PRMD register is only meaningful on the beginning stage of exception
entry, and it is overwritten with nested irq or exception.
When CPU runs in VM mode, interrupt need be enabled on host. And the
mode for host had better be kernel mode rather than random or user mode.
When VM is running, the running mode with top command comes from CRMD
register, and running mode should be kernel mode since kernel function
is executing with perf command. It needs be consistent with both top and
perf command.
Signed-off-by: Bibo Mao <maobibo@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Cache attribute comes from GPA->HPA secondary mmu page table and is
configured when kvm is enabled. It is the same for all VMs, so remove
duplicated cache attribute setting on vCPU context switch.
Signed-off-by: Bibo Mao <maobibo@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
This is typo issue and misusage about GCFG feature macro. The code
is wrong, only that it does not cause obvious problem since GCFG is
set again on vCPU context switch.
Fixes: 0d0df3c99d ("LoongArch: KVM: Implement kvm hardware enable, disable interface")
Signed-off-by: Bibo Mao <maobibo@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Commit 69e3a6aa6b ("LoongArch: Add checksum optimization for 64-bit
system") would cause an undefined shift and an out-of-bounds read.
Commit 8bd795fedb ("arm64: csum: Fix OoB access in IP checksum code
for negative lengths") fixes the same issue on ARM64.
Fixes: 69e3a6aa6b ("LoongArch: Add checksum optimization for 64-bit system")
Co-developed-by: Wentao Guan <guanwentao@uniontech.com>
Signed-off-by: Wentao Guan <guanwentao@uniontech.com>
Signed-off-by: Yuli Wang <wangyuli@uniontech.com>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
The notifier hook mechanism in proc and cpuinfo is actually unnecessary
for LoongArch because it's not used anywhere.
It was originally added to the MIPS code in commit d6d3c9afaa ("MIPS:
MT: proc: Add support for printing VPE and TC ids"), and LoongArch then
inherited it.
But as the kernel code stands now, this notifier hook mechanism doesn't
really make sense for either LoongArch or MIPS.
In addition, the seq_file forward declaration needs to be moved to its
proper place, as only the show_ipi_list() function in smp.c requires it.
Co-developed-by: Wentao Guan <guanwentao@uniontech.com>
Signed-off-by: Wentao Guan <guanwentao@uniontech.com>
Signed-off-by: Yuli Wang <wangyuli@uniontech.com>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Now kernel_page_present() always return true for KPRANGE/XKPRANGE
addresses, this isn't correct because hibernation (ACPI S4) use it
to distinguish whether a page is saveable. If all KPRANGE/XKPRANGE
addresses are considered as saveable, then reserved memory such as
EFI_RUNTIME_SERVICES_CODE / EFI_RUNTIME_SERVICES_DATA will also be
saved and restored.
Fix this by returning true only if the KPRANGE/XKPRANGE address is in
memblock.memory.
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
LoongArch re-enables interrupts on its idle routine and performs a
TIF_NEED_RESCHED check afterwards before putting the CPU to sleep.
The IRQs firing between the check and the idle instruction may set the
TIF_NEED_RESCHED flag. In order to deal with such a race, IRQs
interrupting __arch_cpu_idle() rollback their return address to the
beginning of __arch_cpu_idle() so that TIF_NEED_RESCHED is checked
again before going back to sleep.
However idle IRQs can also queue timers that may require a tick
reprogramming through a new generic idle loop iteration but those timers
would go unnoticed here because __arch_cpu_idle() only checks
TIF_NEED_RESCHED. It doesn't check for pending timers.
Fix this with fast-forwarding idle IRQs return address to the end of the
idle routine instead of the beginning, so that the generic idle loop can
handle both TIF_NEED_RESCHED and pending timers.
Fixes: 0603839b18 ("LoongArch: Add exception/interrupt handling")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Marco Crivellari <marco.crivellari@suse.com>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Pull LoongArch updates from Huacai Chen:
- Migrate to the generic rule for built-in DTB
- Disable FIX_EARLYCON_MEM when ARCH_IOREMAP is enabled
- Derive timer max_delta from PRCFG1's timer_bits
- Correct the cacheinfo sharing information
- Add pgprot_nx() implementation
- Add debugfs entries to switch SFB/TSO state
- Change the maximum number of watchpoints
- Some bug fixes and other small changes
* tag 'loongarch-6.14' of git://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson:
LoongArch: Extend the maximum number of watchpoints
LoongArch: Change 8 to 14 for LOONGARCH_MAX_{BRP,WRP}
LoongArch: Add debugfs entries to switch SFB/TSO state
LoongArch: Fix warnings during S3 suspend
LoongArch: Adjust SETUP_SLEEP and SETUP_WAKEUP
LoongArch: Refactor bug_handler() implementation
LoongArch: Add pgprot_nx() implementation
LoongArch: Correct the __switch_to() prototype in comments
LoongArch: Correct the cacheinfo sharing information
LoongArch: Derive timer max_delta from PRCFG1's timer_bits
LoongArch: Disable FIX_EARLYCON_MEM when ARCH_IOREMAP is enabled
LoongArch: Migrate to the generic rule for built-in DTB
Pull MM updates from Andrew Morton:
"The various patchsets are summarized below. Plus of course many
indivudual patches which are described in their changelogs.
