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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id BDBF0C67871 for ; Thu, 27 Oct 2022 10:27:45 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 358BB8E0002; Thu, 27 Oct 2022 06:27:45 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 2E1848E0001; Thu, 27 Oct 2022 06:27:45 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 15BEE8E0002; Thu, 27 Oct 2022 06:27:45 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id F3F568E0001 for ; Thu, 27 Oct 2022 06:27:44 -0400 (EDT) Received: from smtpin18.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id BD08A81069 for ; Thu, 27 Oct 2022 10:27:44 +0000 (UTC) X-FDA: 80066353248.18.803E9FF Received: from mail-lf1-f52.google.com (mail-lf1-f52.google.com [209.85.167.52]) by imf13.hostedemail.com (Postfix) with ESMTP id 223172000E for ; Thu, 27 Oct 2022 10:27:43 +0000 (UTC) Received: by mail-lf1-f52.google.com with SMTP id b2so1835563lfp.6 for ; Thu, 27 Oct 2022 03:27:43 -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=CZw8TmvzMZ1bZ/B85BNjtQAbElqWiRxDl1rLP37ufjnoe1oyiK1jOamDU69iGHnGwp c6/LhwucKffJlCjM3v2EPqSfaHiFkYXdzZenRmJ/9lpq0q10LsjvtfADdz69nFp4lKvj CBSEGzeoxZBANFjqxNdalqMRzPrY7IZzO62X7hdk6jBA3Q6DVP99AlGYNOdU0SLtfrNX /4AoRuLw6ajCl1jaYvdW7OsGPyab7y02iIbZWO7JJVbTNHomA3xmtCpezpi0Fhu1OJ6S x5b90UtowJJ+vVARVz0zlFSPjdRhxpufnKooviRZ5IIeIiNCjLy0oSWGNwaXwc4aTzCV 07Ug== X-Gm-Message-State: ACrzQf0FfGSRxmJanX8Ppe+yJkImrJUs80madHIwrshuRMoUuGgSPJYf BD5XZSh6Mik8ZO2px1C88i0hMhaWUmj1TCi+1WCmtQ== 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" ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1666866464; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=ht1qDbWjn1s/Tw8Yqm0aVlTSVNxYRnuUWU/s2QqT7o4=; b=Q3sG5g8F3gE1Jxnc8fELlHuI6HQLMgfuu+u3A+FzxlV33yjDXUbLWV9pZMtUL6I625z1/y fsk6If96ktr+GD2/33Gn9sxo6qWow3Y6p3JVoG/FFNWR9fO5DyQ4UnkyolIev16XtRHD5p Aa/aGIw6ruNeETs3WrLWppx4obzYqSc= ARC-Authentication-Results: i=1; imf13.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=i9fpSLzo; spf=pass (imf13.hostedemail.com: domain of tabba@google.com designates 209.85.167.52 as permitted sender) smtp.mailfrom=tabba@google.com; dmarc=pass (policy=reject) header.from=google.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1666866464; a=rsa-sha256; cv=none; b=W0Xmeqww6AjBXdc2/5kOSMZQ8UAosKbETFu0D3VNA4ufNQ2YSMMLh49E1N1Ke+JN7ogPpz vtLG9QYydm4iqrRl3MzlwlUtAWEfU/avSjg5cFYzxA8srQTF4fjuksBfApX9eOMCbv6QPk SktIfDxPbgS33ASbd169B4/diRzO1Fc= Authentication-Results: imf13.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=i9fpSLzo; spf=pass (imf13.hostedemail.com: domain of tabba@google.com designates 209.85.167.52 as permitted sender) smtp.mailfrom=tabba@google.com; dmarc=pass (policy=reject) header.from=google.com X-Stat-Signature: o5ghe74pyg83hb1dy7curyjjk6qkfxc7 X-Rspamd-Queue-Id: 223172000E X-Rspamd-Server: rspam07 X-Rspam-User: X-HE-Tag: 1666866463-648207 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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 >