fallocate() will fail, let's print a nicer error message.

Message-ID: <20230906120503.359863-6-david@redhat.com>
Suggested-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>

Let's remap with the proper protection that we can derive from
RAM_READONLY.

Message-ID: <20230906120503.359863-5-david@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: David Hildenbrand <david@redhat.com>

There is a difference between how we open a file and how we mmap it,
and we want to support writable private mappings of readonly files. Let's
define RAM_READONLY and RAM_READONLY_FD flags, to replace the single
"readonly" parameter for file-related functions.

In memory_region_init_ram_from_fd() and memory_region_init_ram_from_file(),
initialize mr->readonly based on the new RAM_READONLY flag.

While at it, add some RAM_* flags we missed to add to the list of accepted
flags in the documentation of some functions.

No change in functionality intended. We'll make use of both flags next
and start setting them independently for memory-backend-file.

Message-ID: <20230906120503.359863-3-david@redhat.com>
Acked-by: Peter Xu <peterx@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>

After system startup, run the update to memory_dispatch
and the tlb_flush on the cpu.  This eliminates a race,
wherein a running cpu sees the memory_dispatch change
but has not yet seen the tlb_flush.

Since the update now happens on the cpu, we need not use
qatomic_rcu_read to protect the read of memory_dispatch.

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1826
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1834
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1846


Tested-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Acked-by: Alex Bennée <alex.bennee@linaro.org>
Suggested-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

ram_block_discard_range() cannot possibly do the right thing in
MAP_PRIVATE file mappings in the general case.

To achieve the documented semantics, we also have to punch a hole into
the file, possibly messing with other MAP_PRIVATE/MAP_SHARED mappings
of such a file.

For example, using VM templating -- see commit b17fbbe5 ("migration:
allow private destination ram with x-ignore-shared") -- in combination with
any mechanism that relies on discarding of RAM is problematic. This
includes:
* Postcopy live migration
* virtio-balloon inflation/deflation or free-page-reporting
* virtio-mem

So at least warn that there is something possibly dangerous is going on
when using ram_block_discard_range() in these cases.

Message-ID: <20230706075612.67404-2-david@redhat.com>
Acked-by: Peter Xu <peterx@redhat.com>
Tested-by: Mario Casquero <mcasquer@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>

Since TARGET_PAGE_MASK is poisoned in target-agnostic code,
introduce the qemu_target_page_mask() helper to get this
value from target-agnostic code at runtime.

Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <20230524093744.88442-2-philmd@linaro.org>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>

migrate_ignore_shared() is an optimization that avoids copying memory
that is visible and can be mapped on the target.  However, a
memory-backend-ram or a memory-backend-memfd block with the RAM_SHARED
flag set is not migrated when migrate_ignore_shared() is true.  This is
wrong, because the block has no named backing store, and its contents will
be lost.  To fix, ignore shared memory iff it is a named file.  Define a
new flag RAM_NAMED_FILE to distinguish this case.

Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Message-Id: <1686151116-253260-1-git-send-email-steven.sistare@oracle.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>

qatomic_mb_read and qatomic_mb_set were the very first atomic primitives
introduced for QEMU; their semantics are unclear and they provide a false
sense of safety.

The last use of qatomic_mb_read() has been removed, so delete it.
qatomic_mb_set() instead can survive as an optimized
qatomic_set()+smp_mb(), similar to Linux's smp_store_mb(), but
rename it to qatomic_set_mb() to match the order of the two
operations.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Add an option for hostmem-file to start the memory object at an offset
into the target file. This is useful if multiple memory objects reside
inside the same target file, such as a device node.

In particular, it's useful to map guest memory directly into /dev/mem
for experimentation.

To make this work consistently, also fix up all places in QEMU that
expect fd offsets to be 0.

Signed-off-by: Alexander Graf <graf@amazon.com>
Message-Id: <20230403221421.60877-1-graf@amazon.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
Acked-by: Peter Xu <peterx@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>

Function that convert a number of target_pages into its size in MiB.

Suggested-by: Richard Henderson <richard.henderson@linaro.org>
Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Message-Id: <20230511141208.17779-2-quintela@redhat.com>

Pass the address of the last byte to be changed, rather than
the first address past the last byte.  This avoids overflow
when the last page of the address space is involved.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Bring the files in line with the QEMU coding style, with spaces
for indentation.

