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2008-12-31KVM: Enable Function Level Reset for assigned deviceSheng Yang1-0/+5
Ideally, every assigned device should in a clear condition before and after assignment, so that the former state of device won't affect later work. Some devices provide a mechanism named Function Level Reset, which is defined in PCI/PCI-e document. We should execute it before and after device assignment. (But sadly, the feature is new, and most device on the market now don't support it. We are considering using D0/D3hot transmit to emulate it later, but not that elegant and reliable as FLR itself.) [Update: Reminded by Xiantao, execute FLR after we ensure that the device can be assigned to the guest.] Signed-off-by: Sheng Yang <sheng@linux.intel.com> Signed-off-by: Avi Kivity <avi@redhat.com>
2008-12-31KVM: IRQ ACK notifier should be used with in-kernel irqchipSheng Yang2-3/+7
Also remove unnecessary parameter of unregister irq ack notifier. Signed-off-by: Sheng Yang <sheng@linux.intel.com> Signed-off-by: Avi Kivity <avi@redhat.com>
2008-12-31KVM: Kick NMI receiving VCPUJan Kiszka1-0/+1
Kick the NMI receiving VCPU in case the triggering caller runs in a different context. Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> Signed-off-by: Avi Kivity <avi@redhat.com>
2008-10-28KVM: Fix guest shared interrupt with in-kernel irqchipSheng Yang2-7/+47
Every call of kvm_set_irq() should offer an irq_source_id, which is allocated by kvm_request_irq_source_id(). Based on irq_source_id, we identify the irq source and implement logical OR for shared level interrupts. The allocated irq_source_id can be freed by kvm_free_irq_source_id(). Currently, we support at most sizeof(unsigned long) different irq sources. [Amit: - rebase to kvm.git HEAD - move definition of KVM_USERSPACE_IRQ_SOURCE_ID to common file - move kvm_request_irq_source_id to the update_irq ioctl] [Xiantao: - Add kvm/ia64 stuff and make it work for kvm/ia64 guests] Signed-off-by: Sheng Yang <sheng@linux.intel.com> Signed-off-by: Amit Shah <amit.shah@redhat.com> Signed-off-by: Xiantao Zhang <xiantao.zhang@intel.com> Signed-off-by: Avi Kivity <avi@redhat.com>
2008-10-15KVM: Move irqchip_in_kernel() from ioapic.h to irq.hXiantao Zhang1-7/+0
Moving irqchip_in_kernel() from ioapic.h to irq.h. Signed-off-by: Xiantao Zhang <xiantao.zhang@intel.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-10-15KVM: Separate irq ack notification out of arch/x86/kvm/irq.cXiantao Zhang1-0/+60
Moving irq ack notification logic as common, and make it shared with ia64 side. Signed-off-by: Xiantao Zhang <xiantao.zhang@intel.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-10-15KVM: Change is_mmio_pfn to kvm_is_mmio_pfn, and make it common for all archsXiantao Zhang1-8/+8
Add a kvm_ prefix to avoid polluting kernel's name space. Signed-off-by: Xiantao Zhang <xiantao.zhang@intel.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-10-15KVM: Move device assignment logic to common codeXiantao Zhang1-2/+266
To share with other archs, this patch moves device assignment logic to common parts. Signed-off-by: Xiantao Zhang <xiantao.zhang@intel.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-10-15KVM: Device Assignment: Move vtd.c from arch/x86/kvm/ to virt/kvm/Zhang xiantao1-0/+191
Preparation for kvm/ia64 VT-d support. Signed-off-by: Zhang xiantao <xiantao.zhang@intel.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-10-15KVM: Device Assignment: Map mmio pages into VT-d page tableWeidong Han1-1/+1
Assigned device could DMA to mmio pages, so also need to map mmio pages into VT-d page table. Signed-off-by: Weidong Han <weidong.han@intel.com> Signed-off-by: Avi Kivity <avi@redhat.com>
2008-10-15KVM: Remove useless intel-iommu.h header inclusionWeidong Han1-1/+0
Currently "#include <linux/intel-iommu.h>" is not needed in virt/kvm/kvm_main.c. Signed-off-by: Weidong Han <weidong.han@intel.com> Signed-off-by: Avi Kivity <avi@redhat.com>
2008-10-15KVM: Don't destroy vcpu in case vcpu_setup failsGlauber Costa1-3/+2
One of vcpu_setup responsibilities is to do mmu initialization. However, in case we fail in kvm_arch_vcpu_reset, before we get the chance to init mmu. OTOH, vcpu_destroy will attempt to destroy mmu, triggering a bug. Keeping track of whether or not mmu is initialized would unnecessarily complicate things. Rather, we just make return, making sure any needed uninitialization is done before we return, in case we fail. Signed-off-by: Glauber Costa <glommer@redhat.com> Signed-off-by: Avi Kivity <avi@redhat.com>
