From nobody Thu Oct 2 19:27:58 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 68AEB2DEA8F for ; Fri, 12 Sep 2025 23:24:13 +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=1757719454; cv=none; b=UFMkP8o6KY90f9EHAF5NrdTK3m+nDy3p7u+sCW7KLpulikQWHjrwpuClZpRiKA/JOyEJ/TnGrBaWOtwaN5naq3viOYlDv/TvbxLhs1NWw4MmHAh4uxuo40lmf0P9pp9CDgV2eeooEgwCWCfcNvbubx7xeKgo4PR8DYcwmiR3nz0= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757719454; c=relaxed/simple; bh=LAJPzAlmyWIBgpqdwLkUgQB3TkWNzFrLEjxU5EluKAM=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=qhORTa9n+z01NBuHW6eXAlKZc4Jn+EEtsgo/x7NwHghgSIVGieXYUNx/YlKSAMmvq8HTGs2+o7In/GwyDe6QZjtpfOJct89IR4K/L1EQf9Z91CTRuePbzatHVLtk/gIzAFcBaciWqTG8Wk8YVhCN5oKbJY359py5btgLUHBc43g= 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=jbllZj0x; 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="jbllZj0x" Received: by mail-pj1-f73.google.com with SMTP id 98e67ed59e1d1-32811874948so1949955a91.2 for ; Fri, 12 Sep 2025 16:24:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1757719453; x=1758324253; 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=hzDjAlD4iHwUuuZo4Nh78/wEEXvtZ0Xx1CFsvM7LDXc=; b=jbllZj0xb15tQlQOvp/7SAdhWDVaRdzc7YwkhwTgFh9rDQ5r0lZxytdWjnFD+mFWkX JEwm0awEbAGhoBQivBWHN2/MSVW6R1nDpVWPe+H3RBwrKHseZpWUS5cc7OjVfaHj8i+g 36VKXMXB8OfDkL2s7ze3Yadsq6p5jRFOdEZfBG8+sT8hweURfhk/4BLKilTj8Ys+6Jdm J8zOuSPY8J64mK9B5uG44Qar+zDNzR6VWVURSwzaQq+Y9BUZmCWqKJE0eGNEgCovuTAc fr3wU1ZMQCPFndB08n3n/OfiGhzk9JTZjsqQl1xzUjTbwfj16c6SWvTBKmGR3SoaSKBs 9C0A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1757719453; x=1758324253; 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=hzDjAlD4iHwUuuZo4Nh78/wEEXvtZ0Xx1CFsvM7LDXc=; b=HpM574Gd1ZYxNZojaxf5TLFO3lHx1O3GJ+logL0j8KB6p0ij1BR19VSdnMBE4oe3iU narZdgaLXlCTcIxys+9s1q/pxkhPnivx+GeGEkIb/pTAyQwrPz9ZeK+sk4Lf9rEQfsI4 HDXkbR1cAgWxnImICyVRtLjm22U281fVhdn9y2nHlbOLH6Ng6o96EDvYv804FegHU9a7 jaHMuKGSdQRZ7rbJVZFpN6g+taQf5rNI1Cv+RoqAR/RapjrRUgXpNwlxa+PNQ+qnOiEV qUXOuQO2nUwsqJOlyaL9gmymEh80/liFSIDTwBbUvFxGIerU4L8HhSojC9wDLDFR3f7x Qhbg== X-Forwarded-Encrypted: i=1; AJvYcCWlaEIQXGBPHzoCFGAGPo1JpZMxDy8gsp3I5KRTYbtBZP40Z80XvK7lfmLSP4tpaZaO9DiE/QthPUJtUa8=@vger.kernel.org X-Gm-Message-State: AOJu0YyqvRupXgNZr3hnnpD7ixVscfjQOmgo8Id7npbxKTt87Ezqq6l5 MZk/x0HYU+5pqe9L2NBpu7UcJCtsxromyuICHT1ri40FjL8PpPKBPWJ1JTm82uTJ0IihltMeSpy oyHZWpg== X-Google-Smtp-Source: AGHT+IHSdGKZy5soiUAoOrnYCvC/h4VFq/ncPK5C7FSM5qNoiAhCXYyzhUL/nqH5X5GNExI4WprY3NEICjc= X-Received: from pjbqa16.prod.google.com ([2002:a17:90b:4fd0:b0:329:e84e:1c50]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90a:da88:b0:32c:c40e:db12 with SMTP id 98e67ed59e1d1-32de4f858f4mr5231651a91.17.1757719452938; Fri, 12 Sep 2025 16:24:12 -0700 (PDT) Reply-To: Sean Christopherson Date: Fri, 12 Sep 2025 16:23:04 -0700 In-Reply-To: <20250912232319.429659-1-seanjc@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250912232319.429659-1-seanjc@google.com> X-Mailer: git-send-email 2.51.0.384.g4c02a37b29-goog Message-ID: <20250912232319.429659-27-seanjc@google.com> Subject: [PATCH v15 26/41] 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 , Maxim Levitsky , Xiaoyao Li , Zhang Yi Z 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 2.51.0.384.g4c02a37b29-goog