Commit Graph

8502 Commits

Author SHA1 Message Date
K. Y. Srinivasan
6b48cb5f83 X86/Hyper-V: Enlighten APIC access
Hyper-V supports MSR based APIC access; implement
the enlightenment.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Cc: olaf@aepfle.de
Cc: sthemmin@microsoft.com
Cc: gregkh@linuxfoundation.org
Cc: jasowang@redhat.com
Cc: Michael.H.Kelley@microsoft.com
Cc: hpa@zytor.com
Cc: apw@canonical.com
Cc: devel@linuxdriverproject.org
Cc: vkuznets@redhat.com
Link: https://lkml.kernel.org/r/20180516215334.6547-1-kys@linuxonhyperv.com
2018-05-19 13:23:17 +02:00
Kirill A. Shutemov
1ea66554d3 x86/mm: Mark p4d_offset() __always_inline
__pgtable_l5_enabled shouldn't be needed after system has booted, we can
mark it as __initdata, but it requires preparation.

KASAN initialization code is a user of USE_EARLY_PGTABLE_L5, so all
pgtable_l5_enabled() translated to __pgtable_l5_enabled there, including
the one in p4d_offset().

It may lead to section mismatch, if a compiler would not inline
p4d_offset(), but leave it as a standalone function: p4d_offset() is not
marked as __init.

Marking p4d_offset() as __always_inline fixes the issue.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20180518103528.59260-7-kirill.shutemov@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-05-19 11:56:57 +02:00
Kirill A. Shutemov
ed7588d5dc x86/mm: Stop pretending pgtable_l5_enabled is a variable
pgtable_l5_enabled is defined using cpu_feature_enabled() but we refer
to it as a variable. This is misleading.

Make pgtable_l5_enabled() a function.

We cannot literally define it as a function due to circular dependencies
between header files. Function-alike macros is close enough.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20180518103528.59260-4-kirill.shutemov@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-05-19 11:56:57 +02:00
Kirill A. Shutemov
ad3fe525b9 x86/mm: Unify pgtable_l5_enabled usage in early boot code
Usually pgtable_l5_enabled is defined using cpu_feature_enabled().
cpu_feature_enabled() is not available in early boot code. We use
several different preprocessor tricks to get around it. It's messy.

Unify them all.

If cpu_feature_enabled() is not yet available, USE_EARLY_PGTABLE_L5 can
be defined before all includes. It makes pgtable_l5_enabled rely on
__pgtable_l5_enabled variable instead. This approach fits all early
users.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20180518103528.59260-3-kirill.shutemov@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-05-19 11:56:57 +02:00
Ingo Molnar
177bfd725b Merge branches 'x86/urgent' and 'core/urgent' into x86/boot, to pick up fixes and avoid conflicts
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-05-19 08:18:56 +02:00
Konrad Rzeszutek Wilk
240da953fc x86/bugs: Rename SSBD_NO to SSB_NO
The "336996 Speculative Execution Side Channel Mitigations" from
May defines this as SSB_NO, hence lets sync-up.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2018-05-18 11:17:30 +02:00
Andy Shevchenko
6469a0ee0a x86/io: Define readq()/writeq() to use 64-bit type
Since non atomic readq() and writeq() were added some of the drivers
would like to use it in a manner of:

 #include <io-64-nonatomic-lo-hi.h>
 ...
 pr_debug("Debug value of some register: %016llx\n", readq(addr));

However, lo_hi_readq() always returns __u64 data, while readq()
on x86_64 defines it as unsigned long. and thus compiler warns
about type mismatch, although they are both 64-bit on x86_64.

Convert readq() and writeq() on x86 to operate on deterministic
64-bit type. The most of architectures in the kernel already are using
either unsigned long long, or u64 type for readq() / writeq().
This change propagates consistency in that sense.

While this is not an issue per se, though if someone wants to address it,
the anchor could be the commit:

  797a796a13 ("asm-generic: architecture independent readq/writeq for 32bit environment")

where non-atomic variants had been introduced.

Note, there are only few users of above pattern and they will not be
affected because they do cast returned value. The actual warning has
been issued on not-yet-upstreamed code.

Potentially we might get a new warnings if some 64-bit only code
assigns returned value to unsigned long type of variable. This is
assumed to be addressed on case-by-case basis.

Reported-by: lkp <lkp@intel.com>
Tested-by: Sohil Mehta <sohil.mehta@intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20180515115211.55050-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-05-18 09:11:26 +02:00
Michael S. Tsirkin
633711e828 kvm: rename KVM_HINTS_DEDICATED to KVM_HINTS_REALTIME
KVM_HINTS_DEDICATED seems to be somewhat confusing:

Guest doesn't really care whether it's the only task running on a host
CPU as long as it's not preempted.

