linux-toradex.git/arch/x86/include, branch v3.10.52

x86_64/entry/xen: Do not invoke espfix64 on Xen

2014-08-07T21:30:26+00:00

commit 7209a75d2009dbf7745e2fd354abf25c3deb3ca3 upstream.

This moves the espfix64 logic into native_iret.  To make this work,
it gets rid of the native patch for INTERRUPT_RETURN:
INTERRUPT_RETURN on native kernels is now 'jmp native_iret'.

This changes the 16-bit SS behavior on Xen from OOPSing to leaking
some bits of the Xen hypervisor's RSP (I think).

[ hpa: this is a nonzero cost on native, but probably not enough to
  measure. Xen needs to fix this in their own code, probably doing
  something equivalent to espfix64. ]

Signed-off-by: Andy Lutomirski 
Link: http://lkml.kernel.org/r/7b8f1d8ef6597cb16ae004a43c56980a7de3cf94.1406129132.git.luto@amacapital.net
Signed-off-by: H. Peter Anvin 
Signed-off-by: Greg Kroah-Hartman

x86, espfix: Fix broken header guard

2014-08-07T21:30:26+00:00

commit 20b68535cd27183ebd3651ff313afb2b97dac941 upstream.

Header guard is #ifndef, not #ifdef...

Reported-by: Fengguang Wu 
Signed-off-by: H. Peter Anvin 
Signed-off-by: Greg Kroah-Hartman

x86, espfix: Move espfix definitions into a separate header file

2014-08-07T21:30:26+00:00

commit e1fe9ed8d2a4937510d0d60e20705035c2609aea upstream.

Sparse warns that the percpu variables aren't declared before they are
defined.  Rather than hacking around it, move espfix definitions into
a proper header file.

Reported-by: Fengguang Wu 
Signed-off-by: H. Peter Anvin 
Signed-off-by: Greg Kroah-Hartman

x86-64, espfix: Don't leak bits 31:16 of %esp returning to 16-bit stack

2014-08-07T21:30:26+00:00

commit 3891a04aafd668686239349ea58f3314ea2af86b upstream.

The IRET instruction, when returning to a 16-bit segment, only
restores the bottom 16 bits of the user space stack pointer.  This
causes some 16-bit software to break, but it also leaks kernel state
to user space.  We have a software workaround for that ("espfix") for
the 32-bit kernel, but it relies on a nonzero stack segment base which
is not available in 64-bit mode.

In checkin:

    b3b42ac2cbae x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

we "solved" this by forbidding 16-bit segments on 64-bit kernels, with
the logic that 16-bit support is crippled on 64-bit kernels anyway (no
V86 support), but it turns out that people are doing stuff like
running old Win16 binaries under Wine and expect it to work.

This works around this by creating percpu "ministacks", each of which
is mapped 2^16 times 64K apart.  When we detect that the return SS is
on the LDT, we copy the IRET frame to the ministack and use the
relevant alias to return to userspace.  The ministacks are mapped
readonly, so if IRET faults we promote #GP to #DF which is an IST
vector and thus has its own stack; we then do the fixup in the #DF
handler.

(Making #GP an IST exception would make the msr_safe functions unsafe
in NMI/MC context, and quite possibly have other effects.)

Special thanks to:

- Andy Lutomirski, for the suggestion of using very small stack slots
  and copy (as opposed to map) the IRET frame there, and for the
  suggestion to mark them readonly and let the fault promote to #DF.
- Konrad Wilk for paravirt fixup and testing.
- Borislav Petkov for testing help and useful comments.

Reported-by: Brian Gerst 
Signed-off-by: H. Peter Anvin 
Link: http://lkml.kernel.org/r/1398816946-3351-1-git-send-email-hpa@linux.intel.com
Cc: Konrad Rzeszutek Wilk 
Cc: Borislav Petkov 
Cc: Andrew Lutomriski 
Cc: Linus Torvalds 
Cc: Dirk Hohndel 
Cc: Arjan van de Ven 
Cc: comex 
Cc: Alexander van Heukelum 
Cc: Boris Ostrovsky 
Signed-off-by: Greg Kroah-Hartman

KVM: x86: preserve the high 32-bits of the PAT register

2014-07-09T18:14:02+00:00

commit 7cb060a91c0efc5ff94f83c6df3ed705e143cdb9 upstream.

KVM does not really do much with the PAT, so this went unnoticed for a
long time.  It is exposed however if you try to do rdmsr on the PAT
register.

Reported-by: Valentine Sinitsyn 
Signed-off-by: Paolo Bonzini 
Signed-off-by: Greg Kroah-Hartman

KVM: x86: Increase the number of fixed MTRR regs to 10

2014-07-09T18:14:02+00:00

commit 682367c494869008eb89ef733f196e99415ae862 upstream.

Recent Intel CPUs have 10 variable range MTRRs. Since operating systems
sometime make assumptions on CPUs while they ignore capability MSRs, it is
better for KVM to be consistent with recent CPUs. Reporting more MTRRs than
actually supported has no functional implications.

