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2014-09-24kvm: Faults which trigger IO release the mmap_semAndres Lagar-Cavilla1-3/+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 Torvalds1-3/+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 Nesterov1-1/+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 Nesterov1-2/+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 Nesterov1-4/+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 Dingel1-1/+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 Dingel1-0/+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 Dingel1-2/+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 wen1-12/+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 Krčmář1-4/+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 Krčmář1-1/+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 Guangrong1-2/+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 Guangrong1-1/+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 Guangrong1-2/+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 Guangrong1-2/+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 Guangrong1-1/+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 Guangrong1-16/+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 Natapov1-1/+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 Natapov1-0/+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 Natapov1-0/+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 Natapov1-0/+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>
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