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 5234045C6E9 for ; Fri, 11 Sep 2026 11:22:06 +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=1789125736; cv=none; b=S2v3T1rNn2eE5bmZcfqE6cvcAhgUqK/etTDpSZSKLd/EEEV/wXuahE0gECotDHV3pBWeyTHJ6RZob94blDG7qVT+uA0OZu+AnbdyA7MRkFqqTu11s1FlGH8RmP8dHKOq8I6++7rmykePKi3p7c2+N0WwlJsPkbPiPJ03GyhmV8o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789125736; c=relaxed/simple; bh=hwztA+btlADmy9TLjKXHn8t117cJsHPT7/bAI9dGyWY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=UsraSUOaFzrcnuPC+BF9UAFbHE6Fx9yDEfGo/B2vFVN19grxj9ygu482AxH9wj9HjY+tdlml9q4nAOXZl3DnpX28OR6QEMulyWE250DlEu5lNkL/JPUi01gAvuRwAMXQ4zTYJJ2oo7pzbOYYGbw1URgSBhkUF+RyKgTjNhpvwhA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ocvIRd1q; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ocvIRd1q" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A9C5F1F000FF; Fri, 11 Sep 2026 11:22:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789125723; bh=LGsTlaVj4k9lnOnI0+Rg2PFjWTXLTGKnqXApAmSVuXY=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=ocvIRd1qOhUK0vZcTtYSVIv6uw7XCan01RLBuvy9KeW2YXoOEny8rNbSBheuvvD7c +2t1MwR+XYonM12uOyw4vRuTUUyB4Ip+2tLK62XFCbWsk0HXRvAV2t7dqP6UGytUPF flkxq5Gid1vnkj5KnTR22DZ2Ef1Jy4MkaCn0T/LyERZ7QAj9Jtm9DLyZCwpkwFO0kN E2Za8Wu9OSGjM4BK+L6rsGpXzrmhykpQcHGLAn48N8pFK9PhDNoY/qD7tSRgs2bJL+ 79IxRBzYi5qBouFq8O/8xz1NHJGRxJTl+OZE7exTSUAWHNkf4GhNJpIJi89R66b91J NcPhs7UqwmeQQ== From: Sasha Levin To: stable@vger.kernel.org Cc: Yosry Ahmed , Sean Christopherson , Sasha Levin Subject: [PATCH 6.18.y] KVM: x86: Disallow EFER.LME and EFER.LMA if long mode is not supported Date: Fri, 11 Sep 2026 07:22:01 -0400 Message-ID: <20260911112201.351751-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026090914-replace-unpleased-ddd4@gregkh> References: <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-Transfer-Encoding: 8bit From: Yosry Ahmed [ Upstream commit e62392bf39ebfdf60d1d082799397fe1cbf8dfc5 ] 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 [ relocated hunks to x86.c and its kvm_x86_vendor_init() because msrs.c and kvm_setup_efer_caps() are absent. ] Signed-off-by: Sasha Levin --- arch/x86/kvm/x86.c | 13 ++++--------- 1 file changed, 4 insertions(+), 9 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index a5a77dd0c77b3..867252433188d 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -106,16 +106,8 @@ EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_host); #define emul_to_vcpu(ctxt) \ ((struct kvm_vcpu *)(ctxt)->vcpu) -/* 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 KVM_EXIT_HYPERCALL_VALID_MASK (1 << KVM_HC_MAP_GPA_RANGE) @@ -10157,6 +10149,9 @@ int kvm_x86_vendor_init(struct kvm_x86_init_ops *ops) if (r != 0) goto out_mmu_exit; + if (kvm_cpu_cap_has(X86_FEATURE_LM)) + kvm_enable_efer_bits(EFER_LME | EFER_LMA); + enable_device_posted_irqs &= enable_apicv && irq_remapping_cap(IRQ_POSTING_CAP); -- 2.53.0