- "Allocate and free frozen pages" from Matthew Wilcox reorganizes
the page allocator so we end up with the ability to allocate and
free zero-refcount pages. So that callers (ie, slab) can avoid a
refcount inc & dec
- "Support large folios for tmpfs" from Baolin Wang teaches tmpfs to
use large folios other than PMD-sized ones
- "Fix mm/rodata_test" from Petr Tesarik performs some maintenance
and fixes for this small built-in kernel selftest
- "mas_anode_descend() related cleanup" from Wei Yang tidies up part
of the mapletree code
- "mm: fix format issues and param types" from Keren Sun implements a
few minor code cleanups
- "simplify split calculation" from Wei Yang provides a few fixes and
a test for the mapletree code
- "mm/vma: make more mmap logic userland testable" from Lorenzo
Stoakes continues the work of moving vma-related code into the
(relatively) new mm/vma.c
- "mm/page_alloc: gfp flags cleanups for alloc_contig_*()" from David
Hildenbrand cleans up and rationalizes handling of gfp flags in the
page allocator
- "readahead: Reintroduce fix for improper RA window sizing" from Jan
Kara is a second attempt at fixing a readahead window sizing issue.
It should reduce the amount of unnecessary reading
- "synchronously scan and reclaim empty user PTE pages" from Qi Zheng
addresses an issue where "huge" amounts of pte pagetables are
accumulated:
https://lore.kernel.org/lkml/cover.1718267194.git.zhengqi.arch@bytedance.com/
Qi's series addresses this windup by synchronously freeing PTE
memory within the context of madvise(MADV_DONTNEED)
- "selftest/mm: Remove warnings found by adding compiler flags" from
Muhammad Usama Anjum fixes some build warnings in the selftests
code when optional compiler warnings are enabled
- "mm: don't use __GFP_HARDWALL when migrating remote pages" from
David Hildenbrand tightens the allocator's observance of
__GFP_HARDWALL
- "pkeys kselftests improvements" from Kevin Brodsky implements
various fixes and cleanups in the MM selftests code, mainly
pertaining to the pkeys tests
- "mm/damon: add sample modules" from SeongJae Park enhances DAMON to
estimate application working set size
- "memcg/hugetlb: Rework memcg hugetlb charging" from Joshua Hahn
provides some cleanups to memcg's hugetlb charging logic
- "mm/swap_cgroup: remove global swap cgroup lock" from Kairui Song
removes the global swap cgroup lock. A speedup of 10% for a
tmpfs-based kernel build was demonstrated
- "zram: split page type read/write handling" from Sergey Senozhatsky
has several fixes and cleaups for zram in the area of
zram_write_page(). A watchdog softlockup warning was eliminated
- "move pagetable_*_dtor() to __tlb_remove_table()" from Kevin
Brodsky cleans up the pagetable destructor implementations. A rare
use-after-free race is fixed
- "mm/debug: introduce and use VM_WARN_ON_VMG()" from Lorenzo Stoakes
simplifies and cleans up the debugging code in the VMA merging
logic
- "Account page tables at all levels" from Kevin Brodsky cleans up
and regularizes the pagetable ctor/dtor handling. This results in
improvements in accounting accuracy
- "mm/damon: replace most damon_callback usages in sysfs with new
core functions" from SeongJae Park cleans up and generalizes
DAMON's sysfs file interface logic
- "mm/damon: enable page level properties based monitoring" from
SeongJae Park increases the amount of information which is
presented in response to DAMOS actions
- "mm/damon: remove DAMON debugfs interface" from SeongJae Park
removes DAMON's long-deprecated debugfs interfaces. Thus the
migration to sysfs is completed
- "mm/hugetlb: Refactor hugetlb allocation resv accounting" from
Peter Xu cleans up and generalizes the hugetlb reservation
accounting
- "mm: alloc_pages_bulk: small API refactor" from Luiz Capitulino
removes a never-used feature of the alloc_pages_bulk() interface
- "mm/damon: extend DAMOS filters for inclusion" from SeongJae Park
extends DAMOS filters to support not only exclusion (rejecting),
but also inclusion (allowing) behavior
- "Add zpdesc memory descriptor for zswap.zpool" from Alex Shi
introduces a new memory descriptor for zswap.zpool that currently
overlaps with struct page for now. This is part of the effort to
reduce the size of struct page and to enable dynamic allocation of
memory descriptors
- "mm, swap: rework of swap allocator locks" from Kairui Song redoes
and simplifies the swap allocator locking. A speedup of 400% was
demonstrated for one workload. As was a 35% reduction for kernel
build time with swap-on-zram
- "mm: update mips to use do_mmap(), make mmap_region() internal"
from Lorenzo Stoakes reworks MIPS's use of mmap_region() so that
mmap_region() can be made MM-internal
- "mm/mglru: performance optimizations" from Yu Zhao fixes a few
MGLRU regressions and otherwise improves MGLRU performance
- "Docs/mm/damon: add tuning guide and misc updates" from SeongJae
Park updates DAMON documentation
- "Cleanup for memfd_create()" from Isaac Manjarres does that thing
- "mm: hugetlb+THP folio and migration cleanups" from David
Hildenbrand provides various cleanups in the areas of hugetlb
folios, THP folios and migration
- "Uncached buffered IO" from Jens Axboe implements the new
RWF_DONTCACHE flag which provides synchronous dropbehind for
pagecache reading and writing. To permite userspace to address
issues with massive buildup of useless pagecache when
reading/writing fast devices
- "selftests/mm: virtual_address_range: Reduce memory" from Thomas
Weißschuh fixes and optimizes some of the MM selftests"
* tag 'mm-stable-2025-01-26-14-59' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (321 commits)
mm/compaction: fix UBSAN shift-out-of-bounds warning
s390/mm: add missing ctor/dtor on page table upgrade
kasan: sw_tags: use str_on_off() helper in kasan_init_sw_tags()
tools: add VM_WARN_ON_VMG definition
mm/damon/core: use str_high_low() helper in damos_wmark_wait_us()
seqlock: add missing parameter documentation for raw_seqcount_try_begin()
mm/page-writeback: consolidate wb_thresh bumping logic into __wb_calc_thresh
mm/page_alloc: remove the incorrect and misleading comment
zram: remove zcomp_stream_put() from write_incompressible_page()
mm: separate move/undo parts from migrate_pages_batch()
mm/kfence: use str_write_read() helper in get_access_type()
selftests/mm/mkdirty: fix memory leak in test_uffdio_copy()
kasan: hw_tags: Use str_on_off() helper in kasan_init_hw_tags()
selftests/mm: virtual_address_range: avoid reading from VM_IO mappings
selftests/mm: vm_util: split up /proc/self/smaps parsing
selftests/mm: virtual_address_range: unmap chunks after validation
selftests/mm: virtual_address_range: mmap() without PROT_WRITE
selftests/memfd/memfd_test: fix possible NULL pointer dereference
mm: add FGP_DONTCACHE folio creation flag
mm: call filemap_fdatawrite_range_kick() after IOCB_DONTCACHE issue
...
