From nobody Thu Oct 2 07:48:30 2025 Received: from mail-pj1-f73.google.com (mail-pj1-f73.google.com [209.85.216.73]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8E0EB303A1D for ; Fri, 19 Sep 2025 22:34:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.73 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758321252; cv=none; b=VIjWWnfdJI+FCvo8QygmdbqOcOrAHwCMwP9D2obugTW7OlfDqtqtvzrfMWKTBIbKQx0aMXSWbqL+Gcz69iUbf0orAvN3uVAotf5dUotIGvpGjwdZbbiOE+Y5iBbZLZNNHuC3tWJS/HVRAs7o3hULUmazyqjkwem7NGhh80HMJUo= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758321252; c=relaxed/simple; bh=nKZ5Q7RgK3XRxdc3o7cKqV6DWFuIWGsdh+EcSzBiSww=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=lnQ2dEzVEzeVDNlZSSyf6IhGi7MEFUY6Di8QL4QXrdW+T+VnxzCtz9cNS8HMhLu4q8WPMDrNTKO2GQWaKQEObHB7qBFBoUAaB5MYqWmdx3qvWZlTZan2kwsmq7pxO+KboVq/Gz6ZQWzh3/4Q+bSvdDcrO0dhUlG7TuiEJ9NaM94= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=ZkNcRkZV; arc=none smtp.client-ip=209.85.216.73 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="ZkNcRkZV" Received: by mail-pj1-f73.google.com with SMTP id 98e67ed59e1d1-32ea7fcddd8so4983457a91.3 for ; Fri, 19 Sep 2025 15:34:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1758321250; x=1758926050; darn=vger.kernel.org; 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=cYHRrx1Rwo9eQXWeqWJXpUpu9aJ7cOqVN25IkcGdX1A=; b=ZkNcRkZV/lVfWvgwZpfuXapRTN2IuUSGBZt5f/46+pFyf/J63unGfnM9z/hZmHnRMO XQGmwxb0Ix3BPmIEPO5Drl4Q63sHzRPn+C3eDFndrT7Ilz7RmrcmhBb4WE5Czwv87GhQ UjvINhQWdcxKsa3AQOxcpbeCIapWXZEgOcR1onzU5lM9x6VGZOLzw/3sQpa4MRl97QdT Agh7fIwY/bEljUWD5YD1EDYC7kuwuWS9ys4IfC62nzjBAGhGabZ9SeqJEHi2OeJDr1hb /HaNyv7MBr2MW3I4ldUAU5dPR17b4qpt8tTEy5g0BrrSO5KiUzv1rK2Fth7WoU7x351z HUnA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1758321250; x=1758926050; 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=cYHRrx1Rwo9eQXWeqWJXpUpu9aJ7cOqVN25IkcGdX1A=; b=LRGOw3rFMPMdSO4C5Lm9KyguXOyd6pPC+TZu+xzxhV4jaPiEl9kPkfJ09+Enldlize TfuzevKAbGx5D4t/0UAs9fVRkC+h0om6Kon7lDriQ47LBuxUbS3qIHOUmgoiciyKoMOp 98ays9PSMY3YHKZDcBt3C67kMBXUFU9N9mUEuf8ufCTaVBWxRRIh6Pci/PMXjhQbPVdM EmPmOaxpOpxBCRfsfHixa+oAOmUJcLvTNLeElqyVTGuAzh3kpyxQhrPOQ8ZCmbDfb7xB HSerMhxD/ev3IPT5KASM8TkMzvq967ZmuO6bHBXeQuF/YSZEEaDeTfNRNme1uIr4mC8F pBDw== X-Forwarded-Encrypted: i=1; AJvYcCV8Hvn27vHk0i44ps/eK181XC2cx76MWGa0Cw0eH1Rxv5slPJRpRUw4UwjVqmvSDYqYXPfl4ZVRGEMM3ZY=@vger.kernel.org X-Gm-Message-State: AOJu0YxJddocQtInJG4TSKHA0JmeFYZ8+t5xfD/lb6ZwwnUnbkZLWAZ9 qy/rnWQB9Z+cqOtOMurCUsS31qoI4Vw02/bGQwwmX2PmV83F/hv0ZAdLLdO/zAob+JN18ozedbI cX4TQOw== X-Google-Smtp-Source: AGHT+IEW7HITViOOE/8pfh1gBFeALqS2Mwkwb0jK0TfcwCqmDCr4DL2x+WvNHZBBQhSy5ImpJhKVudjl1j8= X-Received: from pjbpd9.prod.google.com ([2002:a17:90b:1dc9:b0:32b:5548:d659]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90a:d60c:b0:32e:8c1e:1301 with SMTP id 98e67ed59e1d1-3309838dec4mr5848473a91.34.1758321249933; Fri, 