From: "Maciej S. Szmigiero" <mail@maciej.szmigiero.name>
To: Sean Christopherson <seanjc@google.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>,
Igor Mammedov <imammedo@redhat.com>,
Marc Zyngier <maz@kernel.org>, James Morse <james.morse@arm.com>,
Julien Thierry <julien.thierry.kdev@gmail.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Huacai Chen <chenhuacai@kernel.org>,
Aleksandar Markovic <aleksandar.qemu.devel@gmail.com>,
Paul Mackerras <paulus@ozlabs.org>,
Christian Borntraeger <borntraeger@de.ibm.com>,
Janosch Frank <frankja@linux.ibm.com>,
David Hildenbrand <david@redhat.com>,
Cornelia Huck <cohuck@redhat.com>,
Claudio Imbrenda <imbrenda@linux.ibm.com>,
Joerg Roedel <joro@8bytes.org>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5 05/13] KVM: Integrate gfn_to_memslot_approx() into search_memslots()
Date: Wed, 20 Oct 2021 20:41:26 +0200 [thread overview]
Message-ID: <fcb2a5ce-852a-d3c1-3900-e43be1a9cf00@maciej.szmigiero.name> (raw)
In-Reply-To: <YW9XCp3B+ogPIl7i@google.com>
On 20.10.2021 01:38, Sean Christopherson wrote:
> On Mon, Sep 20, 2021, Maciej S. Szmigiero wrote:
>> @@ -1267,7 +1280,7 @@ search_memslots(struct kvm_memslots *slots, gfn_t gfn, int *index)
>> * itself isn't here as an inline because that would bloat other code too much.
>> */
>> static inline struct kvm_memory_slot *
>> -__gfn_to_memslot(struct kvm_memslots *slots, gfn_t gfn)
>> +__gfn_to_memslot_approx(struct kvm_memslots *slots, gfn_t gfn, bool approx)
>
> This function name is a misnomer. The helper is not an "approx" version, it's an
> inner helper that takes an @approx param. Unless someone has a more clever name,
> the dreaded four underscores seems like the way to go. Warning away users is a
> good thing in this case...
>
>> {
>> struct kvm_memory_slot *slot;
>> int slot_index = atomic_read(&slots->last_used_slot);
>> @@ -1276,7 +1289,7 @@ __gfn_to_memslot(struct kvm_memslots *slots, gfn_t gfn)
>> if (slot)
>> return slot;
>>
>> - slot = search_memslots(slots, gfn, &slot_index);
>> + slot = search_memslots(slots, gfn, &slot_index, approx);
>> if (slot) {
>> atomic_set(&slots->last_used_slot, slot_index);
>> return slot;
>> @@ -1285,6 +1298,12 @@ __gfn_to_memslot(struct kvm_memslots *slots, gfn_t gfn)
>> return NULL;
>> }
>>
>
> There's a comment that doesn't show up in this diff that should also be moved,
> and opportunistically updated.
>
>> +static inline struct kvm_memory_slot *
>> +__gfn_to_memslot(struct kvm_memslots *slots, gfn_t gfn)
>> +{
>> + return __gfn_to_memslot_approx(slots, gfn, false);
>> +}
>> +
>> static inline unsigned long
>> __gfn_to_hva_memslot(const struct kvm_memory_slot *slot, gfn_t gfn)
>> {
>
> E.g. this as fixup?
>
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index 540fa948baa5..2964c773b36c 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -1964,10 +1964,15 @@ static int kvm_s390_peek_cmma(struct kvm *kvm, struct kvm_s390_cmma_log *args,
> return 0;
> }
>
> +static int gfn_to_memslot_approx(struct kvm_memslots *slots, gfn_t gfn)
> +{
> + return ____gfn_to_memslot(slots, cur_gfn, true);
> +}
> +
> static unsigned long kvm_s390_next_dirty_cmma(struct kvm_memslots *slots,
> unsigned long cur_gfn)
> {
> - struct kvm_memory_slot *ms = __gfn_to_memslot_approx(slots, cur_gfn, true);
> + struct kvm_memory_slot *ms = gfn_to_memslot_approx(slots, cur_gfn);
> int slotidx = ms - slots->memslots;
> unsigned long ofs = cur_gfn - ms->base_gfn;
>
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index 8fd9644f40b2..ec1a074c2f6e 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -1274,13 +1274,8 @@ search_memslots(struct kvm_memslots *slots, gfn_t gfn, int *index, bool approx)
> return NULL;
> }
>
> -/*
> - * __gfn_to_memslot() and its descendants are here because it is called from
> - * non-modular code in arch/powerpc/kvm/book3s_64_vio{,_hv}.c. gfn_to_memslot()
> - * itself isn't here as an inline because that would bloat other code too much.
> - */
> static inline struct kvm_memory_slot *
> -__gfn_to_memslot_approx(struct kvm_memslots *slots, gfn_t gfn, bool approx)
> +____gfn_to_memslot(struct kvm_memslots *slots, gfn_t gfn, bool approx)
> {
> struct kvm_memory_slot *slot;
> int slot_index = atomic_read(&slots->last_used_slot);
> @@ -1298,10 +1293,15 @@ __gfn_to_memslot_approx(struct kvm_memslots *slots, gfn_t gfn, bool approx)
> return NULL;
> }
>
> +/*
> + * __gfn_to_memslot() and its descendants are here to allow arch code to inline
> + * the lookups in hot paths. gfn_to_memslot() itself isn't here as an inline
> + * because that would bloat other code too much.