The maximum number of load/store watchpoints and fetch instruction
watchpoints is 14 each according to LoongArch Reference Manual, so
extend the maximum number of watchpoints from 8 to 14 for ptrace.
By the way, just simply change 8 to 14 for the definition in struct
user_watch_state at the beginning, but it may corrupt uapi, then add
a new struct user_watch_state_v2 directly.
As far as I can tell, the only users for this struct in the userspace
are GDB and LLDB, there are no any problems of software compatibility
between the application and kernel according to the analysis.
The compatibility problem has been considered while developing and
testing. When the applications in the userspace get watchpoint state,
the length will be specified which is no bigger than the sizeof struct
user_watch_state or user_watch_state_v2, the actual length is assigned
as the minimal value of the application and kernel in the generic code
of ptrace:
kernel/ptrace.c: ptrace_regset():
kiov->iov_len = min(kiov->iov_len,
(__kernel_size_t) (regset->n * regset->size));
if (req == PTRACE_GETREGSET)
return copy_regset_to_user(task, view, regset_no, 0,
kiov->iov_len, kiov->iov_base);
else
return copy_regset_from_user(task, view, regset_no, 0,
kiov->iov_len, kiov->iov_base);
For example, there are four kind of combinations, all of them work well.
(1) "older kernel + older gdb", the actual length is 8+(8+8+4+4)*8=200;
(2) "newer kernel + newer gdb", the actual length is 8+(8+8+4+4)*14=344;
(3) "older kernel + newer gdb", the actual length is 8+(8+8+4+4)*8=200;
(4) "newer kernel + older gdb", the actual length is 8+(8+8+4+4)*8=200.
Link: https://loongson.github.io/LoongArch-Documentation/LoongArch-Vol1-EN.html#control-and-status-registers-related-to-watchpoints
Cc: stable@vger.kernel.org
Fixes: 1a69f7a161 ("LoongArch: ptrace: Expose hardware breakpoints to debuggers")
Reviewed-by: WANG Xuerui <git@xen0n.name>
Reviewed-by: Xi Ruoyao <xry111@xry111.site>
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
We need to switch SFB (Store Fill Buffer) and TSO (Total Store Order)
state at runtime to debug memory management and KVM virtualization, so
add two debugfs entries "sfb_state" and "tso_state" under the directory
/sys/kernel/debug/loongarch.
Query SFB:
cat /sys/kernel/debug/loongarch/sfb_state
Enable SFB:
echo 1 > /sys/kernel/debug/loongarch/sfb_state
Disable SFB:
echo 0 > /sys/kernel/debug/loongarch/sfb_state
Query TSO:
cat /sys/kernel/debug/loongarch/tso_state
Switch TSO:
echo [TSO] > /sys/kernel/debug/loongarch/tso_state
Available [TSO] states:
0 (No Load No Store) 1 (All Load No Store) 3 (Same Load No Store)
4 (No Load All Store) 5 (All Load All Store) 7 (Same Load All Store)
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
The enable_gpe_wakeup() function calls acpi_enable_all_wakeup_gpes(),
and the later one may call the preempt_schedule_common() function,
resulting in a thread switch and causing the CPU to be in an interrupt
enabled state after the enable_gpe_wakeup() function returns, leading
to the warnings as follow.
[ C0] WARNING: ... at kernel/time/timekeeping.c:845 ktime_get+0xbc/0xc8
[ C0] ...
[ C0] Call Trace:
[ C0] [<90000000002243b4>] show_stack+0x64/0x188
[ C0] [<900000000164673c>] dump_stack_lvl+0x60/0x88
[ C0] [<90000000002687e4>] __warn+0x8c/0x148
[ C0] [<90000000015e9978>] report_bug+0x1c0/0x2b0
[ C0] [<90000000016478e4>] do_bp+0x204/0x3b8
[ C0] [<90000000025b1924>] exception_handlers+0x1924/0x10000
[ C0] [<9000000000343bbc>] ktime_get+0xbc/0xc8
[ C0] [<9000000000354c08>] tick_sched_timer+0x30/0xb0
[ C0] [<90000000003408e0>] __hrtimer_run_queues+0x160/0x378
[ C0] [<9000000000341f14>] hrtimer_interrupt+0x144/0x388
[ C0] [<9000000000228348>] constant_timer_interrupt+0x38/0x48
[ C0] [<90000000002feba4>] __handle_irq_event_percpu+0x64/0x1e8
[ C0] [<90000000002fed48>] handle_irq_event_percpu+0x20/0x80
[ C0] [<9000000000306b9c>] handle_percpu_irq+0x5c/0x98
[ C0] [<90000000002fd4a0>] generic_handle_domain_irq+0x30/0x48
[ C0] [<9000000000d0c7b0>] handle_cpu_irq+0x70/0xa8
[ C0] [<9000000001646b30>] handle_loongarch_irq+0x30/0x48
[ C0] [<9000000001646bc8>] do_vint+0x80/0xe0
[ C0] [<90000000002aea1c>] finish_task_switch.isra.0+0x8c/0x2a8
[ C0] [<900000000164e34c>] __schedule+0x314/0xa48
[ C0] [<900000000164ead8>] schedule+0x58/0xf0
[ C0] [<9000000000294a2c>] worker_thread+0x224/0x498
[ C0] [<900000000029d2f0>] kthread+0xf8/0x108
[ C0] [<9000000000221f28>] ret_from_kernel_thread+0xc/0xa4
[ C0]
[ C0] ---[ end trace 0000000000000000 ]---
The root cause is acpi_enable_all_wakeup_gpes() uses a mutex to protect
acpi_hw_enable_all_wakeup_gpes(), and acpi_ut_acquire_mutex() may cause
a thread switch. Since there is no longer concurrent execution during
loongarch_acpi_suspend(), we can call acpi_hw_enable_all_wakeup_gpes()
directly in enable_gpe_wakeup().
