Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7D6CFC4332F for ; Fri, 12 Nov 2021 05:51:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5A01360FE3 for ; Fri, 12 Nov 2021 05:51:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231350AbhKLFy2 (ORCPT ); Fri, 12 Nov 2021 00:54:28 -0500 Received: from mga14.intel.com ([192.55.52.115]:36075 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229910AbhKLFy0 (ORCPT ); Fri, 12 Nov 2021 00:54:26 -0500 X-IronPort-AV: E=McAfee;i="6200,9189,10165"; a="233325187" X-IronPort-AV: E=Sophos;i="5.87,228,1631602800"; d="scan'208";a="233325187" Received: from orsmga007.jf.intel.com ([10.7.209.58]) by fmsmga103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Nov 2021 21:51:36 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.87,228,1631602800"; d="scan'208";a="492855072" Received: from chaop.bj.intel.com (HELO localhost) ([10.240.192.101]) by orsmga007.jf.intel.com with ESMTP; 11 Nov 2021 21:51:27 -0800 Date: Fri, 12 Nov 2021 13:50:38 +0800 From: Chao Peng To: Mika =?iso-8859-1?Q?Penttil=E4?= Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, qemu-devel@nongnu.org, Wanpeng Li , luto@kernel.org, david@redhat.com, "J . Bruce Fields" , dave.hansen@intel.com, "H . Peter Anvin" , ak@linux.intel.com, Jonathan Corbet , Joerg Roedel , x86@kernel.org, Hugh Dickins , Ingo Molnar , Borislav Petkov , jun.nakajima@intel.com, Thomas Gleixner , Vitaly Kuznetsov , Jim Mattson , Sean Christopherson , susie.li@intel.com, Jeff Layton , john.ji@intel.com, Yu Zhang , Paolo Bonzini , Andrew Morton , "Kirill A . Shutemov" Subject: Re: [RFC PATCH 5/6] kvm: x86: add KVM_EXIT_MEMORY_ERROR exit Message-ID: <20211112055038.GB27969@chaop.bj.intel.com> Reply-To: Chao Peng References: <20211111141352.26311-1-chao.p.peng@linux.intel.com> <20211111141352.26311-6-chao.p.peng@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Nov 11, 2021 at 05:08:47PM +0200, Mika Penttil? wrote: > > > On 11.11.2021 16.13, Chao Peng wrote: > > Currently support to exit to userspace for private/shared memory > > conversion. > > > > Signed-off-by: Sean Christopherson > > Signed-off-by: Yu Zhang > > Signed-off-by: Chao Peng > > --- > > arch/x86/kvm/mmu/mmu.c | 20 ++++++++++++++++++++ > > include/uapi/linux/kvm.h | 15 +++++++++++++++ > > 2 files changed, 35 insertions(+) > > > > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c > > index af5ecf4ef62a..780868888aa8 100644 > > --- a/arch/x86/kvm/mmu/mmu.c > > +++ b/arch/x86/kvm/mmu/mmu.c > > @@ -3950,6 +3950,17 @@ static bool try_async_pf(struct kvm_vcpu *vcpu, bool prefault, gfn_t gfn, > > slot = __kvm_vcpu_gfn_to_memslot(vcpu, gfn, private); > > + /* > > + * Exit to userspace to map the requested private/shared memory region > > + * if there is no memslot and (a) the access is private or (b) there is > > + * an existing private memslot. Emulated MMIO must be accessed through > > + * shared GPAs, thus a memslot miss on a private GPA is always handled > > + * as an implicit conversion "request". > > + */ > > + if (!slot && > > + (private || __kvm_vcpu_gfn_to_memslot(vcpu, gfn, true))) > > + goto out_convert; > > + > > /* Don't expose aliases for no slot GFNs or private memslots */ > > if ((cr2_or_gpa & vcpu_gpa_stolen_mask(vcpu)) && > > !kvm_is_visible_memslot(slot)) { > > @@ -3994,6 +4005,15 @@ static bool try_async_pf(struct kvm_vcpu *vcpu, bool prefault, gfn_t gfn, > > *pfn = __gfn_to_pfn_memslot(slot, gfn, false, NULL, > > write, writable, hva); > > return false; > > + > > +out_convert: > > + vcpu->run->exit_reason = KVM_EXIT_MEMORY_ERROR; > > + vcpu->run->mem.type = private ? KVM_EXIT_MEM_MAP_PRIVATE > > + : KVM_EXIT_MEM_MAP_SHARE; > > + vcpu->run->mem.u.map.gpa = cr2_or_gpa; > > + vcpu->run->mem.u.map.size = PAGE_SIZE; > > + return true; > > + > I think this does just retry, no exit to user space? Good catch, thanks. Chao > > > > > > } > > static int direct_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code, > > diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h > > index 8d20caae9180..470c472a9451 100644 > > --- a/include/uapi/linux/kvm.h > > +++ b/include/uapi/linux/kvm.h > > @@ -233,6 +233,18 @@ struct kvm_xen_exit { > > } u; > > }; > > +struct kvm_memory_exit { > > +#define KVM_EXIT_MEM_MAP_SHARE 1 > > +#define KVM_EXIT_MEM_MAP_PRIVATE 2 > > + __u32 type; > > + union { > > + struct { > > + __u64 gpa; > > + __u64 size; > > + } map; > > + } u; > > +}; > > + > > #define KVM_S390_GET_SKEYS_NONE 1 > > #define KVM_S390_SKEYS_MAX 1048576 > > @@ -272,6 +284,7 @@ struct kvm_xen_exit { > > #define KVM_EXIT_X86_BUS_LOCK 33 > > #define KVM_EXIT_XEN 34 > > #define KVM_EXIT_TDVMCALL 35 > > +#define KVM_EXIT_MEMORY_ERROR 36 > > /* For KVM_EXIT_INTERNAL_ERROR */ > > /* Emulate instruction failed. */ > > @@ -455,6 +468,8 @@ struct kvm_run { > > __u64 subfunc; > > __u64 param[4]; > > } tdvmcall; > > + /* KVM_EXIT_MEMORY_ERROR */ > > + struct kvm_memory_exit mem; > > /* Fix the size of the union. */ > > char padding[256]; > > }; >