2008-10-15KVM: switch to get_user_pages_fastMarcelo Tosatti1-5/+5
Convert gfn_to_pfn to use get_user_pages_fast, which can do lockless pagetable lookups on x86. Kernel compilation on 4-way guest is 3.7% faster on VMX. Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Avi Kivity <avi@redhat.com>
2008-10-15KVM: opencode gfn_to_page in kvm_vm_faultMarcelo Tosatti1-7/+12
kvm_vm_fault is invoked with mmap_sem held in read mode. Since gfn_to_page will be converted to get_user_pages_fast, which requires this lock NOT to be held, switch to opencoded get_user_pages. Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Avi Kivity <avi@redhat.com>
2008-10-15KVM: Device Assignment with VT-dBen-Ami Yassour1-1/+8
Based on a patch by: Kay, Allen M <allen.m.kay@intel.com> This patch enables PCI device assignment based on VT-d support. When a device is assigned to the guest, the guest memory is pinned and the mapping is updated in the VT-d IOMMU. [Amit: Expose KVM_CAP_IOMMU so we can check if an IOMMU is present and also control enable/disable from userspace] Signed-off-by: Kay, Allen M <allen.m.kay@intel.com> Signed-off-by: Weidong Han <weidong.han@intel.com> Signed-off-by: Ben-Ami Yassour <benami@il.ibm.com> Signed-off-by: Amit Shah <amit.shah@qumranet.com> Acked-by: Mark Gross <mgross@linux.intel.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-10-15KVM: x86: do not execute halted vcpusMarcelo Tosatti1-5/+5
Offline or uninitialized vcpu's can be executed if requested to perform userspace work. Follow Avi's suggestion to handle halted vcpu's in the main loop, simplifying kvm_emulate_halt(). Introduce a new vcpu->requests bit to indicate events that promote state from halted to running. Also standardize vcpu wake sites. Signed-off-by: Marcelo Tosatti <mtosatti <at> redhat.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-10-15KVM: Don't call get_user_pages(.force = 1)Avi Kivity1-1/+1
This is esoteric and only needed to break COW on MAP_SHARED mappings. Since KVM no longer does these sorts of mappings, breaking COW on them is no longer necessary. Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-10-15KVM: ia64: add a dummy irq ack notificationXiantao Zhang1-1/+1
Before enabling notify_acked_irq for ia64, leave the related APIs as nop-op first. Signed-off-by: Xiantao Zhang <xiantao.zhang@intel.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-10-15KVM: Reduce stack usage in kvm_vcpu_ioctl()Dave Hansen1-18/+28
Signed-off-by: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-10-15KVM: direct mmio pfn checkBen-Ami Yassour1-7/+15
Userspace may specify memory slots that are backed by mmio pages rather than normal RAM. In some cases it is not enough to identify these mmio pages by pfn_valid(). This patch adds checking the PageReserved as well. Signed-off-by: Ben-Ami Yassour <benami@il.ibm.com> Signed-off-by: Muli Ben-Yehuda <muli@il.ibm.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-10-15KVM: irq ack notificationMarcelo Tosatti2-8/+15
Based on a patch from: Ben-Ami Yassour <benami@il.ibm.com> which was based on a patch from: Amit Shah <amit.shah@qumranet.com> Notify IRQ acking on PIC/APIC emulation. The previous patch missed two things: - Edge triggered interrupts on IOAPIC - PIC reset with IRR/ISR set should be equivalent to ack (LAPIC probably needs something similar). Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> CC: Amit Shah <amit.shah@qumranet.com> CC: Ben-Ami Yassour <benami@il.ibm.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-10-15KVM: kvmtrace: replace get_cycles with ktime_get v3Christian Ehrhardt1-9/+10
The current kvmtrace code uses get_cycles() while the interpretation would be easier using using nanoseconds. ktime_get() should give at least the same accuracy as get_cycles on all architectures (even better on 32bit archs) but at a better unit (e.g. comparable between hosts with different frequencies. [avi: avoid ktime_t in public header] Signed-off-by: Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com> Acked-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-10-15KVM: kvmtrace: Remove use of bit fields in kvm trace structureChristian Ehrhardt1-8/+9