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/378


Signed-off-by: Yeqi Fu <fufuyqqqqqq@gmail.com>
Message-Id: <20230315032649.57568-1-fufuyqqqqqq@gmail.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>

It's convenient to dump HVA and RW/RO status of a ramblock in "info ramblock"
for debug purpose.

Before:
            Offset               Used              Total
0x0000000000000000 0x0000000400000000 0x0000000400000000

After:
            Offset               Used              Total                HVA  RO
0x0000000000000000 0x0000000400000000 0x0000000400000000 0x00007f12ebe00000  rw

Signed-off-by: Ted Chen <znscnchen@gmail.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <20221205120712.269013-1-znscnchen@gmail.com>
[PMD: Add uintptr_t cast for 32-bit hosts]
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

We found a case where the source passed to flatview_write_continue() may
overlap with the destination when fuzzing igb, a new proposed network
device with sanitizers.

igb uses pci_dma_map() to get Tx packet, and pci_dma_write() to write Rx
buffer. While pci_dma_write() is usually used to write data from
memory not mapped to the guest, if igb is configured to perform
loopback, the data will be sourced from the guest memory. The source and
destination can overlap and the usage of memcpy() will be invalid in
such a case.

While we do not really have to deal with such an invalid request for
igb, detecting the overlap in igb code beforehand requires complex code,
and only covers this specific case. Instead, just replace memcpy() with
memmove() to tolerate overlaps. Using memmove() will slightly damage the
performance as it will need to check overlaps before using SIMD
instructions for copying, but the cost should be negligible, considering
the inherent complexity of flatview_write_continue().

The test cases generated by the fuzzer is available at:
https://patchew.org/QEMU/20230129053316.1071513-1-alxndr@bu.edu/



The fixed test case is:
fuzz/crash_47dfe62d9f911bf523ff48cd441b61c0013ed805

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Acked-by: Alexander Bulekov <alxndr@bu.edu>
Acked-by: David Hildenbrand <david@redhat.com>
Message-Id: <20230131030155.18932-1-akihiko.odaki@daynix.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

The watchpoint API is specific to TCG system emulation.

Move it to a new compile unit. The inlined stubs are used
for user-mode and non-TCG accelerators.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20221209141254.68662-1-philmd@linaro.org>

We have two inclusion loops:

       block/block.h
    -> block/block-global-state.h
    -> block/block-common.h
    -> block/blockjob.h
    -> block/block.h

       block/block.h
    -> block/block-io.h
    -> block/block-common.h
    -> block/blockjob.h
    -> block/block.h

I believe these go back to Emanuele's reorganization of the block API,
merged a few months ago in commit d7e2fe4a.

Fortunately, breaking them is merely a matter of deleting unnecessary
includes from headers, and adding them back in places where they are
now missing.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20221221133551.3967339-2-armbru@redhat.com>

The 'hwaddr' type is defined in "exec/hwaddr.h" as:

    hwaddr is the type of a physical address
   (its size can be different from 'target_ulong').

All definitions use the 'HWADDR_' prefix, except TARGET_FMT_plx:

 $ fgrep define include/exec/hwaddr.h
 #define HWADDR_H
 #define HWADDR_BITS 64
 #define HWADDR_MAX UINT64_MAX
 #define TARGET_FMT_plx "%016" PRIx64
         ^^^^^^
 #define HWADDR_PRId PRId64
 #define HWADDR_PRIi PRIi64
 #define HWADDR_PRIo PRIo64
 #define HWADDR_PRIu PRIu64
 #define HWADDR_PRIx PRIx64
 #define HWADDR_PRIX PRIX64

Since hwaddr's size can be *different* from target_ulong, it is
very confusing to read one of its format using the 'TARGET_FMT_'
prefix, normally used for the target_long / target_ulong types:

$ fgrep TARGET_FMT_ include/exec/cpu-defs.h
 #define TARGET_FMT_lx "%08x"
 #define TARGET_FMT_ld "%d"
 #define TARGET_FMT_lu "%u"
 #define TARGET_FMT_lx "%016" PRIx64
 #define TARGET_FMT_ld "%" PRId64
 #define TARGET_FMT_lu "%" PRIu64

