user/sven/linux.git/virt/kvm/async_pf.c, branch leds/master

mm: gup: kvm use get_user_pages_unlocked

2015-02-12T01:06:05Z

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 Reviewed-by: Andres Lagar-Cavilla Reviewed-by: Kirill A. Shutemov Cc: Peter Feiner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

kvm: Faults which trigger IO release the mmap_sem

2014-09-24T12:07:54Z

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 Signed-off-by: Andres Lagar-Cavilla Acked-by: Andrew Morton Signed-off-by: Paolo Bonzini

Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm into next

2014-06-04T15:47:12Z

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 ...

KVM: async_pf: change async_pf_execute() to use get_user_pages(tsk => NULL)

2014-04-28T15:24:55Z

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 Suggested-by: Andrea Arcangeli Signed-off-by: Paolo Bonzini

KVM: async_pf: kill the unnecessary use_mm/unuse_mm async_pf_execute()

2014-04-28T15:24:25Z

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 Reviewed-by: Andrea Arcangeli Signed-off-by: Paolo Bonzini

KVM: async_pf: mm->mm_users can not pin apf->mm

2014-04-28T11:04:46Z

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 Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini

KVM: async_pf: Add missing call for async page present

2014-02-04T03:24:05Z

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 Signed-off-by: Dominik Dingel Signed-off-by: Paolo Bonzini

KVM: async_pf: Allow to wait for outstanding work

2014-01-30T11:52:20Z

On s390 we are not able to cancel work. Instead we will flush the work and wait for completion. Signed-off-by: Dominik Dingel Signed-off-by: Christian Borntraeger

KVM: async_pf: Provide additional direct page notification

2014-01-30T11:51:38Z

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 Signed-off-by: Christian Borntraeger

KVM: Drop FOLL_GET in GUP when doing async page fault

2013-10-15T10:43:37Z

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 Signed-off-by: Gu zheng Signed-off-by: chai wen Signed-off-by: Gleb Natapov