And there are more reasons for Guest to be preempted than host CPU
sharing, for example, with memory overcommit it can get preempted on a
memory access, post copy migration can cause preemption, etc.

Let's call it KVM_HINTS_REALTIME which seems to better
match what guests expect.

Also, the flag most be set on all vCPUs - current guests assume this.
Note so in the documentation.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2018-05-17 19:12:13 +02:00
Tom Lendacky
bc226f07dc KVM: SVM: Implement VIRT_SPEC_CTRL support for SSBD
Expose the new virtualized architectural mechanism, VIRT_SSBD, for using
speculative store bypass disable (SSBD) under SVM.  This will allow guests
to use SSBD on hardware that uses non-architectural mechanisms for enabling
SSBD.

[ tglx: Folded the migration fixup from Paolo Bonzini ]

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2018-05-17 17:09:21 +02:00
Thomas Gleixner
47c61b3955 x86/speculation, KVM: Implement support for VIRT_SPEC_CTRL/LS_CFG
Add the necessary logic for supporting the emulated VIRT_SPEC_CTRL MSR to
x86_virt_spec_ctrl().  If either X86_FEATURE_LS_CFG_SSBD or
X86_FEATURE_VIRT_SPEC_CTRL is set then use the new guest_virt_spec_ctrl
argument to check whether the state must be modified on the host. The
update reuses speculative_store_bypass_update() so the ZEN-specific sibling
coordination can be reused.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2018-05-17 17:09:21 +02:00
Thomas Gleixner
4b59bdb569 x86/bugs: Remove x86_spec_ctrl_set()
x86_spec_ctrl_set() is only used in bugs.c and the extra mask checks there
provide no real value as both call sites can just write x86_spec_ctrl_base
to MSR_SPEC_CTRL. x86_spec_ctrl_base is valid and does not need any extra
masking or checking.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2018-05-17 17:09:20 +02:00
Thomas Gleixner
fa8ac49882 x86/bugs: Expose x86_spec_ctrl_base directly
x86_spec_ctrl_base is the system wide default value for the SPEC_CTRL MSR.
x86_spec_ctrl_get_default() returns x86_spec_ctrl_base and was intended to
prevent modification to that variable. Though the variable is read only
after init and globaly visible already.

Remove the function and export the variable instead.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2018-05-17 17:09:19 +02:00
Borislav Petkov
cc69b34989 x86/bugs: Unify x86_spec_ctrl_{set_guest,restore_host}
Function bodies are very similar and are going to grow more almost
identical code. Add a bool arg to determine whether SPEC_CTRL is being set
for the guest or restored to the host.

No functional changes.

Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2018-05-17 17:09:19 +02:00
Thomas Gleixner
0270be3e34 x86/speculation: Rework speculative_store_bypass_update()
The upcoming support for the virtual SPEC_CTRL MSR on AMD needs to reuse
speculative_store_bypass_update() to avoid code duplication. Add an
argument for supplying a thread info (TIF) value and create a wrapper
speculative_store_bypass_update_current() which is used at the existing
call site.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2018-05-17 17:09:19 +02:00
Tom Lendacky
11fb068349 x86/speculation: Add virtualized speculative store bypass disable support
Some AMD processors only support a non-architectural means of enabling
speculative store bypass disable (SSBD).  To allow a simplified view of
this to a guest, an architectural definition has been created through a new
CPUID bit, 0x80000008_EBX[25], and a new MSR, 0xc001011f.  With this, a
hypervisor can virtualize the existence of this definition and provide an
architectural method for using SSBD to a guest.

Add the new CPUID feature, the new MSR and update the existing SSBD
support to use this MSR when present.

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
2018-05-17 17:09:18 +02:00
Thomas Gleixner
ccbcd26744 x86/bugs, KVM: Extend speculation control for VIRT_SPEC_CTRL
AMD is proposing a VIRT_SPEC_CTRL MSR to handle the Speculative Store
Bypass Disable via MSR_AMD64_LS_CFG so that guests do not have to care
about the bit position of the SSBD bit and thus facilitate migration.
Also, the sibling coordination on Family 17H CPUs can only be done on
the host.

Extend x86_spec_ctrl_set_guest() and x86_spec_ctrl_restore_host() with an
extra argument for the VIRT_SPEC_CTRL MSR.

