From: Chao Peng <chao.p.peng@linux.intel.com>
To: Sean Christopherson <seanjc@google.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
linux-api@vger.kernel.org, qemu-devel@nongnu.org,
Paolo Bonzini <pbonzini@redhat.com>,
Jonathan Corbet <corbet@lwn.net>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
x86@kernel.org, "H . Peter Anvin" <hpa@zytor.com>,
Hugh Dickins <hughd@google.com>, Jeff Layton <jlayton@kernel.org>,
"J . Bruce Fields" <bfields@fieldses.org>,
Andrew Morton <akpm@linux-foundation.org>,
Mike Rapoport <rppt@kernel.org>,
Steven Price <steven.price@arm.com>,
"Maciej S . Szmigiero" <mail@maciej.szmigiero.name>,
Vlastimil Babka <vbabka@suse.cz>,
Vishal Annapurve <vannapurve@google.com>,
Yu Zhang <yu.c.zhang@linux.intel.com>,
"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
luto@kernel.org, jun.nakajima@intel.com, dave.hansen@intel.com,
ak@linux.intel.com, david@redhat.com
Subject: Re: [PATCH v5 12/13] KVM: Expose KVM_MEM_PRIVATE
Date: Tue, 12 Apr 2022 20:56:18 +0800 [thread overview]
Message-ID: <20220412125618.GC8013@chaop.bj.intel.com> (raw)
In-Reply-To: <YkNaPLVLk/pO0zjr@google.com>
On Tue, Mar 29, 2022 at 07:13:00PM +0000, Sean Christopherson wrote:
> On Thu, Mar 10, 2022, Chao Peng wrote:
> > KVM_MEM_PRIVATE is not exposed by default but architecture code can turn
> > on it by implementing kvm_arch_private_memory_supported().
> >
> > Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com>
> > Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com>
> > ---
> > include/linux/kvm_host.h | 1 +
> > virt/kvm/kvm_main.c | 24 +++++++++++++++++++-----
> > 2 files changed, 20 insertions(+), 5 deletions(-)
> >
> > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> > index 186b9b981a65..0150e952a131 100644
> > --- a/include/linux/kvm_host.h
> > +++ b/include/linux/kvm_host.h
> > @@ -1432,6 +1432,7 @@ bool kvm_arch_dy_has_pending_interrupt(struct kvm_vcpu *vcpu);
> > int kvm_arch_post_init_vm(struct kvm *kvm);
> > void kvm_arch_pre_destroy_vm(struct kvm *kvm);
> > int kvm_arch_create_vm_debugfs(struct kvm *kvm);
> > +bool kvm_arch_private_memory_supported(struct kvm *kvm);
> >
> > #ifndef __KVM_HAVE_ARCH_VM_ALLOC
> > /*
> > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> > index 52319f49d58a..df5311755a40 100644
> > --- a/virt/kvm/kvm_main.c
> > +++ b/virt/kvm/kvm_main.c
> > @@ -1485,10 +1485,19 @@ static void kvm_replace_memslot(struct kvm *kvm,
> > }
> > }
> >
> > -static int check_memory_region_flags(const struct kvm_userspace_memory_region *mem)
> > +bool __weak kvm_arch_private_memory_supported(struct kvm *kvm)
> > +{
> > + return false;
> > +}
> > +
> > +static int check_memory_region_flags(struct kvm *kvm,
> > + const struct kvm_userspace_memory_region *mem)
> > {
> > u32 valid_flags = KVM_MEM_LOG_DIRTY_PAGES;
> >
> > + if (kvm_arch_private_memory_supported(kvm))
> > + valid_flags |= KVM_MEM_PRIVATE;
> > +
> > #ifdef __KVM_HAVE_READONLY_MEM
> > valid_flags |= KVM_MEM_READONLY;
> > #endif
> > @@ -1900,7 +1909,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
> > int as_id, id;
> > int r;
> >
> > - r = check_memory_region_flags(mem);
> > + r = check_memory_region_flags(kvm, mem);
> > if (r)
> > return r;
> >
> > @@ -1913,10 +1922,12 @@ int __kvm_set_memory_region(struct kvm *kvm,
> > return -EINVAL;
> > if (mem->guest_phys_addr & (PAGE_SIZE - 1))
> > return -EINVAL;
> > - /* We can read the guest memory with __xxx_user() later on. */
> > if ((mem->userspace_addr & (PAGE_SIZE - 1)) ||
> > - (mem->userspace_addr != untagged_addr(mem->userspace_addr)) ||
> > - !access_ok((void __user *)(unsigned long)mem->userspace_addr,
> > + (mem->userspace_addr != untagged_addr(mem->userspace_addr)))
> > + return -EINVAL;
> > + /* We can read the guest memory with __xxx_user() later on. */
> > + if (!(mem->flags & KVM_MEM_PRIVATE) &&
> > + !access_ok((void __user *)(unsigned long)mem->userspace_addr,
>
> This should sanity check private_offset for private memslots. At a bare minimum,
> wrapping should be disallowed.
Will add this.
