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(bras-base-toroon474qw-grc-65-184-144-111-238.dsl.bell.ca. [184.144.111.238]) by smtp.gmail.com with ESMTPSA id d16sm1154974qtj.69.2021.07.30.15.06.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 30 Jul 2021 15:06:06 -0700 (PDT) From: Peter Xu To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: Maxim Levitsky , Sean Christopherson , Vitaly Kuznetsov , peterx@redhat.com, Paolo Bonzini Subject: [PATCH v3 7/7] KVM: X86: Optimize zapping rmap Date: Fri, 30 Jul 2021 18:06:05 -0400 Message-Id: <20210730220605.26377-1-peterx@redhat.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210730220455.26054-1-peterx@redhat.com> References: <20210730220455.26054-1-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 | 41 +++++++++++++++++++++++++++++------------ 1 file changed, 29 insertions(+), 12 deletions(-) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 111c37141dbe..9b2616760e23 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -1027,6 +1027,34 @@ unsigned int pte_list_count(struct kvm_rmap_head *rmap_head) return count; } +/* Return true if rmap existed, false otherwise */ +static bool pte_list_destroy(struct kvm_rmap_head *rmap_head) +{ + struct pte_list_desc *desc, *next; + int i; + + if (!rmap_head->val) + return false; + + if (!(rmap_head->val & 1)) { + mmu_spte_clear_track_bits((u64 *)rmap_head->val); + goto out; + } + + desc = (struct pte_list_desc *)(rmap_head->val & ~1ul); + + for (; desc; desc = next) { + for (i = 0; i < desc->spte_count; i++) + mmu_spte_clear_track_bits(desc->sptes[i]); + next = desc->more; + mmu_free_pte_list_desc(desc); + } +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, const struct kvm_memory_slot *slot) { @@ -1418,18 +1446,7 @@ 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, const 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); } static bool kvm_unmap_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head, -- 2.31.1