19 Sep 2025 15:34:09 -0700 (PDT) Reply-To: Sean Christopherson Date: Fri, 19 Sep 2025 15:32:43 -0700 In-Reply-To: <20250919223258.1604852-1-seanjc@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250919223258.1604852-1-seanjc@google.com> X-Mailer: git-send-email 2.51.0.470.ga7dc726c21-goog Message-ID: <20250919223258.1604852-37-seanjc@google.com> Subject: [PATCH v16 36/51] KVM: nSVM: Save/load CET Shadow Stack state to/from vmcb12/vmcb02 From: Sean Christopherson To: Paolo Bonzini , Sean Christopherson Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Tom Lendacky , Mathias Krause , John Allen , Rick Edgecombe , Chao Gao , Binbin Wu , Xiaoyao Li , Maxim Levitsky , Zhang Yi Z , Xin Li Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Transfer the three CET Shadow Stack VMCB fields (S_CET, ISST_ADDR, and SSP) on VMRUN, #VMEXIT, and loading nested state (saving nested state simply copies the entire save area). SVM doesn't provide a way to disallow L1 from enabling Shadow Stacks for L2, i.e. KVM *must* provide nested support before advertising SHSTK to userspace. Signed-off-by: Sean Christopherson --- arch/x86/kvm/svm/nested.c | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c index 826473f2d7c7..a6443feab252 100644 --- a/arch/x86/kvm/svm/nested.c +++ b/arch/x86/kvm/svm/nested.c @@ -636,6 +636,14 @@ static void nested_vmcb02_prepare_save(struct vcpu_svm= *svm, struct vmcb *vmcb12 vmcb_mark_dirty(vmcb02, VMCB_DT); } =20 + if (guest_cpu_cap_has(vcpu, X86_FEATURE_SHSTK) && + (unlikely(new_vmcb12 || vmcb_is_dirty(vmcb12, VMCB_CET)))) { + vmcb02->save.s_cet =3D vmcb12->save.s_cet; + vmcb02->save.isst_addr =3D vmcb12->save.isst_addr; + vmcb02->save.ssp =3D vmcb12->save.ssp; + vmcb_mark_dirty(vmcb02, VMCB_CET); + } + kvm_set_rflags(vcpu, vmcb12->save.rflags | X86_EFLAGS_FIXED); =20 svm_set_efer(vcpu, svm->nested.save.efer); @@ -1044,6 +1052,12 @@ void svm_copy_vmrun_state(struct vmcb_save_area *to_= save, to_save->rsp =3D from_save->rsp; to_save->rip =3D from_save->rip; to_save->cpl =3D 0; + + if (kvm_cpu_cap_has(X86_FEATURE_SHSTK)) { + to_save->s_cet =3D from_save->s_cet; + to_save->isst_addr =3D from_save->isst_addr; + to_save->ssp =3D from_save->ssp; + } } =20 void svm_copy_vmloadsave_state(struct vmcb *to_vmcb, struct vmcb *from_vmc= b) @@ -1111,6 +1125,12 @@ int nested_svm_vmexit(struct vcpu_svm *svm) vmcb12->save.dr6 =3D svm->vcpu.arch.dr6; vmcb12->save.cpl =3D vmcb02->save.cpl; =20 + if (guest_cpu_cap_has(vcpu, X86_FEATURE_SHSTK)) { + vmcb12->save.s_cet =3D vmcb02->save.s_cet; + vmcb12->save.isst_addr =3D vmcb02->save.isst_addr; + vmcb12->save.ssp =3D vmcb02->save.ssp; + } + vmcb12->control.int_state =3D vmcb02->control.int_state; vmcb12->control.exit_code =3D vmcb02->control.exit_code; vmcb12->control.exit_code_hi =3D vmcb02->control.exit_code_hi; --=20 2.51.0.470.ga7dc726c21-goog