From patchwork Mon May 17 13:58:51 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 440838 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=-19.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, 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 91F4EC433ED for ; Mon, 17 May 2021 14:55:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 750E161019 for ; Mon, 17 May 2021 14:55:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242465AbhEQO4g (ORCPT ); Mon, 17 May 2021 10:56:36 -0400 Received: from mail.kernel.org ([198.145.29.99]:51760 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241986AbhEQOyW (ORCPT ); Mon, 17 May 2021 10:54:22 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id ACF51619A9; Mon, 17 May 2021 14:24:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1621261474; bh=9Y+5+dD6HCwmndVAudU9kiFO8fBTUHvYYZUyIyyt/Xg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ItmN/yTgGoaA+gDkzUne6vAPJDuEcAyReYtoQw1vG0XiadAf9VCv7/KnLajAuo7/y UcLe52R1jxMQL1mJCXT6lG1nZDCHfE2eurnD8/5L8NzfN5AXYjzWClkhWD3Qr1IvdV wn2xDA7NKL4VPDJjP+13dFaa0YD3QJC5hHtl9z5k= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Lai Jiangshan , Thomas Gleixner Subject: [PATCH 5.10 006/289] KVM/VMX: Invoke NMI non-IST entry instead of IST entry Date: Mon, 17 May 2021 15:58:51 +0200 Message-Id: <20210517140305.381591977@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210517140305.140529752@linuxfoundation.org> References: <20210517140305.140529752@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Lai Jiangshan commit a217a6593cec8b315d4c2f344bae33660b39b703 upstream. In VMX, the host NMI handler needs to be invoked after NMI VM-Exit. Before commit 1a5488ef0dcf6 ("KVM: VMX: Invoke NMI handler via indirect call instead of INTn"), this was done by INTn ("int $2"). But INTn microcode is relatively expensive, so the commit reworked NMI VM-Exit handling to invoke the kernel handler by function call. But this missed a detail. The NMI entry point for direct invocation is fetched from the IDT table and called on the kernel stack. But on 64-bit the NMI entry installed in the IDT expects to be invoked on the IST stack. It relies on the "NMI executing" variable on the IST stack to work correctly, which is at a fixed position in the IST stack. When the entry point is unexpectedly called on the kernel stack, the RSP-addressed "NMI executing" variable is obviously also on the kernel stack and is "uninitialized" and can cause the NMI entry code to run in the wrong way. Provide a non-ist entry point for VMX which shares the C-function with the regular NMI entry and invoke the new asm entry point instead. On 32-bit this just maps to the regular NMI entry point as 32-bit has no ISTs and is not affected. [ tglx: Made it independent for backporting, massaged changelog ] Fixes: 1a5488ef0dcf6 ("KVM: VMX: Invoke NMI handler via indirect call instead of INTn") Signed-off-by: Lai Jiangshan Signed-off-by: Thomas Gleixner Tested-by: Lai Jiangshan Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/87r1imi8i1.ffs@nanos.tec.linutronix.de Signed-off-by: Greg Kroah-Hartman --- arch/x86/include/asm/idtentry.h | 15 +++++++++++++++ arch/x86/kernel/nmi.c | 10 ++++++++++ arch/x86/kvm/vmx/vmx.c | 16 +++++++++------- 3 files changed, 34 insertions(+), 7 deletions(-) --- a/arch/x86/include/asm/idtentry.h +++ b/arch/x86/include/asm/idtentry.h @@ -588,6 +588,21 @@ DECLARE_IDTENTRY_RAW(X86_TRAP_MC, exc_ma #endif /* NMI */ + +#if defined(CONFIG_X86_64) && IS_ENABLED(CONFIG_KVM_INTEL) +/* + * Special NOIST entry point for VMX which invokes this on the kernel + * stack. asm_exc_nmi() requires an IST to work correctly vs. the NMI + * 'executing' marker. + * + * On 32bit this just uses the regular NMI entry point because 32-bit does + * not have ISTs. + */ +DECLARE_IDTENTRY(X86_TRAP_NMI, exc_nmi_noist); +#else +#define asm_exc_nmi_noist asm_exc_nmi +#endif + DECLARE_IDTENTRY_NMI(X86_TRAP_NMI, exc_nmi); #ifdef CONFIG_XEN_PV DECLARE_IDTENTRY_RAW(X86_TRAP_NMI, xenpv_exc_nmi); --- a/arch/x86/kernel/nmi.c +++ b/arch/x86/kernel/nmi.c @@ -524,6 +524,16 @@ nmi_restart: mds_user_clear_cpu_buffers(); } +#if defined(CONFIG_X86_64) && IS_ENABLED(CONFIG_KVM_INTEL) +DEFINE_IDTENTRY_RAW(exc_nmi_noist) +{ + exc_nmi(regs); +} +#endif +#if IS_MODULE(CONFIG_KVM_INTEL) +EXPORT_SYMBOL_GPL(asm_exc_nmi_noist); +#endif + void stop_nmi(void) { ignore_nmis++; --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -36,6 +36,7 @@ #include #include #include +#include #include #include #include @@ -6354,18 +6355,17 @@ static void vmx_apicv_post_state_restore void vmx_do_interrupt_nmi_irqoff(unsigned long entry); -static void handle_interrupt_nmi_irqoff(struct kvm_vcpu *vcpu, u32 intr_info) +static void handle_interrupt_nmi_irqoff(struct kvm_vcpu *vcpu, + unsigned long entry) { - unsigned int vector = intr_info & INTR_INFO_VECTOR_MASK; - gate_desc *desc = (gate_desc *)host_idt_base + vector; - kvm_before_interrupt(vcpu); - vmx_do_interrupt_nmi_irqoff(gate_offset(desc)); + vmx_do_interrupt_nmi_irqoff(entry); kvm_after_interrupt(vcpu); } static void handle_exception_nmi_irqoff(struct vcpu_vmx *vmx) { + const unsigned long nmi_entry = (unsigned long)asm_exc_nmi_noist; u32 intr_info = vmx_get_intr_info(&vmx->vcpu); /* if exit due to PF check for async PF */ @@ -6376,18 +6376,20 @@ static void handle_exception_nmi_irqoff( kvm_machine_check(); /* We need to handle NMIs before interrupts are enabled */ else if (is_nmi(intr_info)) - handle_interrupt_nmi_irqoff(&vmx->vcpu, intr_info); + handle_interrupt_nmi_irqoff(&vmx->vcpu, nmi_entry); } static void handle_external_interrupt_irqoff(struct kvm_vcpu *vcpu) { u32 intr_info = vmx_get_intr_info(vcpu); + unsigned int vector = intr_info & INTR_INFO_VECTOR_MASK; + gate_desc *desc = (gate_desc *)host_idt_base + vector; if (WARN_ONCE(!is_external_intr(intr_info), "KVM: unexpected VM-Exit interrupt info: 0x%x", intr_info)) return; - handle_interrupt_nmi_irqoff(vcpu, intr_info); + handle_interrupt_nmi_irqoff(vcpu, gate_offset(desc)); } static void vmx_handle_exit_irqoff(struct kvm_vcpu *vcpu)