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 X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 13FF7C33CB1 for ; Fri, 17 Jan 2020 06:26:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DBE4D20748 for ; Fri, 17 Jan 2020 06:26:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727561AbgAQG0j (ORCPT ); Fri, 17 Jan 2020 01:26:39 -0500 Received: from mga17.intel.com ([192.55.52.151]:14600 "EHLO mga17.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726370AbgAQG0i (ORCPT ); Fri, 17 Jan 2020 01:26:38 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by fmsmga107.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 16 Jan 2020 22:26:38 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,329,1574150400"; d="scan'208";a="424342472" Received: from sjchrist-coffee.jf.intel.com ([10.54.74.202]) by fmsmga005.fm.intel.com with ESMTP; 16 Jan 2020 22:26:30 -0800 From: Sean Christopherson To: Paolo Bonzini Cc: Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Derek Yerger , kernel@najdan.com, Thomas Lambertz , Rik van Riel , Sebastian Andrzej Siewior , Borislav Petkov , Dave Hansen , Thomas Gleixner Subject: [PATCH 1/4] KVM: x86: Handle TIF_NEED_FPU_LOAD in kvm_{load,put}_guest_fpu() Date: Thu, 16 Jan 2020 22:26:25 -0800 Message-Id: <20200117062628.6233-2-sean.j.christopherson@intel.com> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200117062628.6233-1-sean.j.christopherson@intel.com> References: <20200117062628.6233-1-sean.j.christopherson@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Handle TIF_NEED_FPU_LOAD similar to how fpu__copy() handles the flag when duplicating FPU state to a new task struct. TIF_NEED_FPU_LOAD can be set any time control is transferred out of KVM, be it voluntarily, e.g. if I/O is triggered during a KVM call to get_user_pages, or involuntarily, e.g. if softirq runs after an IRQ occurs. Therefore, KVM must account for TIF_NEED_FPU_LOAD whenever it is (potentially) accessing CPU FPU state. Fixes: 5f409e20b7945 ("x86/fpu: Defer FPU state load until return to userspace") Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson --- arch/x86/kvm/x86.c | 27 ++++++++++++++++++++++++--- 1 file changed, 24 insertions(+), 3 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index cf917139de6b..0c7211491f98 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -8476,8 +8476,20 @@ static void kvm_load_guest_fpu(struct kvm_vcpu *vcpu) { fpregs_lock(); - copy_fpregs_to_fpstate(vcpu->arch.user_fpu); - /* PKRU is separately restored in kvm_x86_ops->run. */ + /* + * If userspace's FPU state is not resident in the CPU registers, just + * memcpy() from current, else save CPU state directly to user_fpu. + */ + if (test_thread_flag(TIF_NEED_FPU_LOAD)) + memcpy(&vcpu->arch.user_fpu->state, ¤t->thread.fpu.state, + fpu_kernel_xstate_size); + else + copy_fpregs_to_fpstate(vcpu->arch.user_fpu); + + /* + * Load guest's FPU state to the CPU registers. PKRU is separately + * loaded in kvm_x86_ops->run. + */ __copy_kernel_to_fpregs(&vcpu->arch.guest_fpu->state, ~XFEATURE_MASK_PKRU); @@ -8492,7 +8504,16 @@ static void kvm_put_guest_fpu(struct kvm_vcpu *vcpu) { fpregs_lock(); - copy_fpregs_to_fpstate(vcpu->arch.guest_fpu); + /* + * If guest's FPU state is not resident in the CPU registers, just + * memcpy() from current, else save CPU state directly to guest_fpu. + */ + if (test_thread_flag(TIF_NEED_FPU_LOAD)) + memcpy(&vcpu->arch.guest_fpu->state, ¤t->thread.fpu.state, + fpu_kernel_xstate_size); + else + copy_fpregs_to_fpstate(vcpu->arch.guest_fpu); + copy_kernel_to_fpregs(&vcpu->arch.user_fpu->state); fpregs_mark_activate(); -- 2.24.1