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From: Jerome Glisse <jglisse@redhat.com>
To: "Adalbert Lazăr" <alazar@bitdefender.com>
Cc: "Matthew Wilcox" <willy@infradead.org>,
	kvm@vger.kernel.org, linux-mm@kvack.org,
	virtualization@lists.linux-foundation.org,
	"Paolo Bonzini" <pbonzini@redhat.com>,
	"Radim Krčmář" <rkrcmar@redhat.com>,
	"Konrad Rzeszutek Wilk" <konrad.wilk@oracle.com>,
	"Tamas K Lengyel" <tamas@tklengyel.com>,
	"Mathieu Tarral" <mathieu.tarral@protonmail.com>,
	"Samuel Laurén" <samuel.lauren@iki.fi>,
	"Patrick Colp" <patrick.colp@oracle.com>,
	"Jan Kiszka" <jan.kiszka@siemens.com>,
	"Stefan Hajnoczi" <stefanha@redhat.com>,
	"Weijiang Yang" <weijiang.yang@intel.com>,
	"Yu C" <yu.c.zhang@intel.com>,
	"Mihai Donțu" <mdontu@bitdefender.com>,
	"Mircea Cîrjaliu" <mcirjaliu@bitdefender.com>
Subject: Re: DANGER WILL ROBINSON, DANGER
Date: Thu, 15 Aug 2019 16:16:30 -0400
Message-ID: <20190815201630.GA25517@redhat.com> (raw)
In-Reply-To: <20190815191929.GA9253@redhat.com>

On Thu, Aug 15, 2019 at 03:19:29PM -0400, Jerome Glisse wrote:
> On Tue, Aug 13, 2019 at 02:01:35PM +0300, Adalbert Lazăr wrote:
> > On Fri, 9 Aug 2019 09:24:44 -0700, Matthew Wilcox <willy@infradead.org> wrote:
> > > On Fri, Aug 09, 2019 at 07:00:26PM +0300, Adalbert Lazăr wrote:
> > > > +++ b/include/linux/page-flags.h
> > > > @@ -417,8 +417,10 @@ PAGEFLAG(Idle, idle, PF_ANY)
> > > >   */
> > > >  #define PAGE_MAPPING_ANON	0x1
> > > >  #define PAGE_MAPPING_MOVABLE	0x2
> > > > +#define PAGE_MAPPING_REMOTE	0x4
> > > 
> > > Uh.  How do you know page->mapping would otherwise have bit 2 clear?
> > > Who's guaranteeing that?
> > > 
> > > This is an awfully big patch to the memory management code, buried in
> > > the middle of a gigantic series which almost guarantees nobody would
> > > look at it.  I call shenanigans.
> > > 
> > > > @@ -1021,7 +1022,7 @@ void page_move_anon_rmap(struct page *page, struct vm_area_struct *vma)
> > > >   * __page_set_anon_rmap - set up new anonymous rmap
> > > >   * @page:	Page or Hugepage to add to rmap
> > > >   * @vma:	VM area to add page to.
> > > > - * @address:	User virtual address of the mapping	
> > > > + * @address:	User virtual address of the mapping
> > > 
> > > And mixing in fluff changes like this is a real no-no.  Try again.
> > > 
> > 
> > No bad intentions, just overzealous.
> > I didn't want to hide anything from our patches.
> > Once we advance with the introspection patches related to KVM we'll be
> > back with the remote mapping patch, split and cleaned.
> 
> They are not bit left in struct page ! Looking at the patch it seems
> you want to have your own pin count just for KVM. This is bad, we are
> already trying to solve the GUP thing (see all various patchset about
> GUP posted recently).
> 
> You need to rethink how you want to achieve this. Why not simply a
> remote read()/write() into the process memory ie KVMI would call
> an ioctl that allow to read or write into a remote process memory
> like ptrace() but on steroid ...
> 
> Adding this whole big complex infrastructure without justification
> of why we need to avoid round trip is just too much really.

