Preemption is disabled between kernel_fpu_begin/end() and as such
it is not a good idea to use these routines in kvm_load/put_guest_fpu()
which can be very far apart.

kvm_load/put_guest_fpu() routines are already called with
preemption disabled and KVM already uses the preempt notifier to save
the guest fpu state using kvm_put_guest_fpu().

So introduce __kernel_fpu_begin/end() routines which don't touch
preemption and use them instead of kernel_fpu_begin/end()
for KVM's use model of saving/restoring guest FPU state.

Also with this change (and with eagerFPU model), fix the host cr0.TS vm-exit
state in the case of VMX. For eagerFPU case, host cr0.TS is always clear.
So no need to worry about it. For the traditional lazyFPU restore case,
change the cr0.TS bit for the host state during vm-exit to be always clear
and cr0.TS bit is set in the __vmx_load_host_state() when the FPU
(guest FPU or the host task's FPU) state is not active. This ensures
that the host/guest FPU state is properly saved, restored
during context-switch and with interrupts (using irq_fpu_usable()) not
stomping on the active FPU state.
Signed-off-by: NSuresh Siddha <suresh.b.siddha@intel.com>
Link: http://lkml.kernel.org/r/1348164109.26695.338.camel@sbsiddha-desk.sc.intel.com
Cc: Avi Kivity <avi@redhat.com>
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>

The changes to entry_32.S got missed in checkin:

63bcff2a x86, smap: Add STAC and CLAC instructions to control user space access

The resulting kernel was largely functional but SMAP protection could
have been bypassed.
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/r/1348256595-29119-9-git-send-email-hpa@linux.intel.com

Signal handling contains a bunch of accesses to individual user space
items, which causes an excessive number of STAC and CLAC
instructions.  Instead, let get/put_user_try ... get/put_user_catch()
contain the STAC and CLAC instructions.

This means that get/put_user_try no longer nests, and furthermore that
it is no longer legal to use user space access functions other than
__get/put_user_ex() inside those blocks.  However, these macros are
x86-specific anyway and are only used in the signal-handling paths; a
simple reordering of moving the larger subroutine calls out of the
try...catch blocks resolves that problem.
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/r/1348256595-29119-12-git-send-email-hpa@linux.intel.com

If we get a page fault due to SMAP, trigger an oops rather than
spinning forever.
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/r/1348256595-29119-11-git-send-email-hpa@linux.intel.com

If Supervisor Mode Access Prevention is available and not disabled by
the user, turn it on.  Also fix the expansion of SMEP (Supervisor Mode
Execution Prevention.)
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/r/1348256595-29119-10-git-send-email-hpa@linux.intel.com

When Supervisor Mode Access Prevention (SMAP) is enabled, access to
userspace from the kernel is controlled by the AC flag.  To make the
performance of manipulating that flag acceptable, there are two new
instructions, STAC and CLAC, to set and clear it.

This patch adds those instructions, via alternative(), when the SMAP
feature is enabled.  It also adds X86_EFLAGS_AC unconditionally to the
SYSCALL entry mask; there is simply no reason to make that one
conditional.
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/r/1348256595-29119-9-git-send-email-hpa@linux.intel.com

The prototypes for clear_user() and __clear_user() are identical in
the 32- and 64-bit headers.  No functionality change.
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/r/1348256595-29119-8-git-send-email-hpa@linux.intel.com

The STAC/CLAC instructions are only available with SMAP, but on the
other hand they aren't needed if SMAP is not available, or before we
start to run userspace, so construct them as alternatives which start
out as noops and are enabled by the alternatives mechanism.
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/r/1348256595-29119-7-git-send-email-hpa@linux.intel.com

Add header guards to protect <asm/alternative-asm.h> against multiple
inclusion.
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/r/1348256595-29119-6-git-send-email-hpa@linux.intel.com

.section/.previous doesn't nest.  Use .pushsection/.popsection in
<asm/alternative.h> so that they can be properly nested.
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/r/1348256595-29119-5-git-send-email-hpa@linux.intel.com