>
> > mem->memory_size))
> > return -EINVAL;
> > if (as_id >= KVM_ADDRESS_SPACE_NUM || id >= KVM_MEM_SLOTS_NUM)
> > @@ -1957,6 +1968,9 @@ int __kvm_set_memory_region(struct kvm *kvm,
> > if ((kvm->nr_memslot_pages + npages) < kvm->nr_memslot_pages)
> > return -EINVAL;
> > } else { /* Modify an existing slot. */
> > + /* Private memslots are immutable, they can only be deleted. */
> > + if (mem->flags & KVM_MEM_PRIVATE)
> > + return -EINVAL;
>
> These sanity checks belong in "KVM: Register private memslot to memory backing store",
> e.g. that patch is "broken" without the immutability restriction. It's somewhat moot
> because the code is unreachable, but it makes reviewing confusing/difficult.
>
> But rather than move the sanity checks back, I think I'd prefer to pull all of patch 10
> here. I think it also makes sense to drop "KVM: Use memfile_pfn_ops to obtain pfn for
> private pages" and add the pointer in "struct kvm_memory_slot" in patch "KVM: Extend the
> memslot to support fd-based private memory", with the use of the ops folded into
> "KVM: Handle page fault for private memory". Adding code to KVM and KVM-x86 in a single
> patch is ok, and overall makes things easier to review because the new helpers have a
> user right away, especially since there will be #ifdeffery.
>
> I.e. end up with something like:
>
> mm: Introduce memfile_notifier
> mm/shmem: Restrict MFD_INACCESSIBLE memory against RLIMIT_MEMLOCK
> KVM: Extend the memslot to support fd-based private memory
> KVM: Use kvm_userspace_memory_region_ext
> KVM: Add KVM_EXIT_MEMORY_ERROR exit
> KVM: Handle page fault for private memory
> KVM: Register private memslot to memory backing store
> KVM: Zap existing KVM mappings when pages changed in the private fd
> KVM: Enable and expose KVM_MEM_PRIVATE
Thanks for the suggestion. That makes sense.
Chao
>
> > if ((mem->userspace_addr != old->userspace_addr) ||
> > (npages != old->npages) ||
> > ((mem->flags ^ old->flags) & KVM_MEM_READONLY))
> > --
> > 2.17.1
> >
next prev parent reply other threads:[~2022-04-12 13:14 UTC|newest]
Thread overview: 117+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-10 14:08 [PATCH v5 00/13] KVM: mm: fd-based approach for supporting KVM guest private memory Chao Peng
2022-03-10 14:08 ` [PATCH v5 01/13] mm/memfd: Introduce MFD_INACCESSIBLE flag Chao Peng
2022-04-11 15:10 ` Kirill A. Shutemov
2022-04-12 13:11 ` Chao Peng
2022-04-23 5:43 ` Vishal Annapurve
2022-04-24 8:15 ` Chao Peng
2022-03-10 14:09 ` [PATCH v5 02/13] mm: Introduce memfile_notifier Chao Peng
2022-03-29 18:45 ` Sean Christopherson
2022-04-08 12:54 ` Chao Peng
[not found] ` <20220412143654.6313-1-hdanton@sina.com>
2022-04-13 6:47 ` Chao Peng
2022-03-10 14:09 ` [PATCH v5 03/13] mm/shmem: Support memfile_notifier Chao Peng
2022-03-10 23:08 ` Dave Chinner
2022-03-11 8:42 ` Chao Peng
2022-04-11 15:26 ` Kirill A. Shutemov
2022-04-12 13:12 ` Chao Peng
2022-04-19 22:40 ` Vishal Annapurve
2022-04-20 3:24 ` Chao Peng
2022-03-10 14:09 ` [PATCH v5 04/13] mm/shmem: Restrict MFD_INACCESSIBLE memory against RLIMIT_MEMLOCK Chao Peng
2022-04-07 16:05 ` Sean Christopherson
2022-04-07 17:09 ` Andy Lutomirski
2022-04-08 17:56 ` Sean Christopherson
2022-04-08 18:54 ` David Hildenbrand
2022-04-12 14:36 ` Jason Gunthorpe
2022-04-12 21:27 ` Andy Lutomirski
2022-04-13 16:30 ` David Hildenbrand
2022-04-13 16:24 ` David Hildenbrand
2022-04-13 17:52 ` Jason Gunthorpe
2022-04-25 14:07 ` David Hildenbrand
2022-04-08 13:02 ` Chao Peng
2022-04-11 15:34 ` Kirill A. Shutemov
2022-04-12 5:14 ` Hugh Dickins
2022-04-11 15:32 ` Kirill A. Shutemov
2022-04-12 13:39 ` Chao Peng
