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2017-03-02sched/headers: Prepare for new header dependencies before moving code to ↵Ingo Molnar-0/+1
<linux/sched/mm.h> We are going to split <linux/sched/mm.h> out of <linux/sched.h>, which will have to be picked up from other headers and a couple of .c files. Create a trivial placeholder <linux/sched/mm.h> file that just maps to <linux/sched.h> to make this patch obviously correct and bisectable. The APIs that are going to be moved first are: mm_alloc() __mmdrop() mmdrop() mmdrop_async_fn() mmdrop_async() mmget_not_zero() mmput() mmput_async() get_task_mm() mm_access() mm_release() Include the new header in the files that are going to need it. Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-02-27mm: add new mmget() helperVegard Nossum-1/+1
Apart from adding the helper function itself, the rest of the kernel is converted mechanically using: git grep -l 'atomic_inc.*mm_users' | xargs sed -i 's/atomic_inc(&\(.*\)->mm_users);/mmget\(\1\);/' git grep -l 'atomic_inc.*mm_users' | xargs sed -i 's/atomic_inc(&\(.*\)\.mm_users);/mmget\(\&\1\);/' This is needed for a later patch that hooks into the helper, but might be a worthwhile cleanup on its own. (Michal Hocko provided most of the kerneldoc comment.) Link: http://lkml.kernel.org/r/20161218123229.22952-2-vegard.nossum@oracle.com Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-12-14mm: unexport __get_user_pages_unlocked()Lorenzo Stoakes-3/+7
Unexport the low-level __get_user_pages_unlocked() function and replaces invocations with calls to more appropriate higher-level functions. In hva_to_pfn_slow() we are able to replace __get_user_pages_unlocked() with get_user_pages_unlocked() since we can now pass gup_flags. In async_pf_execute() and process_vm_rw_single_vec() we need to pass different tsk, mm arguments so get_user_pages_remote() is the sane replacement in these cases (having added manual acquisition and release of mmap_sem.) Additionally get_user_pages_remote() reintroduces use of the FOLL_TOUCH flag. However, this flag was originally silently dropped by commit 1e9877902dc7 ("mm/gup: Introduce get_user_pages_remote()"), so this appears to have been unintentional and reintroducing it is therefore not an issue. [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/20161027095141.2569-3-lstoakes@gmail.com Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Jan Kara <jack@suse.cz> Cc: Hugh Dickins <hughd@google.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Radim Krcmar <rkrcmar@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-11-19KVM: async_pf: avoid recursive flushing of work itemsPaolo Bonzini-1/+12
This was reported by syzkaller: [ INFO: possible recursive locking detected ] 4.9.0-rc4+ #49 Not tainted --------------------------------------------- kworker/2:1/5658 is trying to acquire lock: ([ 1644.769018] (&work->work) [< inline >] list_empty include/linux/compiler.h:243 [<ffffffff8128dd60>] flush_work+0x0/0x660 kernel/workqueue.c:1511 but task is already holding lock: ([ 1644.769018] (&work->work) [<ffffffff812916ab>] process_one_work+0x94b/0x1900 kernel/workqueue.c:2093 stack backtrace: CPU: 2 PID: 5658 Comm: kworker/2:1 Not tainted 4.9.0-rc4+ #49 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 Workqueue: events async_pf_execute ffff8800676ff630 ffffffff81c2e46b ffffffff8485b930 ffff88006b1fc480 0000000000000000 ffffffff8485b930 ffff8800676ff7e0 ffffffff81339b27 ffff8800676ff7e8 0000000000000046 ffff88006b1fcce8 ffff88006b1fccf0 Call Trace: ... [<ffffffff8128ddf3>] flush_work+0x93/0x660 kernel/workqueue.c:2846 [<ffffffff812954ea>] __cancel_work_timer+0x17a/0x410 kernel/workqueue.c:2916 [<ffffffff81295797>] cancel_work_sync+0x17/0x20 kernel/workqueue.c:2951 [<ffffffff81073037>] kvm_clear_async_pf_completion_queue+0xd7/0x400 virt/kvm/async_pf.c:126 [< inline >] kvm_free_vcpus arch/x86/kvm/x86.c:7841 [<ffffffff810b728d>] kvm_arch_destroy_vm+0x23d/0x620 arch/x86/kvm/x86.c:7946 [< inline >] kvm_destroy_vm virt/kvm/kvm_main.c:731 [<ffffffff8105914e>] kvm_put_kvm+0x40e/0x790 virt/kvm/kvm_main.c:752 [<ffffffff81072b3d>] async_pf_execute+0x23d/0x4f0 virt/kvm/async_pf.c:111 [<ffffffff8129175c>] process_one_work+0x9fc/0x1900 kernel/workqueue.c:2096 [<ffffffff8129274f>] worker_thread+0xef/0x1480 kernel/workqueue.c:2230 [<ffffffff812a5a94>] kthread+0x244/0x2d0 kernel/kthread.c:209 [<ffffffff831f102a>] ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:433 The reason is that kvm_put_kvm is causing the destruction of the VM, but the page fault is still on the ->queue list. The ->queue list is owned by the VCPU, not by the work items, so we cannot just add list_del to the work item. Instead, use work->vcpu to note async page faults that have been resolved and will be processed through the done list. There is no need to flush those. Cc: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
