From patchwork Tue Jun 8 18:28:03 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 457534 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=-18.9 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 CAD11C48BCD for ; Tue, 8 Jun 2021 19:20:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B812D61008 for ; Tue, 8 Jun 2021 19:20:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236998AbhFHTWE (ORCPT ); Tue, 8 Jun 2021 15:22:04 -0400 Received: from mail.kernel.org ([198.145.29.99]:39610 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237979AbhFHTSR (ORCPT ); Tue, 8 Jun 2021 15:18:17 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id B4672613D5; Tue, 8 Jun 2021 18:51:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1623178309; bh=DVBeyatvDebWri3AZG/X69iLC0EkFGCYVNKbWGyVWy4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Y9yMbukU9JHbFaRZECQ94oPwHbNlkTwoJ2sP670pu/rCs/S9NTWW4MCM8rMs52t6x h2yQokEywtHmz6REivwdUNcs84WnM5aYcfkI4Opk0DxN8air2NKGDp/mjNJ9r0ZK1b UscOCN1onI7+yCAJmL1pryGPvpNHB3ZEF5V0iUOY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Greg Kroah-Hartman , Vitaly Kuznetsov , Paolo Bonzini , Krzysztof Kozlowski Subject: [PATCH 5.12 153/161] x86/kvm: Disable all PV features on crash Date: Tue, 8 Jun 2021 20:28:03 +0200 Message-Id: <20210608175950.623160501@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210608175945.476074951@linuxfoundation.org> References: <20210608175945.476074951@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Vitaly Kuznetsov commit 3d6b84132d2a57b5a74100f6923a8feb679ac2ce upstream. Crash shutdown handler only disables kvmclock and steal time, other PV features remain active so we risk corrupting memory or getting some side-effects in kdump kernel. Move crash handler to kvm.c and unify with CPU offline. Signed-off-by: Vitaly Kuznetsov Message-Id: <20210414123544.1060604-5-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini Signed-off-by: Krzysztof Kozlowski Signed-off-by: Greg Kroah-Hartman --- arch/x86/include/asm/kvm_para.h | 6 ----- arch/x86/kernel/kvm.c | 44 +++++++++++++++++++++++++++++----------- arch/x86/kernel/kvmclock.c | 21 ------------------- 3 files changed, 32 insertions(+), 39 deletions(-) --- a/arch/x86/include/asm/kvm_para.h +++ b/arch/x86/include/asm/kvm_para.h @@ -92,7 +92,6 @@ unsigned int kvm_arch_para_hints(void); void kvm_async_pf_task_wait_schedule(u32 token); void kvm_async_pf_task_wake(u32 token); u32 kvm_read_and_reset_apf_flags(void); -void kvm_disable_steal_time(void); bool __kvm_handle_async_pf(struct pt_regs *regs, u32 token); DECLARE_STATIC_KEY_FALSE(kvm_async_pf_enabled); @@ -137,11 +136,6 @@ static inline u32 kvm_read_and_reset_apf return 0; } -static inline void kvm_disable_steal_time(void) -{ - return; -} - static __always_inline bool kvm_handle_async_pf(struct pt_regs *regs, u32 token) { return false; --- a/arch/x86/kernel/kvm.c +++ b/arch/x86/kernel/kvm.c @@ -38,6 +38,7 @@ #include #include #include +#include #include DEFINE_STATIC_KEY_FALSE(kvm_async_pf_enabled); @@ -375,6 +376,14 @@ static void kvm_pv_disable_apf(void) pr_info("Unregister pv shared memory for cpu %d\n", smp_processor_id()); } +static void kvm_disable_steal_time(void) +{ + if (!has_steal_clock) + return; + + wrmsr(MSR_KVM_STEAL_TIME, 0, 0); +} + static void kvm_pv_guest_cpu_reboot(void *unused) { /* @@ -417,14 +426,6 @@ static u64 kvm_steal_clock(int cpu) return steal; } -void kvm_disable_steal_time(void) -{ - if (!has_steal_clock) - return; - - wrmsr(MSR_KVM_STEAL_TIME, 0, 0); -} - static inline void __set_percpu_decrypted(void *ptr, unsigned long size) { early_set_memory_decrypted((unsigned long) ptr, size); @@ -461,13 +462,14 @@ static bool pv_tlb_flush_supported(void) static DEFINE_PER_CPU(cpumask_var_t, __pv_cpu_mask); -static void kvm_guest_cpu_offline(void) +static void kvm_guest_cpu_offline(bool shutdown) { kvm_disable_steal_time(); if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) wrmsrl(MSR_KVM_PV_EOI_EN, 0); kvm_pv_disable_apf(); - apf_task_wake_all(); + if (!shutdown) + apf_task_wake_all(); kvmclock_disable(); } @@ -613,7 +615,7 @@ static int kvm_cpu_down_prepare(unsigned unsigned long flags; local_irq_save(flags); - kvm_guest_cpu_offline(); + kvm_guest_cpu_offline(false); local_irq_restore(flags); return 0; } @@ -622,7 +624,7 @@ static int kvm_cpu_down_prepare(unsigned static int kvm_suspend(void) { - kvm_guest_cpu_offline(); + kvm_guest_cpu_offline(false); return 0; } @@ -637,6 +639,20 @@ static struct syscore_ops kvm_syscore_op .resume = kvm_resume, }; +/* + * After a PV feature is registered, the host will keep writing to the + * registered memory location. If the guest happens to shutdown, this memory + * won't be valid. In cases like kexec, in which you install a new kernel, this + * means a random memory location will be kept being written. + */ +#ifdef CONFIG_KEXEC_CORE +static void kvm_crash_shutdown(struct pt_regs *regs) +{ + kvm_guest_cpu_offline(true); + native_machine_crash_shutdown(regs); +} +#endif + static void kvm_flush_tlb_others(const struct cpumask *cpumask, const struct flush_tlb_info *info) { @@ -705,6 +721,10 @@ static void __init kvm_guest_init(void) kvm_guest_cpu_init(); #endif +#ifdef CONFIG_KEXEC_CORE + machine_ops.crash_shutdown = kvm_crash_shutdown; +#endif + register_syscore_ops(&kvm_syscore_ops); /* --- a/arch/x86/kernel/kvmclock.c +++ b/arch/x86/kernel/kvmclock.c @@ -20,7 +20,6 @@ #include #include #include -#include #include static int kvmclock __initdata = 1; @@ -203,23 +202,6 @@ static void kvm_setup_secondary_clock(vo } #endif -/* - * After the clock is registered, the host will keep writing to the - * registered memory location. If the guest happens to shutdown, this memory - * won't be valid. In cases like kexec, in which you install a new kernel, this - * means a random memory location will be kept being written. So before any - * kind of shutdown from our side, we unregister the clock by writing anything - * that does not have the 'enable' bit set in the msr - */ -#ifdef CONFIG_KEXEC_CORE -static void kvm_crash_shutdown(struct pt_regs *regs) -{ - native_write_msr(msr_kvm_system_time, 0, 0); - kvm_disable_steal_time(); - native_machine_crash_shutdown(regs); -} -#endif - void kvmclock_disable(void) { native_write_msr(msr_kvm_system_time, 0, 0); @@ -349,9 +331,6 @@ void __init kvmclock_init(void) #endif x86_platform.save_sched_clock_state = kvm_save_sched_clock_state; x86_platform.restore_sched_clock_state = kvm_restore_sched_clock_state; -#ifdef CONFIG_KEXEC_CORE - machine_ops.crash_shutdown = kvm_crash_shutdown; -#endif kvm_get_preset_lpj(); /*