The solution is similar to commit 22db06337f ("ACPI: sleep: Avoid
breaking S3 wakeup due to might_sleep()").
Fixes: 366bb35a8e ("LoongArch: Add suspend (ACPI S3) support")
Signed-off-by: Qunqin Zhao <zhaoqunqin@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
We already have a generic implementation of alloc/free up to P4D level, as
well as pgd_free(). Let's finish the work and add a generic PGD-level
alloc helper as well.
Unlike at lower levels, almost all architectures need some specific magic
at PGD level (typically initialising PGD entries), so introducing a
generic pgd_alloc() isn't worth it. Instead we introduce two new helpers,
__pgd_alloc() and __pgd_free(), and make use of them in the arch-specific
pgd_alloc() and pgd_free() wherever possible. To accommodate as many arch
as possible, __pgd_alloc() takes a page allocation order.
Because pagetable_alloc() allocates zeroed pages, explicit zeroing in
pgd_alloc() becomes redundant and we can get rid of it. Some trivial
implementations of pgd_free() also become unnecessary once __pgd_alloc()
is used; remove them.
Another small improvement is consistent accounting of PGD pages by using
GFP_PGTABLE_{USER,KERNEL} as appropriate.
Not all PGD allocations can be handled by the generic helpers. In
particular, multiple architectures allocate PGDs from a kmem_cache, and
those PGDs may not be page-sized.
Link: https://lkml.kernel.org/r/20250103184415.2744423-6-kevin.brodsky@arm.com
Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Memory hotplug presently auto-onlines memory into a zone the kernel deems
appropriate if CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE=y.
The memhp_default_state boot param enables runtime config, but it's not
possible to do this at build-time.
Remove CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE, and replace it with
CONFIG_MHP_DEFAULT_ONLINE_TYPE_* choices that sync with the boot param.
Selections:
CONFIG_MHP_DEFAULT_ONLINE_TYPE_OFFLINE
=> mhp_default_online_type = "offline"
Memory will not be onlined automatically.
CONFIG_MHP_DEFAULT_ONLINE_TYPE_ONLINE_AUTO
=> mhp_default_online_type = "online"
Memory will be onlined automatically in a zone deemed.
appropriate by the kernel.
CONFIG_MHP_DEFAULT_ONLINE_TYPE_ONLINE_KERNEL
=> mhp_default_online_type = "online_kernel"
Memory will be onlined automatically.
The zone may allow kernel data (e.g. ZONE_NORMAL).
CONFIG_MHP_DEFAULT_ONLINE_TYPE_ONLINE_MOVABLE
=> mhp_default_online_type = "online_movable"
Memory will be onlined automatically.
The zone will be ZONE_MOVABLE.
Default to CONFIG_MHP_DEFAULT_ONLINE_TYPE_OFFLINE to match the existing
default CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE=n behavior.
Existing users of CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE=y should use
CONFIG_MHP_DEFAULT_ONLINE_TYPE_ONLINE_AUTO.
[gourry@gourry.net: update KConfig comments]
Link: https://lkml.kernel.org/r/20241226182918.648799-1-gourry@gourry.net
Link: https://lkml.kernel.org/r/20241220210709.300066-1-gourry@gourry.net
Signed-off-by: Gregory Price <gourry@gourry.net>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: WANG Xuerui <kernel@xen0n.name>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Pull kvm updates from Paolo Bonzini:
"Loongarch:
- Clear LLBCTL if secondary mmu mapping changes
- Add hypercall service support for usermode VMM
x86:
- Add a comment to kvm_mmu_do_page_fault() to explain why KVM
performs a direct call to kvm_tdp_page_fault() when RETPOLINE is
enabled
- Ensure that all SEV code is compiled out when disabled in Kconfig,
even if building with less brilliant compilers
- Remove a redundant TLB flush on AMD processors when guest CR4.PGE
changes
- Use str_enabled_disabled() to replace open coded strings
- Drop kvm_x86_ops.hwapic_irr_update() as KVM updates hardware's
APICv cache prior to every VM-Enter
- Overhaul KVM's CPUID feature infrastructure to track all vCPU
capabilities instead of just those where KVM needs to manage state
and/or explicitly enable the feature in hardware. Along the way,
refactor the code to make it easier to add features, and to make it
more self-documenting how KVM is handling each feature
- Rework KVM's handling of VM-Exits during event vectoring; this
plugs holes where KVM unintentionally puts the vCPU into infinite
loops in some scenarios (e.g. if emulation is triggered by the
exit), and brings parity between VMX and SVM
- Add pending request and interrupt injection information to the
kvm_exit and kvm_entry tracepoints respectively
- Fix a relatively benign flaw where KVM would end up redoing RDPKRU
when loading guest/host PKRU, due to a refactoring of the kernel
helpers that didn't account for KVM's pre-checking of the need to
do WRPKRU
- Make the completion of hypercalls go through the complete_hypercall
function pointer argument, no matter if the hypercall exits to
userspace or not.
