From nobody Sun Sep 14 00:06:35 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 88DBAC54EAA for ; Fri, 27 Jan 2023 18:28:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235416AbjA0S2g (ORCPT ); Fri, 27 Jan 2023 13:28:36 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60614 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235342AbjA0S2T (ORCPT ); Fri, 27 Jan 2023 13:28:19 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0AEE084FA5; Fri, 27 Jan 2023 10:27:28 -0800 (PST) Date: Fri, 27 Jan 2023 18:26:56 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1674844016; h=from:from:sender:sender:reply-to: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; bh=QU3D1MVl4nF12dfqXKBPUAzNEWPP6wcbOhCTHK/byU8=; b=BR2yPxn5qEXFU3+oe32J7VXsBmiWCfl8fN0gB5HX2tQIZmxAwIVEbjq/88AmEm3XA8Us2m a+WUlhreRnAIkvEB0jMpTvOETBlJvOcGdHugvHtkukIHPqQLpTl4dK41QJ2d5zv8Dtt0c/ iReCVYsUNw/U1gJxlhFKYbSD7Y1CC0MG5z32ybixvOeaDsXfgTTA0iMKV2Jm7LvWm8qOgW rnktT/c4tSL9a4TPqAMa4cBpeb2XjkeozfGp9DfF7wHYSqrnpQpOqKOcNCEh0Cx850+0EK lgDrXku48e+Oc5f1q2+/GxNUvNp3vCR3ayCgYo/AsrwU2sfaccf9MaTAhMThJQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1674844016; h=from:from:sender:sender:reply-to: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; bh=QU3D1MVl4nF12dfqXKBPUAzNEWPP6wcbOhCTHK/byU8=; b=IC/19wwIS/2KBYmfmmyc0PGI1+9wb+6uiRyMwAVhaqoPYSnVM5pmzDAaGJcUhero2qidIj t1oBPU1CATpC7ZAQ== From: "tip-bot2 for Kirill A. Shutemov" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: x86/tdx] x86/tdx: Use ReportFatalError to report missing SEPT_VE_DISABLE Cc: "Kirill A. Shutemov" , Dave Hansen , x86@kernel.org, linux-kernel@vger.kernel.org MIME-Version: 1.0 Message-ID: <167484401624.4906.9634557672121237563.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the x86/tdx branch of tip: Commit-ID: 71acdcd7cd0abee7698c2d5e5a8a66602a00b12c Gitweb: https://git.kernel.org/tip/71acdcd7cd0abee7698c2d5e5a8a66602= a00b12c Author: Kirill A. Shutemov AuthorDate: Fri, 27 Jan 2023 01:11:57 +03:00 Committer: Dave Hansen CommitterDate: Fri, 27 Jan 2023 09:45:55 -08:00 x86/tdx: Use ReportFatalError to report missing SEPT_VE_DISABLE Linux TDX guests require that the SEPT_VE_DISABLE "attribute" be set. If it is not set, the kernel is theoretically required to handle exceptions anywhere that kernel memory is accessed, including places like NMI handlers and in the syscall entry gap. Rather than even try to handle these exceptions, the kernel refuses to run if SEPT_VE_DISABLE is unset. However, the SEPT_VE_DISABLE detection and refusal code happens very early in boot, even before earlyprintk runs. Calling panic() will effectively just hang the system. Instead, call a TDX-specific panic() function. This makes a very simple TDVMCALL which gets a short error string out to the hypervisor without any console infrastructure. Use TDG.VP.VMCALL to report the error. The hypercall can encode message up to 64 bytes in eight registers. [ dhansen: tweak comment and remove while loop brackets. ] Signed-off-by: Kirill A. Shutemov Signed-off-by: Dave Hansen Link: https://lore.kernel.org/all/20230126221159.8635-6-kirill.shutemov%40l= inux.intel.com --- arch/x86/coco/tdx/tdx.c | 38 +++++++++++++++++++++++++++++++++++++- 1 file changed, 37 insertions(+), 1 deletion(-) diff --git a/arch/x86/coco/tdx/tdx.c b/arch/x86/coco/tdx/tdx.c index 669d9e4..fbb9913 100644 --- a/arch/x86/coco/tdx/tdx.c +++ b/arch/x86/coco/tdx/tdx.c @@ -22,6 +22,7 @@ =20 /* TDX hypercall Leaf IDs */ #define TDVMCALL_MAP_GPA 0x10001 +#define TDVMCALL_REPORT_FATAL_ERROR 0x10003 =20 /* MMIO direction */ #define EPT_READ 0 @@ -140,6 +141,41 @@ int tdx_mcall_get_report0(u8 *reportdata, u8 *tdreport) } EXPORT_SYMBOL_GPL(tdx_mcall_get_report0); =20 +static void __noreturn tdx_panic(const char *msg) +{ + struct tdx_hypercall_args args =3D { + .r10 =3D TDX_HYPERCALL_STANDARD, + .r11 =3D TDVMCALL_REPORT_FATAL_ERROR, + .r12 =3D 0, /* Error code: 0 is Panic */ + }; + union { + /* Define register order according to the GHCI */ + struct { u64 r14, r15, rbx, rdi, rsi, r8, r9, rdx; }; + + char str[64]; + } message; + + /* VMM assumes '\0' in byte 65, if the message took all 64 bytes */ + strncpy(message.str, msg, 64); + + args.r8 =3D message.r8; + args.r9 =3D message.r9; + args.r14 =3D message.r14; + args.r15 =3D message.r15; + args.rdi =3D message.rdi; + args.rsi =3D message.rsi; + args.rbx =3D message.rbx; + args.rdx =3D message.rdx; + + /* + * This hypercall should never return and it is not safe + * to keep the guest running. Call it forever if it + * happens to return. + */ + while (1) + __tdx_hypercall(&args, 0); +} + static void tdx_parse_tdinfo(u64 *cc_mask) { struct tdx_module_output out; @@ -172,7 +208,7 @@ static void tdx_parse_tdinfo(u64 *cc_mask) */ td_attr =3D out.rdx; if (!(td_attr & ATTR_SEPT_VE_DISABLE)) - panic("TD misconfiguration: SEPT_VE_DISABLE attibute must be set.\n"); + tdx_panic("TD misconfiguration: SEPT_VE_DISABLE attribute must be set."); } =20 /*