From patchwork Thu Dec 6 00:40:57 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Graf X-Patchwork-Id: 204066 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id E0D332C018B for ; Thu, 6 Dec 2012 11:42:40 +1100 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753867Ab2LFAmf (ORCPT ); Wed, 5 Dec 2012 19:42:35 -0500 Received: from cantor2.suse.de ([195.135.220.15]:35641 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753838Ab2LFAl1 (ORCPT ); Wed, 5 Dec 2012 19:41:27 -0500 Received: from relay1.suse.de (unknown [195.135.220.254]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mx2.suse.de (Postfix) with ESMTP id 5C0F5A3B99; Thu, 6 Dec 2012 01:41:26 +0100 (CET) From: Alexander Graf To: Marcelo Tosatti Cc: Gleb Natapov , kvm-ppc , KVM list , Paul Mackerras Subject: [PATCH 08/28] KVM: PPC: Book3S HV: Reset reverse-map chains when resetting the HPT Date: Thu, 6 Dec 2012 01:40:57 +0100 Message-Id: <1354754477-15472-9-git-send-email-agraf@suse.de> X-Mailer: git-send-email 1.6.0.2 In-Reply-To: <1354754477-15472-1-git-send-email-agraf@suse.de> References: <1354754477-15472-1-git-send-email-agraf@suse.de> Sender: kvm-ppc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm-ppc@vger.kernel.org From: Paul Mackerras With HV-style KVM, we maintain reverse-mapping lists that enable us to find all the HPT (hashed page table) entries that reference each guest physical page, with the heads of the lists in the memslot->arch.rmap arrays. When we reset the HPT (i.e. when we reboot the VM), we clear out all the HPT entries but we were not clearing out the reverse mapping lists. The result is that as we create new HPT entries, the lists get corrupted, which can easily lead to loops, resulting in the host kernel hanging when it tries to traverse those lists. This fixes the problem by zeroing out all the reverse mapping lists when we zero out the HPT. This incidentally means that we are also zeroing our record of the referenced and changed bits (not the bits in the Linux PTEs, used by the Linux MM subsystem, but the bits used by the KVM_GET_DIRTY_LOG ioctl, and those used by kvm_age_hva() and kvm_test_age_hva()). Signed-off-by: Paul Mackerras Signed-off-by: Alexander Graf --- arch/powerpc/kvm/book3s_64_mmu_hv.c | 24 ++++++++++++++++++++++++ 1 files changed, 24 insertions(+), 0 deletions(-) diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c index 0aa4073..1029e22 100644 --- a/arch/powerpc/kvm/book3s_64_mmu_hv.c +++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c @@ -46,6 +46,7 @@ static long kvmppc_virtmode_do_h_enter(struct kvm *kvm, unsigned long flags, long pte_index, unsigned long pteh, unsigned long ptel, unsigned long *pte_idx_ret); +static void kvmppc_rmap_reset(struct kvm *kvm); long kvmppc_alloc_hpt(struct kvm *kvm, u32 *htab_orderp) { @@ -144,6 +145,10 @@ long kvmppc_alloc_reset_hpt(struct kvm *kvm, u32 *htab_orderp) /* Set the entire HPT to 0, i.e. invalid HPTEs */ memset((void *)kvm->arch.hpt_virt, 0, 1ul << order); /* + * Reset all the reverse-mapping chains for all memslots + */ + kvmppc_rmap_reset(kvm); + /* * Set the whole last_vcpu array to an invalid vcpu number. * This ensures that each vcpu will flush its TLB on next entry. */ @@ -772,6 +777,25 @@ int kvmppc_book3s_hv_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu, goto out_put; } +static void kvmppc_rmap_reset(struct kvm *kvm) +{ + struct kvm_memslots *slots; + struct kvm_memory_slot *memslot; + int srcu_idx; + + srcu_idx = srcu_read_lock(&kvm->srcu); + slots = kvm->memslots; + kvm_for_each_memslot(memslot, slots) { + /* + * This assumes it is acceptable to lose reference and + * change bits across a reset. + */ + memset(memslot->arch.rmap, 0, + memslot->npages * sizeof(*memslot->arch.rmap)); + } + srcu_read_unlock(&kvm->srcu, srcu_idx); +} + static int kvm_handle_hva_range(struct kvm *kvm, unsigned long start, unsigned long end,