Previously, the code assumed that KVM_HC_MAP_GPA_RANGE specifically
went to userspace, and all the others did not; the new code need
not special case KVM_HC_MAP_GPA_RANGE and in fact does not care at
all whether there was an exit to userspace or not
- As part of enabling TDX virtual machines, support support
separation of private/shared EPT into separate roots.
When TDX will be enabled, operations on private pages will need to
go through the privileged TDX Module via SEAMCALLs; as a result,
they are limited and relatively slow compared to reading a PTE.
The patches included in 6.14 allow KVM to keep a mirror of the
private EPT in host memory, and define entries in kvm_x86_ops to
operate on external page tables such as the TDX private EPT
- The recently introduced conversion of the NX-page reclamation
kthread to vhost_task moved the task under the main process. The
task is created as soon as KVM_CREATE_VM was invoked and this, of
course, broke userspace that didn't expect to see any child task of
the VM process until it started creating its own userspace threads.
In particular crosvm refuses to fork() if procfs shows any child
task, so unbreak it by creating the task lazily. This is arguably a
userspace bug, as there can be other kinds of legitimate worker
tasks and they wouldn't impede fork(); but it's not like userspace
has a way to distinguish kernel worker tasks right now. Should they
show as "Kthread: 1" in proc/.../status?
x86 - Intel:
- Fix a bug where KVM updates hardware's APICv cache of the highest
ISR bit while L2 is active, while ultimately results in a
hardware-accelerated L1 EOI effectively being lost
- Honor event priority when emulating Posted Interrupt delivery
during nested VM-Enter by queueing KVM_REQ_EVENT instead of
immediately handling the interrupt
- Rework KVM's processing of the Page-Modification Logging buffer to
reap entries in the same order they were created, i.e. to mark gfns
dirty in the same order that hardware marked the page/PTE dirty
- Misc cleanups
Generic:
- Cleanup and harden kvm_set_memory_region(); add proper lockdep
assertions when setting memory regions and add a dedicated API for
setting KVM-internal memory regions. The API can then explicitly
disallow all flags for KVM-internal memory regions
- Explicitly verify the target vCPU is online in kvm_get_vcpu() to
fix a bug where KVM would return a pointer to a vCPU prior to it
being fully online, and give kvm_for_each_vcpu() similar treatment
to fix a similar flaw
- Wait for a vCPU to come online prior to executing a vCPU ioctl, to
fix a bug where userspace could coerce KVM into handling the ioctl
on a vCPU that isn't yet onlined
- Gracefully handle xarray insertion failures; even though such
failures are impossible in practice after xa_reserve(), reserving
an entry is always followed by xa_store() which does not know (or
differentiate) whether there was an xa_reserve() before or not
RISC-V:
- Zabha, Svvptc, and Ziccrse extension support for guests. None of
them require anything in KVM except for detecting them and marking
them as supported; Zabha adds byte and halfword atomic operations,
while the others are markers for specific operation of the TLB and
of LL/SC instructions respectively
- Virtualize SBI system suspend extension for Guest/VM
- Support firmware counters which can be used by the guests to
collect statistics about traps that occur in the host
Selftests:
- Rework vcpu_get_reg() to return a value instead of using an
out-param, and update all affected arch code accordingly
- Convert the max_guest_memory_test into a more generic
mmu_stress_test. The basic gist of the "conversion" is to have the
test do mprotect() on guest memory while vCPUs are accessing said
memory, e.g. to verify KVM and mmu_notifiers are working as
intended
- Play nice with treewrite builds of unsupported architectures, e.g.
arm (32-bit), as KVM selftests' Makefile doesn't do anything to
ensure the target architecture is actually one KVM selftests
supports
- Use the kernel's $(ARCH) definition instead of the target triple
for arch specific directories, e.g. arm64 instead of aarch64,
mainly so as not to be different from the rest of the kernel
- Ensure that format strings for logging statements are checked by
the compiler even when the logging statement itself is disabled
- Attempt to whack the last LLC references/misses mole in the Intel
PMU counters test by adding a data load and doing CLFLUSH{OPT} on
the data instead of the code being executed. It seems that modern
Intel CPUs have learned new code prefetching tricks that bypass the
PMU counters
- Fix a flaw in the Intel PMU counters test where it asserts that
events are counting correctly without actually knowing what the
events count given the underlying hardware; this can happen if
Intel reuses a formerly microarchitecture-specific event encoding
as an architectural event, as was the case for Top-Down Slots"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (151 commits)
kvm: defer huge page recovery vhost task to later
KVM: x86/mmu: Return RET_PF* instead of 1 in kvm_mmu_page_fault()
KVM: Disallow all flags for KVM-internal memslots
KVM: x86: Drop double-underscores from __kvm_set_memory_region()
KVM: Add a dedicated API for setting KVM-internal memslots
KVM: Assert slots_lock is held when setting memory regions
KVM: Open code kvm_set_memory_region() into its sole caller (ioctl() API)
LoongArch: KVM: Add hypercall service support for usermode VMM
LoongArch: KVM: Clear LLBCTL if secondary mmu mapping is changed
KVM: SVM: Use str_enabled_disabled() helper in svm_hardware_setup()
KVM: VMX: read the PML log in the same order as it was written
KVM: VMX: refactor PML terminology
KVM: VMX: Fix comment of handle_vmx_instruction()
KVM: VMX: Reinstate __exit attribute for vmx_exit()
KVM: SVM: Use str_enabled_disabled() helper in sev_hardware_setup()
KVM: x86: Avoid double RDPKRU when loading host/guest PKRU
KVM: x86: Use LVT_TIMER instead of an open coded literal
RISC-V: KVM: Add new exit statstics for redirected traps
RISC-V: KVM: Update firmware counters for various events
RISC-V: KVM: Redirect instruction access fault trap to guest
...