This patch fixes kvmtrace use on big endian systems. When using bit fields the compiler will lay data out in the wrong order expected when laid down into a file. This fixes it by using one variable instead of using bit fields. Signed-off-by: Jerone Young <jyoung5@us.ibm.com> Signed-off-by: Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-07-29KVM: Synchronize guest physical memory map to host virtual memory mapAndrea Arcangeli1-0/+135
Synchronize changes to host virtual addresses which are part of a KVM memory slot to the KVM shadow mmu. This allows pte operations like swapping, page migration, and madvise() to transparently work with KVM. Signed-off-by: Andrea Arcangeli <andrea@qumranet.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-07-29KVM: Allow browsing memslots with mmu_lockAndrea Arcangeli1-4/+16
This allows reading memslots with only the mmu_lock hold for mmu notifiers that runs in atomic context and with mmu_lock held. Signed-off-by: Andrea Arcangeli <andrea@qumranet.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-07-24flag parameters: anon_inode_getfd extensionUlrich Drepper1-2/+2
This patch just extends the anon_inode_getfd interface to take an additional parameter with a flag value. The flag value is passed on to get_unused_fd_flags in anticipation for a use with the O_CLOEXEC flag. No actual semantic changes here, the changed callers all pass 0 for now. [akpm@linux-foundation.org: KVM fix] Signed-off-by: Ulrich Drepper <drepper@redhat.com> Acked-by: Davide Libenzi <davidel@xmailserver.org> Cc: Michael Kerrisk <mtk.manpages@googlemail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-20KVM: Adjust smp_call_function_mask() callers to new requirementsAvi Kivity1-6/+12
smp_call_function_mask() now complains when called in a preemptible context; adjust its callers accordingly. Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-07-20KVM: MMU: nuke shadowed pgtable pages and ptes on memslot destructionMarcelo Tosatti1-0/+3
Flush the shadow mmu before removing regions to avoid stale entries. Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-07-20KVM: s390: dont allocate dirty bitmapCarsten Otte1-0/+2
This patch #ifdefs the bitmap array for dirty tracking. We don't have dirty tracking on s390 today, and we'd love to use our storage keys to store the dirty information for migration. Therefore, we won't need this array at all, and due to our limited amount of vmalloc space this limits the amount of guests we can run. Signed-off-by: Carsten Otte <cotte@de.ibm.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-07-20KVM: Support mixed endian machinesTan, Li1-6/+12
Currently kvmtrace is not portable. This will prevent from copying a trace file from big-endian target to little-endian workstation for analysis. In the patch, kernel outputs metadata containing a magic number to trace log, and changes 64-bit words to be u64 instead of a pair of u32s. Signed-off-by: Tan Li <li.tan@intel.com> Acked-by: Jerone Young <jyoung5@us.ibm.com> Acked-by: Hollis Blanchard <hollisb@us.ibm.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-07-20KVM: Add coalesced MMIO support (common part)Laurent Vivier3-0/+236
This patch adds all needed structures to coalesce MMIOs. Until an architecture uses it, it is not compiled. Coalesced MMIO introduces two ioctl() to define where are the MMIO zones that can be coalesced: - KVM_REGISTER_COALESCED_MMIO registers a coalesced MMIO zone. It requests one parameter (struct kvm_coalesced_mmio_zone) which defines a memory area where MMIOs can be coalesced until the next switch to user space. The maximum number of MMIO zones is KVM_COALESCED_MMIO_ZONE_MAX. - KVM_UNREGISTER_COALESCED_MMIO cancels all registered zones inside the given bounds (bounds are also given by struct kvm_coalesced_mmio_zone). The userspace client can check kernel coalesced MMIO availability by asking ioctl(KVM_CHECK_EXTENSION) for the KVM_CAP_COALESCED_MMIO capability. The ioctl() call to KVM_CAP_COALESCED_MMIO will return 0 if not supported, or the page offset where will be stored the ring buffer. The page offset depends on the architecture. After an ioctl(KVM_RUN), the first page of the KVM memory mapped points to a kvm_run structure. The offset given by KVM_CAP_COALESCED_MMIO is an offset to the coalesced MMIO ring expressed in PAGE_SIZE relatively to the address of the start of th kvm_run structure. The MMIO ring buffer is defined by the structure kvm_coalesced_mmio_ring. [akio: fix oops during guest shutdown] Signed-off-by: Laurent Vivier <Laurent.Vivier@bull.net> Signed-off-by: Akio Takebe <takebe_akio@jp.fujitsu.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-07-20KVM: kvm_io_device: extend in_range() to manage len and write attributeLaurent Vivier3-6/+10
