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[184.144.111.238]) by smtp.gmail.com with ESMTPSA id 67sm3126275iob.15.2021.06.25.08.34.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 25 Jun 2021 08:34:20 -0700 (PDT) From: Peter Xu To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: peterx@redhat.com, Maxim Levitsky , Vitaly Kuznetsov , Sean Christopherson , Paolo Bonzini Subject: [PATCH v2 9/9] KVM: X86: Optimize zapping rmap Date: Fri, 25 Jun 2021 11:34:19 -0400 Message-Id: <20210625153419.43671-1-peterx@redhat.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210625153214.43106-1-peterx@redhat.com> References: <20210625153214.43106-1-peterx@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Using rmap_get_first() and rmap_remove() for zapping a huge rmap list could be slow. The easy way is to travers the rmap list, collecting the a/d bits and free the slots along the way. Provide a pte_list_destroy() and do exactly that. Signed-off-by: Peter Xu --- arch/x86/kvm/mmu/mmu.c | 45 +++++++++++++++++++++++++++++++----------- 1 file changed, 33 insertions(+), 12 deletions(-) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index ba0258bdebc4..45aac78dcabc 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -1014,6 +1014,38 @@ unsigned int pte_list_count(struct kvm_rmap_head *rmap_head) return count; } +/* Return true if rmap existed and callback called, false otherwise */ +static bool pte_list_destroy(struct kvm_rmap_head *rmap_head, + int (*callback)(u64 *sptep)) +{ + struct pte_list_desc *desc, *next; + int i; + + if (!rmap_head->val) + return false; + + if (!(rmap_head->val & 1)) { + if (callback) + callback((u64 *)rmap_head->val); + goto out; + } + + desc = (struct pte_list_desc *)(rmap_head->val & ~1ul); + + while (desc) { + if (callback) + for (i = 0; i < desc->spte_count; i++) + callback(desc->sptes[i]); + next = desc->more; + mmu_free_pte_list_desc(desc); + desc = next; + } +out: + /* rmap_head is meaningless now, remember to reset it */ + rmap_head->val = 0; + return true; +} + static struct kvm_rmap_head *__gfn_to_rmap(gfn_t gfn, int level, struct kvm_memory_slot *slot) { @@ -1403,18 +1435,7 @@ static bool rmap_write_protect(struct kvm_vcpu *vcpu, u64 gfn) static bool kvm_zap_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head, struct kvm_memory_slot *slot) { - u64 *sptep; - struct rmap_iterator iter; - bool flush = false; - - while ((sptep = rmap_get_first(rmap_head, &iter))) { - rmap_printk("spte %p %llx.\n", sptep, *sptep); - - pte_list_remove(rmap_head, sptep); - flush = true; - } - - return flush; + return pte_list_destroy(rmap_head, mmu_spte_clear_track_bits); } static bool kvm_unmap_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head, -- 2.31.1