From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg1-f198.google.com (mail-pg1-f198.google.com [209.85.215.198]) by kanga.kvack.org (Postfix) with ESMTP id 77BDF6B5FD9 for ; Sat, 1 Sep 2018 22:21:10 -0400 (EDT) Received: by mail-pg1-f198.google.com with SMTP id q12-v6so8859993pgp.6 for ; Sat, 01 Sep 2018 19:21:10 -0700 (PDT) Received: from mga04.intel.com (mga04.intel.com. [192.55.52.120]) by mx.google.com with ESMTPS id d32-v6si13682201pla.93.2018.09.01.19.21.09 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sat, 01 Sep 2018 19:21:09 -0700 (PDT) Message-Id: <20180901124811.469883138@intel.com> Date: Sat, 01 Sep 2018 19:28:19 +0800 From: Fengguang Wu Subject: [RFC][PATCH 1/5] [PATCH 1/5] kvm: register in task_struct References: <20180901112818.126790961@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline; filename=0001-kvm-register-in-task_struct.patch Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Linux Memory Management List , Fengguang Wu , Peng DongX , Liu Jingqi , Dong Eddie , Dave Hansen , Huang Ying , Brendan Gregg , kvm@vger.kernel.org, LKML The added pointer will be used by the /proc/PID/idle_bitmap code to quickly identify QEMU task and walk EPT/NPT accordingly. For virtual machines, the A bits will be set in guest page tables and EPT/NPT, rather than the QEMU task page table. This costs 8 bytes in task_struct which could be wasteful for the majority normal tasks. The alternative is to add a flag only, and let it find the corresponding VM in kvm vm_list. Signed-off-by: Fengguang Wu --- include/linux/sched.h | 10 ++++++++++ virt/kvm/kvm_main.c | 1 + 2 files changed, 11 insertions(+) diff --git a/include/linux/sched.h b/include/linux/sched.h index 43731fe51c97..26c8549bbc28 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -38,6 +38,7 @@ struct cfs_rq; struct fs_struct; struct futex_pi_state; struct io_context; +struct kvm; struct mempolicy; struct nameidata; struct nsproxy; @@ -1179,6 +1180,9 @@ struct task_struct { /* Used by LSM modules for access restriction: */ void *security; #endif +#if IS_ENABLED(CONFIG_KVM) + struct kvm *kvm; +#endif /* * New fields for task_struct should be added above here, so that @@ -1898,4 +1902,10 @@ static inline void rseq_syscall(struct pt_regs *regs) #endif +#if IS_ENABLED(CONFIG_KVM) +static inline struct kvm *task_kvm(struct task_struct *t) { return t->kvm; } +#else +static inline struct kvm *task_kvm(struct task_struct *t) { return NULL; } +#endif + #endif diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 8b47507faab5..0c483720de8d 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -3892,6 +3892,7 @@ static void kvm_uevent_notify_change(unsigned int type, struct kvm *kvm) if (type == KVM_EVENT_CREATE_VM) { add_uevent_var(env, "EVENT=create"); kvm->userspace_pid = task_pid_nr(current); + current->kvm = kvm; } else if (type == KVM_EVENT_DESTROY_VM) { add_uevent_var(env, "EVENT=destroy"); } -- 2.15.0