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Brijesh Singh eccd906484 x86/mm: Do not use set_{pud, pmd}_safe() when splitting a large page 
The commit

  0a9fe8ca84 ("x86/mm: Validate kernel_physical_mapping_init() PTE population")

triggers this warning in SEV guests:

  WARNING: CPU: 0 PID: 0 at arch/x86/include/asm/pgalloc.h:87 phys_pmd_init+0x30d/0x386
  Call Trace:
   kernel_physical_mapping_init+0xce/0x259
   early_set_memory_enc_dec+0x10f/0x160
   kvm_smp_prepare_boot_cpu+0x71/0x9d
   start_kernel+0x1c9/0x50b
   secondary_startup_64+0xa4/0xb0

A SEV guest calls kernel_physical_mapping_init() to clear the encryption
mask from an existing mapping. While doing so, it also splits large
pages into smaller.

To split a page, kernel_physical_mapping_init() allocates a new page and
updates the existing entry. The set_{pud,pmd}_safe() helpers trigger a
warning when updating an entry with a page in the present state.

Add a new kernel_physical_mapping_change() helper which uses the
non-safe variants of set_{pmd,pud,p4d}() and {pmd,pud,p4d}_populate()
routines when updating the entry.

Since kernel_physical_mapping_change() may replace an existing
entry with a new entry, the caller is responsible to flush
the TLB at the end. Change early_set_memory_enc_dec() to use
kernel_physical_mapping_change() when it wants to clear the memory
encryption mask from the page table entry.

 [ bp:
   - massage commit message.
   - flesh out comment according to dhansen's request.
   - align function arguments at opening brace. ]

Fixes: 0a9fe8ca84 ("x86/mm: Validate kernel_physical_mapping_init() PTE population")
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Dave Hansen <dave.hansen@intel.com>
Acked-by:  Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Thomas Lendacky <Thomas.Lendacky@amd.com>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20190417154102.22613-1-brijesh.singh@amd.com
2019-05-08 19:08:35 +02:00
arch x86/mm: Do not use set_{pud, pmd}_safe() when splitting a large page 2019-05-08 19:08:35 +02:00
block bfq: update internal depth state when queue depth changes 2019-04-13 19:08:22 -06:00
certs kexec, KEYS: Make use of platform keyring for signature verify 2019-02-04 17:34:07 -05:00
crypto crypto: lrw - Fix atomic sleep when walking skcipher 2019-04-18 22:13:46 +08:00
Documentation * amd64_edac: Family 0x17, models 0x30-.. enablement (Yazen Ghannam) 2019-05-06 19:53:11 -07:00
drivers Merge branch 'ras-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-05-06 19:54:57 -07:00
fs Merge branch 'core-stacktrace-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-05-06 13:11:48 -07:00
include * amd64_edac: Family 0x17, models 0x30-.. enablement (Yazen Ghannam) 2019-05-06 19:53:11 -07:00
init x86/mm: Initialize PGD cache during mm initialization 2019-05-05 20:32:46 +02:00
ipc Merge branch 'work.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2019-03-12 14:08:19 -07:00
kernel Power management updates for 5.2-rc1 2019-05-06 19:40:31 -07:00
lib Merge branch 'core-stacktrace-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-05-06 13:11:48 -07:00
LICENSES LICENSES: Add GCC runtime library exception text 2019-01-16 14:54:15 -07:00
mm arm64 updates for 5.2 2019-05-06 17:54:22 -07:00
net Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-05-06 14:50:46 -07:00
samples Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-03-11 08:54:01 -07:00
scripts Merge branch 'core-objtool-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-05-06 11:39:17 -07:00
security s390 updates for the 5.2 merge window 2019-05-06 16:42:54 -07:00
sound ACPI updates for 5.2-rc1 2019-05-06 19:35:13 -07:00
tools ACPI updates for 5.2-rc1 2019-05-06 19:35:13 -07:00
usr user/Makefile: Fix typo and capitalization in comment section 2018-12-11 00:18:03 +09:00
virt arm64 updates for 5.2 2019-05-06 17:54:22 -07:00
.clang-format clang-format: Update with the latest for_each macro list 2019-04-12 12:49:54 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Add hch to .get_maintainer.ignore 2015-08-21 14:30:10 -07:00
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore kbuild: Add support for DT binding schema checks 2018-12-13 09:41:32 -06:00
.mailmap Update Nicolas Pitre's email address 2019-04-02 18:12:44 -10:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS Char/Misc driver patches for 5.1-rc1 2019-03-06 14:18:59 -08:00
Kbuild Kbuild updates for v5.1 2019-03-10 17:48:21 -07:00
Kconfig kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
MAINTAINERS Merge branch 'ras-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-05-06 19:54:57 -07:00
Makefile Linux 5.1 2019-05-05 17:42:58 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

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.