SETUP_SLEEP should only save the GPR context, which is symmetric to
SETUP_WAKEUP, so move the acpi_saved_sp handling out of SETUP_SLEEP.
Move "addi.d sp, sp, PT_SIZE" into SETUP_WAKEUP for the same reason.
No functional changes.
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
1. Early return for user mode triggered exception with all types.
2. Give a chance to call fixup_exception() for default types (like
S390).
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Commit cca98e9f8b ("mm: enforce that vmap can't map pages
executable") enforces the W^X protection by not allowing remapping
existing pages as executable. Add LoongArch bits so that LoongArch
can benefit the same protection.
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Correct the __switch_to() prototype in comments, keep it be the same as
the declaration in switch_to.h.
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
SMT cores and their sibling cores share the same L1 and L2 private
caches (of course last level cache is also shared), so correct the
cacheinfo sharing information to let shared_cpu_map correctly reflect
this relationship.
Below is the output of "lscpu" on Loongson-3A6000 (4 cores, 8 threads).
1. Before patch:
L1d: 512 KiB (8 instances)
L1i: 512 KiB (8 instances)
L2: 2 MiB (8 instances)
L3: 16 MiB (1 instance)
2. After patch:
L1d: 256 KiB (4 instances)
L1i: 256 KiB (4 instances)
L2: 1 MiB (4 instances)
L3: 16 MiB (1 instance)
Reported-by: Chao Li <lichao@loongson.cn>
Signed-off-by: Juxin Gao <gaojuxin@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
As per arch spec, maximum timer bits is configurable and should not be
hardcoded in any way.
Probe timer bits from PRCFG1 and use that to determine the clockevent's
max_delta to be conformance.
Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
When ARCH_IOREMAP is enabled, we are using always accessible DMW for
ioremap(). It makes no sense to create a dedicated mapping for earlycon
given that we can access the region via DMW.
Disable FIX_EARLYCON_MEM when ARCH_IOREMAP is selected. This can ease
debugging for early mapping issues.
Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Commit 654102df2a ("kbuild: add generic support for built-in boot
DTBs") introduced generic support for built-in DTBs.
Select GENERIC_BUILTIN_DTB when built-in DTB support is enabled.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Pull CRC updates from Eric Biggers:
- Reorganize the architecture-optimized CRC32 and CRC-T10DIF code to be
directly accessible via the library API, instead of requiring the
crypto API. This is much simpler and more efficient.
- Convert some users such as ext4 to use the CRC32 library API instead
of the crypto API. More conversions like this will come later.
- Add a KUnit test that tests and benchmarks multiple CRC variants.
Remove older, less-comprehensive tests that are made redundant by
this.
- Add an entry to MAINTAINERS for the kernel's CRC library code. I'm
volunteering to maintain it. I have additional cleanups and
optimizations planned for future cycles.
* tag 'crc-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiggers/linux: (31 commits)
MAINTAINERS: add entry for CRC library
powerpc/crc: delete obsolete crc-vpmsum_test.c
lib/crc32test: delete obsolete crc32test.c
lib/crc16_kunit: delete obsolete crc16_kunit.c
lib/crc_kunit.c: add KUnit test suite for CRC library functions
powerpc/crc-t10dif: expose CRC-T10DIF function through lib
arm64/crc-t10dif: expose CRC-T10DIF function through lib
arm/crc-t10dif: expose CRC-T10DIF function through lib
x86/crc-t10dif: expose CRC-T10DIF function through lib
crypto: crct10dif - expose arch-optimized lib function
lib/crc-t10dif: add support for arch overrides
lib/crc-t10dif: stop wrapping the crypto API
scsi: target: iscsi: switch to using the crc32c library
f2fs: switch to using the crc32 library
jbd2: switch to using the crc32c library
ext4: switch to using the crc32c library
lib/crc32: make crc32c() go directly to lib
bcachefs: Explicitly select CRYPTO from BCACHEFS_FS
x86/crc32: expose CRC32 functions through lib
x86/crc32: update prototype for crc32_pclmul_le_16()
...
Pull ftrace updates from Steven Rostedt:
- Have fprobes built on top of function graph infrastructure
The fprobe logic is an optimized kprobe that uses ftrace to attach to
functions when a probe is needed at the start or end of the function.
The fprobe and kretprobe logic implements a similar method as the
function graph tracer to trace the end of the function. That is to
hijack the return address and jump to a trampoline to do the trace
when the function exits. To do this, a shadow stack needs to be
created to store the original return address. Fprobes and function
graph do this slightly differently. Fprobes (and kretprobes) has
slots per callsite that are reserved to save the return address. This
is fine when just a few points are traced. But users of fprobes, such
as BPF programs, are starting to add many more locations, and this
method does not scale.
The function graph tracer was created to trace all functions in the
kernel. In order to do this, when function graph tracing is started,
every task gets its own shadow stack to hold the return address that
is going to be traced. The function graph tracer has been updated to
allow multiple users to use its infrastructure. Now have fprobes be
one of those users. This will also allow for the fprobe and kretprobe
methods to trace the return address to become obsolete. With new
technologies like CFI that need to know about these methods of
hijacking the return address, going toward a solution that has only
one method of doing this will make the kernel less complex.
- Cleanup with guard() and free() helpers
There were several places in the code that had a lot of "goto out" in
the error paths to either unlock a lock or free some memory that was
allocated. But this is error prone. Convert the code over to use the
guard() and free() helpers that let the compiler unlock locks or free
memory when the function exits.