2022-04-12 19:28 ` Kirill A. Shutemov
2022-04-13 9:15 ` Chao Peng
2022-03-10 14:09 ` [PATCH v5 05/13] KVM: Extend the memslot to support fd-based private memory Chao Peng
2022-03-28 21:27 ` Sean Christopherson
2022-04-08 13:21 ` Chao Peng
2022-03-28 21:56 ` Sean Christopherson
2022-04-08 13:46 ` Chao Peng
2022-04-08 17:45 ` Sean Christopherson
2022-03-10 14:09 ` [PATCH v5 06/13] KVM: Use kvm_userspace_memory_region_ext Chao Peng
2022-03-28 22:26 ` Sean Christopherson
2022-04-08 13:58 ` Chao Peng
2022-03-10 14:09 ` [PATCH v5 07/13] KVM: Add KVM_EXIT_MEMORY_ERROR exit Chao Peng
2022-03-28 22:33 ` Sean Christopherson
2022-04-08 13:59 ` Chao Peng
2022-03-10 14:09 ` [PATCH v5 08/13] KVM: Use memfile_pfn_ops to obtain pfn for private pages Chao Peng
2022-03-28 23:56 ` Sean Christopherson
2022-04-08 14:07 ` Chao Peng
2022-04-28 12:37 ` Chao Peng
2022-03-10 14:09 ` [PATCH v5 09/13] KVM: Handle page fault for private memory Chao Peng
2022-03-29 1:07 ` Sean Christopherson
2022-04-12 12:10 ` Chao Peng
2022-03-10 14:09 ` [PATCH v5 10/13] KVM: Register private memslot to memory backing store Chao Peng
2022-03-29 19:01 ` Sean Christopherson
2022-04-12 12:40 ` Chao Peng
2022-03-10 14:09 ` [PATCH v5 11/13] KVM: Zap existing KVM mappings when pages changed in the private fd Chao Peng
2022-03-29 19:23 ` Sean Christopherson
2022-04-12 12:43 ` Chao Peng
2022-04-05 23:45 ` Michael Roth
2022-04-08 3:06 ` Sean Christopherson
2022-04-19 22:43 ` Vishal Annapurve
2022-04-20 3:17 ` Chao Peng
2022-03-10 14:09 ` [PATCH v5 12/13] KVM: Expose KVM_MEM_PRIVATE Chao Peng
2022-03-29 19:13 ` Sean Christopherson
2022-04-12 12:56 ` Chao Peng [this message]
2022-03-10 14:09 ` [PATCH v5 13/13] memfd_create.2: Describe MFD_INACCESSIBLE flag Chao Peng
2022-03-24 15:51 ` [PATCH v5 00/13] KVM: mm: fd-based approach for supporting KVM guest private memory Quentin Perret
2022-03-28 17:13 ` Sean Christopherson
2022-03-28 18:00 ` Quentin Perret
2022-03-28 18:58 ` Sean Christopherson
2022-03-29 17:01 ` Quentin Perret
2022-03-30 8:58 ` Steven Price
2022-03-30 10:39 ` Quentin Perret
2022-03-30 17:58 ` Sean Christopherson
2022-03-31 16:04 ` Andy Lutomirski
2022-04-01 14:59 ` Quentin Perret
2022-04-01 17:14 ` Sean Christopherson
2022-04-01 18:03 ` Quentin Perret
2022-04-01 18:24 ` Sean Christopherson
2022-04-01 19:56 ` Andy Lutomirski
2022-04-04 15:01 ` Quentin Perret
2022-04-04 17:06 ` Sean Christopherson
2022-04-04 22:04 ` Andy Lutomirski
2022-04-05 10:36 ` Quentin Perret
2022-04-05 17:51 ` Andy Lutomirski
2022-04-05 18:30 ` Sean Christopherson
2022-04-06 18:42 ` Andy Lutomirski
2022-04-06 13:05 ` Quentin Perret
2022-04-05 18:03 ` Sean Christopherson
2022-04-06 10:34 ` Quentin Perret
2022-04-22 10:56 ` Chao Peng
2022-04-22 11:06 ` Paolo Bonzini
2022-04-24 8:07 ` Chao Peng
2022-04-24 16:59 ` Andy Lutomirski
2022-04-25 13:40 ` Chao Peng
2022-04-25 14:52 ` Andy Lutomirski
2022-04-25 20:30 ` Sean Christopherson
2022-06-10 19:18 ` Andy Lutomirski
2022-06-10 19:27 ` Sean Christopherson
2022-04-28 12:29 ` Chao Peng
2022-05-03 11:12 ` Quentin Perret
2022-05-09 22:30 ` Michael Roth
2022-05-09 23:29 ` Sean Christopherson
2022-07-21 20:05 ` Gupta, Pankaj
2022-07-21 21:19 ` Sean Christopherson
2022-07-21 21:36 ` Gupta, Pankaj
2022-07-23 3:09 ` Andy Lutomirski
2022-07-25 9:19 ` Gupta, Pankaj
2022-03-30 16:18 ` Sean Christopherson
2022-03-28 20:16 ` Andy Lutomirski
2022-03-28 22:48 ` Nakajima, Jun
2022-03-29 0:04 ` Sean Christopherson
2022-04-08 21:35 ` Vishal Annapurve
2022-04-12 13:00 ` Chao Peng
2022-04-12 19:58 ` Kirill A. Shutemov
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