Re: [PATCH] KVM: x86: Avoid zapping mmio sptes twice for generation wraparound

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Il 03/07/2013 10:53, Gleb Natapov ha scritto:
>>> > > Please wait a while. I can not understand it very clearly.
>>> > > 
>>> > > This conditional check will cause caching a overflow value into mmio spte.
>>> > > The simple case is that kvm adds new slots for many times, the mmio-gen is easily
>>> > > more than MMIO_MAX_GEN.
>>> > > 
>> > 
>> > Actually, the double zapping can be avoided by moving kvm_mmu_invalidate_mmio_sptes to
>> > the end of install_new_memslots().
>> > 
> Exactly. Why should we hide it in obscure functions?

Because kvm_mmu_invalidate_mmio_sptes is an x86-specific function, and
we already have a good arch API to hook into __kvm_set_memory_region.

Another possible implementation is to cache the last memslot generation,
check it in kvm_arch_prepare/commit_memory_region, and call
kvm_mmu_invalidate_mmio_sptes if it changed.  This would avoid the need
to keep "((change == KVM_MR_DELETE) || (change == KVM_MR_MOVE))" in sync
between the two places.  But I don't think it is a substantial improvement.

Paolo
--
To unsubscribe from this list: send the line "unsubscribe kvm" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html




[Index of Archives]     [KVM ARM]     [KVM ia64]     [KVM ppc]     [Virtualization Tools]     [Spice Development]     [Libvirt]     [Libvirt Users]     [Linux USB Devel]     [Linux Audio Users]     [Yosemite Questions]     [Linux Kernel]     [Linux SCSI]     [XFree86]
  Powered by Linux