Hand in 0 from VMX and in SVM add a new virt_spec_ctrl member to the CPU
data structure which is going to be used in later patches for the actual
implementation.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2018-05-17 17:09:18 +02:00
Thomas Gleixner
1f50ddb4f4 x86/speculation: Handle HT correctly on AMD
The AMD64_LS_CFG MSR is a per core MSR on Family 17H CPUs. That means when
hyperthreading is enabled the SSBD bit toggle needs to take both cores into
account. Otherwise the following situation can happen:

CPU0		CPU1

disable SSB
		disable SSB
		enable  SSB <- Enables it for the Core, i.e. for CPU0 as well

So after the SSB enable on CPU1 the task on CPU0 runs with SSB enabled
again.

On Intel the SSBD control is per core as well, but the synchronization
logic is implemented behind the per thread SPEC_CTRL MSR. It works like
this:

  CORE_SPEC_CTRL = THREAD0_SPEC_CTRL | THREAD1_SPEC_CTRL

i.e. if one of the threads enables a mitigation then this affects both and
the mitigation is only disabled in the core when both threads disabled it.

Add the necessary synchronization logic for AMD family 17H. Unfortunately
that requires a spinlock to serialize the access to the MSR, but the locks
are only shared between siblings.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2018-05-17 17:09:18 +02:00
Thomas Gleixner
d1035d9718 x86/cpufeatures: Add FEATURE_ZEN
Add a ZEN feature bit so family-dependent static_cpu_has() optimizations
can be built for ZEN.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2018-05-17 17:09:18 +02:00
Thomas Gleixner
52817587e7 x86/cpufeatures: Disentangle SSBD enumeration
The SSBD enumeration is similarly to the other bits magically shared
between Intel and AMD though the mechanisms are different.

Make X86_FEATURE_SSBD synthetic and set it depending on the vendor specific
features or family dependent setup.

Change the Intel bit to X86_FEATURE_SPEC_CTRL_SSBD to denote that SSBD is
controlled via MSR_SPEC_CTRL and fix up the usage sites.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2018-05-17 17:09:17 +02:00
Thomas Gleixner
7eb8956a7f x86/cpufeatures: Disentangle MSR_SPEC_CTRL enumeration from IBRS
The availability of the SPEC_CTRL MSR is enumerated by a CPUID bit on
Intel and implied by IBRS or STIBP support on AMD. That's just confusing
and in case an AMD CPU has IBRS not supported because the underlying
problem has been fixed but has another bit valid in the SPEC_CTRL MSR,
the thing falls apart.

Add a synthetic feature bit X86_FEATURE_MSR_SPEC_CTRL to denote the
availability on both Intel and AMD.

While at it replace the boot_cpu_has() checks with static_cpu_has() where
possible. This prevents late microcode loading from exposing SPEC_CTRL, but
late loading is already very limited as it does not reevaluate the
mitigation options and other bits and pieces. Having static_cpu_has() is
the simplest and least fragile solution.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2018-05-17 17:09:17 +02:00
Borislav Petkov
e7c587da12 x86/speculation: Use synthetic bits for IBRS/IBPB/STIBP
Intel and AMD have different CPUID bits hence for those use synthetic bits
which get set on the respective vendor's in init_speculation_control(). So
that debacles like what the commit message of

  c65732e4f7 ("x86/cpu: Restore CPUID_8000_0008_EBX reload")

talks about don't happen anymore.

Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Tested-by: Jörg Otte <jrg.otte@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Link: https://lkml.kernel.org/r/20180504161815.GG9257@pd.tnic
2018-05-17 17:09:16 +02:00
Dan Williams
8780356ef6 x86/asm/memcpy_mcsafe: Define copy_to_iter_mcsafe()
Use the updated memcpy_mcsafe() implementation to define
copy_user_mcsafe() and copy_to_iter_mcsafe(). The most significant
difference from typical copy_to_iter() is that the ITER_KVEC and
ITER_BVEC iterator types can fail to complete a full transfer.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: hch@lst.de
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-nvdimm@lists.01.org
Link: http://lkml.kernel.org/r/152539239150.31796.9189779163576449784.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-05-15 08:32:42 +02:00
Dan Williams
12c89130a5 x86/asm/memcpy_mcsafe: Add write-protection-fault handling
In preparation for using memcpy_mcsafe() to handle user copies it needs
to be to handle write-protection faults while writing user pages. Add
MMU-fault handlers alongside the machine-check exception handlers.

