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From: Peter Xu <peterx@redhat.com>
To: Fengguang Wu <fengguang.wu@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Linux Memory Management List <linux-mm@kvack.org>,
	Nikita Leshenko <nikita.leshchenko@oracle.com>,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	kvm@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
	Fan Du <fan.du@intel.com>, Yao Yuan <yuan.yao@intel.com>,
	Peng Dong <dongx.peng@intel.com>,
	Huang Ying <ying.huang@intel.com>,
	Liu Jingqi <jingqi.liu@intel.com>,
	Dong Eddie <eddie.dong@intel.com>,
	Dave Hansen <dave.hansen@intel.com>,
	Zhang Yi <yi.z.zhang@linux.intel.com>,
	Dan Williams <dan.j.williams@intel.com>,
	Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [RFC][PATCH v2 14/21] kvm: register in mm_struct
Date: Sat, 2 Feb 2019 14:57:41 +0800	[thread overview]
Message-ID: <20190202065741.GA1011@xz-x1> (raw)
In-Reply-To: <20181226133351.894160986@intel.com>

On Wed, Dec 26, 2018 at 09:15:00PM +0800, Fengguang Wu wrote:
> VM is associated with an address space and not a specific thread.
> 
> >From Documentation/virtual/kvm/api.txt:
>    Only run VM ioctls from the same process (address space) that was used
>    to create the VM.

Hi, Fengguang,

AFAIU the commit message only explains why a kvm object needs to bind
to a single mm object (say, the reason why there is kvm->mm) however
not the reverse (say, the reason why there is mm->kvm), while the
latter is what this patch really needs?

I'm thinking whether it's legal for multiple VMs to run on a single mm
address space.  I don't see a limitation so far but it's very possible
I am just missing something there (if there is, IMHO they might be
something nice to put into the commit message?).  Thanks,

> 
> CC: Nikita Leshenko <nikita.leshchenko@oracle.com>
> CC: Christian Borntraeger <borntraeger@de.ibm.com>
> Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
> ---
>  include/linux/mm_types.h |   11 +++++++++++
>  virt/kvm/kvm_main.c      |    3 +++
>  2 files changed, 14 insertions(+)
> 
> --- linux.orig/include/linux/mm_types.h	2018-12-23 19:58:06.993417137 +0800
> +++ linux/include/linux/mm_types.h	2018-12-23 19:58:06.993417137 +0800
> @@ -27,6 +27,7 @@ typedef int vm_fault_t;
>  struct address_space;
>  struct mem_cgroup;
>  struct hmm;
> +struct kvm;
>  
>  /*
>   * Each physical page in the system has a struct page associated with
> @@ -496,6 +497,10 @@ struct mm_struct {
>  		/* HMM needs to track a few things per mm */
>  		struct hmm *hmm;
>  #endif
> +
> +#if IS_ENABLED(CONFIG_KVM)
> +		struct kvm *kvm;
> +#endif
>  	} __randomize_layout;
>  
>  	/*
> @@ -507,6 +512,12 @@ struct mm_struct {
>  
>  extern struct mm_struct init_mm;
>  
> +#if IS_ENABLED(CONFIG_KVM)
> +static inline struct kvm *mm_kvm(struct mm_struct *mm) { return mm->kvm; }
> +#else
> +static inline struct kvm *mm_kvm(struct mm_struct *mm) { return NULL; }
> +#endif
> +
>  /* Pointer magic because the dynamic array size confuses some compilers. */
>  static inline void mm_init_cpumask(struct mm_struct *mm)
>  {
> --- linux.orig/virt/kvm/kvm_main.c	2018-12-23 19:58:06.993417137 +0800
> +++ linux/virt/kvm/kvm_main.c	2018-12-23 19:58:06.993417137 +0800
> @@ -727,6 +727,7 @@ static void kvm_destroy_vm(struct kvm *k
>  	struct mm_struct *mm = kvm->mm;
>  
>  	kvm_uevent_notify_change(KVM_EVENT_DESTROY_VM, kvm);
> +	mm->kvm = NULL;
>  	kvm_destroy_vm_debugfs(kvm);
>  	kvm_arch_sync_events(kvm);
>  	spin_lock(&kvm_lock);
> @@ -3224,6 +3225,8 @@ static int kvm_dev_ioctl_create_vm(unsig
>  		fput(file);
>  		return -ENOMEM;
>  	}
> +
> +	kvm->mm->kvm = kvm;
>  	kvm_uevent_notify_change(KVM_EVENT_CREATE_VM, kvm);
>  
>  	fd_install(r, file);
> 
> 