2016-10-18mm: remove write/force parameters from __get_user_pages_unlocked()Lorenzo Stoakes-1/+2
This removes the redundant 'write' and 'force' parameters from __get_user_pages_unlocked() to make the use of FOLL_FORCE explicit in callers as use of this flag can result in surprising behaviour (and hence bugs) within the mm subsystem. Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com> Acked-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Jan Kara <jack@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-03-20Merge branch 'mm-pkeys-for-linus' of ↵Linus Torvalds-1/+7
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 protection key support from Ingo Molnar: "This tree adds support for a new memory protection hardware feature that is available in upcoming Intel CPUs: 'protection keys' (pkeys). There's a background article at LWN.net: https://lwn.net/Articles/643797/ The gist is that protection keys allow the encoding of user-controllable permission masks in the pte. So instead of having a fixed protection mask in the pte (which needs a system call to change and works on a per page basis), the user can map a (handful of) protection mask variants and can change the masks runtime relatively cheaply, without having to change every single page in the affected virtual memory range. This allows the dynamic switching of the protection bits of large amounts of virtual memory, via user-space instructions. It also allows more precise control of MMU permission bits: for example the executable bit is separate from the read bit (see more about that below). This tree adds the MM infrastructure and low level x86 glue needed for that, plus it adds a high level API to make use of protection keys - if a user-space application calls: mmap(..., PROT_EXEC); or mprotect(ptr, sz, PROT_EXEC); (note PROT_EXEC-only, without PROT_READ/WRITE), the kernel will notice this special case, and will set a special protection key on this memory range. It also sets the appropriate bits in the Protection Keys User Rights (PKRU) register so that the memory becomes unreadable and unwritable. So using protection keys the kernel is able to implement 'true' PROT_EXEC on x86 CPUs: without protection keys PROT_EXEC implies PROT_READ as well. Unreadable executable mappings have security advantages: they cannot be read via information leaks to figure out ASLR details, nor can they be scanned for ROP gadgets - and they cannot be used by exploits for data purposes either. We know about no user-space code that relies on pure PROT_EXEC mappings today, but binary loaders could start making use of this new feature to map binaries and libraries in a more secure fashion. There is other pending pkeys work that offers more high level system call APIs to manage protection keys - but those are not part of this pull request. Right now there's a Kconfig that controls this feature (CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS) that is default enabled (like most x86 CPU feature enablement code that has no runtime overhead), but it's not user-configurable at the moment. If there's any serious problem with this then we can make it configurable and/or flip the default" * 'mm-pkeys-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (38 commits) x86/mm/pkeys: Fix mismerge of protection keys CPUID bits mm/pkeys: Fix siginfo ABI breakage caused by new u64 field x86/mm/pkeys: Fix access_error() denial of writes to write-only VMA mm/core, x86/mm/pkeys: Add execute-only protection keys support x86/mm/pkeys: Create an x86 arch_calc_vm_prot_bits() for VMA flags x86/mm/pkeys: Allow kernel to modify user pkey rights register x86/fpu: Allow setting of XSAVE state x86/mm: Factor out LDT init from context init mm/core, x86/mm/pkeys: Add arch_validate_pkey() mm/core, arch, powerpc: Pass a protection key in to calc_vm_flag_bits() x86/mm/pkeys: Actually enable Memory Protection Keys in the CPU x86/mm/pkeys: Add Kconfig prompt to existing config option x86/mm/pkeys: Dump pkey from VMA in /proc/pid/smaps x86/mm/pkeys: Dump PKRU with other kernel registers mm/core, x86/mm/pkeys: Differentiate instruction fetches x86/mm/pkeys: Optimize fault handling in access_error() mm/core: Do not enforce PKEY permissions on remote mm access um, pkeys: Add UML arch_*_access_permitted() methods mm/gup, x86/mm/pkeys: Check VMAs and PTEs for protection keys x86/mm/gup: Simplify get_user_pages() PTE bit handling ...