Apparently this format was missed during commit a8170e5e
("Rename target_phys_addr_t to hwaddr"), so complete it by
doing a bulk-rename with:

 $ sed -i -e s/TARGET_FMT_plx/HWADDR_FMT_plx/g $(git grep -l TARGET_FMT_plx)

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <20230110212947.34557-1-philmd@linaro.org>
[thuth: Fix some warnings from checkpatch.pl along the way]
Signed-off-by: Thomas Huth <thuth@redhat.com>

Tweak the semantic patch to drop redundant parenthesis around the
return expression.

Coccinelle drops a comment in hw/rdma/vmw/pvrdma_cmd.c; restored
manually.

Coccinelle messes up vmdk_co_create(), not sure why.  Change dropped,
will be done manually in the next commit.

Line breaks in target/avr/cpu.h and hw/rdma/vmw/pvrdma_cmd.c tidied up
manually.

Whitespace in tools/virtiofsd/fuse_lowlevel.c tidied up manually.

checkpatch.pl complains "return of an errno should typically be -ve"
two times for hw/9pfs/9p-synth.c.  Preexisting, the patch merely makes
it visible to checkpatch.pl.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20221122134917.1217307-2-armbru@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

The end address of memory region section isn't correctly calculated
which leads to overflowed mtree dump:

  Dispatch
    Physical sections
      ......
      #70 @0000000000002000..0000000000011fff io [ROOT]
      #71 @0000000000005000..0000000000005fff (noname)
      #72 @0000000000005000..0000000000014fff io [ROOT]
      #73 @0000000000005658..0000000000005658 vmport
      #74 @0000000000005659..0000000000015658 io [ROOT]
      #75 @0000000000006000..0000000000015fff io [ROOT]

After fix:
      #70 @0000000000002000..0000000000004fff io [ROOT]
      #71 @0000000000005000..0000000000005fff (noname)
      #72 @0000000000005000..0000000000005657 io [ROOT]
      #73 @0000000000005658..0000000000005658 vmport
      #74 @0000000000005659..0000000000005fff io [ROOT]
      #75 @0000000000006000..000000000000ffff io [ROOT]

Fixes: 5e8fd947 ("memory: Rework "info mtree" to print flat views and dispatch trees")
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <20220622095912.3430583-1-zhenzhong.duan@intel.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>

Add a function to get the file descriptor for a RAMBlock. Device
emulation code typically uses the MemoryRegion APIs but vhost-style code
may use RAMBlock directly for sharing guest memory with another process.

This new API will be used by the libblkio block driver so it can share
guest memory via .bdrv_register_buf().

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 20221013185908.1297568-11-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

The base qemu_ram_addr_from_host function is already in
softmmu/physmem.c; move the nofail version to be adjacent.

Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>
Tested-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Now that host_memory_backend_pagesize() is not depending on the hugetlb
memory path handling anymore, we can also remove the #ifdef and the
TOCTTOU comment from the calling functions - the code should now work
equally well on all host architectures.

Message-Id: <20220810125720.3849835-3-thuth@redhat.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Acked-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>

The bug is an uninitialized memory read, along the translate_fail
path, which results in garbage being read from iotlb_to_section,
which can lead to a crash in io_readx/io_writex.

The bug may be fixed by writing any value with zero
in ~TARGET_PAGE_MASK, so that the call to iotlb_to_section using
the xlat'ed address returns io_mem_unassigned, as desired by the
translate_fail path.

It is most useful to record the original physical page address,
which will eventually be logged by memory_region_access_valid
when the access is rejected by unassigned_mem_accepts.

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1065


Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <20220621153829.366423-1-richard.henderson@linaro.org>

Determine the BARs used by the PCI device and register handlers to
manage the access to the same.

Signed-off-by: Elena Ufimtseva <elena.ufimtseva@oracle.com>
Signed-off-by: John G Johnson <john.g.johnson@oracle.com>
Signed-off-by: Jagannathan Raman <jag.raman@oracle.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 3373e10b5be5f42846f0632d4382466e1698c505.1655151679.git.jag.raman@oracle.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

Since the implementation unit is page-vary.c.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20220323155743.1585078-24-marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Replace the global variables with inlined helper functions. getpagesize() is very
likely annotated with a "const" function attribute (at least with glibc), and thus
optimization should apply even better.

