Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755217Ab3DXM73 (ORCPT ); Wed, 24 Apr 2013 08:59:29 -0400 Received: from mx1.redhat.com ([209.132.183.28]:29258 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753254Ab3DXM72 (ORCPT ); Wed, 24 Apr 2013 08:59:28 -0400 Date: Wed, 24 Apr 2013 15:59:12 +0300 From: Gleb Natapov To: Xiao Guangrong Cc: mtosatti@redhat.com, linux-kernel@vger.kernel.org, kvm@vger.kernel.org Subject: Re: [PATCH v2 6/6] KVM: MMU: init kvm generation close to mmio wrap-around value Message-ID: <20130424125911.GQ12401@redhat.com> References: <1364810209-25954-1-git-send-email-xiaoguangrong@linux.vnet.ibm.com> <1364810209-25954-7-git-send-email-xiaoguangrong@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1364810209-25954-7-git-send-email-xiaoguangrong@linux.vnet.ibm.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2133 Lines: 53 On Mon, Apr 01, 2013 at 05:56:49PM +0800, Xiao Guangrong wrote: > Then it has chance to trigger mmio generation number wrap-around > > Signed-off-by: Xiao Guangrong > --- > arch/x86/include/asm/kvm_host.h | 1 + > arch/x86/kvm/mmu.c | 8 ++++++++ > virt/kvm/kvm_main.c | 6 ++++++ > 3 files changed, 15 insertions(+), 0 deletions(-) > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > index 6c1e642..4e1f7cb 100644 > --- a/arch/x86/include/asm/kvm_host.h > +++ b/arch/x86/include/asm/kvm_host.h > @@ -767,6 +767,7 @@ void kvm_mmu_write_protect_pt_masked(struct kvm *kvm, > struct kvm_memory_slot *slot, > gfn_t gfn_offset, unsigned long mask); > void kvm_mmu_zap_all(struct kvm *kvm); > +void kvm_arch_init_generation(struct kvm *kvm); > void kvm_mmu_invalid_mmio_sptes(struct kvm *kvm); > unsigned int kvm_mmu_calculate_mmu_pages(struct kvm *kvm); > void kvm_mmu_change_mmu_pages(struct kvm *kvm, unsigned int kvm_nr_mmu_pages); > diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c > index d314e21..dcc059c 100644 > --- a/arch/x86/kvm/mmu.c > +++ b/arch/x86/kvm/mmu.c > @@ -4279,6 +4279,14 @@ restart: > spin_unlock(&kvm->mmu_lock); > } > > +void kvm_arch_init_generation(struct kvm *kvm) > +{ > + mutex_lock(&kvm->slots_lock); > + /* It is easier to trigger mmio generation-number wrap-around. */ > + kvm_memslots(kvm)->generation = MMIO_MAX_GEN - 13; kvm_memslots(kvm)->generation should never overflow since (read|write)_cached mechanism does not handle it. Initialising it to anything but 0 makes overflow more likely. You can hide mmio overflow trick in kvm_current_mmio_generation(): static unsigned int kvm_current_mmio_generation(struct kvm *kvm) { return (kvm_memslots(kvm)->generation + MMIO_MAX_GEN - 13) & MMIO_GEN_MASK; } -- Gleb. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/