Thinking a bit more about this, you can achieve the same thing without
adding a single line to any mm code. Instead of having mmap with
PROT_NONE | MAP_LOCKED you have userspace mmap some kvm device file
(i am assuming this is something you already have and can control
the mmap callback).

So now kernel side you have a vma with a vm_operations_struct under
your control this means that everything you want to block mm wise
from within the inspector process can be block through those call-
backs (find_special_page() specificaly for which you have to return
NULL all the time).

To mirror target process memory you can use hmm_mirror, when you
populate the inspector process page table you use insert_pfn()
(mmap of the kvm device file must mark this vma as PFNMAP).

By following the hmm_mirror API, anytime the target process has
a change in its page table (ie virtual address -> page) you will
get a callback and all you have to do is clear the page table
within the inspector process and flush tlb (use zap_page_range).

On page fault within the inspector process the fault callback of
vm_ops will get call and from there you call hmm_mirror following
its API.

Oh also mark the vma with VM_WIPEONFORK to avoid any issue if the
inspector process use fork() (you could support fork but then you
would need to mark the vma as SHARED and use unmap_mapping_pages
instead of zap_page_range).


There everything you want to do with already upstream mm code.

Cheers,
Jérôme

  reply index

Thread overview: 133+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-09 15:59 [RFC PATCH v6 00/92] VM introspection Adalbert Lazăr
2019-08-09 15:59 ` [RFC PATCH v6 01/92] kvm: introduce KVMI (VM introspection subsystem) Adalbert Lazăr
2019-08-12 20:20   ` Sean Christopherson
2019-08-13  9:11     ` Paolo Bonzini
     [not found]     ` <5d52a5ae.1c69fb81.5c260.1573SMTPIN_ADDED_BROKEN@mx.google.com>
2019-08-13 12:09       ` Paolo Bonzini
2019-08-13 15:01         ` Sean Christopherson
2019-08-13 21:03           ` Paolo Bonzini
     [not found]           ` <5d53d8d1.1c69fb81.7d32.0bedSMTPIN_ADDED_BROKEN@mx.google.com>
2019-08-14 10:37             ` Paolo Bonzini
2019-08-09 15:59 ` [RFC PATCH v6 02/92] kvm: introspection: add basic ioctls (hook/unhook) Adalbert Lazăr
2019-08-13  8:44   ` Paolo Bonzini
2019-08-09 15:59 ` [RFC PATCH v6 03/92] kvm: introspection: add permission access ioctls Adalbert Lazăr
2019-08-09 15:59 ` [RFC PATCH v6 04/92] kvm: introspection: add the read/dispatch message function Adalbert Lazăr
2019-08-09 15:59 ` [RFC PATCH v6 05/92] kvm: introspection: add KVMI_GET_VERSION Adalbert Lazăr
2019-08-09 15:59 ` [RFC PATCH v6 06/92] kvm: introspection: add KVMI_CONTROL_CMD_RESPONSE Adalbert Lazăr
2019-08-13  9:15   ` Paolo Bonzini
