache_alloc_node+0x16a/0x440
 ? xa_load+0x6e/0xa0
 sgx_vma_fault+0x119/0x230
 __do_fault+0x36/0x140
 do_fault+0x12f/0x400
 __handle_mm_fault+0x728/0x1110
 handle_mm_fault+0x105/0x310
 do_user_addr_fault+0x1ee/0x750
 ? __this_cpu_preempt_check+0x13/0x20
 exc_page_fault+0x76/0x180
 asm_exc_page_fault+0x27/0x30

Fixes: 5a90d2c3f5ef ("x86/sgx: Support adding of pages to an initialized enclave")
Signed-off-by: Haitao Huang &lt;haitao.huang@linux.intel.com&gt;
Signed-off-by: Dave Hansen &lt;dave.hansen@linux.intel.com&gt;
Reviewed-by: Jarkko Sakkinen &lt;jarkko@kernel.org&gt;
Reviewed-by: Kai Huang &lt;kai.huang@intel.com&gt;
Acked-by: Reinette Chatre &lt;reinette.chatre@intel.com&gt;
Cc:stable@vger.kernel.org
Link: https://lore.kernel.org/all/20230728051024.33063-1-haitao.huang%40linux.intel.com
</content>
</entry>
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