lkml.org 
[lkml]   [2013]   [Apr]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH v3 15/15] KVM: MMU: replace kvm_zap_all with kvm_mmu_invalid_all_pages
    On Thu, Apr 18, 2013 at 12:03:45PM +0800, Xiao Guangrong wrote:
    > On 04/18/2013 08:08 AM, Marcelo Tosatti wrote:
    > > On Tue, Apr 16, 2013 at 02:32:53PM +0800, Xiao Guangrong wrote:
    > >> Use kvm_mmu_invalid_all_pages in kvm_arch_flush_shadow_all and
    > >> rename kvm_zap_all to kvm_free_all which is used to free all
    > >> memmory used by kvm mmu when vm is being destroyed, at this time,
    > >> no vcpu exists and mmu-notify has been unregistered, so we can
    > >> free the shadow pages out of mmu-lock
    > >
    > > Since there is no contention for mmu-lock its also not a problem to
    > > grab the lock right?
    >
    > This still has contention. Other mmu-notify can happen when we handle
    > ->release(). On the other handle, spin-lock is not preemptable.

    Don't think so:

    kvm_coalesced_mmio_free(kvm);
    #if defined(CONFIG_MMU_NOTIFIER) && defined(KVM_ARCH_WANT_MMU_NOTIFIER)
    mmu_notifier_unregister(&kvm->mmu_notifier, kvm->mm);
    #else
    kvm_arch_flush_shadow_all(kvm);
    #endif
    kvm_arch_destroy_vm(kvm);

    > > Automated verification of locking/srcu might complain.
    >
    > We hold slot-lock to free shadow page out of mmu-lock, it can avoid
    > the complain. No?

    Not if it realizes srcu is required to access the data structures.



    \
     
     \ /
      Last update: 2013-04-20 20:21    [W:3.714 / U:0.216 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site