Modify member in_range() of structure kvm_io_device to pass length and the type of the I/O (write or read). This modification allows to use kvm_io_device with coalesced MMIO. Signed-off-by: Laurent Vivier <Laurent.Vivier@bull.net> Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-07-20KVM: IOAPIC/LAPIC: Enable NMI supportSheng Yang1-2/+18
[avi: fix ia64 build breakage] Signed-off-by: Sheng Yang <sheng.yang@intel.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-07-20KVM: Remove decache_vcpus_on_cpu() and related callbacksAvi Kivity1-1/+0
Obsoleted by the vmx-specific per-cpu list. Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-07-20KVM: Handle virtualization instruction #UD faults during rebootAvi Kivity1-0/+15
KVM turns off hardware virtualization extensions during reboot, in order to disassociate the memory used by the virtualization extensions from the processor, and in order to have the system in a consistent state. Unfortunately virtual machines may still be running while this goes on, and once virtualization extensions are turned off, any virtulization instruction will #UD on execution. Fix by adding an exception handler to virtualization instructions; if we get an exception during reboot, we simply spin waiting for the reset to complete. If it's a true exception, BUG() so we can have our stack trace. Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-07-20KVM: Handle vma regions with no backing pageAnthony Liguori1-12/+37
This patch allows VMAs that contain no backing page to be used for guest memory. This is useful for assigning mmio regions to a guest. Signed-off-by: Anthony Liguori <aliguori@us.ibm.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-07-20KVM: remove long -> void *user -> long castChristian Borntraeger1-2/+1
kvm_dev_ioctl casts the arg value to void __user *, just to recast it again to long. This seems unnecessary. According to objdump the binary code on x86 is unchanged by this patch. Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-07-15Merge branch 'generic-ipi' into generic-ipi-for-linusIngo Molnar1-7/+7
Conflicts: arch/powerpc/Kconfig arch/s390/kernel/time.c arch/x86/kernel/apic_32.c arch/x86/kernel/cpu/perfctr-watchdog.c arch/x86/kernel/i8259_64.c arch/x86/kernel/ldt.c arch/x86/kernel/nmi_64.c arch/x86/kernel/smpboot.c arch/x86/xen/smp.c include/asm-x86/hw_irq_32.h include/asm-x86/hw_irq_64.h include/asm-x86/mach-default/irq_vectors.h include/asm-x86/mach-voyager/irq_vectors.h include/asm-x86/smp.h kernel/Makefile Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-07-06KVM: IOAPIC: Fix level-triggered irq injection hangMark McLoughlin1-1/+1
The "remote_irr" variable is used to indicate an interrupt which has been received by the LAPIC, but not acked. In our EOI handler, we unset remote_irr and re-inject the interrupt if the interrupt line is still asserted. However, we do not set remote_irr here, leading to a situation where if kvm_ioapic_set_irq() is called, then we go ahead and call ioapic_service(). This means that IRR is re-asserted even though the interrupt is currently in service (i.e. LAPIC IRR is cleared and ISR/TMR set) The issue with this is that when the currently executing interrupt handler finishes and writes LAPIC EOI, then TMR is unset and EOI sent to the IOAPIC. Since IRR is now asserted, but TMR is not, then when the second interrupt is handled, no EOI is sent and if there is any pending interrupt, it is not re-injected. This fixes a hang only seen while running mke2fs -j on an 8Gb virtio disk backed by a fully sparse raw file, with aliguori "avoid fragmented virtio-blk transfers by copying" changes. Signed-off-by: Mark McLoughlin <markmc@redhat.com> Acked-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-06-26on_each_cpu(): kill unused 'retry' parameterJens Axboe1-4/+4
It's not even passed on to smp_call_function() anymore, since that was removed. So kill it. Acked-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-06-26smp_call_function: get rid of the unused nonatomic/retry argumentJens Axboe1-3/+3