Note that the machine check fault exception handling makes assumptions
about source buffer alignment and poison alignment. In the write fault
case, given the destination buffer is arbitrarily aligned, it needs a
separate / additional fault handling approach. The mcsafe_handle_tail()
helper is reused. The @limit argument is set to @len since there is no
safety concern about retriggering an MMU fault, and this simplifies the
assembly.

Co-developed-by: Tony Luck <tony.luck@intel.com>
Reported-by: Mika Penttilä <mika.penttila@nextfour.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: hch@lst.de
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-nvdimm@lists.01.org
Link: http://lkml.kernel.org/r/152539238635.31796.14056325365122961778.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-05-15 08:32:42 +02:00
Dan Williams
60622d6822 x86/asm/memcpy_mcsafe: Return bytes remaining
Machine check safe memory copies are currently deployed in the pmem
driver whenever reading from persistent memory media, so that -EIO is
returned rather than triggering a kernel panic. While this protects most
pmem accesses, it is not complete in the filesystem-dax case. When
filesystem-dax is enabled reads may bypass the block layer and the
driver via dax_iomap_actor() and its usage of copy_to_iter().

In preparation for creating a copy_to_iter() variant that can handle
machine checks, teach memcpy_mcsafe() to return the number of bytes
remaining rather than -EFAULT when an exception occurs.

Co-developed-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: hch@lst.de
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-nvdimm@lists.01.org
Link: http://lkml.kernel.org/r/152539238119.31796.14318473522414462886.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-05-15 08:32:42 +02:00
Dan Williams
da7bc9c57e x86/asm/memcpy_mcsafe: Remove loop unrolling
In preparation for teaching memcpy_mcsafe() to return 'bytes remaining'
rather than pass / fail, simplify the implementation to remove loop
unrolling. The unrolling complicates the fault handling for negligible
benefit given modern CPUs perform loop stream detection.

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: hch@lst.de
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-nvdimm@lists.01.org
Link: http://lkml.kernel.org/r/152539237092.31796.9115692316555638048.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-05-15 08:32:41 +02:00
Daniel Borkmann
36256009b2 bpf, x64: clean up retpoline emission slightly
Make the RETPOLINE_{RA,ED}X_BPF_JIT() a bit more readable by
cleaning up the macro, aligning comments and spacing.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2018-05-14 19:11:45 -07:00
Jim Mattson
1313cc2bd8 kvm: mmu: Add guest_mode to kvm_mmu_page_role
L1 and L2 need to have disjoint mappings, so that L1's APIC access
page (under VMX) can be omitted from L2's mappings.

Signed-off-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Krish Sadhukhan <krish.sadhukhan@oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2018-05-14 18:24:25 +02:00
Jim Mattson
8d860bbeed kvm: vmx: Basic APIC virtualization controls have three settings
Previously, we toggled between SECONDARY_EXEC_VIRTUALIZE_X2APIC_MODE
and SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES, depending on whether or
not the EXTD bit was set in MSR_IA32_APICBASE. However, if the local
APIC is disabled, we should not set either of these APIC
virtualization control bits.

Signed-off-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Krish Sadhukhan <krish.sadhukhan@oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2018-05-14 18:24:24 +02:00
Vitaly Kuznetsov
ceef7d10df KVM: x86: VMX: hyper-v: Enlightened MSR-Bitmap support
Enlightened MSR-Bitmap is a natural extension of Enlightened VMCS:
Hyper-V Top Level Functional Specification states:

"The L1 hypervisor may collaborate with the L0 hypervisor to make MSR
accesses more efficient. It can enable enlightened MSR bitmaps by setting
the corresponding field in the enlightened VMCS to 1. When enabled, the L0
hypervisor does not monitor the MSR bitmaps for changes. Instead, the L1
hypervisor must invalidate the corresponding clean field after making
changes to one of the MSR bitmaps."

I reached out to Hyper-V team for additional details and I got the
following information:

"Current Hyper-V implementation works as following:

If the enlightened MSR bitmap is not enabled:
- All MSR accesses of L2 guests cause physical VM-Exits

If the enlightened MSR bitmap is enabled:
- Physical VM-Exits for L2 accesses to certain MSRs (currently FS_BASE,
  GS_BASE and KERNEL_GS_BASE) are avoided, thus making these MSR accesses
  faster."

