From patchwork Fri Mar 7 21:20:52 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paolo Bonzini X-Patchwork-Id: 14007154 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E94C925C6F6 for ; Fri, 7 Mar 2025 21:21:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741382477; cv=none; b=VTYdRBWkv57XiYkrqL/EPfvM2obTnnqjKR+nATd4OqcojrK2yUC6ADXvmNqZpOkTQgxQJQUPOZhg3jRroTeoWlOXnKd+OJL2WbDlP5/Y4XVfk2Mm7dOaKIYiqV71acS+1QNprysv0ts9LeU+SqqZGm1qGjQKVJHg3zsJfYDPda4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741382477; c=relaxed/simple; bh=g2riD0EhQdCn1umYVNZvlC9toT0pyKdqzR+R1wNMjJ0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=SacFlraM1MBnlAapk8clFguUXJ//XXt/ZTvbX4k4UjIh4XTVHjwhqTIl1uq77K8IMKpHiqK1P9/9/Hk/DvWBjB7h+P4Ng1eOAf1AjzsqJTYVDwOcXC8VOm0uD0/zxX9PavgWmCqzrU2rHkR2nUPd7YcocDcDGXhs97ZCGQ+04Nk= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=agt2qCmk; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="agt2qCmk" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1741382474; h=from:from: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:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=e2QbkSJbF2R3Y+8qFTfoMonS1boKEh/L+DLVqHOtaPQ=; b=agt2qCmkvYSF5Qz6rQErtCxOtbSurfgRvSMRfAyV4uRVRL3NH4zD1QbxBHEjkefsM9DaNb NyW+xHIOupuXZtsGJGnnq2J64JbwbCQmvvlcvPj+e63pLVA0dusN7xhl1syDoG60A20zSk JtZUSOBHQiEDdUeGxYBELgophaQWSX4= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-620-lhMSqSH_Oo-qwSJXUGtfpA-1; Fri, 07 Mar 2025 16:21:13 -0500 X-MC-Unique: lhMSqSH_Oo-qwSJXUGtfpA-1 X-Mimecast-MFC-AGG-ID: lhMSqSH_Oo-qwSJXUGtfpA_1741382471 Received: from mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.15]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 77D92180AB19; Fri, 7 Mar 2025 21:21:11 +0000 (UTC) Received: from virtlab1023.lab.eng.rdu2.redhat.com (virtlab1023.lab.eng.rdu2.redhat.com [10.8.1.187]) by mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id E31861956095; Fri, 7 Mar 2025 21:21:09 +0000 (UTC) From: Paolo Bonzini To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: xiaoyao.li@intel.com, adrian.hunter@intel.com, seanjc@google.com, rick.p.edgecombe@intel.com, Isaku Yamahata , Sean Christopherson , Chao Gao , Binbin Wu Subject: [PATCH v3 10/10] KVM: x86: Add a switch_db_regs flag to handle TDX's auto-switched behavior Date: Fri, 7 Mar 2025 16:20:52 -0500 Message-ID: <20250307212053.2948340-11-pbonzini@redhat.com> In-Reply-To: <20250307212053.2948340-1-pbonzini@redhat.com> References: <20250307212053.2948340-1-pbonzini@redhat.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.15 From: Isaku Yamahata Add a flag KVM_DEBUGREG_AUTO_SWITCH to skip saving/restoring guest DRs. TDX-SEAM unconditionally saves/restores guest DRs on TD exit/enter, and resets DRs to architectural INIT state on TD exit. Use the new flag KVM_DEBUGREG_AUTO_SWITCH to indicate that KVM doesn't need to save/restore guest DRs. KVM still needs to restore host DRs after TD exit if there are active breakpoints in the host, which is covered by the existing code. MOV-DR exiting is always cleared for TDX guests, so the handler for DR access is never called, and KVM_DEBUGREG_WONT_EXIT is never set. Add a warning if both KVM_DEBUGREG_WONT_EXIT and KVM_DEBUGREG_AUTO_SWITCH are set. Opportunistically convert the KVM_DEBUGREG_* definitions to use BIT(). Reported-by: Xiaoyao Li Signed-off-by: Sean Christopherson Co-developed-by: Chao Gao Signed-off-by: Chao Gao Signed-off-by: Isaku Yamahata [binbin: rework changelog] Signed-off-by: Binbin Wu Message-ID: <20241210004946.3718496-2-binbin.wu@linux.intel.com> Signed-off-by: Paolo Bonzini Message-ID: <20250129095902.16391-13-adrian.hunter@intel.com> Signed-off-by: Paolo Bonzini --- arch/x86/include/asm/kvm_host.h | 11 +++++++++-- arch/x86/kvm/vmx/tdx.c | 1 + arch/x86/kvm/x86.c | 4 +++- 3 files changed, 13 insertions(+), 3 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 1208aee90df1..c0b1ee39a92c 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -606,8 +606,15 @@ struct kvm_pmu { struct kvm_pmu_ops; enum { - KVM_DEBUGREG_BP_ENABLED = 1, - KVM_DEBUGREG_WONT_EXIT = 2, + KVM_DEBUGREG_BP_ENABLED = BIT(0), + KVM_DEBUGREG_WONT_EXIT = BIT(1), + /* + * Guest debug registers (DR0-3, DR6 and DR7) are saved/restored by + * hardware on exit from or enter to guest. KVM needn't switch them. + * DR0-3, DR6 and DR7 are set to their architectural INIT value on VM + * exit, host values need to be restored. + */ + KVM_DEBUGREG_AUTO_SWITCH = BIT(2), }; struct kvm_mtrr { diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c index 25972e12504b..2270d854ccab 100644 --- a/arch/x86/kvm/vmx/tdx.c +++ b/arch/x86/kvm/vmx/tdx.c @@ -630,6 +630,7 @@ int tdx_vcpu_create(struct kvm_vcpu *vcpu) vcpu->arch.efer = EFER_SCE | EFER_LME | EFER_LMA | EFER_NX; + vcpu->arch.switch_db_regs = KVM_DEBUGREG_AUTO_SWITCH; vcpu->arch.cr0_guest_owned_bits = -1ul; vcpu->arch.cr4_guest_owned_bits = -1ul; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 6dcf8998a34f..df76c17215e2 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -10978,7 +10978,8 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) if (vcpu->arch.guest_fpu.xfd_err) wrmsrl(MSR_IA32_XFD_ERR, vcpu->arch.guest_fpu.xfd_err); - if (unlikely(vcpu->arch.switch_db_regs)) { + if (unlikely(vcpu->arch.switch_db_regs && + !(vcpu->arch.switch_db_regs & KVM_DEBUGREG_AUTO_SWITCH))) { set_debugreg(0, 7); set_debugreg(vcpu->arch.eff_db[0], 0); set_debugreg(vcpu->arch.eff_db[1], 1); @@ -11028,6 +11029,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) */ if (unlikely(vcpu->arch.switch_db_regs & KVM_DEBUGREG_WONT_EXIT)) { WARN_ON(vcpu->guest_debug & KVM_GUESTDBG_USE_HW_BP); + WARN_ON(vcpu->arch.switch_db_regs & KVM_DEBUGREG_AUTO_SWITCH); kvm_x86_call(sync_dirty_debug_regs)(vcpu); kvm_update_dr0123(vcpu); kvm_update_dr7(vcpu);