Add X86_CR4_SMAP to <asm/processor-flags.h>.
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/r/1348256595-29119-4-git-send-email-hpa@linux.intel.com

PAGE_READONLY includes user permission, but this is a page used
exclusively by the kernel; use PAGE_KERNEL_RO instead.
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/r/1348256595-29119-3-git-send-email-hpa@linux.intel.com

CPUs with FXSAVE but no XMM/MXCSR (Pentium II from Intel,
Crusoe/TM-3xxx/5xxx from Transmeta, and presumably some of the K6
generation from AMD) ever looked at the mxcsr field during
fxrstor/fxsave. So remove the cpu_has_xmm check in the fx_finit()
Reported-by: NAl Viro <viro@zeniv.linux.org.uk>
Acked-by: NH. Peter Anvin <hpa@zytor.com>
Signed-off-by: NSuresh Siddha <suresh.b.siddha@intel.com>
Link: http://lkml.kernel.org/r/1347300665-6209-6-git-send-email-suresh.b.siddha@intel.comSigned-off-by: NH. Peter Anvin <hpa@linux.intel.com>

Add the "eagerfpu=auto" (that selects the default scheme in
enabling eagerfpu) which can override compiled-in boot parameters
like "eagerfpu=on/off" (that force enable/disable eagerfpu).
Signed-off-by: NSuresh Siddha <suresh.b.siddha@intel.com>
Link: http://lkml.kernel.org/r/1347300665-6209-5-git-send-email-suresh.b.siddha@intel.comSigned-off-by: NH. Peter Anvin <hpa@linux.intel.com>

xsaveopt/xrstor support optimized state save/restore by tracking the
INIT state and MODIFIED state during context-switch.

Enable eagerfpu by default for processors supporting xsaveopt.
Can be disabled by passing "eagerfpu=off" boot parameter.
Signed-off-by: NSuresh Siddha <suresh.b.siddha@intel.com>
Link: http://lkml.kernel.org/r/1347300665-6209-3-git-send-email-suresh.b.siddha@intel.comSigned-off-by: NH. Peter Anvin <hpa@linux.intel.com>

Decouple non-lazy/eager fpu restore policy from the existence of the xsave
feature. Introduce a synthetic CPUID flag to represent the eagerfpu
policy. "eagerfpu=on" boot paramter will enable the policy.
Requested-by: NH. Peter Anvin <hpa@zytor.com>
Requested-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NSuresh Siddha <suresh.b.siddha@intel.com>
Link: http://lkml.kernel.org/r/1347300665-6209-2-git-send-email-suresh.b.siddha@intel.comSigned-off-by: NH. Peter Anvin <hpa@linux.intel.com>

Fundamental model of the current Linux kernel is to lazily init and
restore FPU instead of restoring the task state during context switch.
This changes that fundamental lazy model to the non-lazy model for
the processors supporting xsave feature.

Reasons driving this model change are:

i. Newer processors support optimized state save/restore using xsaveopt and
xrstor by tracking the INIT state and MODIFIED state during context-switch.
This is faster than modifying the cr0.TS bit which has serializing semantics.

ii. Newer glibc versions use SSE for some of the optimized copy/clear routines.
With certain workloads (like boot, kernel-compilation etc), application
completes its work with in the first 5 task switches, thus taking upto 5 #DNA
traps with the kernel not getting a chance to apply the above mentioned
pre-load heuristic.

iii. Some xstate features (like AMD's LWP feature) don't honor the cr0.TS bit
and thus will not work correctly in the presence of lazy restore. Non-lazy
state restore is needed for enabling such features.

Some data on a two socket SNB system:
 * Saved 20K DNA exceptions during boot on a two socket SNB system.
 * Saved 50K DNA exceptions during kernel-compilation workload.
 * Improved throughput of the AVX based checksumming function inside the
   kernel by ~15% as xsave/xrstor is faster than the serializing clts/stts
   pair.