I tested my series with a tight rdmsrl loop in L2, for KERNEL_GS_BASE the
results are:

Without Enlightened MSR-Bitmap: 1300 cycles/read
With Enlightened MSR-Bitmap: 120 cycles/read

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Tested-by: Lan Tianyu <Tianyu.Lan@microsoft.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2018-05-14 18:14:24 +02:00
Junaid Shahid
74b566e6cf kvm: x86: Refactor mmu_free_roots()
Extract the logic to free a root page in a separate function to avoid code
duplication in mmu_free_roots(). Also, change it to an exported function
i.e. kvm_mmu_free_roots().

Signed-off-by: Junaid Shahid <junaids@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2018-05-14 18:14:23 +02:00
Frederic Weisbecker
1a8bc8f8d6 softirq/x86: Switch to generic local_softirq_pending() implementation
Remove the ad-hoc implementation, the generic code now allows us not to
reinvent the wheel.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: James E.J. Bottomley <jejb@parisc-linux.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Link: http://lkml.kernel.org/r/1525786706-22846-11-git-send-email-frederic@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-05-14 11:25:28 +02:00
Dave Hansen
2fa9d1cfaf x86/pkeys: Do not special case protection key 0
mm_pkey_is_allocated() treats pkey 0 as unallocated.  That is
inconsistent with the manpages, and also inconsistent with
mm->context.pkey_allocation_map.  Stop special casing it and only
disallow values that are actually bad (< 0).

The end-user visible effect of this is that you can now use
mprotect_pkey() to set pkey=0.

This is a bit nicer than what Ram proposed[1] because it is simpler
and removes special-casing for pkey 0.  On the other hand, it does
allow applications to pkey_free() pkey-0, but that's just a silly
thing to do, so we are not going to protect against it.

The scenario that could happen is similar to what happens if you free
any other pkey that is in use: it might get reallocated later and used
to protect some other data.  The most likely scenario is that pkey-0
comes back from pkey_alloc(), an access-disable or write-disable bit
is set in PKRU for it, and the next stack access will SIGSEGV.  It's
not horribly different from if you mprotect()'d your stack or heap to
be unreadable or unwritable, which is generally very foolish, but also
not explicitly prevented by the kernel.

1. http://lkml.kernel.org/r/1522112702-27853-1-git-send-email-linuxram@us.ibm.com

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>p
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael Ellermen <mpe@ellerman.id.au>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ram Pai <linuxram@us.ibm.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Cc: stable@vger.kernel.org
Fixes: 58ab9a088d ("x86/pkeys: Check against max pkey to avoid overflows")
Link: http://lkml.kernel.org/r/20180509171358.47FD785E@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-05-14 11:14:45 +02:00
Dave Hansen
0a0b152083 x86/pkeys: Override pkey when moving away from PROT_EXEC
I got a bug report that the following code (roughly) was
causing a SIGSEGV:

	mprotect(ptr, size, PROT_EXEC);
	mprotect(ptr, size, PROT_NONE);
	mprotect(ptr, size, PROT_READ);
	*ptr = 100;

The problem is hit when the mprotect(PROT_EXEC)
is implicitly assigned a protection key to the VMA, and made
that key ACCESS_DENY|WRITE_DENY.  The PROT_NONE mprotect()
failed to remove the protection key, and the PROT_NONE->
PROT_READ left the PTE usable, but the pkey still in place
and left the memory inaccessible.

To fix this, we ensure that we always "override" the pkee
at mprotect() if the VMA does not have execute-only
permissions, but the VMA has the execute-only pkey.

We had a check for PROT_READ/WRITE, but it did not work
for PROT_NONE.  This entirely removes the PROT_* checks,
which ensures that PROT_NONE now works.

Reported-by: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael Ellermen <mpe@ellerman.id.au>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ram Pai <linuxram@us.ibm.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Cc: stable@vger.kernel.org
Fixes: 62b5f7d013 ("mm/core, x86/mm/pkeys: Add execute-only protection keys support")
Link: http://lkml.kernel.org/r/20180509171351.084C5A71@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-05-14 11:14:45 +02:00
Jim Mattson
5f2b745f5e x86/cpu: Make alternative_msr_write work for 32-bit code
Cast val and (val >> 32) to (u32), so that they fit in a
general-purpose register in both 32-bit and 64-bit code.

[ tglx: Made it u32 instead of uintptr_t ]

Fixes: c65732e4f7 ("x86/cpu: Restore CPUID_8000_0008_EBX reload")
Signed-off-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-05-14 10:34:28 +02:00
Alexei Starovoitov
b1ae32dbab x86/cpufeature: Guard asm_volatile_goto usage for BPF compilation
Workaround for the sake of BPF compilation which utilizes kernel
headers, but clang does not support ASM GOTO and fails the build.

