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[87.19.3.42]) by smtp.gmail.com with ESMTPSA id gw6sm936959ejb.86.2021.05.20.06.36.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 20 May 2021 06:36:17 -0700 (PDT) From: Andrea Righi To: kernel-team@lists.ubuntu.com Subject: [SRU][F][PATCH 4/5] x86/kvm: Disable all PV features on crash Date: Thu, 20 May 2021 15:36:10 +0200 Message-Id: <20210520133611.39540-5-andrea.righi@canonical.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210520133611.39540-1-andrea.righi@canonical.com> References: <20210520133611.39540-1-andrea.righi@canonical.com> MIME-Version: 1.0 X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.20 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: "kernel-team" From: Vitaly Kuznetsov BugLink: https://bugs.launchpad.net/bugs/1920944 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 (backported from 3d6b84132d2a57b5a74100f6923a8feb679ac2ce) Signed-off-by: Andrea Righi --- arch/x86/include/asm/kvm_para.h | 5 ---- arch/x86/kernel/kvm.c | 44 ++++++++++++++++++++++++--------- arch/x86/kernel/kvmclock.c | 21 ---------------- 3 files changed, 32 insertions(+), 38 deletions(-) diff --git a/arch/x86/include/asm/kvm_para.h b/arch/x86/include/asm/kvm_para.h index a617fd360023..7ff8ad490a78 100644 --- a/arch/x86/include/asm/kvm_para.h +++ b/arch/x86/include/asm/kvm_para.h @@ -91,7 +91,6 @@ unsigned int kvm_arch_para_hints(void); void kvm_async_pf_task_wait(u32 token, int interrupt_kernel); void kvm_async_pf_task_wake(u32 token); u32 kvm_read_and_reset_pf_reason(void); -extern void kvm_disable_steal_time(void); void do_async_page_fault(struct pt_regs *regs, unsigned long error_code, unsigned long address); #ifdef CONFIG_PARAVIRT_SPINLOCKS @@ -126,10 +125,6 @@ static inline u32 kvm_read_and_reset_pf_reason(void) return 0; } -static inline void kvm_disable_steal_time(void) -{ - return; -} #endif #endif /* _ASM_X86_KVM_PARA_H */ diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c index 1d6e64a32278..af04f51810d1 100644 --- a/arch/x86/kernel/kvm.c +++ b/arch/x86/kernel/kvm.c @@ -34,6 +34,7 @@ #include #include #include +#include static int kvmapf = 1; @@ -352,6 +353,14 @@ static void kvm_pv_disable_apf(void) 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) { /* @@ -394,14 +403,6 @@ 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); @@ -548,13 +549,14 @@ static void __init kvm_smp_prepare_boot_cpu(void) kvm_spinlock_init(); } -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(); } @@ -573,7 +575,7 @@ static int kvm_cpu_down_prepare(unsigned int cpu) unsigned long flags; local_irq_save(flags); - kvm_guest_cpu_offline(); + kvm_guest_cpu_offline(false); local_irq_restore(flags); return 0; } @@ -614,7 +616,7 @@ static void kvm_flush_tlb_others(const struct cpumask *cpumask, static int kvm_suspend(void) { - kvm_guest_cpu_offline(); + kvm_guest_cpu_offline(false); return 0; } @@ -629,6 +631,20 @@ static struct syscore_ops kvm_syscore_ops = { .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 __init kvm_guest_init(void) { int i; @@ -672,6 +688,10 @@ 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); /* diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c index bd3962953f78..4a0802af2e3e 100644 --- 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; @@ -197,23 +196,6 @@ static void kvm_setup_secondary_clock(void) } #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); @@ -344,9 +326,6 @@ 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(); /*