Also now kernel_fpu_begin/end() relies on the patched
alternative instructions. So move check_fpu() which uses the
kernel_fpu_begin/end() after alternative_instructions().
Signed-off-by: NSuresh Siddha <suresh.b.siddha@intel.com>
Link: http://lkml.kernel.org/r/1345842782-24175-7-git-send-email-suresh.b.siddha@intel.com
Merge 32-bit boot fix from,
Link: http://lkml.kernel.org/r/1347300665-6209-4-git-send-email-suresh.b.siddha@intel.com
Cc: Jim Kukunas <james.t.kukunas@linux.intel.com>
Cc: NeilBrown <neilb@suse.de>
Cc: Avi Kivity <avi@redhat.com>
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>

use kernel_fpu_begin/end() instead of unconditionally accessing cr0 and
saving/restoring just the few used xmm/ymm registers.

This has some advantages like:
* If the task's FPU state is already active, then kernel_fpu_begin()
  will just save the user-state and avoiding the read/write of cr0.
  In general, cr0 accesses are much slower.

* Manual save/restore of xmm/ymm registers will affect the 'modified' and
  the 'init' optimizations brought in the by xsaveopt/xrstor
  infrastructure.

* Foward compatibility with future vector register extensions will be a
  problem if the xmm/ymm registers are manually saved and restored
  (corrupting the extended state of those vector registers).

With this patch, there was no significant difference in the xor throughput
using AVX, measured during boot.
Signed-off-by: NSuresh Siddha <suresh.b.siddha@intel.com>
Link: http://lkml.kernel.org/r/1345842782-24175-5-git-send-email-suresh.b.siddha@intel.com
Cc: Jim Kukunas <james.t.kukunas@linux.intel.com>
Cc: NeilBrown <neilb@suse.de>
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>

kvm's guest fpu save/restore should be wrapped around
kernel_fpu_begin/end(). This will avoid for example taking a DNA
in kvm_load_guest_fpu() when it tries to load the fpu immediately
after doing unlazy_fpu() on the host side.

More importantly this will prevent the host process fpu from being
corrupted.
Signed-off-by: NSuresh Siddha <suresh.b.siddha@intel.com>
Link: http://lkml.kernel.org/r/1345842782-24175-4-git-send-email-suresh.b.siddha@intel.com
Cc: Avi Kivity <avi@redhat.com>
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>

Few lines below we do drop_fpu() which is more safer. Remove the
unnecessary user_fpu_end() in save_xstate_sig(), which allows
the drop_fpu() to ignore any pending exceptions from the user-space
and drop the current fpu.
Signed-off-by: NSuresh Siddha <suresh.b.siddha@intel.com>
Link: http://lkml.kernel.org/r/1345842782-24175-3-git-send-email-suresh.b.siddha@intel.comSigned-off-by: NH. Peter Anvin <hpa@linux.intel.com>

No need to save the state with unlazy_fpu(), that is about to get overwritten
by the state from the signal frame. Instead use drop_fpu() and continue
to restore the new state.

Also fold the stop_fpu_preload() into drop_fpu().
Signed-off-by: NSuresh Siddha <suresh.b.siddha@intel.com>
Link: http://lkml.kernel.org/r/1345842782-24175-2-git-send-email-suresh.b.siddha@intel.comSigned-off-by: NH. Peter Anvin <hpa@linux.intel.com>

Currently for x86 and x86_32 binaries, fpstate in the user sigframe is copied
to/from the fpstate in the task struct.

And in the case of signal delivery for x86_64 binaries, if the fpstate is live
in the CPU registers, then the live state is copied directly to the user
sigframe. Otherwise  fpstate in the task struct is copied to the user sigframe.
During restore, fpstate in the user sigframe is restored directly to the live
CPU registers.

Historically, different code paths led to different bugs. For example,
x86_64 code path was not preemption safe till recently. Also there is lot
of code duplication for support of new features like xsave etc.

Unify signal handling code paths for x86 and x86_64 kernels.

New strategy is as follows:

Signal delivery: Both for 32/64-bit frames, align the core math frame area to
64bytes as needed by xsave (this where the main fpu/extended state gets copied
to and excludes the legacy compatibility fsave header for the 32-bit [f]xsave
frames). If the state is live, copy the register state directly to the user
frame. If not live, copy the state in the thread struct to the user frame. And
for 32-bit [f]xsave frames, construct the fsave header separately before
the actual [f]xsave area.