2019-08-09 15:59 ` [RFC PATCH v6 07/92] kvm: introspection: honor the reply option when handling the KVMI_GET_VERSION command Adalbert Lazăr
2019-08-13  9:16   ` Paolo Bonzini
2019-08-09 15:59 ` [RFC PATCH v6 08/92] kvm: introspection: add KVMI_CHECK_COMMAND and KVMI_CHECK_EVENT Adalbert Lazăr
2019-08-09 15:59 ` [RFC PATCH v6 09/92] kvm: introspection: add KVMI_GET_GUEST_INFO Adalbert Lazăr
2019-08-09 15:59 ` [RFC PATCH v6 10/92] kvm: introspection: add KVMI_CONTROL_VM_EVENTS Adalbert Lazăr
2019-08-09 15:59 ` [RFC PATCH v6 11/92] kvm: introspection: add vCPU related data Adalbert Lazăr
2019-08-09 15:59 ` [RFC PATCH v6 12/92] kvm: introspection: add a jobs list to every introspected vCPU Adalbert Lazăr
2019-08-09 15:59 ` [RFC PATCH v6 13/92] kvm: introspection: make the vCPU wait even when its jobs list is empty Adalbert Lazăr
2019-08-13  8:43   ` Paolo Bonzini
2019-08-09 15:59 ` [RFC PATCH v6 14/92] kvm: introspection: handle introspection commands before returning to guest Adalbert Lazăr
2019-08-13  8:26   ` Paolo Bonzini
     [not found]     ` <5d52c10e.1c69fb81.26904.fd34SMTPIN_ADDED_BROKEN@mx.google.com>
2019-08-13 14:45       ` Paolo Bonzini
2019-08-09 15:59 ` [RFC PATCH v6 15/92] kvm: introspection: handle vCPU related introspection commands Adalbert Lazăr
2019-08-09 15:59 ` [RFC PATCH v6 16/92] kvm: introspection: handle events and event replies Adalbert Lazăr
2019-08-13  8:55   ` Paolo Bonzini
2019-08-09 15:59 ` [RFC PATCH v6 17/92] kvm: introspection: introduce event actions Adalbert Lazăr
2019-08-09 15:59 ` [RFC PATCH v6 18/92] kvm: introspection: add KVMI_EVENT_UNHOOK Adalbert Lazăr
2019-08-09 15:59 ` [RFC PATCH v6 19/92] kvm: introspection: add KVMI_EVENT_CREATE_VCPU Adalbert Lazăr
2019-08-09 15:59 ` [RFC PATCH v6 20/92] kvm: introspection: add KVMI_GET_VCPU_INFO Adalbert Lazăr
2019-08-09 15:59 ` [RFC PATCH v6 21/92] kvm: page track: add track_create_slot() callback Adalbert Lazăr
2019-08-09 15:59 ` [RFC PATCH v6 22/92] kvm: x86: provide all page tracking hooks with the guest virtual address Adalbert Lazăr
2019-08-09 15:59 ` [RFC PATCH v6 23/92] kvm: page track: add support for preread, prewrite and preexec Adalbert Lazăr
2019-08-09 15:59 ` [RFC PATCH v6 24/92] kvm: x86: wire in the preread/prewrite/preexec page trackers Adalbert Lazăr
2019-08-09 15:59 ` [RFC PATCH v6 25/92] kvm: x86: intercept the write access on sidt and other emulated instructions Adalbert Lazăr
2019-08-09 15:59 ` [RFC PATCH v6 26/92] kvm: x86: add kvm_mmu_nested_pagefault() Adalbert Lazăr
2019-08-13  8:12   ` Paolo Bonzini
2019-08-09 15:59 ` [RFC PATCH v6 27/92] kvm: introspection: use page track Adalbert Lazăr
2019-08-13  9:06   ` Paolo Bonzini
