From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 196CE52B1DF for ; Wed, 9 Sep 2026 10:42:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788950565; cv=none; b=LV8GApmfeX56BtJ/uciYwlJ0wz+k7nHy1A6LOkQSTlb+3TpQ6sumznyc5CVcHNkjpPawU/MXHU48elH3C/bsq3XtlqkP+AHXKbGJ7HvHMysn151L+51AFlXucsI8ijTV485l6Ru4LXiR/GQiov63ScVa3y+yDlJ60/KdPUY6guc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788950565; c=relaxed/simple; bh=FCF7kymS241RkTiM5ki7ioP5fdCibbw2v5U6fpYB6qo=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=MVliFLZ7RIAKp2c02AuM7yb0MtmSauQDaAqm83vlISCr1qFcdJ0Ra71+enSjGNnVB98XvrVI0wJeyjVu67SOVBsJW4VLzrXepINHsa6LQj1GLbNEOrjpStqHbi1lYzpJUw8dxVT2OP5tku0odS6k1jmFgIqiGfiObeuCp8477cM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=K6Vqpneo; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="K6Vqpneo" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 183701F00A3A; Wed, 9 Sep 2026 10:42:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1788950563; bh=fXsa+z4yBTv315arol6Wgnca9npwA7Jz8a/+cpXS8xs=; h=Subject:To:Cc:From:Date; b=K6VqpneoyygHrSS0mE2ALDOpfOINsTMqDFh1CIwdHh3PZrpqMaHUnaZg7/RRIOrWU DWnyPYFHwIfVUUcM0WHYvD3KQcsR4OeKfJGbxIOJVwhNlzD6AI+MT+AKzkwCW4kv38 2LjfvnVRXv2BFbwquAVEmqOGVmNiDaVtsJ43Oakw= Subject: FAILED: patch "[PATCH] KVM: x86: Disallow EFER.LME and EFER.LMA if long mode is not" failed to apply to 6.18-stable tree To: yosry@kernel.org,seanjc@google.com Cc: From: Date: Wed, 09 Sep 2026 12:32:14 +0200 Message-ID: <2026090914-replace-unpleased-ddd4@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.18-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.18.y git checkout FETCH_HEAD git cherry-pick -x e62392bf39ebfdf60d1d082799397fe1cbf8dfc5 # git commit -s git send-email --to '' --in-reply-to '2026090914-replace-unpleased-ddd4@gregkh' --subject-prefix 'PATCH 6.18.y' 'HEAD^..' Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From e62392bf39ebfdf60d1d082799397fe1cbf8dfc5 Mon Sep 17 00:00:00 2001 From: Yosry Ahmed Date: Mon, 13 Jul 2026 18:10:17 +0000 Subject: [PATCH] KVM: x86: Disallow EFER.LME and EFER.LMA if long mode is not supported Remove EFER.LME and EFER.LMA from EFER reserved bits only if long mode is actually supported. KVM does check long-mode support before allowing the bits for guest writes and userspace writes through KVM_SET_SREGS* (in __kvm_valid_efer()), but userspace writes through KVM_SET_MSRS only check reserved bits. In practice, this doesn't really matter. The true motiviation is getting rid of the #ifdeffery when initializing efer_reserved_bits. Cc: stable@vger.kernel.org Signed-off-by: Yosry Ahmed Link: https://patch.msgid.link/20260713181020.2735367-3-yosry@kernel.org Signed-off-by: Sean Christopherson diff --git a/arch/x86/kvm/msrs.c b/arch/x86/kvm/msrs.c index c230b18d87e3..67481429ad6b 100644 --- a/arch/x86/kvm/msrs.c +++ b/arch/x86/kvm/msrs.c @@ -19,16 +19,8 @@ bool __read_mostly report_ignored_msrs = true; module_param(report_ignored_msrs, bool, 0644); EXPORT_SYMBOL_FOR_KVM_INTERNAL(report_ignored_msrs); -/* EFER defaults: - * - enable syscall per default because its emulated by KVM - * - enable LME and LMA per default on 64 bit KVM - */ -#ifdef CONFIG_X86_64 -static -u64 __read_mostly efer_reserved_bits = ~((u64)(EFER_SCE | EFER_LME | EFER_LMA)); -#else +/* Enable syscall by default because its emulated by KVM */ static u64 __read_mostly efer_reserved_bits = ~((u64)EFER_SCE); -#endif #define MAX_IO_MSRS 256 diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index a4216b858194..0845551c6cab 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -6910,6 +6910,9 @@ EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_setup_xss_caps); static void kvm_setup_efer_caps(void) { + if (kvm_cpu_cap_has(X86_FEATURE_LM)) + kvm_enable_efer_bits(EFER_LME | EFER_LMA); + if (kvm_cpu_cap_has(X86_FEATURE_NX)) kvm_enable_efer_bits(EFER_NX);