2016-03-16Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvmLinus Torvalds-4/+4
Pull KVM updates from Paolo Bonzini: "One of the largest releases for KVM... Hardly any generic changes, but lots of architecture-specific updates. ARM: - VHE support so that we can run the kernel at EL2 on ARMv8.1 systems - PMU support for guests - 32bit world switch rewritten in C - various optimizations to the vgic save/restore code. PPC: - enabled KVM-VFIO integration ("VFIO device") - optimizations to speed up IPIs between vcpus - in-kernel handling of IOMMU hypercalls - support for dynamic DMA windows (DDW). s390: - provide the floating point registers via sync regs; - separated instruction vs. data accesses - dirty log improvements for huge guests - bugfixes and documentation improvements. x86: - Hyper-V VMBus hypercall userspace exit - alternative implementation of lowest-priority interrupts using vector hashing (for better VT-d posted interrupt support) - fixed guest debugging with nested virtualizations - improved interrupt tracking in the in-kernel IOAPIC - generic infrastructure for tracking writes to guest memory - currently its only use is to speedup the legacy shadow paging (pre-EPT) case, but in the future it will be used for virtual GPUs as well - much cleanup (LAPIC, kvmclock, MMU, PIT), including ubsan fixes" * tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (217 commits) KVM: x86: remove eager_fpu field of struct kvm_vcpu_arch KVM: x86: disable MPX if host did not enable MPX XSAVE features arm64: KVM: vgic-v3: Only wipe LRs on vcpu exit arm64: KVM: vgic-v3: Reset LRs at boot time arm64: KVM: vgic-v3: Do not save an LR known to be empty arm64: KVM: vgic-v3: Save maintenance interrupt state only if required arm64: KVM: vgic-v3: Avoid accessing ICH registers KVM: arm/arm64: vgic-v2: Make GICD_SGIR quicker to hit KVM: arm/arm64: vgic-v2: Only wipe LRs on vcpu exit KVM: arm/arm64: vgic-v2: Reset LRs at boot time KVM: arm/arm64: vgic-v2: Do not save an LR known to be empty KVM: arm/arm64: vgic-v2: Move GICH_ELRSR saving to its own function KVM: arm/arm64: vgic-v2: Save maintenance interrupt state only if required KVM: arm/arm64: vgic-v2: Avoid accessing GICH registers KVM: s390: allocate only one DMA page per VM KVM: s390: enable STFLE interpretation only if enabled for the guest KVM: s390: wake up when the VCPU cpu timer expires KVM: s390: step the VCPU timer while in enabled wait KVM: s390: protect VCPU cpu timer with a seqcount KVM: s390: step VCPU cpu timer during kvm_run ioctl ...