- Remove disabling of interrupts in the function graph tracer
When function graph tracer was first introduced, it could race with
interrupts and NMIs. To prevent that race, it would disable
interrupts and not trace NMIs. But the code has changed to allow NMIs
and also interrupts. This change was done a long time ago, but the
disabling of interrupts was never removed. Remove the disabling of
interrupts in the function graph tracer is it is not needed. This
greatly improves its performance.
- Allow the :mod: command to enable tracing module functions on the
kernel command line.
The function tracer already has a way to enable functions to be
traced in modules by writing ":mod:<module>" into set_ftrace_filter.
That will enable either all the functions for the module if it is
loaded, or if it is not, it will cache that command, and when the
module is loaded that matches <module>, its functions will be
enabled. This also allows init functions to be traced. But currently
events do not have that feature.
Because enabling function tracing can be done very early at boot up
(before scheduling is enabled), the commands that can be done when
function tracing is started is limited. Having the ":mod:" command to
trace module functions as they are loaded is very useful. Update the
kernel command line function filtering to allow it.
* tag 'ftrace-v6.14' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (26 commits)
ftrace: Implement :mod: cache filtering on kernel command line
tracing: Adopt __free() and guard() for trace_fprobe.c
bpf: Use ftrace_get_symaddr() for kprobe_multi probes
ftrace: Add ftrace_get_symaddr to convert fentry_ip to symaddr
Documentation: probes: Update fprobe on function-graph tracer
selftests/ftrace: Add a test case for repeating register/unregister fprobe
selftests: ftrace: Remove obsolate maxactive syntax check
tracing/fprobe: Remove nr_maxactive from fprobe
fprobe: Add fprobe_header encoding feature
fprobe: Rewrite fprobe on function-graph tracer
s390/tracing: Enable HAVE_FTRACE_GRAPH_FUNC
ftrace: Add CONFIG_HAVE_FTRACE_GRAPH_FUNC
bpf: Enable kprobe_multi feature if CONFIG_FPROBE is enabled
tracing/fprobe: Enable fprobe events with CONFIG_DYNAMIC_FTRACE_WITH_ARGS
tracing: Add ftrace_fill_perf_regs() for perf event
tracing: Add ftrace_partial_regs() for converting ftrace_regs to pt_regs
fprobe: Use ftrace_regs in fprobe exit handler
fprobe: Use ftrace_regs in fprobe entry handler
fgraph: Pass ftrace_regs to retfunc
fgraph: Replace fgraph_ret_regs with ftrace_regs
...
Some VMMs provides special hypercall service in usermode, KVM should not
handle the usermode hypercall service, thus pass it to usermode, let the
usermode VMM handle it.
Here a new code KVM_HCALL_CODE_USER_SERVICE is added for the user-mode
hypercall service, KVM lets all six registers visible to usermode VMM.
Signed-off-by: Bibo Mao <maobibo@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
LLBCTL is a separated guest CSR register from host, host exception ERET
instruction will clear the host LLBCTL CSR register, and guest exception
will clear the guest LLBCTL CSR register.
VCPU0 atomic64_fetch_add_unless VCPU1 atomic64_fetch_add_unless
ll.d %[p], %[c]
beq %[p], %[u], 1f
Here secondary mmu mapping is changed, host hpa page is replaced with a
new page. And VCPU1 will execute atomic instruction on the new page.
ll.d %[p], %[c]
beq %[p], %[u], 1f
add.d %[rc], %[p], %[a]
sc.d %[rc], %[c]
add.d %[rc], %[p], %[a]
sc.d %[rc], %[c]
LLBCTL is set on VCPU0 and it represents the memory is not modified by
other VCPUs, sc.d will modify the memory directly.
So clear WCLLB of the guest LLBCTL register when mapping is the changed.
Signed-off-by: Bibo Mao <maobibo@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Remove the vmac64 template, as it has no known users. It also continues
to have longstanding bugs such as alignment violations (see
https://lore.kernel.org/r/20241226134847.6690-1-evepolonium@gmail.com/).
This code was added in 2009 by commit f1939f7c56 ("crypto: vmac - New
hash algorithm for intel_txt support"). Based on the mention of
intel_txt support in the commit title, it seems it was added as a
prerequisite for the contemporaneous patch
"intel_txt: add s3 userspace memory integrity verification"
(https://lore.kernel.org/r/4ABF2B50.6070106@intel.com/). In the design
proposed by that patch, when an Intel Trusted Execution Technology (TXT)
enabled system resumed from suspend, the "tboot" trusted executable
launched the Linux kernel without verifying userspace memory, and then
the Linux kernel used VMAC to verify userspace memory.
However, that patch was never merged, as reviewers had objected to the
design. It was later reworked into commit 4bd96a7a81 ("x86, tboot:
Add support for S3 memory integrity protection") which made tboot verify
the memory instead. Thus the VMAC support in Linux was never used.
No in-tree user has appeared since then, other than potentially the
usual components that allow specifying arbitrary hash algorithms by
name, namely AF_ALG and dm-integrity. However there are no indications
that VMAC is being used with these components. Debian Code Search and
web searches for "vmac64" (the actual algorithm name) do not return any
results other than the kernel itself, suggesting that it does not appear
in any other code or documentation. Explicitly grepping the source code
of the usual suspects (libell, iwd, cryptsetup) finds no matches either.
Before 2018, the vmac code was also completely broken due to using a
hardcoded nonce and the wrong endianness for the MAC. It was then fixed
by commit ed331adab3 ("crypto: vmac - add nonced version with big
endian digest") and commit 0917b87312 ("crypto: vmac - remove insecure
version with hardcoded nonce"). These were intentionally breaking
changes that changed all the computed MAC values as well as the
algorithm name ("vmac" to "vmac64"). No complaints were ever received
about these breaking changes, strongly suggesting the absence of users.