Regards,

-- 
Peter Xu


  parent reply	other threads:[~2019-02-02  6:57 UTC|newest]

Thread overview: 99+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-12-26 13:14 [RFC][PATCH v2 00/21] PMEM NUMA node and hotness accounting/migration Fengguang Wu
2018-12-26 13:14 ` Fengguang Wu
2018-12-26 13:14 ` [RFC][PATCH v2 01/21] e820: cheat PMEM as DRAM Fengguang Wu
2018-12-26 13:14   ` Fengguang Wu
2018-12-27  3:41   ` Matthew Wilcox
2018-12-27  4:11     ` Fengguang Wu
2018-12-27  5:13       ` Dan Williams
2018-12-27  5:13         ` Dan Williams
2018-12-27 19:32         ` Yang Shi
2018-12-27 19:32           ` Yang Shi
2018-12-28  3:27           ` Fengguang Wu
2018-12-26 13:14 ` [RFC][PATCH v2 02/21] acpi/numa: memorize NUMA node type from SRAT table Fengguang Wu
2018-12-26 13:14   ` Fengguang Wu
2018-12-26 13:14 ` [RFC][PATCH v2 03/21] x86/numa_emulation: fix fake NUMA in uniform case Fengguang Wu
2018-12-26 13:14   ` Fengguang Wu
2018-12-26 13:14 ` [RFC][PATCH v2 04/21] x86/numa_emulation: pass numa node type to fake nodes Fengguang Wu
2018-12-26 13:14   ` Fengguang Wu
2018-12-26 13:14 ` [RFC][PATCH v2 05/21] mmzone: new pgdat flags for DRAM and PMEM Fengguang Wu
2018-12-26 13:14   ` Fengguang Wu
2018-12-26 13:14 ` [RFC][PATCH v2 06/21] x86,numa: update numa node type Fengguang Wu
2018-12-26 13:14   ` Fengguang Wu
2018-12-26 13:14 ` [RFC][PATCH v2 07/21] mm: export node type {pmem|dram} under /sys/bus/node Fengguang Wu
2018-12-26 13:14   ` Fengguang Wu
2018-12-26 13:14 ` [RFC][PATCH v2 08/21] mm: introduce and export pgdat peer_node Fengguang Wu
2018-12-26 13:14   ` Fengguang Wu
2018-12-27 20:07   ` Christopher Lameter
2018-12-27 20:07     ` Christopher Lameter
2018-12-28  2:31     ` Fengguang Wu
2018-12-26 13:14 ` [RFC][PATCH v2 09/21] mm: avoid duplicate peer target node Fengguang Wu
2018-12-26 13:14   ` Fengguang Wu
2018-12-26 13:14 ` [RFC][PATCH v2 10/21] mm: build separate zonelist for PMEM and DRAM node Fengguang Wu
2018-12-26 13:14   ` Fengguang Wu
2019-01-01  9:14   ` Aneesh Kumar K.V
2019-01-01  9:14     ` Aneesh Kumar K.V
2019-01-07  9:57     ` Fengguang Wu
2019-01-07 14:09       ` Aneesh Kumar K.V
2018-12-26 13:14 ` [RFC][PATCH v2 11/21] kvm: allocate page table pages from DRAM Fengguang Wu
2018-12-26 13:14   ` Fengguang Wu
2019-01-01  9:23   ` Aneesh Kumar K.V
2019-01-01  9:23     ` Aneesh Kumar K.V
2019-01-02  0:59     ` Yuan Yao
2019-01-02 16:47   ` Dave Hansen
2019-01-07 10:21     ` Fengguang Wu
2018-12-26 13:14 ` [RFC][PATCH v2 12/21] x86/pgtable: " Fengguang Wu
2018-12-26 13:14   ` Fengguang Wu
2018-12-26 13:14 ` [RFC][PATCH v2 13/21] x86/pgtable: dont check PMD accessed bit Fengguang Wu
2018-12-26 13:14   ` Fengguang Wu
2018-12-26 13:15 ` [RFC][PATCH v2 14/21] kvm: register in mm_struct Fengguang Wu