2016-03-09Merge tag 'kvm-arm-for-4.6' of ↵Paolo Bonzini-1/+1
git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD KVM/ARM updates for 4.6 - VHE support so that we can run the kernel at EL2 on ARMv8.1 systems - PMU support for guests - 32bit world switch rewritten in C - Various optimizations to the vgic save/restore code Conflicts: include/uapi/linux/kvm.h
2016-02-29Merge branch 'sched/urgent' into sched/core, to pick up fixes before ↵Ingo Molnar-1/+1
applying new changes Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-02-25KVM: Use simple waitqueue for vcpu->wqMarcelo Tosatti-2/+2
The problem: On -rt, an emulated LAPIC timer instances has the following path: 1) hard interrupt 2) ksoftirqd is scheduled 3) ksoftirqd wakes up vcpu thread 4) vcpu thread is scheduled This extra context switch introduces unnecessary latency in the LAPIC path for a KVM guest. The solution: Allow waking up vcpu thread from hardirq context, thus avoiding the need for ksoftirqd to be scheduled. Normal waitqueues make use of spinlocks, which on -RT are sleepable locks. Therefore, waking up a waitqueue waiter involves locking a sleeping lock, which is not allowed from hard interrupt context. cyclictest command line: This patch reduces the average latency in my tests from 14us to 11us. Daniel writes: Paolo asked for numbers from kvm-unit-tests/tscdeadline_latency benchmark on mainline. The test was run 1000 times on tip/sched/core 4.4.0-rc8-01134-g0905f04: ./x86-run x86/tscdeadline_latency.flat -cpu host with idle=poll. The test seems not to deliver really stable numbers though most of them are smaller. Paolo write: "Anything above ~10000 cycles means that the host went to C1 or lower---the number means more or less nothing in that case. The mean shows an improvement indeed." Before: min max mean std count 1000.000000 1000.000000 1000.000000 1000.000000 mean 5162.596000 2019270.084000 5824.491541 20681.645558 std 75.431231 622607.723969 89.575700 6492.272062 min 4466.000000 23928.000000 5537.926500 585.864966 25% 5163.000000 1613252.750000 5790.132275 16683.745433 50% 5175.000000 2281919.000000 5834.654000 23151.990026 75% 5190.000000 2382865.750000 5861.412950 24148.206168 max 5228.000000 4175158.000000 6254.827300 46481.048691 After min max mean std count 1000.000000 1000.00000 1000.000000 1000.000000 mean 5143.511000 2076886.10300 5813.312474 21207.357565 std 77.668322 610413.09583 86.541500 6331.915127 min 4427.000000 25103.00000 5529.756600 559.187707 25% 5148.000000 1691272.75000 5784.889825 17473.518244 50% 5160.000000 2308328.50000 5832.025000 23464.837068 75% 5172.000000 2393037.75000 5853.177675 24223.969976 max 5222.000000 3922458.00000 6186.720500 42520.379830 [Patch was originaly based on the swait implementation found in the -rt tree. Daniel ported it to mainline's version and gathered the benchmark numbers for tscdeadline_latency test.] Signed-off-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: linux-rt-users@vger.kernel.org Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Link: http://lkml.kernel.org/r/1455871601-27484-4-git-send-email-wagi@monom.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2016-02-24KVM: async_pf: do not warn on page allocation failuresChristian Borntraeger-1/+1
In async_pf we try to allocate with NOWAIT to get an element quickly or fail. This code also handle failures gracefully. Lets silence potential page allocation failures under load. qemu-system-s39: page allocation failure: order:0,mode:0x2200000 [...] Call Trace: ([<00000000001146b8>] show_trace+0xf8/0x148) [<000000000011476a>] show_stack+0x62/0xe8 [<00000000004a36b8>] dump_stack+0x70/0x98 [<0000000000272c3a>] warn_alloc_failed+0xd2/0x148 [<000000000027709e>] __alloc_pages_nodemask+0x94e/0xb38 [<00000000002cd36a>] new_slab+0x382/0x400 [<00000000002cf7ac>] ___slab_alloc.constprop.30+0x2dc/0x378 [<00000000002d03d0>] kmem_cache_alloc+0x160/0x1d0 [<0000000000133db4>] kvm_setup_async_pf+0x6c/0x198 [<000000000013dee8>] kvm_arch_vcpu_ioctl_run+0xd48/0xd58 [<000000000012fcaa>] kvm_vcpu_ioctl+0x372/0x690 [<00000000002f66f6>] do_vfs_ioctl+0x3be/0x510 [<00000000002f68ec>] SyS_ioctl+0xa4/0xb8 [<0000000000781c5e>] system_call+0xd6/0x264 [<000003ffa24fa06a>] 0x3ffa24fa06a Cc: stable@vger.kernel.org Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Reviewed-by: Dominik Dingel <dingel@linux.vnet.ibm.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-02-23KVM: async_pf: use list_first_entryGeliang Tang-4/+4
To make the intention clearer, use list_first_entry instead of list_entry. Signed-off-by: Geliang Tang <geliangtang@163.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-02-16mm/gup: Introduce get_user_pages_remote()Dave Hansen-1/+7