Fixes: d0266046ad ("x86: Remove FAST_FEATURE_TESTS")
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: daniel@iogearbox.net
Cc: peterz@infradead.org
Cc: netdev@vger.kernel.org
Cc: bp@alien8.de
Cc: yhs@fb.com
Cc: kernel-team@fb.com
Cc: torvalds@linux-foundation.org
Cc: davem@davemloft.net
Link: https://lkml.kernel.org/r/20180513193222.1997938-1-ast@kernel.org
2018-05-13 21:49:14 +02:00
Masami Hiramatsu
ee6a7354a3 kprobes/x86: Prohibit probing on exception masking instructions
Since MOV SS and POP SS instructions will delay the exceptions until the
next instruction is executed, single-stepping on it by kprobes must be
prohibited.

However, kprobes usually executes those instructions directly on trampoline
buffer (a.k.a. kprobe-booster), except for the kprobes which has
post_handler. Thus if kprobe user probes MOV SS with post_handler, it will
do single-stepping on the MOV SS.

This means it is safe that if it is used via ftrace or perf/bpf since those
don't use the post_handler.

Anyway, since the stack switching is a rare case, it is safer just
rejecting kprobes on such instructions.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Cc: Francis Deslauriers <francis.deslauriers@efficios.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: "H . Peter Anvin" <hpa@zytor.com>
Cc: Yonghong Song <yhs@fb.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "David S . Miller" <davem@davemloft.net>
Link: https://lkml.kernel.org/r/152587069574.17316.3311695234863248641.stgit@devbox
2018-05-13 19:52:55 +02:00
Thomas Gleixner
b5cf8707e6 x86/CPU: Move cpu local function declarations to local header
No point in exposing all these functions globaly as they are strict local
to the cpu management code.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2018-05-13 12:06:12 +02:00
Konrad Rzeszutek Wilk
9f65fb2937 x86/bugs: Rename _RDS to _SSBD
Intel collateral will reference the SSB mitigation bit in IA32_SPEC_CTL[2]
as SSBD (Speculative Store Bypass Disable).

Hence changing it.

It is unclear yet what the MSR_IA32_ARCH_CAPABILITIES (0x10a) Bit(4) name
is going to be. Following the rename it would be SSBD_NO but that rolls out
to Speculative Store Bypass Disable No.

Also fixed the missing space in X86_FEATURE_AMD_SSBD.

[ tglx: Fixup x86_amd_rds_enable() and rds_tif_to_amd_ls_cfg() as well ]

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2018-05-09 21:41:38 +02:00
Michael Ellerman
3f36c94239 x86/pkeys: Add arch_pkeys_enabled()
This will be used in future patches to check for arch support for
pkeys in generic code.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Dave Hansen <dave.hansen@intel.com>
2018-05-09 11:51:28 +10:00
Michael Ellerman
555934a71b x86/pkeys: Move vma_pkey() into asm/pkeys.h
Move the last remaining pkey helper, vma_pkey() into asm/pkeys.h

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Dave Hansen <dave.hansen@intel.com>
2018-05-09 11:51:00 +10:00
Michael Ellerman
dbec10e58d mm/pkeys, powerpc, x86: Provide an empty vma_pkey() in linux/pkeys.h
Consolidate the pkey handling by providing a common empty definition
of vma_pkey() in pkeys.h when CONFIG_ARCH_HAS_PKEYS=n.

This also removes another entanglement of pkeys.h and
asm/mmu_context.h.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Ram Pai <linuxram@us.ibm.com>
Reviewed-by: Dave Hansen <dave.hansen@intel.com>
2018-05-09 11:50:41 +10:00
David S. Miller
01adc4851a Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
Minor conflict, a CHECK was placed into an if() statement
in net-next, whilst a newline was added to that CHECK
call in 'net'.  Thanks to Daniel for the merge resolution.

Signed-off-by: David S. Miller <davem@davemloft.net>
2018-05-07 23:35:08 -04:00
Thomas Gleixner
4fe581d7f1 Merge tag 'y2038-ipc' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/playground into timers/2038
Pull 'y2038: IPC system call conversion' from Arnd Bergmann:

"This is a follow-up to Deepa's work on the timekeeping system calls,
 providing a y2038-safe syscall API for SYSVIPC. It uses a combination
 of two strategies:

 For sys_msgctl, sys_semctl and sys_shmctl, I do not introduce a completely
 new set of replacement system calls, but instead extend the existing
 ones to return data in the reserved fields of the normal data structure.

