From mboxrd@z Thu Jan 1 00:00:00 1970 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id EA951C63703 for ; Wed, 7 Dec 2022 15:16:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229870AbiLGPQm (ORCPT ); Wed, 7 Dec 2022 10:16:42 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58578 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229848AbiLGPQZ (ORCPT ); Wed, 7 Dec 2022 10:16:25 -0500 Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8B68E61BBC; Wed, 7 Dec 2022 07:16:24 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1670426184; x=1701962184; h=date:from:to:cc:subject:message-id:reply-to:references: mime-version:in-reply-to; bh=zcEUcKUODXd/C5+5w7MS4mpwFmKmZd9eZ5keOKWclik=; b=f+L3vRsi7SQwHdlJrFUFhHASaSEcraV7j3Hws2fjJLYwcXPqysRGlCTY b2VeXYpwcHt2EfQsB7ZgQorBuRHY0iFkaV7T0AIgnFDxRpZQXvJAUotzY u2s/FDSGmPIQXiyPpnIwyuRPYo/mVEkj1TXhMjv7pogiu10XTyuRyEL2A A5ZFSh/64A3ju6BkS7sjo8z7rRohafy5IMyyVXIAPmIFFg9DjAh4mSYIb 1WRyennJE3QQHSUKbDVLe9l680R22EKzc9kwxkETZBshYYbQcw3oAesCK F374a11t2rNyVfOnXXTRCIoVgRhBxpb21Pa6nEtjiJCq2dstCvBI1wnqa A==; X-IronPort-AV: E=McAfee;i="6500,9779,10553"; a="343947700" X-IronPort-AV: E=Sophos;i="5.96,225,1665471600"; d="scan'208";a="343947700" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Dec 2022 07:16:23 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6500,9779,10553"; a="710095974" X-IronPort-AV: E=Sophos;i="5.96,225,1665471600"; d="scan'208";a="710095974" Received: from chaop.bj.intel.com (HELO localhost) ([10.240.193.75]) by fmsmga008.fm.intel.com with ESMTP; 07 Dec 2022 07:16:13 -0800 Date: Wed, 7 Dec 2022 23:11:53 +0800 From: Chao Peng To: Fuad Tabba Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, linux-doc@vger.kernel.org, qemu-devel@nongnu.org, Paolo Bonzini , Jonathan Corbet , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Arnd Bergmann , Naoya Horiguchi , Miaohe Lin , x86@kernel.org, "H . Peter Anvin" , Hugh Dickins , Jeff Layton , "J . Bruce Fields" , Andrew Morton , Shuah Khan , Mike Rapoport , Steven Price , "Maciej S . Szmigiero" , Vlastimil Babka , Vishal Annapurve , Yu Zhang , "Kirill A . Shutemov" , luto@kernel.org, jun.nakajima@intel.com, dave.hansen@intel.com, ak@linux.intel.com, david@redhat.com, aarcange@redhat.com, ddutile@redhat.com, dhildenb@redhat.com, Quentin Perret , Michael Roth , mhocko@suse.com, wei.w.wang@intel.com Subject: Re: [PATCH v10 4/9] KVM: Add KVM_EXIT_MEMORY_FAULT exit Message-ID: <20221207151153.GE1275553@chaop.bj.intel.com> Reply-To: Chao Peng References: <20221202061347.1070246-1-chao.p.peng@linux.intel.com> <20221202061347.1070246-5-chao.p.peng@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Dec 06, 2022 at 03:47:20PM +0000, Fuad Tabba wrote: > Hi, > > On Fri, Dec 2, 2022 at 6:19 AM Chao Peng wrote: > > > > This new KVM exit allows userspace to handle memory-related errors. It > > indicates an error happens in KVM at guest memory range [gpa, gpa+size). > > The flags includes additional information for userspace to handle the > > error. Currently bit 0 is defined as 'private memory' where '1' > > indicates error happens due to private memory access and '0' indicates > > error happens due to shared memory access. > > > > When private memory is enabled, this new exit will be used for KVM to > > exit to userspace for shared <-> private memory conversion in memory > > encryption usage. In such usage, typically there are two kind of memory > > conversions: > > - explicit conversion: happens when guest explicitly calls into KVM > > to map a range (as private or shared), KVM then exits to userspace > > to perform the map/unmap operations. > > - implicit conversion: happens in KVM page fault handler where KVM > > exits to userspace for an implicit conversion when the page is in a > > different state than requested (private or shared). > > > > Suggested-by: Sean Christopherson > > Co-developed-by: Yu Zhang > > Signed-off-by: Yu Zhang > > Signed-off-by: Chao Peng > > Reviewed-by: Fuad Tabba > > --- > > Documentation/virt/kvm/api.rst | 22 ++++++++++++++++++++++ > > include/uapi/linux/kvm.h | 8 ++++++++ > > 2 files changed, 30 insertions(+) > > > > diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst > > index 99352170c130..d9edb14ce30b 100644 > > --- a/Documentation/virt/kvm/api.rst > > +++ b/Documentation/virt/kvm/api.rst > > @@ -6634,6 +6634,28 @@ array field represents return values. The userspace should update the return > > values of SBI call before resuming the VCPU. For more details on RISC-V SBI > > spec refer, https://github.com/riscv/riscv-sbi-doc. > > > > +:: > > + > > + /* KVM_EXIT_MEMORY_FAULT */ > > + struct { > > + #define KVM_MEMORY_EXIT_FLAG_PRIVATE (1ULL << 0) > > + __u64 flags; > > I see you've removed the padding and increased the flag size. Yes Sean suggested this and also looks good to me. Chao > > Reviewed-by: Fuad Tabba > Tested-by: Fuad Tabba > > Cheers, > /fuad > > > > > > + __u64 gpa; > > + __u64 size; > > + } memory; > > + > > +If exit reason is KVM_EXIT_MEMORY_FAULT then it indicates that the VCPU has > > +encountered a memory error which is not handled by KVM kernel module and > > +userspace may choose to handle it. The 'flags' field indicates the memory > > +properties of the exit. > > + > > + - KVM_MEMORY_EXIT_FLAG_PRIVATE - indicates the memory error is caused by > > + private memory access when the bit is set. Otherwise the memory error is > > + caused by shared memory access when the bit is clear. > > + > > +'gpa' and 'size' indicate the memory range the error occurs at. The userspace > > +may handle the error and return to KVM to retry the previous memory access. > > + > > :: > > > > /* KVM_EXIT_NOTIFY */ > > diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h > > index 13bff963b8b0..c7e9d375a902 100644 > > --- a/include/uapi/linux/kvm.h > > +++ b/include/uapi/linux/kvm.h > > @@ -300,6 +300,7 @@ struct kvm_xen_exit { > > #define KVM_EXIT_RISCV_SBI 35 > > #define KVM_EXIT_RISCV_CSR 36 > > #define KVM_EXIT_NOTIFY 37 > > +#define KVM_EXIT_MEMORY_FAULT 38 > > > > /* For KVM_EXIT_INTERNAL_ERROR */ > > /* Emulate instruction failed. */ > > @@ -541,6 +542,13 @@ struct kvm_run { > > #define KVM_NOTIFY_CONTEXT_INVALID (1 << 0) > > __u32 flags; > > } notify; > > + /* KVM_EXIT_MEMORY_FAULT */ > > + struct { > > +#define KVM_MEMORY_EXIT_FLAG_PRIVATE (1ULL << 0) > > + __u64 flags; > > + __u64 gpa; > > + __u64 size; > > + } memory; > > /* Fix the size of the union. */ > > char padding[256]; > > }; > > -- > > 2.25.1 > >