For protection keys, we need to understand whether protections should be enforced in software or not. In general, we enforce protections when working on our own task, but not when on others. We call these "current" and "remote" operations. This patch introduces a new get_user_pages() variant: get_user_pages_remote() Which is a replacement for when get_user_pages() is called on non-current tsk/mm. We also introduce a new gup flag: FOLL_REMOTE which can be used for the "__" gup variants to get this new behavior. The uprobes is_trap_at_addr() location holds mmap_sem and calls get_user_pages(current->mm) on an instruction address. This makes it a pretty unique gup caller. Being an instruction access and also really originating from the kernel (vs. the app), I opted to consider this a 'remote' access where protection keys will not be enforced. Without protection keys, this patch should not change any behavior. Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Dave Hansen <dave@sr71.net> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: jack@suse.cz Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/20160212210154.3F0E51EA@viggo.jf.intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-11-25KVM-async_pf: Delete an unnecessary check before the function call ↵Markus Elfring-2/+1
"kmem_cache_destroy" The kmem_cache_destroy() function tests whether its argument is NULL and then returns immediately. Thus the test around the call is not needed. This issue was detected by using the Coccinelle software. Signed-off-by: Markus Elfring <elfring@users.sourceforge.net> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-10-14kvm: fix waitqueue_active without memory barrier in virt/kvm/async_pf.cKosuke Tatsukawa-0/+4
async_pf_execute() seems to be missing a memory barrier which might cause the waker to not notice the waiter and miss sending a wake_up as in the following figure. async_pf_execute kvm_vcpu_block ------------------------------------------------------------------------ spin_lock(&vcpu->async_pf.lock); if (waitqueue_active(&vcpu->wq)) /* The CPU might reorder the test for the waitqueue up here, before prior writes complete */ prepare_to_wait(&vcpu->wq, &wait, TASK_INTERRUPTIBLE); /*if (kvm_vcpu_check_block(vcpu) < 0) */ /*if (kvm_arch_vcpu_runnable(vcpu)) { */ ... return (vcpu->arch.mp_state == KVM_MP_STATE_RUNNABLE && !vcpu->arch.apf.halted) || !list_empty_careful(&vcpu->async_pf.done) ... return 0; list_add_tail(&apf->link, &vcpu->async_pf.done); spin_unlock(&vcpu->async_pf.lock); waited = true; schedule(); ------------------------------------------------------------------------ The attached patch adds the missing memory barrier. I found this issue when I was looking through the linux source code for places calling waitqueue_active() before wake_up*(), but without preceding memory barriers, after sending a patch to fix a similar issue in drivers/tty/n_tty.c (Details about the original issue can be found here: https://lkml.org/lkml/2015/9/28/849). Signed-off-by: Kosuke Tatsukawa <tatsu@ab.jp.nec.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-02-11mm: gup: kvm use get_user_pages_unlockedAndrea Arcangeli-1/+1
Use the more generic get_user_pages_unlocked which has the additional benefit of passing FAULT_FLAG_ALLOW_RETRY at the very first page fault (which allows the first page fault in an unmapped area to be always able to block indefinitely by being allowed to release the mmap_sem). Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Reviewed-by: Andres Lagar-Cavilla <andreslc@google.com> Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Peter Feiner <pfeiner@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-09-24kvm: Faults which trigger IO release the mmap_semAndres Lagar-Cavilla-3/+1
When KVM handles a tdp fault it uses FOLL_NOWAIT. If the guest memory has been swapped out or is behind a filemap, this will trigger async readahead and return immediately. The rationale is that KVM will kick back the guest with an "async page fault" and allow for some other guest process to take over. If async PFs are enabled the fault is retried asap from an async workqueue. If not, it's retried immediately in the same code path. In either case the retry will not relinquish the mmap semaphore and will block on the IO. This is a bad thing, as other mmap semaphore users now stall as a function of swap or filemap latency. This patch ensures both the regular and async PF path re-enter the fault allowing for the mmap semaphore to be relinquished in the case of IO wait. Reviewed-by: Radim Krčmář <rkrcmar@redhat.com> Signed-off-by: Andres Lagar-Cavilla <andreslc@google.com> Acked-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2014-06-04Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm into nextLinus Torvalds-3/+1