2019-08-09 15:59 ` [RFC PATCH v6 28/92] kvm: x86: consult the page tracking from kvm_mmu_get_page() and __direct_map() Adalbert Lazăr
2019-08-09 15:59 ` [RFC PATCH v6 29/92] kvm: introspection: add KVMI_CONTROL_EVENTS Adalbert Lazăr
2019-08-09 15:59 ` [RFC PATCH v6 30/92] kvm: x86: add kvm_spt_fault() Adalbert Lazăr
2019-08-09 15:59 ` [RFC PATCH v6 31/92] kvm: introspection: add KVMI_EVENT_PF Adalbert Lazăr
2019-08-09 15:59 ` [RFC PATCH v6 32/92] kvm: introspection: add KVMI_GET_PAGE_ACCESS Adalbert Lazăr
2019-08-09 15:59 ` [RFC PATCH v6 33/92] kvm: introspection: add KVMI_SET_PAGE_ACCESS Adalbert Lazăr
2019-08-09 15:59 ` [RFC PATCH v6 34/92] Documentation: Introduce EPT based Subpage Protection Adalbert Lazăr
2019-08-09 15:59 ` [RFC PATCH v6 35/92] KVM: VMX: Add control flags for SPP enabling Adalbert Lazăr
2019-08-09 15:59 ` [RFC PATCH v6 36/92] KVM: VMX: Implement functions for SPPT paging setup Adalbert Lazăr
2019-08-09 15:59 ` [RFC PATCH v6 37/92] KVM: VMX: Introduce SPP access bitmap and operation functions Adalbert Lazăr
2019-08-09 15:59 ` [RFC PATCH v6 38/92] KVM: VMX: Add init/set/get functions for SPP Adalbert Lazăr
2019-08-09 15:59 ` [RFC PATCH v6 39/92] KVM: VMX: Introduce SPP user-space IOCTLs Adalbert Lazăr
2019-08-09 15:59 ` [RFC PATCH v6 40/92] KVM: VMX: Handle SPP induced vmexit and page fault Adalbert Lazăr
2019-08-09 15:59 ` [RFC PATCH v6 41/92] KVM: MMU: Enable Lazy mode SPPT setup Adalbert Lazăr
2019-08-09 15:59 ` [RFC PATCH v6 42/92] KVM: MMU: Handle host memory remapping and reclaim Adalbert Lazăr
2019-08-09 15:59 ` [RFC PATCH v6 43/92] kvm: introspection: add KVMI_CONTROL_SPP Adalbert Lazăr
2019-08-09 15:59 ` [RFC PATCH v6 44/92] kvm: introspection: extend the internal database of tracked pages with write_bitmap info Adalbert Lazăr
2019-08-09 16:00 ` [RFC PATCH v6 45/92] kvm: introspection: add KVMI_GET_PAGE_WRITE_BITMAP Adalbert Lazăr
2019-08-09 16:00 ` [RFC PATCH v6 46/92] kvm: introspection: add KVMI_SET_PAGE_WRITE_BITMAP Adalbert Lazăr
2019-08-09 16:00 ` [RFC PATCH v6 47/92] kvm: introspection: add KVMI_READ_PHYSICAL and KVMI_WRITE_PHYSICAL Adalbert Lazăr
2019-08-09 16:00 ` [RFC PATCH v6 48/92] kvm: add kvm_vcpu_kick_and_wait() Adalbert Lazăr
2019-08-09 16:00 ` [RFC PATCH v6 49/92] kvm: introspection: add KVMI_PAUSE_VCPU and KVMI_EVENT_PAUSE_VCPU Adalbert Lazăr
2019-08-09 16:00 ` [RFC PATCH v6 50/92] kvm: introspection: add KVMI_GET_REGISTERS Adalbert Lazăr
2019-08-09 16:00 ` [RFC PATCH v6 51/92] kvm: introspection: add KVMI_SET_REGISTERS Adalbert Lazăr
2019-08-09 16:00 ` [RFC PATCH v6 52/92] kvm: introspection: add KVMI_GET_CPUID Adalbert Lazăr
2019-08-09 16:00 ` [RFC PATCH v6 53/92] kvm: introspection: add KVMI_INJECT_EXCEPTION + KVMI_EVENT_TRAP Adalbert Lazăr
