Messages in this thread | | | From | Tianyu Lan <> | Date | Thu, 10 Jan 2019 17:06:25 +0800 | Subject | Re: [PATCH 9/11] KVM/MMU: Flush tlb in the kvm_mmu_write_protect_pt_masked() |
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On Tue, Jan 8, 2019 at 12:26 AM Paolo Bonzini <pbonzini@redhat.com> wrote: > > On 04/01/19 09:54, lantianyu1986@gmail.com wrote: > > rmap_head = __gfn_to_rmap(slot->base_gfn + gfn_offset + __ffs(mask), > > PT_PAGE_TABLE_LEVEL, slot); > > - __rmap_write_protect(kvm, rmap_head, false); > > + flush |= __rmap_write_protect(kvm, rmap_head, false); > > > > /* clear the first set bit */ > > mask &= mask - 1; > > } > > + > > + if (flush && kvm_available_flush_tlb_with_range()) { > > + kvm_flush_remote_tlbs_with_address(kvm, > > + slot->base_gfn + gfn_offset, > > + hweight_long(mask)); > > Mask is zero here, so this probably won't work. > > In addition, I suspect calling the hypercall once for every 64 pages is > not very efficient. Passing a flush list into > kvm_mmu_write_protect_pt_masked, and flushing in > kvm_arch_mmu_enable_log_dirty_pt_masked, isn't efficient either because > kvm_arch_mmu_enable_log_dirty_pt_masked is also called once per word. > Yes, this is not efficient.
> I don't have any good ideas, except for moving the whole > kvm_clear_dirty_log_protect loop into architecture-specific code (which > is not the direction we want---architectures should share more code, not > less).
kvm_vm_ioctl_clear_dirty_log/get_dirty_log() is to get/clear dirty log with memslot as unit. We may just flush tlbs of the affected memslot instead of entire page table's when range flush is available.
> > Paolo > > > + flush = false; > > + } > > + >
-- Best regards Tianyu Lan
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