Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755744Ab3CSDPx (ORCPT ); Mon, 18 Mar 2013 23:15:53 -0400 Received: from e23smtp01.au.ibm.com ([202.81.31.143]:45630 "EHLO e23smtp01.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753970Ab3CSDPv (ORCPT ); Mon, 18 Mar 2013 23:15:51 -0400 Message-ID: <5147D858.4010805@linux.vnet.ibm.com> Date: Tue, 19 Mar 2013 11:15:36 +0800 From: Xiao Guangrong User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130110 Thunderbird/17.0.2 MIME-Version: 1.0 To: Eric Northup CC: Marcelo Tosatti , Gleb Natapov , LKML , KVM Subject: Re: [PATCH 5/5] KVM: MMU: fast invalid all mmio sptes References: <51433D98.4050605@linux.vnet.ibm.com> <51433E71.2070107@linux.vnet.ibm.com> In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13031903-1618-0000-0000-000003878601 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2575 Lines: 56 On 03/19/2013 06:16 AM, Eric Northup wrote: > On Fri, Mar 15, 2013 at 8:29 AM, Xiao Guangrong > wrote: >> This patch tries to introduce a very simple and scale way to invalid all >> mmio sptes - it need not walk any shadow pages and hold mmu-lock >> >> KVM maintains a global mmio invalid generation-number which is stored in >> kvm->arch.mmio_invalid_gen and every mmio spte stores the current global >> generation-number into his available bits when it is created >> >> When KVM need zap all mmio sptes, it just simply increase the global >> generation-number. When guests do mmio access, KVM intercepts a MMIO #PF >> then it walks the shadow page table and get the mmio spte. If the >> generation-number on the spte does not equal the global generation-number, >> it will go to the normal #PF handler to update the mmio spte >> >> Since 19 bits are used to store generation-number on mmio spte, the >> generation-number can be round after 33554432 times. It is large enough >> for nearly all most cases, but making the code be more strong, we zap all >> shadow pages when the number is round >> >> Signed-off-by: Xiao Guangrong >> --- >> arch/x86/include/asm/kvm_host.h | 2 + >> arch/x86/kvm/mmu.c | 61 +++++++++++++++++++++++++++++++++------ >> arch/x86/kvm/mmutrace.h | 17 +++++++++++ >> arch/x86/kvm/paging_tmpl.h | 7 +++- >> arch/x86/kvm/vmx.c | 4 ++ >> arch/x86/kvm/x86.c | 6 +-- >> 6 files changed, 82 insertions(+), 15 deletions(-) >> >> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h >> index ef7f4a5..572398e 100644 >> --- a/arch/x86/include/asm/kvm_host.h >> +++ b/arch/x86/include/asm/kvm_host.h >> @@ -529,6 +529,7 @@ struct kvm_arch { >> unsigned int n_requested_mmu_pages; >> unsigned int n_max_mmu_pages; >> unsigned int indirect_shadow_pages; >> + unsigned int mmio_invalid_gen; > > Could this get initialized to something close to the wrap-around > value, so that the wrap-around case gets more real-world coverage? I am afraid we can not. We cache the current mmio_invalid_gen into mmio spte when it is created no matter what the initiation value is. If you have a better way, please show me. ;) -- 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/