2019-08-09 16:00 ` [RFC PATCH v6 54/92] kvm: introspection: add KVMI_CONTROL_CR and KVMI_EVENT_CR Adalbert Lazăr
2019-08-09 16:00 ` [RFC PATCH v6 55/92] kvm: introspection: add KVMI_CONTROL_MSR and KVMI_EVENT_MSR Adalbert Lazăr
2019-08-12 21:05   ` Sean Christopherson
2019-08-15  6:36     ` Nicusor CITU
2019-08-09 16:00 ` [RFC PATCH v6 56/92] kvm: x86: block any attempt to disable MSR interception if tracked by introspection Adalbert Lazăr
2019-08-09 16:00 ` [RFC PATCH v6 57/92] kvm: introspection: add KVMI_GET_XSAVE Adalbert Lazăr
2019-08-09 16:00 ` [RFC PATCH v6 58/92] kvm: introspection: add KVMI_GET_MTRR_TYPE Adalbert Lazăr
2019-08-09 16:00 ` [RFC PATCH v6 59/92] kvm: introspection: add KVMI_EVENT_XSETBV Adalbert Lazăr
2019-08-09 16:00 ` [RFC PATCH v6 60/92] kvm: x86: add kvm_arch_vcpu_set_guest_debug() Adalbert Lazăr
2019-08-09 16:00 ` [RFC PATCH v6 61/92] kvm: introspection: add KVMI_EVENT_BREAKPOINT Adalbert Lazăr
2019-08-09 16:00 ` [RFC PATCH v6 62/92] kvm: introspection: add KVMI_EVENT_HYPERCALL Adalbert Lazăr
2019-08-09 16:00 ` [RFC PATCH v6 63/92] kvm: introspection: add KVMI_EVENT_DESCRIPTOR Adalbert Lazăr
2019-08-09 16:00 ` [RFC PATCH v6 64/92] kvm: introspection: add single-stepping Adalbert Lazăr
2019-08-12 20:50   ` Sean Christopherson
2019-08-14 12:36     ` Nicusor CITU
2019-08-14 12:53       ` Paolo Bonzini
2019-08-09 16:00 ` [RFC PATCH v6 65/92] kvm: introspection: add KVMI_EVENT_SINGLESTEP Adalbert Lazăr
2019-08-09 16:00 ` [RFC PATCH v6 66/92] kvm: introspection: add custom input when single-stepping a vCPU Adalbert Lazăr
2019-08-09 16:00 ` [RFC PATCH v6 67/92] kvm: introspection: use single stepping on unimplemented instructions Adalbert Lazăr
2019-08-09 16:00 ` [RFC PATCH v6 68/92] kvm: x86: emulate a guest page table walk on SPT violations due to A/D bit updates Adalbert Lazăr
2019-08-09 16:00 ` [RFC PATCH v6 69/92] kvm: x86: keep the page protected if tracked by the introspection tool Adalbert Lazăr
2019-08-09 16:00 ` [RFC PATCH v6 70/92] kvm: x86: filter out access rights only when " Adalbert Lazăr
2019-08-13  9:08   ` Paolo Bonzini
2019-08-09 16:00 ` [RFC PATCH v6 71/92] mm: add support for remote mapping Adalbert Lazăr
2019-08-09 16:24   ` DANGER WILL ROBINSON, DANGER Matthew Wilcox
2019-08-13  9:29     ` Paolo Bonzini
2019-08-13 11:24       ` Matthew Wilcox
2019-08-13 12:02         ` Paolo Bonzini
     [not found]     ` <1565694095.D172a51.28640.@15f23d3a749365d981e968181cce585d2dcb3ffa>
2019-08-15 19:19       ` Jerome Glisse
2019-08-15 20:16         ` Jerome Glisse [this message]
2019-08-16 17:45           ` Jason Gunthorpe
2019-08-09 16:00 ` [RFC PATCH v6 72/92] kvm: introspection: add memory map/unmap support on the guest side Adalbert Lazăr
2019-08-09 16:00 ` [RFC PATCH v6 73/92] kvm: introspection: use remote mapping Adalbert Lazăr