Pull KVM updates from Paolo Bonzini: "At over 200 commits, covering almost all supported architectures, this was a pretty active cycle for KVM. Changes include: - a lot of s390 changes: optimizations, support for migration, GDB support and more - ARM changes are pretty small: support for the PSCI 0.2 hypercall interface on both the guest and the host (the latter acked by Catalin) - initial POWER8 and little-endian host support - support for running u-boot on embedded POWER targets - pretty large changes to MIPS too, completing the userspace interface and improving the handling of virtualized timer hardware - for x86, a larger set of changes is scheduled for 3.17. Still, we have a few emulator bugfixes and support for running nested fully-virtualized Xen guests (para-virtualized Xen guests have always worked). And some optimizations too. The only missing architecture here is ia64. It's not a coincidence that support for KVM on ia64 is scheduled for removal in 3.17" * tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (203 commits) KVM: add missing cleanup_srcu_struct KVM: PPC: Book3S PR: Rework SLB switching code KVM: PPC: Book3S PR: Use SLB entry 0 KVM: PPC: Book3S HV: Fix machine check delivery to guest KVM: PPC: Book3S HV: Work around POWER8 performance monitor bugs KVM: PPC: Book3S HV: Make sure we don't miss dirty pages KVM: PPC: Book3S HV: Fix dirty map for hugepages KVM: PPC: Book3S HV: Put huge-page HPTEs in rmap chain for base address KVM: PPC: Book3S HV: Fix check for running inside guest in global_invalidates() KVM: PPC: Book3S: Move KVM_REG_PPC_WORT to an unused register number KVM: PPC: Book3S: Add ONE_REG register names that were missed KVM: PPC: Add CAP to indicate hcall fixes KVM: PPC: MPIC: Reset IRQ source private members KVM: PPC: Graciously fail broken LE hypercalls PPC: ePAPR: Fix hypercall on LE guest KVM: PPC: BOOK3S: Remove open coded make_dsisr in alignment handler KVM: PPC: BOOK3S: Always use the saved DAR value PPC: KVM: Make NX bit available with magic page KVM: PPC: Disable NX for old magic page using guests KVM: PPC: BOOK3S: HV: Add mixed page-size support for guest ...
2014-04-28KVM: async_pf: change async_pf_execute() to use get_user_pages(tsk => NULL)Oleg Nesterov-1/+1
async_pf_execute() passes tsk == current to gup(), this is doesn't hurt but unnecessary and misleading. "tsk" is only used to account the number of faults and current is the random workqueue thread. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Suggested-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2014-04-28KVM: async_pf: kill the unnecessary use_mm/unuse_mm async_pf_execute()Oleg Nesterov-2/+0
async_pf_execute() has no reasons to adopt apf->mm, gup(current, mm) should work just fine even if current has another or NULL ->mm. Recently kvm_async_page_present_sync() was added insedie the "use_mm" section, but it seems that it doesn't need current->mm too. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Reviewed-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2014-04-28KVM: async_pf: mm->mm_users can not pin apf->mmOleg Nesterov-4/+4
get_user_pages(mm) is simply wrong if mm->mm_users == 0 and exit_mmap/etc was already called (or is in progress), mm->mm_count can only pin mm->pgd and mm_struct itself. Change kvm_setup_async_pf/async_pf_execute to inc/dec mm->mm_users. kvm_create_vm/kvm_destroy_vm play with ->mm_count too but this case looks fine at first glance, it seems that this ->mm is only used to verify that current->mm == kvm->mm. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2014-02-04KVM: async_pf: Add missing call for async page presentDominik Dingel-1/+1
Commit KVM: async_pf: Provide additional direct page notification missed the call from kvm_check_async_pf_completion to the new introduced function. Reported-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Dominik Dingel <dingel@linux.vnet.ibm.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2014-01-30KVM: async_pf: Allow to wait for outstanding workDominik Dingel-0/+5
On s390 we are not able to cancel work. Instead we will flush the work and wait for completion. Signed-off-by: Dominik Dingel <dingel@linux.vnet.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
2014-01-30KVM: async_pf: Provide additional direct page notificationDominik Dingel-2/+18
By setting a Kconfig option, the architecture can control when guest notifications will be presented by the apf backend. There is the default batch mechanism, working as before, where the vcpu thread should pull in this information. Opposite to this, there is now the direct mechanism, that will push the information to the guest. This way s390 can use an already existing architecture interface. Still the vcpu thread should call check_completion to cleanup leftovers. Signed-off-by: Dominik Dingel <dingel@linux.vnet.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
2013-10-15KVM: Drop FOLL_GET in GUP when doing async page faultchai wen-12/+5
Page pinning is not mandatory in kvm async page fault processing since after async page fault event is delivered to a guest it accesses page once again and does its own GUP. Drop the FOLL_GET flag in GUP in async_pf code, and do some simplifying in check/clear processing. Suggested-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Gu zheng <guz.fnst@cn.fujitsu.com> Signed-off-by: chai wen <chaiw.fnst@cn.fujitsu.com> Signed-off-by: Gleb Natapov <gleb@redhat.com>