This avoids the need for a constructor initialization too.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20220323155743.1585078-12-marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Add the 'memory' bit to the memory attributes to restrict bus
controller accesses to memories.

Introduce flatview_access_allowed() to check bus permission
before running any bus transaction.

Have read/write accessors return MEMTX_ACCESS_ERROR if an access is
restricted.

There is no change for the default case where 'memory' is not set.

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20211215182421.418374-4-philmd@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
[thuth: Replaced MEMTX_BUS_ERROR with MEMTX_ACCESS_ERROR, remove "inline"]
Signed-off-by: Thomas Huth <thuth@redhat.com>

Remove unuseful local 'result' variables.

Reviewed-by: Peter Xu <peterx@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Alexander Bulekov <alxndr@bu.edu>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20211215182421.418374-3-philmd@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>

Move the various memalign-related functions out of osdep.h and into
their own header, which we include only where they are used.
While we're doing this, add some brief documentation comments.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20220226180723.1706285-10-peter.maydell@linaro.org

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20220207075426.81934-14-f4bug@amsat.org>

cpu_memory_rw_debug() is declared in "exec/cpu-all.h" which
contains target-specific declarations. To be able to use it
from target agnostic source, move the declaration to the
generic "exec/cpu-common.h" header.

Replace the target-specific 'target_ulong' type by 'vaddr'
which better reflects the argument type, and is target agnostic.

Suggested-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20220207075426.81934-5-f4bug@amsat.org>

The function qemu_madvise() and the QEMU_MADV_* constants associated
with it are used in only 10 files.  Move them out of osdep.h to a new
qemu/madvise.h header that is included where it is needed.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20220208200856.3558249-2-peter.maydell@linaro.org

dma_memory_set() does a DMA barrier, set the address space with
a constant value. The constant value filling code is not specific
to DMA and can be used for AddressSpace. Extract it as a new
helper: address_space_set().

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
[lv: rebase]
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Message-Id: <20220115203725.3834712-2-laurent@vivier.eu>

When we set cpu->cflags_next_tb it is because we want to carefully
control the execution of the next TB. Currently there is a race that
causes the second stage of watchpoint handling to get ignored if an
IRQ is processed before we finish executing the instruction that
triggers the watchpoint. Use the new CF_NOIRQ facility to avoid the
race.

We also suppress IRQs when handling precise self modifying code to
avoid unnecessary bouncing.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Cc: Pavel Dovgalyuk <pavel.dovgalyuk@ispras.ru>
Fixes: https://gitlab.com/qemu-project/qemu/-/issues/245


Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20211129140932.4115115-3-alex.bennee@linaro.org>

This is a counterpart to the HMP "info ramblock" command. It is being
added with an "x-" prefix because this QMP command is intended as an
adhoc debugging tool and will thus not be modelled in QAPI as fully
structured data, nor will it have long term guaranteed stability.
The existing HMP command is rewritten to call the QMP command.

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

Watchpoints that should fire after the memory access
break an execution of the current block, try to
translate current instruction into the separate block,
which then causes debug interrupt.
But cpu_interrupt can't be called in such block when
icount is enabled, because interrupts muse be allowed
explicitly.
This patch sets CF_LAST_IO flag for retranslated block,
allowing interrupt request for the last instruction.

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <163542169727.2127597.8141772572696627329.stgit@pasha-ThinkPad-X280>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

cpu_check_watchpoint function checks cpu->watchpoint_hit at the entry.
But then it also does the same in the middle of the function,
while this field can't change.
That is why this patch removes this useless condition.

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <163542169094.2127597.8801843697434113110.stgit@pasha-ThinkPad-X280>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Watchpoint processing code restores vCPU state twice:
in tb_check_watchpoint and in cpu_loop_exit_restore/cpu_restore_state.
Normally it does not affect anything, but in icount mode instruction
counter is incremented twice and becomes incorrect.
This patch eliminates unneeded CPU state restore.

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <163542168516.2127597.8781375223437124644.stgit@pasha-ThinkPad-X280>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>