 This should be completely transparent to any existing user space, and
 only after the 32-bit time_t wraps, it will make a difference in the
 returned data.

 libc implementations will consequently have to provide their own data
 structures when they move to 64-bit time_t, and convert the structures
 in user space from the ones returned by the kernel.

 In contrast, mq_timedsend, mq_timedreceive and and semtimedop all do
 need to change because having a libc redefine the timespec type
 breaks the ABI, so with this series there will be two separate entry
 points for 32-bit architectures.

 There are three cases here:

 - little-endian architectures (except powerpc and mips) can use
   the normal layout and just cast the data structure to the user space
   type that contains 64-bit numbers.

 - parisc and sparc can do the same thing with big-endian user space

 - little-endian powerpc and most big-endian architectures have
   to flip the upper and lower 32-bit halves of the time_t value in memory,
   but can otherwise keep using the normal layout

 - mips and big-endian xtensa need to be more careful because
   they are not consistent in their definitions, and they have to provide
   custom libc implementations for the system calls to use 64-bit time_t."
2018-05-07 14:21:39 +02:00
Christoph Hellwig
325ef1857f PCI: remove PCI_DMA_BUS_IS_PHYS
This was used by the ide, scsi and networking code in the past to
determine if they should bounce payloads.  Now that the dma mapping
always have to support dma to all physical memory (thanks to swiotlb
for non-iommu systems) there is no need to this crude hack any more.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Palmer Dabbelt <palmer@sifive.com> (for riscv)
Reviewed-by: Jens Axboe <axboe@kernel.dk>
2018-05-07 07:15:41 +02:00
Suravee Suthikulpanit
6c4f5abaf3 x86/CPU: Modify detect_extended_topology() to return result
Current implementation does not communicate whether it can successfully
detect CPUID function 0xB information. Therefore, modify the function to
return success or error codes. This will be used by subsequent patches.

Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: http://lkml.kernel.org/r/1524865681-112110-2-git-send-email-suravee.suthikulpanit@amd.com
2018-05-06 12:49:16 +02:00
Suravee Suthikulpanit
68091ee7ac x86/CPU/AMD: Calculate last level cache ID from number of sharing threads
Last Level Cache ID can be calculated from the number of threads sharing
the cache, which is available from CPUID Fn0x8000001D (Cache Properties).
This is used to left-shift the APIC ID to derive LLC ID.

Therefore, default to this method unless the APIC ID enumeration does not
follow the scheme.

Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1524864877-111962-5-git-send-email-suravee.suthikulpanit@amd.com
2018-05-06 12:49:15 +02:00
Borislav Petkov
f8b64d08dd x86/CPU/AMD: Have smp_num_siblings and cpu_llc_id always be present
Move smp_num_siblings and cpu_llc_id to cpu/common.c so that they're
always present as symbols and not only in the CONFIG_SMP case. Then,
other code using them doesn't need ugly ifdeffery anymore. Get rid of
some ifdeffery.

Signed-off-by: Borislav Petkov <bpetkov@suse.de>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1524864877-111962-2-git-send-email-suravee.suthikulpanit@amd.com
2018-05-06 12:49:14 +02:00
Ingo Molnar
12e2c41148 Merge branch 'linus' into locking/core, to pick up fixes
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-05-05 10:01:34 +02:00
Kees Cook
f21b53b20c x86/speculation: Make "seccomp" the default mode for Speculative Store Bypass
Unless explicitly opted out of, anything running under seccomp will have
SSB mitigations enabled. Choosing the "prctl" mode will disable this.

[ tglx: Adjusted it to the new arch_seccomp_spec_mitigate() mechanism ]

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2018-05-05 00:51:45 +02:00
Wang YanQing
03f5781be2 bpf, x86_32: add eBPF JIT compiler for ia32
The JIT compiler emits ia32 bit instructions. Currently, It supports eBPF
only. Classic BPF is supported because of the conversion by BPF core.

Almost all instructions from eBPF ISA supported except the following:
BPF_ALU64 | BPF_DIV | BPF_K
BPF_ALU64 | BPF_DIV | BPF_X
BPF_ALU64 | BPF_MOD | BPF_K
BPF_ALU64 | BPF_MOD | BPF_X
BPF_STX | BPF_XADD | BPF_W
BPF_STX | BPF_XADD | BPF_DW

It doesn't support BPF_JMP|BPF_CALL with BPF_PSEUDO_CALL at the moment.