It's never used and the comments refer to nonatomic and retry interchangably. So get rid of it. Acked-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-06-24KVM: ioapic: fix lost interrupt when changing a device's irqAvi Kivity1-20/+11
The ioapic acknowledge path translates interrupt vectors to irqs. It currently uses a first match algorithm, stopping when it finds the first redirection table entry containing the vector. That fails however if the guest changes the irq to a different line, leaving the old redirection table entry in place (though masked). Result is interrupts not making it to the guest. Fix by always scanning the entire redirection table. Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-06-06KVM: IOAPIC: only set remote_irr if interrupt was injectedMarcelo Tosatti1-10/+11
There's a bug in the IOAPIC code for level-triggered interrupts. Its relatively easy to trigger by sharing (virtio-blk + usbtablet was the testcase, initially reported by Gerd von Egidy). The "remote_irr" variable is used to indicate accepted but not yet acked interrupts. Its cleared from the EOI handler. Problem is that the EOI handler clears remote_irr unconditionally, even if it reinjected another pending interrupt. In that case, kvm_ioapic_set_irq() proceeds to ioapic_service() which sets remote_irr even if it failed to inject (since the IRR was high due to EOI reinjection). Since the TMR bit has been cleared by the first EOI, the second one fails to clear remote_irr. End result is interrupt line dead. Fix it by setting remote_irr only if a new pending interrupt has been generated (and the TMR bit for vector in question set). Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-05-18KVM: Fix kvm_vcpu_block() task state raceMarcelo Tosatti1-14/+15
There's still a race in kvm_vcpu_block(), if a wake_up_interruptible() call happens before the task state is set to TASK_INTERRUPTIBLE: CPU0 CPU1 kvm_vcpu_block add_wait_queue kvm_cpu_has_interrupt = 0 set interrupt if (waitqueue_active()) wake_up_interruptible() kvm_cpu_has_pending_timer kvm_arch_vcpu_runnable signal_pending set_current_state(TASK_INTERRUPTIBLE) schedule() Can be fixed by using prepare_to_wait() which sets the task state before testing for the wait condition. Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-05-04KVM: Export necessary function for EPTSheng Yang1-0/+1
Signed-off-by: Sheng Yang <sheng.yang@intel.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-05-01[PATCH] sanitize anon_inode_getfd()Al Viro1-16/+5
a) none of the callers even looks at inode or file returned by anon_inode_getfd() b) any caller that would try to look at those would be racy, since by the time it returns we might have raced with close() from another thread and that file would be pining for fjords. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2008-04-27KVM: kill file->f_count abuse in kvmAl Viro1-6/+6
Use kvm own refcounting instead of playing with ->filp->f_count. That will allow to get rid of a lot of crap in anon_inode_getfd() and kill a race in kvm_dev_ioctl_create_vm() (file might have been closed immediately by another thread, so ->filp might point to already freed struct file when we get around to setting it). Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-04-27KVM: Rename debugfs_dir to kvm_debugfs_dirHollis Blanchard2-6/+6
It's a globally exported symbol now. Signed-off-by: Hollis Blanchard <hollisb@us.ibm.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-04-27KVM: add ioctls to save/store mpstateMarcelo Tosatti1-0/+24
So userspace can save/restore the mpstate during migration. [avi: export the #define constants describing the value] [christian: add s390 stubs] [avi: ditto for ia64] Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Carsten Otte <cotte@de.ibm.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-04-27KVM: hlt emulation should take in-kernel APIC/PIT timers into accountMarcelo Tosatti1-0/+1
Timers that fire between guest hlt and vcpu_block's add_wait_queue() are ignored, possibly resulting in hangs. Also make sure that atomic_inc and waitqueue_active tests happen in the specified order, otherwise the following race is open: CPU0 CPU1 if (waitqueue_active(wq)) add_wait_queue() if (!atomic_read(pit_timer->pending)) schedule() atomic_inc(pit_timer->pending) Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
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