From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2E8C8C352A3 for ; Tue, 11 Feb 2020 13:56:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0CC3320870 for ; Tue, 11 Feb 2020 13:56:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729926AbgBKN4S (ORCPT ); Tue, 11 Feb 2020 08:56:18 -0500 Received: from 8bytes.org ([81.169.241.247]:52390 "EHLO theia.8bytes.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729548AbgBKNxZ (ORCPT ); Tue, 11 Feb 2020 08:53:25 -0500 Received: by theia.8bytes.org (Postfix, from userid 1000) id 35481E84; Tue, 11 Feb 2020 14:53:14 +0100 (CET) From: Joerg Roedel To: x86@kernel.org Cc: hpa@zytor.com, Andy Lutomirski , Dave Hansen , Peter Zijlstra , Thomas Hellstrom , Jiri Slaby , Dan Williams , Tom Lendacky , Juergen Gross , Kees Cook , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, Joerg Roedel , Joerg Roedel Subject: [PATCH 39/62] x86/sev-es: Harden runtime #VC handler for exceptions from user-space Date: Tue, 11 Feb 2020 14:52:33 +0100 Message-Id: <20200211135256.24617-40-joro@8bytes.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200211135256.24617-1-joro@8bytes.org> References: <20200211135256.24617-1-joro@8bytes.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Joerg Roedel Send SIGBUS to the user-space process that caused the #VC exception instead of killing the machine. Also ratelimit the error messages so that user-space can't flood the kernel log. Signed-off-by: Joerg Roedel --- arch/x86/kernel/sev-es.c | 32 +++++++++++++++++++++++--------- 1 file changed, 23 insertions(+), 9 deletions(-) diff --git a/arch/x86/kernel/sev-es.c b/arch/x86/kernel/sev-es.c index f5bff4219f6f..d128a9397639 100644 --- a/arch/x86/kernel/sev-es.c +++ b/arch/x86/kernel/sev-es.c @@ -254,16 +254,16 @@ dotraplinkage void do_vmm_communication(struct pt_regs *regs, unsigned long exit finish_insn(&ctxt); break; case ES_UNSUPPORTED: - pr_emerg("Unsupported exit-code 0x%02lx in early #VC exception (IP: 0x%lx)\n", - exit_code, regs->ip); + pr_err_ratelimited("Unsupported exit-code 0x%02lx in early #VC exception (IP: 0x%lx)\n", + exit_code, regs->ip); goto fail; case ES_VMM_ERROR: - pr_emerg("PANIC: Failure in communication with VMM (exit-code 0x%02lx IP: 0x%lx)\n", - exit_code, regs->ip); + pr_err_ratelimited("Failure in communication with VMM (exit-code 0x%02lx IP: 0x%lx)\n", + exit_code, regs->ip); goto fail; case ES_DECODE_FAILED: - pr_emerg("PANIC: Failed to decode instruction (exit-code 0x%02lx IP: 0x%lx)\n", - exit_code, regs->ip); + pr_err_ratelimited("PANIC: Failed to decode instruction (exit-code 0x%02lx IP: 0x%lx)\n", + exit_code, regs->ip); goto fail; case ES_EXCEPTION: forward_exception(&ctxt); @@ -278,10 +278,24 @@ dotraplinkage void do_vmm_communication(struct pt_regs *regs, unsigned long exit return; fail: - show_regs(regs); + if (user_mode(regs)) { + /* + * Do not kill the machine if user-space triggered the + * exception. Send SIGBUS instead and let user-space deal with + * it. + */ + force_sig_fault(SIGBUS, BUS_OBJERR, (void __user *)0); + } else { + /* Show some debug info */ + show_regs(regs); - while (true) - halt(); + /* Ask hypervisor to terminate */ + terminate(GHCB_SEV_ES_REASON_GENERAL_REQUEST); + + /* If that fails and we get here - just halt the machine */ + while (true) + halt(); + } } int __init boot_vc_exception(struct pt_regs *regs) -- 2.17.1 From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joerg Roedel Subject: [PATCH 39/62] x86/sev-es: Harden runtime #VC handler for exceptions from user-space Date: Tue, 11 Feb 2020 14:52:33 +0100 Message-ID: <20200211135256.24617-40-joro@8bytes.org> References: <20200211135256.24617-1-joro@8bytes.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20200211135256.24617-1-joro@8bytes.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: virtualization-bounces@lists.linux-foundation.org Sender: "Virtualization" To: x86@kernel.org Cc: Juergen Gross , Tom Lendacky , Thomas Hellstrom , Joerg Roedel , Kees Cook , kvm@vger.kernel.org, Peter Zijlstra , Joerg Roedel , Dave Hansen , linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, Andy Lutomirski , hpa@zytor.com, Dan Williams , Jiri Slaby List-Id: virtualization@lists.linuxfoundation.org From: Joerg Roedel Send SIGBUS to the user-space process that caused the #VC exception instead of killing the machine. Also ratelimit the error messages so that user-space can't flood the kernel log. Signed-off-by: Joerg Roedel --- arch/x86/kernel/sev-es.c | 32 +++++++++++++++++++++++--------- 1 file changed, 23 insertions(+), 9 deletions(-) diff --git a/arch/x86/kernel/sev-es.c b/arch/x86/kernel/sev-es.c index f5bff4219f6f..d128a9397639 100644 --- a/arch/x86/kernel/sev-es.c +++ b/arch/x86/kernel/sev-es.c @@ -254,16 +254,16 @@ dotraplinkage void do_vmm_communication(struct pt_regs *regs, unsigned long exit finish_insn(&ctxt); break; case ES_UNSUPPORTED: - pr_emerg("Unsupported exit-code 0x%02lx in early #VC exception (IP: 0x%lx)\n", - exit_code, regs->ip); + pr_err_ratelimited("Unsupported exit-code 0x%02lx in early #VC exception (IP: 0x%lx)\n", + exit_code, regs->ip); goto fail; case ES_VMM_ERROR: - pr_emerg("PANIC: Failure in communication with VMM (exit-code 0x%02lx IP: 0x%lx)\n", - exit_code, regs->ip); + pr_err_ratelimited("Failure in communication with VMM (exit-code 0x%02lx IP: 0x%lx)\n", + exit_code, regs->ip); goto fail; case ES_DECODE_FAILED: - pr_emerg("PANIC: Failed to decode instruction (exit-code 0x%02lx IP: 0x%lx)\n", - exit_code, regs->ip); + pr_err_ratelimited("PANIC: Failed to decode instruction (exit-code 0x%02lx IP: 0x%lx)\n", + exit_code, regs->ip); goto fail; case ES_EXCEPTION: forward_exception(&ctxt); @@ -278,10 +278,24 @@ dotraplinkage void do_vmm_communication(struct pt_regs *regs, unsigned long exit return; fail: - show_regs(regs); + if (user_mode(regs)) { + /* + * Do not kill the machine if user-space triggered the + * exception. Send SIGBUS instead and let user-space deal with + * it. + */ + force_sig_fault(SIGBUS, BUS_OBJERR, (void __user *)0); + } else { + /* Show some debug info */ + show_regs(regs); - while (true) - halt(); + /* Ask hypervisor to terminate */ + terminate(GHCB_SEV_ES_REASON_GENERAL_REQUEST); + + /* If that fails and we get here - just halt the machine */ + while (true) + halt(); + } } int __init boot_vc_exception(struct pt_regs *regs) -- 2.17.1