2013-09-24kvm: remove .done from struct kvm_async_pfRadim Krčmář-4/+1
'.done' is used to mark the completion of 'async_pf_execute()', but 'cancel_work_sync()' returns true when the work was canceled, so we use it instead. Signed-off-by: Radim Krčmář <rkrcmar@redhat.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2013-09-17kvm: free resources after canceling async_pfRadim Krčmář-1/+4
When we cancel 'async_pf_execute()', we should behave as if the work was never scheduled in 'kvm_setup_async_pf()'. Fixes a bug when we can't unload module because the vm wasn't destroyed. Signed-off-by: Radim Krčmář <rkrcmar@redhat.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2012-08-06KVM: do not release the error pageXiao Guangrong-2/+2
After commit a2766325cf9f9, the error page is replaced by the error code, it need not be released anymore [ The patch has been compiling tested for powerpc ] Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> Signed-off-by: Avi Kivity <avi@redhat.com>
2012-08-06KVM: introduce KVM_ERR_PTR_BAD_PAGEXiao Guangrong-1/+1
It is used to eliminate the overload of function call and cleanup the code Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> Signed-off-by: Avi Kivity <avi@redhat.com>
2012-07-26KVM: remove dummy pagesXiao Guangrong-2/+1
Currently, kvm allocates some pages and use them as error indicators, it wastes memory and is not good for scalability Base on Avi's suggestion, we use the error codes instead of these pages to indicate the error conditions Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> Signed-off-by: Avi Kivity <avi@redhat.com>
2012-07-26KVM: use kvm_release_page_clean to release the pageXiao Guangrong-2/+2
In kvm_async_pf_wakeup_all, it uses bad_page to generate broadcast wakeup, and uses put_page to release bad_page, the work depends on the fact that bad_page is the normal page. But we will use the error code instead of bad_page, so use kvm_release_page_clean to release the page which will release the error code properly Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> Signed-off-by: Avi Kivity <avi@redhat.com>
2011-01-12KVM: fix the race while wakeup all pv guestXiao Guangrong-1/+4
In kvm_async_pf_wakeup_all(), we add a dummy apf to vcpu->async_pf.done without holding vcpu->async_pf.lock, it will break if we are handling apfs at this time. Also use 'list_empty_careful()' instead of 'list_empty()' Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com> Acked-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2011-01-12KVM: handle more completed apfs if possibleXiao Guangrong-16/+16
If it's no need to inject async #PF to PV guest we can handle more completed apfs at one time, so we can retry guest #PF as early as possible Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com> Acked-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2011-01-12KVM: Inject asynchronous page fault into a PV guest if page is swapped out.Gleb Natapov-1/+2
Send async page fault to a PV guest if it accesses swapped out memory. Guest will choose another task to run upon receiving the fault. Allow async page fault injection only when guest is in user mode since otherwise guest may be in non-sleepable context and will not be able to reschedule. Vcpu will be halted if guest will fault on the same page again or if vcpu executes kernel code. Acked-by: Rik van Riel <riel@redhat.com> Signed-off-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2011-01-12KVM: Add PV MSR to enable asynchronous page faults delivery.Gleb Natapov-0/+20
Guest enables async PF vcpu functionality using this MSR. Reviewed-by: Rik van Riel <riel@redhat.com> Signed-off-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2011-01-12KVM: Retry fault before vmentryGleb Natapov-0/+2
When page is swapped in it is mapped into guest memory only after guest tries to access it again and generate another fault. To save this fault we can map it immediately since we know that guest is going to access the page. Do it only when tdp is enabled for now. Shadow paging case is more complicated. CR[034] and EFER registers should be switched before doing mapping and then switched back. Acked-by: Rik van Riel <riel@redhat.com> Signed-off-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2011-01-12KVM: Halt vcpu if page it tries to access is swapped outGleb Natapov-0/+190
If a guest accesses swapped out memory do not swap it in from vcpu thread context. Schedule work to do swapping and put vcpu into halted state instead. Interrupts will still be delivered to the guest and if interrupt will cause reschedule guest will continue to run another task. [avi: remove call to get_user_pages_noio(), nacked by Linus; this makes everything synchrnous again] Acked-by: Rik van Riel <riel@redhat.com> Signed-off-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>