2018-12-26 13:15   ` Fengguang Wu
2019-02-02  6:57   ` Peter Xu [this message]
2019-02-02 10:50     ` Fengguang Wu
2019-02-04 10:46     ` Paolo Bonzini
2018-12-26 13:15 ` [RFC][PATCH v2 15/21] ept-idle: EPT walk for virtual machine Fengguang Wu
2018-12-26 13:15   ` Fengguang Wu
2018-12-26 13:15 ` [RFC][PATCH v2 16/21] mm-idle: mm_walk for normal task Fengguang Wu
2018-12-26 13:15   ` Fengguang Wu
2018-12-26 13:15 ` [RFC][PATCH v2 17/21] proc: introduce /proc/PID/idle_pages Fengguang Wu
2018-12-26 13:15   ` Fengguang Wu
2018-12-26 13:15 ` [RFC][PATCH v2 18/21] kvm-ept-idle: enable module Fengguang Wu
2018-12-26 13:15   ` Fengguang Wu
2018-12-26 13:15 ` [RFC][PATCH v2 19/21] mm/migrate.c: add move_pages(MPOL_MF_SW_YOUNG) flag Fengguang Wu
2018-12-26 13:15   ` Fengguang Wu
2018-12-26 13:15 ` [RFC][PATCH v2 20/21] mm/vmscan.c: migrate anon DRAM pages to PMEM node Fengguang Wu
2018-12-26 13:15   ` Fengguang Wu
2018-12-26 13:15 ` [RFC][PATCH v2 21/21] mm/vmscan.c: shrink anon list if can migrate to PMEM Fengguang Wu
2018-12-26 13:15   ` Fengguang Wu
2018-12-27 20:31 ` [RFC][PATCH v2 00/21] PMEM NUMA node and hotness accounting/migration Michal Hocko
2018-12-28  5:08   ` Fengguang Wu
2018-12-28  8:41     ` Michal Hocko
2018-12-28  9:42       ` Fengguang Wu
2018-12-28 12:15         ` Michal Hocko
2018-12-28 13:15           ` Fengguang Wu
2018-12-28 13:15             ` Fengguang Wu
2018-12-28 19:46             ` Michal Hocko
2018-12-28 13:31           ` Fengguang Wu
2018-12-28 18:28             ` Yang Shi
2018-12-28 18:28               ` Yang Shi
2018-12-28 19:52             ` Michal Hocko
2019-01-02 12:21               ` Jonathan Cameron
2019-01-02 12:21                 ` Jonathan Cameron
2019-01-08 14:52                 ` Michal Hocko
2019-01-10 15:53                   ` Jerome Glisse
2019-01-10 15:53                     ` Jerome Glisse
2019-01-10 16:42                     ` Michal Hocko
2019-01-10 17:42                       ` Jerome Glisse
2019-01-10 17:42                         ` Jerome Glisse
2019-01-10 18:26                   ` Jonathan Cameron
2019-01-10 18:26                     ` Jonathan Cameron
2019-01-28 17:42                 ` Jonathan Cameron
2019-01-28 17:42                   ` Jonathan Cameron
2019-01-29  2:00                   ` Fengguang Wu
2019-01-03 10:57               ` Mel Gorman
2019-01-10 16:25               ` Jerome Glisse
2019-01-10 16:25                 ` Jerome Glisse
2019-01-10 16:50                 ` Michal Hocko
2019-01-10 18:02                   ` Jerome Glisse
2019-01-10 18:02                     ` Jerome Glisse
2019-01-02 18:12       ` Dave Hansen
2019-01-08 14:53         ` Michal Hocko

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