> + */
> static inline struct kvm_memory_slot *
> __gfn_to_memslot(struct kvm_memslots *slots, gfn_t gfn)
> {
> - return __gfn_to_memslot_approx(slots, gfn, false);
> + return ____gfn_to_memslot(slots, gfn, false);
> }
>
> static inline unsigned long
>
Looks sensible, will apply your proposed changes.
Thanks,
Maciej
next prev parent reply other threads:[~2021-10-20 18:41 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-20 21:38 [PATCH v5 00/13] KVM: Scalable memslots implementation Maciej S. Szmigiero
2021-09-20 21:38 ` [PATCH v5 01/13] KVM: x86: Cache total page count to avoid traversing the memslot array Maciej S. Szmigiero
2021-10-19 22:24 ` Sean Christopherson
2021-10-19 22:31 ` Sean Christopherson
2021-10-20 18:40 ` Maciej S. Szmigiero
2021-10-20 18:41 ` Maciej S. Szmigiero
2021-10-20 19:01 ` Sean Christopherson
2021-11-01 22:29 ` Sean Christopherson
2021-11-03 11:59 ` Maciej S. Szmigiero
2021-11-03 14:47 ` Sean Christopherson
2021-11-03 15:38 ` Maciej S. Szmigiero
2021-09-20 21:38 ` [PATCH v5 02/13] KVM: x86: Don't call kvm_mmu_change_mmu_pages() if the count hasn't changed Maciej S. Szmigiero
2021-09-20 21:38 ` [PATCH v5 03/13] KVM: Add "old" memslot parameter to kvm_arch_prepare_memory_region() Maciej S. Szmigiero
2021-09-20 21:38 ` [PATCH v5 04/13] KVM: x86: Move n_memslots_pages recalc " Maciej S. Szmigiero
2021-10-19 22:38 ` Sean Christopherson
2021-10-20 18:41 ` Maciej S. Szmigiero
2021-09-20 21:38 ` [PATCH v5 05/13] KVM: Integrate gfn_to_memslot_approx() into search_memslots() Maciej S. Szmigiero
2021-10-19 23:38 ` Sean Christopherson
2021-10-20 18:41 ` Maciej S. Szmigiero [this message]
2021-09-20 21:38 ` [PATCH v5 06/13] KVM: Move WARN on invalid memslot index to update_memslots() Maciej S. Szmigiero
2021-10-19 23:42 ` Sean Christopherson
2021-09-20 21:38 ` [PATCH v5 07/13] KVM: Just resync arch fields when slots_arch_lock gets reacquired Maciej S. Szmigiero
2021-10-19 23:55 ` Sean Christopherson
2021-10-20 18:41 ` Maciej S. Szmigiero
2021-10-20 18:57 ` Sean Christopherson
2021-10-20 18:58 ` Maciej S. Szmigiero
2021-09-20 21:38 ` [PATCH v5 08/13] KVM: Resolve memslot ID via a hash table instead of via a static array Maciej S. Szmigiero
2021-10-20 0:43 ` Sean Christopherson
2021-10-20 18:42 ` Maciej S. Szmigiero
2021-10-20 22:39 ` Sean Christopherson
2021-10-21 14:15 ` Maciej S. Szmigiero
2021-09-20 21:38 ` [PATCH v5 09/13] KVM: Use interval tree to do fast hva lookup in memslots Maciej S. Szmigiero
2021-10-26 18:19 ` Sean Christopherson
2021-10-26 18:46 ` Maciej S. Szmigiero
2021-09-20 21:38 ` [PATCH v5 10/13] KVM: s390: Introduce kvm_s390_get_gfn_end() Maciej S. Szmigiero
2021-09-20 21:38 ` [PATCH v5 11/13] KVM: Keep memslots in tree-based structures instead of array-based ones Maciej S. Szmigiero
2021-10-27 0:36 ` Sean Christopherson
2021-10-27 23:54 ` Sean Christopherson
2021-10-28 22:22 ` Sean Christopherson
2021-09-20 21:39 ` [PATCH v5 12/13] KVM: Optimize gfn lookup in kvm_zap_gfn_range() Maciej S. Szmigiero
2021-10-20 23:47 ` Sean Christopherson
2021-10-21 14:16 ` Maciej S. Szmigiero
2021-10-21 16:30 ` Sean Christopherson
2021-10-21 21:44 ` Maciej S. Szmigiero
2021-09-20 21:39 ` [PATCH v5 13/13] KVM: Optimize overlapping memslots check Maciej S. Szmigiero
2021-10-26 18:59 ` Sean Christopherson
2021-10-27 13:48 ` Maciej S. Szmigiero
2021-10-28 17:53 ` Sean Christopherson
2021-10-29 16:23 ` Maciej S. Szmigiero
2021-10-30 0:32 ` Sean Christopherson
2021-10-19 22:07 ` [PATCH v5 00/13] KVM: Scalable memslots implementation Sean Christopherson
2021-10-20 18:40 ` Maciej S. Szmigiero
2021-10-20 19:58 ` Sean Christopherson
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