Re: [PATCH 05/11] KVM: page track: introduce kvm_page_track_{add,remove}_page

[Kai Huang <kai.huang@linux.intel.com>]

On 12/15/2015 03:15 PM, Kai Huang wrote:
>
>
> On 12/01/2015 02:26 AM, Xiao Guangrong wrote:
>> These two functions are the user APIs:
>> - kvm_page_track_add_page(): add the page to the tracking pool after
>>    that later specified access on that page will be tracked
>>
>> - kvm_page_track_remove_page(): remove the page from the tracking pool,
>>    the specified access on the page is not tracked after the last 
>> user is
>>    gone
>>
>> Both of these are called under the protection of kvm->srcu or
>> kvm->slots_lock
>>
>> Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
>> ---
>>   arch/x86/include/asm/kvm_page_track.h |  5 ++
>>   arch/x86/kvm/page_track.c             | 95 
>> +++++++++++++++++++++++++++++++++++
>>   2 files changed, 100 insertions(+)
>>
>> diff --git a/arch/x86/include/asm/kvm_page_track.h 
>> b/arch/x86/include/asm/kvm_page_track.h
>> index 347d5c9..9cc17c6 100644
>> --- a/arch/x86/include/asm/kvm_page_track.h
>> +++ b/arch/x86/include/asm/kvm_page_track.h
>> @@ -10,4 +10,9 @@ int kvm_page_track_create_memslot(struct 
>> kvm_memory_slot *slot,
>>                     unsigned long npages);
>>   void kvm_page_track_free_memslot(struct kvm_memory_slot *free,
>>                    struct kvm_memory_slot *dont);
>> +
>> +void kvm_page_track_add_page(struct kvm *kvm, gfn_t gfn,
>> +                 enum kvm_page_track_mode mode);
>> +void kvm_page_track_remove_page(struct kvm *kvm, gfn_t gfn,
>> +                enum kvm_page_track_mode mode);
>>   #endif
>> diff --git a/arch/x86/kvm/page_track.c b/arch/x86/kvm/page_track.c
>> index 0338d36..ad510db 100644
>> --- a/arch/x86/kvm/page_track.c
>> +++ b/arch/x86/kvm/page_track.c
>> @@ -56,3 +56,98 @@ void kvm_page_track_free_memslot(struct 
>> kvm_memory_slot *free,
>>       if (!dont || free->arch.gfn_track != dont->arch.gfn_track)
>>           page_track_slot_free(free);
>>   }
>> +
>> +static bool check_mode(enum kvm_page_track_mode mode)
>> +{
>> +    if (mode < 0 || mode >= KVM_PAGE_TRACK_MAX)
>> +        return false;
>> +
>> +    return true;
>> +}
>> +
>> +static void update_gfn_track(struct kvm_memory_slot *slot, gfn_t gfn,
>> +                 enum kvm_page_track_mode mode, int count)
>> +{
>> +    int index, val;
>> +
>> +    index = gfn_to_index(gfn, slot->base_gfn, PT_PAGE_TABLE_LEVEL);
>> +
>> +    slot->arch.gfn_track[mode][index] += count;
>> +    val = slot->arch.gfn_track[mode][index];
>> +    WARN_ON(val < 0);
>> +}
>> +
>> +/*
>> + * add guest page to the tracking pool so that corresponding access 
>> on that
>> + * page will be intercepted.
>> + *
>> + * It should be called under the protection of kvm->srcu or 
>> kvm->slots_lock
>> + *
>> + * @kvm: the guest instance we are interested in.
>> + * @gfn: the guest page.
>> + * @mode: tracking mode, currently only write track is supported.
>> + */
>> +void kvm_page_track_add_page(struct kvm *kvm, gfn_t gfn,
>> +                 enum kvm_page_track_mode mode)
>> +{
>> +    struct kvm_memslots *slots;
>> +    struct kvm_memory_slot *slot;
>> +    int i;
>> +
>> +    WARN_ON(!check_mode(mode));
>> +
>> +    for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) {
>> +        slots = __kvm_memslots(kvm, i);
>> +        slot = __gfn_to_memslot(slots, gfn);
>> +
>> +        spin_lock(&kvm->mmu_lock);
>> +        update_gfn_track(slot, gfn, mode, 1);
>> +
>> +        /*
>> +         * new track stops large page mapping for the
>> +         * tracked page.
>> +         */
>> +        kvm_mmu_gfn_disallow_lpage(slot, gfn);
> Where is  kvm_mmu_gfn_disallow_lpage? Neither did I see it in your 
> patch nor in my own latest KVM repo without your patch :)
>
>> +
>> +        if (mode == KVM_PAGE_TRACK_WRITE)
>> +            if (kvm_mmu_slot_gfn_write_protect(kvm, slot, gfn))
>> +                kvm_flush_remote_tlbs(kvm);
> Neither can I find kvm_mmu_slot_gfn_write_protect. Did I miss something?
Forget this reply. Looks my thunderbird has something wrong and couldn't 
show your whole patch series, and I missed patch 1~3. Now I see them. Sorry.

Thanks,
-Kai
>
> Thanks,
> -Kai
>> + spin_unlock(&kvm->mmu_lock);
>> +    }
>> +}
>> +
>> +/*
>> + * remove the guest page from the tracking pool which stops the 
>> interception
>> + * of corresponding access on that page. It is the opposed operation of
>> + * kvm_page_track_add_page().
>> + *
>> + * It should be called under the protection of kvm->srcu or 
>> kvm->slots_lock
>> + *
>> + * @kvm: the guest instance we are interested in.
>> + * @gfn: the guest page.
>> + * @mode: tracking mode, currently only write track is supported.
>> + */
>> +void kvm_page_track_remove_page(struct kvm *kvm, gfn_t gfn,
>> +                enum kvm_page_track_mode mode)
>> +{
>> +    struct kvm_memslots *slots;
>> +    struct kvm_memory_slot *slot;
>> +    int i;
>> +
>> +    WARN_ON(!check_mode(mode));
>> +
>> +    for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) {
>> +        slots = __kvm_memslots(kvm, i);
>> +        slot = __gfn_to_memslot(slots, gfn);
>> +
>> +        spin_lock(&kvm->mmu_lock);
>> +        update_gfn_track(slot, gfn, mode, -1);
>> +
>> +        /*
>> +         * allow large page mapping for the tracked page
>> +         * after the tracker is gone.
>> +         */
>> +        kvm_mmu_gfn_allow_lpage(slot, gfn);
>> +        spin_unlock(&kvm->mmu_lock);
>> +    }
>> +}
>
> -- 
> To unsubscribe from this list: send the line "unsubscribe kvm" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>