2019-08-09 16:00 ` [RFC PATCH v6 74/92] kvm: x86: do not unconditionally patch the hypercall instruction during emulation Adalbert Lazăr
2019-08-13  9:20   ` Paolo Bonzini
     [not found]     ` <5d53f965.1c69fb81.cd952.035bSMTPIN_ADDED_BROKEN@mx.google.com>
2019-08-14 12:33       ` Paolo Bonzini
2019-08-09 16:00 ` [RFC PATCH v6 75/92] kvm: x86: disable gpa_available optimization in emulator_read_write_onepage() Adalbert Lazăr
2019-08-13  8:47   ` Paolo Bonzini
     [not found]     ` <5d52ca22.1c69fb81.4ceb8.e90bSMTPIN_ADDED_BROKEN@mx.google.com>
2019-08-13 14:35       ` Paolo Bonzini
2019-08-09 16:00 ` [RFC PATCH v6 76/92] kvm: x86: disable EPT A/D bits if introspection is present Adalbert Lazăr
2019-08-13  9:18   ` Paolo Bonzini
     [not found]     ` <0550f8d65bb97486e98d88255ea45d490da6b802.camel@bitdefender.com>
2019-08-13 21:05       ` Paolo Bonzini
2019-08-14  8:53         ` Mihai Donțu
2019-08-14 10:36           ` Paolo Bonzini
2019-08-09 16:00 ` [RFC PATCH v6 77/92] kvm: introspection: add trace functions Adalbert Lazăr
2019-08-09 16:00 ` [RFC PATCH v6 78/92] kvm: x86: add tracepoints for interrupt and exception injections Adalbert Lazăr
2019-08-09 16:00 ` [RFC PATCH v6 79/92] kvm: x86: emulate movsd xmm, m64 Adalbert Lazăr
2019-08-13  9:17   ` Paolo Bonzini
2019-08-09 16:00 ` [RFC PATCH v6 80/92] kvm: x86: emulate movss xmm, m32 Adalbert Lazăr
2019-08-09 16:00 ` [RFC PATCH v6 81/92] kvm: x86: emulate movq xmm, m64 Adalbert Lazăr
2019-08-09 16:00 ` [RFC PATCH v6 82/92] kvm: x86: emulate movq r, xmm Adalbert Lazăr
2019-08-09 16:00 ` [RFC PATCH v6 83/92] kvm: x86: emulate movd xmm, m32 Adalbert Lazăr
2019-08-09 16:00 ` [RFC PATCH v6 84/92] kvm: x86: enable the half part of movss, movsd, movups Adalbert Lazăr
2019-08-09 16:00 ` [RFC PATCH v6 85/92] kvm: x86: emulate lfence Adalbert Lazăr
2019-08-09 16:00 ` [RFC PATCH v6 86/92] kvm: x86: emulate xorpd xmm2/m128, xmm1 Adalbert Lazăr
2019-08-09 16:00 ` [RFC PATCH v6 87/92] kvm: x86: emulate xorps xmm/m128, xmm Adalbert Lazăr
2019-08-09 16:00 ` [RFC PATCH v6 88/92] kvm: x86: emulate fst/fstp m64fp Adalbert Lazăr
2019-08-09 16:00 ` [RFC PATCH v6 89/92] kvm: x86: make lock cmpxchg r, r/m atomic Adalbert Lazăr
2019-08-09 16:00 ` [RFC PATCH v6 90/92] kvm: x86: emulate lock cmpxchg8b atomically Adalbert Lazăr
2019-08-09 16:00 ` [RFC PATCH v6 91/92] kvm: x86: emulate lock cmpxchg16b m128 Adalbert Lazăr
2019-08-09 16:00 ` [RFC PATCH v6 92/92] kvm: x86: fallback to the single-step on multipage CMPXCHG emulation Adalbert Lazăr
2019-08-12 18:23 ` [RFC PATCH v6 00/92] VM introspection Sean Christopherson
2019-08-12 21:40 ` Sean Christopherson
2019-08-13  9:34 ` Paolo Bonzini

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