Signal return: As the 32-bit frames with [f]xstate has an additional
'fsave' header, copy everything back from the user sigframe to the
fpstate in the task structure and reconstruct the fxstate from the 'fsave'
header (Also user passed pointers may not be correctly aligned for
any attempt to directly restore any partial state). At the next fpstate usage,
everything will be restored to the live CPU registers.
For all the 64-bit frames and the 32-bit fsave frame, restore the state from
the user sigframe directly to the live CPU registers. 64-bit signals always
restored the math frame directly, so we can expect the math frame pointer
to be correctly aligned. For 32-bit fsave frames, there are no alignment
requirements, so we can restore the state directly.

"lat_sig catch" microbenchmark numbers (for x86, x86_64, x86_32 binaries) are
with in the noise range with this change.
Signed-off-by: NSuresh Siddha <suresh.b.siddha@intel.com>
Link: http://lkml.kernel.org/r/1343171129-2747-4-git-send-email-suresh.b.siddha@intel.com
[ Merged in compilation fix ]
Link: http://lkml.kernel.org/r/1344544736.8326.17.camel@sbsiddha-desk.sc.intel.comSigned-off-by: NH. Peter Anvin <hpa@linux.intel.com>

Consolidate x86, x86_64 inline asm routines saving/restoring fpu state
using config_enabled().
Signed-off-by: NSuresh Siddha <suresh.b.siddha@intel.com>
Link: http://lkml.kernel.org/r/1343171129-2747-3-git-send-email-suresh.b.siddha@intel.comSigned-off-by: NH. Peter Anvin <hpa@linux.intel.com>

Use config_enabled() to cleanup the definitions of is_ia32/is_x32. Move
the function prototypes to the header file to cleanup ifdefs,
and move the x32_setup_rt_frame() code around.
Signed-off-by: NSuresh Siddha <suresh.b.siddha@intel.com>
Link: http://lkml.kernel.org/r/1343171129-2747-2-git-send-email-suresh.b.siddha@intel.com
Merged in compilation fix from,
Link: http://lkml.kernel.org/r/1344544736.8326.17.camel@sbsiddha-desk.sc.intel.comSigned-off-by: NH. Peter Anvin <hpa@linux.intel.com>

Add CPUID feature bit for Supervisor Mode Access Prevention (SMAP).
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>
Link: http://lkml.kernel.org/n/tip-ethzcr5nipikl6hd5q8ssepq@git.kernel.org

IOMMU_INIT_POST and IOMMU_INIT_POST_FINISH pass the plain value
0 instead of NULL to __IOMMU_INIT. Fix this and make sparse
happy by doing so.
Signed-off-by: NMathias Krause <minipli@googlemail.com>
Cc: Joerg Roedel <joerg.roedel@amd.com>
Link: http://lkml.kernel.org/r/1346621506-30857-8-git-send-email-minipli@googlemail.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

It's redundant and makes sparse complain about it.
Signed-off-by: NMathias Krause <minipli@googlemail.com>
Cc: Joerg Roedel <joerg.roedel@amd.com>
Link: http://lkml.kernel.org/r/1346621506-30857-7-git-send-email-minipli@googlemail.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

Don't remove the __user annotation of the fpstate pointer, but
drop the superfluous void * cast instead.

This fixes the following sparse warnings:

  xsave.c:135:15: warning: cast removes address space of expression
  xsave.c:135:15: warning: incorrect type in argument 1 (different address spaces)
  xsave.c:135:15:    expected void const volatile [noderef] <asn:1>*<noident>
  [...]
Signed-off-by: NMathias Krause <minipli@googlemail.com>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Link: http://lkml.kernel.org/r/1346621506-30857-6-git-send-email-minipli@googlemail.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

Stay in sync with the declaration and fix the corresponding
sparse warnings.
Signed-off-by: NMathias Krause <minipli@googlemail.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Link: http://lkml.kernel.org/r/1346621506-30857-5-git-send-email-minipli@googlemail.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