IA32 has few general purpose registers, EAX|EDX|ECX|EBX|ESI|EDI. I use
EAX|EDX|ECX|EBX as temporary registers to simulate instructions in eBPF
ISA, and allocate ESI|EDI to BPF_REG_AX for constant blinding, all others
eBPF registers, R0-R10, are simulated through scratch space on stack.

The reasons behind the hardware registers allocation policy are:
1:MUL need EAX:EDX, shift operation need ECX, so they aren't fit
  for general eBPF 64bit register simulation.
2:We need at least 4 registers to simulate most eBPF ISA operations
  on registers operands instead of on register&memory operands.
3:We need to put BPF_REG_AX on hardware registers, or constant blinding
  will degrade jit performance heavily.

Tested on PC (Intel(R) Core(TM) i5-5200U CPU).
Testing results on i5-5200U:
1) test_bpf: Summary: 349 PASSED, 0 FAILED, [319/341 JIT'ed]
2) test_progs: Summary: 83 PASSED, 0 FAILED.
3) test_lpm: OK
4) test_lru_map: OK
5) test_verifier: Summary: 828 PASSED, 0 FAILED.

Above tests are all done in following two conditions separately:
1:bpf_jit_enable=1 and bpf_jit_harden=0
2:bpf_jit_enable=1 and bpf_jit_harden=2

Below are some numbers for this jit implementation:
Note:
  I run test_progs in kselftest 100 times continuously for every condition,
  the numbers are in format: total/times=avg.
  The numbers that test_bpf reports show almost the same relation.

a:jit_enable=0 and jit_harden=0            b:jit_enable=1 and jit_harden=0
  test_pkt_access:PASS:ipv4:15622/100=156    test_pkt_access:PASS:ipv4:10674/100=106
  test_pkt_access:PASS:ipv6:9130/100=91      test_pkt_access:PASS:ipv6:4855/100=48
  test_xdp:PASS:ipv4:240198/100=2401         test_xdp:PASS:ipv4:138912/100=1389
  test_xdp:PASS:ipv6:137326/100=1373         test_xdp:PASS:ipv6:68542/100=685
  test_l4lb:PASS:ipv4:61100/100=611          test_l4lb:PASS:ipv4:37302/100=373
  test_l4lb:PASS:ipv6:101000/100=1010        test_l4lb:PASS:ipv6:55030/100=550

c:jit_enable=1 and jit_harden=2
  test_pkt_access:PASS:ipv4:10558/100=105
  test_pkt_access:PASS:ipv6:5092/100=50
  test_xdp:PASS:ipv4:131902/100=1319
  test_xdp:PASS:ipv6:77932/100=779
  test_l4lb:PASS:ipv4:38924/100=389
  test_l4lb:PASS:ipv6:57520/100=575

The numbers show we get 30%~50% improvement.

See Documentation/networking/filter.txt for more information.

Changelog:

 Changes v5-v6:
 1:Add do {} while (0) to RETPOLINE_RAX_BPF_JIT for
   consistence reason.
 2:Clean up non-standard comments, reported by Daniel Borkmann.
 3:Fix a memory leak issue, repoted by Daniel Borkmann.

 Changes v4-v5:
 1:Delete is_on_stack, BPF_REG_AX is the only one
   on real hardware registers, so just check with
   it.
 2:Apply commit 1612a981b7 ("bpf, x64: fix JIT emission
   for dead code"), suggested by Daniel Borkmann.

 Changes v3-v4:
 1:Fix changelog in commit.
   I install llvm-6.0, then test_progs willn't report errors.
   I submit another patch:
   "bpf: fix misaligned access for BPF_PROG_TYPE_PERF_EVENT program type on x86_32 platform"
   to fix another problem, after that patch, test_verifier willn't report errors too.
 2:Fix clear r0[1] twice unnecessarily in *BPF_IND|BPF_ABS* simulation.

 Changes v2-v3:
 1:Move BPF_REG_AX to real hardware registers for performance reason.
 3:Using bpf_load_pointer instead of bpf_jit32.S, suggested by Daniel Borkmann.
 4:Delete partial codes in 1c2a088a66, suggested by Daniel Borkmann.
 5:Some bug fixes and comments improvement.

 Changes v1-v2:
 1:Fix bug in emit_ia32_neg64.
 2:Fix bug in emit_ia32_arsh_r64.
 3:Delete filename in top level comment, suggested by Thomas Gleixner.
 4:Delete unnecessary boiler plate text, suggested by Thomas Gleixner.
 5:Rewrite some words in changelog.
 6:CodingSytle improvement and a little more comments.

Signed-off-by: Wang YanQing <udknight@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-05-03 18:15:25 +02:00