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 9C39DC67871 for ; Thu, 27 Oct 2022 10:27:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235140AbiJ0K1u (ORCPT ); Thu, 27 Oct 2022 06:27:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56974 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234897AbiJ0K1q (ORCPT ); Thu, 27 Oct 2022 06:27:46 -0400 Received: from mail-lf1-x136.google.com (mail-lf1-x136.google.com [IPv6:2a00:1450:4864:20::136]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 59C1161D5E for ; Thu, 27 Oct 2022 03:27:44 -0700 (PDT) Received: by mail-lf1-x136.google.com with SMTP id r12so1868419lfp.1 for ; Thu, 27 Oct 2022 03:27:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=ht1qDbWjn1s/Tw8Yqm0aVlTSVNxYRnuUWU/s2QqT7o4=; b=i9fpSLzo5jMs1+PlsjmjCMb+bkUFi0v3Bacdvscp0fuYHO+3FGaxuBdH9ct3K7RBFW GOHO2JyUIW1XW5jN40lUo04IVtr6sii/DKrSh0WfspjvZb3qBHVd8hHkcE/+pQE5KgUT S2C3X4NjLiLtUUo2sU1/2YrB8+0hbHtyswI86zJlvJsldbkJ1TcRW77xj3Ekpg2FTn5F yLbrMrtYI7k8BF9mLNKwdIJf3ttus48z491adWnKD4QvBxh4IYkD7eHihmuxCq7D5Fig oDQgpPvQAoHoFBnco6A5aUUG8BlMm3axdurIL1eFAQNWMO59iSALUb8xpG0lZ7hWTkgh HBow== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=ht1qDbWjn1s/Tw8Yqm0aVlTSVNxYRnuUWU/s2QqT7o4=; b=7meUSeB8rwr+afAT5Nlh27pNTzvNN5IFHZIkZhY2nic6t8Q0qfjHJQ+QyAGcevPh9g CVcfIxIlANWb/gRBc4sVJiTYg/e/8Ub/Wv06ZIO8LvEiDpHcICEw7wYwCEfIc9V02WT+ iMLISTgXDtqpiqK5Cvp2a5+42sfvT9QF6J5qTyvdnS03HGMgX0+k5sfzrOxpMo5Wp8tk HHpU99wPcQ5iBkmdKbNT1coFpH/9nf8VxxDTb6qkn376lT+Xao7xJrVccgDbuGy/IrQw G7lI4xuPzamp1o6cJyX08Hl1StPOvNeY9toZqZusYxaQX8IqdBXs9i0PEvprfyT0q3F+ ngfg== X-Gm-Message-State: ACrzQf0sW0PKOPfWjBewUu1/wCe8JJg2AL2EKDvxOFfzx3i55beoJHL4 CqPqWJ98M9Gp8WQ+L4o0PIJas/S+fFn1QB/hfEVj3lw/1GUJgn24 X-Google-Smtp-Source: AMsMyM7ZrmnFdb+RDiq0D6Ba0YwSUUNSHZjttBJh/zpOd85NYIAHkkRHyIoh13rneHkuGCKm3HEm2TuLmTrwb52teuM= X-Received: by 2002:a05:6512:3f8b:b0:492:d1ed:5587 with SMTP id x11-20020a0565123f8b00b00492d1ed5587mr19119426lfa.355.1666866462514; Thu, 27 Oct 2022 03:27:42 -0700 (PDT) MIME-Version: 1.0 References: <20221025151344.3784230-1-chao.p.peng@linux.intel.com> <20221025151344.3784230-4-chao.p.peng@linux.intel.com> In-Reply-To: <20221025151344.3784230-4-chao.p.peng@linux.intel.com> From: Fuad Tabba Date: Thu, 27 Oct 2022 11:27:05 +0100 Message-ID: Subject: Re: [PATCH v9 3/8] KVM: Add KVM_EXIT_MEMORY_FAULT exit To: Chao Peng 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 , 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, Muchun Song , wei.w.wang@intel.com Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-api@vger.kernel.org Hi, On Tue, Oct 25, 2022 at 4:19 PM 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 I have tested the V8 version of this patch on arm64/qemu, and considering this hasn't changed: Tested-by: Fuad Tabba Cheers, /fuad > Documentation/virt/kvm/api.rst | 23 +++++++++++++++++++++++ > include/uapi/linux/kvm.h | 9 +++++++++ > 2 files changed, 32 insertions(+) > > diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst > index f3fa75649a78..975688912b8c 100644 > --- a/Documentation/virt/kvm/api.rst > +++ b/Documentation/virt/kvm/api.rst > @@ -6537,6 +6537,29 @@ 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 (1 << 0) > + __u32 flags; > + __u32 padding; > + __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 f1ae45c10c94..fa60b032a405 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. */ > @@ -538,6 +539,14 @@ struct kvm_run { > #define KVM_NOTIFY_CONTEXT_INVALID (1 << 0) > __u32 flags; > } notify; > + /* KVM_EXIT_MEMORY_FAULT */ > + struct { > +#define KVM_MEMORY_EXIT_FLAG_PRIVATE (1 << 0) > + __u32 flags; > + __u32 padding; > + __u64 gpa; > + __u64 size; > + } memory; > /* Fix the size of the union. */ > char padding[256]; > }; > -- > 2.25.1 >