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[2620:137:e000::1:20]) by mx.google.com with ESMTP id f12-20020a63380c000000b005360d7da569si4348522pga.634.2023.05.26.14.44.55; Fri, 26 May 2023 14:45:11 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20221208 header.b=d6VBKb45; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243668AbjEZVDv (ORCPT + 99 others); Fri, 26 May 2023 17:03:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58308 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242813AbjEZVDq (ORCPT ); Fri, 26 May 2023 17:03:46 -0400 Received: from mail-pj1-x1049.google.com (mail-pj1-x1049.google.com [IPv6:2607:f8b0:4864:20::1049]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BCDA2189 for ; Fri, 26 May 2023 14:03:45 -0700 (PDT) Received: by mail-pj1-x1049.google.com with SMTP id 98e67ed59e1d1-2563aacedccso493025a91.1 for ; Fri, 26 May 2023 14:03:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1685135025; x=1687727025; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:from:to:cc:subject:date:message-id:reply-to; bh=hTzx+6AXt6K1nszy+Fq4+7PqDznMb4tNoA3e1kmsjc4=; b=d6VBKb45i+nhnCfXA61AU9D4t4hC9NNWQ3oHjZy8kPJ8JbUc+p0PI3kEO/JJf4hxha CZp1j4ogdlVssTQXCqM6vFPLjoZaBDAvtmZL/IHXPlKjFVSUP/8calK2Rn3ZgQIPfLGr dvEYi267LxAayQftT9J4qsYNfZc9tmqbmFijCoJOuyYrUqn3d7R8364ynMB2lLDWl15A 3HApw/46yk2n7KEfdo4yjiPuQzTTRxfs6bQzMwDfcUcKD6MKtS7QqAFue/YfhAKtLa5W a2n4EbiHMOkUTMljD58mKPTGTbxVBlyZEIm0RXhO7Jh0s0wysOrHtj4/1nyMBWEvWxbu hXgg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1685135025; x=1687727025; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=hTzx+6AXt6K1nszy+Fq4+7PqDznMb4tNoA3e1kmsjc4=; b=DpHu8dhl40elbPq6Nk+pE6/5umb3/vHEhcYHUoLQaxzUjZKYy6R2dyR/4suxK2g03A n25ixwLU91y+bbyN+jFvI3jChSU7RH6XxdBqPzj7BYpaCREQgcOHnHXNNlzIFwpK1efl tx9YrPUcu51NcAiKHXazeeL/jeI4C1QJqQyia33e7padQnmn+7TbvGOwYA7cvZrH/KJ5 jk7nJhg4XJogo45xEsN0rv3Yf/zRonBCSScihq8e3cMHtX5ZnKie80V6jjPaXj5q65nC wYCdh0n3PbQG9M6aKZdW5UMMWHqRCzPcZoSxIr1WyC/5awXxND0b2xVVw4eHgXuG0Lds g3JQ== X-Gm-Message-State: AC+VfDyzX/3x/Z7+5jofQ8F3fLg90XG9g74T42UE9+DIIQPBhH4WjhTk V38lFnT1PAQqjVIWjg8cKK0GpaIUc8c= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a17:90a:8c83:b0:253:9751:325f with SMTP id b3-20020a17090a8c8300b002539751325fmr780071pjo.4.1685135025225; Fri, 26 May 2023 14:03:45 -0700 (PDT) Reply-To: Sean Christopherson Date: Fri, 26 May 2023 14:03:39 -0700 In-Reply-To: <20230526210340.2799158-1-seanjc@google.com> Mime-Version: 1.0 References: <20230526210340.2799158-1-seanjc@google.com> X-Mailer: git-send-email 2.41.0.rc0.172.g3f132b7071-goog Message-ID: <20230526210340.2799158-2-seanjc@google.com> Subject: [PATCH v3 1/2] KVM: x86: Update number of entries for KVM_GET_CPUID2 on success, not failure From: Sean Christopherson To: Sean Christopherson , Paolo Bonzini Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Takahiro Itazuri X-Spam-Status: No, score=-9.6 required=5.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE, SPF_HELO_NONE,SPF_PASS,T_SCC_BODY_TEXT_LINE,USER_IN_DEF_DKIM_WL autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1766994750993173215?= X-GMAIL-MSGID: =?utf-8?q?1766994750993173215?= Update cpuid->nent if and only if kvm_vcpu_ioctl_get_cpuid2() succeeds. The sole caller copies @cpuid to userspace only on success, i.e. the existing code effectively does nothing. Arguably, KVM should report the number of entries when returning -E2BIG so that userspace doesn't have to guess the size, but all other similar KVM ioctls() don't report the size either, i.e. userspace is conditioned to guess. Suggested-by: Takahiro Itazuri Link: https://lore.kernel.org/all/20230410141820.57328-1-itazur@amazon.com Signed-off-by: Sean Christopherson --- arch/x86/kvm/cpuid.c | 13 ++++--------- 1 file changed, 4 insertions(+), 9 deletions(-) diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index 0c9660a07b23..241f554f1764 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -501,20 +501,15 @@ int kvm_vcpu_ioctl_get_cpuid2(struct kvm_vcpu *vcpu, struct kvm_cpuid2 *cpuid, struct kvm_cpuid_entry2 __user *entries) { - int r; - - r = -E2BIG; if (cpuid->nent < vcpu->arch.cpuid_nent) - goto out; - r = -EFAULT; + return -E2BIG; + if (copy_to_user(entries, vcpu->arch.cpuid_entries, vcpu->arch.cpuid_nent * sizeof(struct kvm_cpuid_entry2))) - goto out; - return 0; + return -EFAULT; -out: cpuid->nent = vcpu->arch.cpuid_nent; - return r; + return 0; } /* Mask kvm_cpu_caps for @leaf with the raw CPUID capabilities of this CPU. */