Fix the following sparse warnings by adding appropriate __user
casts and annotations:

  ia32_signal.c:165:38: warning: incorrect type in argument 1 (different address spaces)
   ia32_signal.c:165:38:    expected struct sigaltstack const [noderef] [usertype] <asn:1>*<noident>
  ia32_signal.c:165:38:    got struct sigaltstack *
  [...]
Signed-off-by: NMathias Krause <minipli@googlemail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Link: http://lkml.kernel.org/r/1346621506-30857-4-git-send-email-minipli@googlemail.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

The address calculated by VDSO32_SYMBOL() is a pointer into
userland. Add the __user annotation to fix related sparse
warnings in its users.
Signed-off-by: NMathias Krause <minipli@googlemail.com>
Cc: Andy Lutomirski <luto@MIT.EDU>
Link: http://lkml.kernel.org/r/1346621506-30857-3-git-send-email-minipli@googlemail.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

Fix the following sparse warnings:

  sys_ia32.c:293:38: warning: incorrect type in argument 2 (different address spaces)
  sys_ia32.c:293:38:    expected unsigned int [noderef] [usertype] <asn:1>*stat_addr
  sys_ia32.c:293:38:    got unsigned int *stat_addr

Ironically, sys_ia32.h was introduced to fix sparse warnings but
missed that one.
Signed-off-by: NMathias Krause <minipli@googlemail.com>
Link: http://lkml.kernel.org/r/1346621506-30857-2-git-send-email-minipli@googlemail.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

In native 32 bit mode the personality flags were not correctly inherited.
This is the s390 version of 59e4c3a2 "powerpc/32: Don't clobber personality
flags on exec".
Reported-by: NMike Frysinger <vapier@gentoo.org>
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

Fix this compile error:

arch/s390/kernel/machine_kexec.c: In function ‘setup_regs’:
arch/s390/kernel/machine_kexec.c:63:3: error: implicit declaration
 of function ‘smp_store_status’ [-Werror=implicit-function-declaration]
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

KVM_GET_MSR was missing support for PV EOI,
which is needed for migration.
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

This reverts commit b1acf1bb.

Something went horribly wrong when I did savedefconfig, not sure what,
but what's in there is busted so let's revert it.
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

For certain speculative events on Power7, 'perf stat' reports far higher
event count than 'perf record' for the same event.

As described in following commit, a performance monitor exception is raised
even when the the performance events are rolled back.

        commit 0837e324
        Author: Anton Blanchard <anton@samba.org>
        Date:   Wed Mar 9 14:38:42 2011 +1100

perf_event_interrupt() records an event only when an overflow occurs. But
this check for overflow is a simple 'if (val < 0)'.

Because the events are rolled back, this check for overflow fails and the
event is not recorded. perf_event_interrupt() later uses pmc_overflow() to
detect the overflow and resets the counters and the events are lost completely.

To properly detect the overflow of rolled back events, use pmc_overflow()
even when recording events.

To reproduce:
        $ cat strcpy.c
        #include <stdio.h>
        #include <string.h>
        main()
        {
                char buf[256];

                alarm(5);
                while(1)
                        strcpy(buf, "string1");
        }

        $ perf record -e r20014 ./strcpy
        $ perf report -n > report.1
        $ perf stat -e r20014 > report.2
        # Compare report.1 and report.2
Reported-by: NMaynard Johnson <mpjohn@us.ibm.com>
Signed-off-by: NSukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

The enhanced prefetch hint patches corrupt the condition register
that was used to check if we are in interrupt. Fix this by using cr1.
Signed-off-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

"powerpc: Use enhanced touch instructions in POWER7
copy_to_user/copy_from_user" was applied twice. Remove one.
Signed-off-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Directly comparing current->personality against PER_LINUX32 doesn't work
in cases when any of the personality flags stored in the top three bytes
are used.

Directly forcefully setting personality to PER_LINUX32 or PER_LINUX
discards any flags stored in the top three bytes

Use personality() macro to compare only PER_MASK bytes and make sure that
we are setting only the bits that should be set, instead of overwriting
the whole value.
Signed-off-by: NJiri Kosina <jkosina@suse.cz>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>