The reason I had put some effort into fixing this code in 2018 is
because it was used by an out-of-tree driver. But if it is still needed
in that particular out-of-tree driver, the code can be carried in that
driver instead. There is no need to carry it upstream.
Cc: Atharva Tiwari <evepolonium@gmail.com>
Cc: Shane Wang <shane.wang@intel.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> # m68k
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
The branch instructions beq, bne, blt, bge, bltu, bgeu and jirl belong
to the format reg2i16, but the sequence of oprand is different for the
instruction jirl. So adjust the parameter order of emit_jirl() to make
it more readable correspond with the Instruction Set Architecture manual.
Here are the instruction formats:
beq rj, rd, offs16
bne rj, rd, offs16
blt rj, rd, offs16
bge rj, rd, offs16
bltu rj, rd, offs16
bgeu rj, rd, offs16
jirl rd, rj, offs16
Link: https://loongson.github.io/LoongArch-Documentation/LoongArch-Vol1-EN.html#branch-instructions
Suggested-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
When executing mm selftests run_vmtests.sh, there is such an error:
BUG: Bad page state in process uffd-unit-tests pfn:00000
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x0
flags: 0xffff0000002000(reserved|node=0|zone=0|lastcpupid=0xffff)
raw: 00ffff0000002000 ffffbf0000000008 ffffbf0000000008 0000000000000000
raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: PAGE_FLAGS_CHECK_AT_FREE flag(s) set
Modules linked in: snd_seq_dummy snd_seq snd_seq_device rfkill vfat fat
virtio_balloon efi_pstore virtio_net pstore net_failover failover fuse
nfnetlink virtio_scsi virtio_gpu virtio_dma_buf dm_multipath efivarfs
CPU: 2 UID: 0 PID: 1913 Comm: uffd-unit-tests Not tainted 6.12.0 #184
Hardware name: QEMU QEMU Virtual Machine, BIOS unknown 2/2/2022
Stack : 900000047c8ac000 0000000000000000 9000000000223a7c 900000047c8ac000
900000047c8af690 900000047c8af698 0000000000000000 900000047c8af7d8
900000047c8af7d0 900000047c8af7d0 900000047c8af5b0 0000000000000001
0000000000000001 900000047c8af698 10b3c7d53da40d26 0000010000000000
0000000000000022 0000000fffffffff fffffffffe000000 ffff800000000000
000000000000002f 0000800000000000 000000017a6d4000 90000000028f8940
0000000000000000 0000000000000000 90000000025aa5e0 9000000002905000
0000000000000000 90000000028f8940 ffff800000000000 0000000000000000
0000000000000000 0000000000000000 9000000000223a94 000000012001839c
00000000000000b0 0000000000000004 0000000000000000 0000000000071c1d
...
Call Trace:
[<9000000000223a94>] show_stack+0x5c/0x180
[<9000000001c3fd64>] dump_stack_lvl+0x6c/0xa0
[<900000000056aa08>] bad_page+0x1a0/0x1f0
[<9000000000574978>] free_unref_folios+0xbf0/0xd20
[<90000000004e65cc>] folios_put_refs+0x1a4/0x2b8
[<9000000000599a0c>] free_pages_and_swap_cache+0x164/0x260
[<9000000000547698>] tlb_batch_pages_flush+0xa8/0x1c0
[<9000000000547f30>] tlb_finish_mmu+0xa8/0x218
[<9000000000543cb8>] exit_mmap+0x1a0/0x360
[<9000000000247658>] __mmput+0x78/0x200
[<900000000025583c>] do_exit+0x43c/0xde8
[<9000000000256490>] do_group_exit+0x68/0x110
[<9000000000256554>] sys_exit_group+0x1c/0x20
[<9000000001c413b4>] do_syscall+0x94/0x130
[<90000000002216d8>] handle_syscall+0xb8/0x158
Disabling lock debugging due to kernel taint
BUG: non-zero pgtables_bytes on freeing mm: -16384
On LoongArch system, invalid huge pte entry should be invalid_pte_table
or a single _PAGE_HUGE bit rather than a zero value. And it should be
the same with invalid pmd entry, since pmd_none() is called by function
free_pgd_range() and pmd_none() return 0 by huge_pte_clear(). So single
_PAGE_HUGE bit is also treated as a valid pte table and free_pte_range()
will be called in free_pmd_range().
free_pmd_range()
pmd = pmd_offset(pud, addr);
do {
next = pmd_addr_end(addr, end);
if (pmd_none_or_clear_bad(pmd))
continue;
free_pte_range(tlb, pmd, addr);
} while (pmd++, addr = next, addr != end);
Here invalid_pte_table is used for both invalid huge pte entry and
pmd entry.
Cc: stable@vger.kernel.org
Fixes: 09cfefb7fa ("LoongArch: Add memory management")
Signed-off-by: Bibo Mao <maobibo@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Performance improvement for reading /proc/interrupts on LoongArch.
On a system with n CPUs and m interrupts, there will be n*m decimal
values yielded via seq_printf(.."%10u "..) which is less efficient than
seq_put_decimal_ull_width(), stress reading /proc/interrupts indicates
~30% performance improvement with this patch (and its friends).
Signed-off-by: David Wang <00107082@163.com>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Since screen_info.lfb_base is a __u32 type, an above-4G address need an
ext_lfb_base to present its higher 32bits. In init_screen_info() we can
use __screen_info_lfb_base() to handle this case for reserving screen
info memory.
Signed-off-by: Xuefeng Zhao <zhaoxuefeng@loongson.cn>
Signed-off-by: Jianmin Lv <lvjianmin@loongson.cn>
Signed-off-by: Tianyang Zhang <zhangtianyang@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