Signed-off-by: Nadav Amit 
Signed-off-by: Paolo Bonzini 
Signed-off-by: Greg Kroah-Hartman

ptrace,x86: force IRET path after a ptrace_stop()

2014-07-07T01:54:15+00:00

commit b9cd18de4db3c9ffa7e17b0dc0ca99ed5aa4d43a upstream.

The 'sysret' fastpath does not correctly restore even all regular
registers, much less any segment registers or reflags values.  That is
very much part of why it's faster than 'iret'.

Normally that isn't a problem, because the normal ptrace() interface
catches the process using the signal handler infrastructure, which
always returns with an iret.

However, some paths can get caught using ptrace_event() instead of the
signal path, and for those we need to make sure that we aren't going to
return to user space using 'sysret'.  Otherwise the modifications that
may have been done to the register set by the tracer wouldn't
necessarily take effect.

Fix it by forcing IRET path by setting TIF_NOTIFY_RESUME from
arch_ptrace_stop_needed() which is invoked from ptrace_stop().

Signed-off-by: Tejun Heo 
Reported-by: Andy Lutomirski 
Acked-by: Oleg Nesterov 
Suggested-by: Linus Torvalds 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

x86, mm, hugetlb: Add missing TLB page invalidation for hugetlb_cow()

2014-06-07T20:25:31+00:00

commit 9844f5462392b53824e8b86726e7c33b5ecbb676 upstream.

The invalidation is required in order to maintain proper semantics
under CoW conditions. In scenarios where a process clones several
threads, a thread operating on a core whose DTLB entry for a
particular hugepage has not been invalidated, will be reading from
the hugepage that belongs to the forked child process, even after
hugetlb_cow().

The thread will not see the updated page as long as the stale DTLB
entry remains cached, the thread attempts to write into the page,
the child process exits, or the thread gets migrated to a different
processor.

Signed-off-by: Anthony Iliopoulos 
Link: http://lkml.kernel.org/r/20140514092948.GA17391@server-36.huawei.corp
Suggested-by: Shay Goikhman 
Acked-by: Dave Hansen 
Signed-off-by: H. Peter Anvin 
Signed-off-by: Greg Kroah-Hartman

x86: fix boot on uniprocessor systems

2014-04-03T19:01:05+00:00

commit 825600c0f20e595daaa7a6dd8970f84fa2a2ee57 upstream.

On x86 uniprocessor systems topology_physical_package_id() returns -1
which causes rapl_cpu_prepare() to leave rapl_pmu variable uninitialized
which leads to GPF in rapl_pmu_init().

See arch/x86/kernel/cpu/perf_event_intel_rapl.c.

It turns out that physical_package_id and core_id can actually be
retreived for uniprocessor systems too.  Enabling them also fixes
rapl_pmu code.

Signed-off-by: Artem Fetishev 
Cc: Stephane Eranian 
Cc: Ingo Molnar 
Cc: "H. Peter Anvin" 
Cc: Thomas Gleixner 
Cc: Peter Zijlstra 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

xen/p2m: check MFN is in range before using the m2p table

2014-02-22T20:41:25+00:00

commit 0160676bba69523e8b0ac83f306cce7d342ed7c8 upstream.

On hosts with more than 168 GB of memory, a 32-bit guest may attempt
to grant map an MFN that is error cannot lookup in its mapping of the
m2p table.  There is an m2p lookup as part of m2p_add_override() and
m2p_remove_override().  The lookup falls off the end of the mapped
portion of the m2p and (because the mapping is at the highest virtual
address) wraps around and the lookup causes a fault on what appears to
be a user space address.

do_page_fault() (thinking it's a fault to a userspace address), tries
to lock mm->mmap_sem.  If the gntdev device is used for the grant map,
m2p_add_override() is called from from gnttab_mmap() with mm->mmap_sem
already locked.  do_page_fault() then deadlocks.

The deadlock would most commonly occur when a 64-bit guest is started
and xenconsoled attempts to grant map its console ring.

Introduce mfn_to_pfn_no_overrides() which checks the MFN is within the
mapped portion of the m2p table before accessing the table and use
this in m2p_add_override(), m2p_remove_override(), and mfn_to_pfn()
(which already had the correct range check).

All faults caused by accessing the non-existant parts of the m2p are
thus within the kernel address space and exception_fixup() is called
without trying to lock mm->mmap_sem.

This means that for MFNs that are outside the mapped range of the m2p
then mfn_to_pfn() will always look in the m2p overrides.  This is
correct because it must be a foreign MFN (and the PFN in the m2p in
this case is only relevant for the other domain).

v3: check for auto_translated_physmap in mfn_to_pfn_no_overrides()
v2: in mfn_to_pfn() look in m2p_overrides if the MFN is out of
    range as it's probably foreign.

Signed-off-by: David Vrabel 
Cc: Stefano Stabellini 
Cc: Jan Beulich 
Signed-off-by: Konrad Rzeszutek Wilk 
Acked-by: Stefano Stabellini 
Signed-off-by: Greg Kroah-Hartman