From: Jason Gunthorpe <jgg@ziepe.ca>
To: David Hildenbrand <david@redhat.com>
Cc: Chao Peng <chao.p.peng@linux.intel.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
qemu-devel@nongnu.org, Paolo Bonzini <pbonzini@redhat.com>,
Jonathan Corbet <corbet@lwn.net>,
Sean Christopherson <seanjc@google.com>,
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>,
Yu Zhang <yu.c.zhang@linux.intel.com>,
"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
luto@kernel.org, john.ji@intel.com, susie.li@intel.com,
jun.nakajima@intel.com, dave.hansen@intel.com,
ak@linux.intel.com
Subject: Re: [RFC v2 PATCH 01/13] mm/shmem: Introduce F_SEAL_GUEST
Date: Mon, 22 Nov 2021 11:09:56 -0400 [thread overview]
Message-ID: <20211122150956.GS876299@ziepe.ca> (raw)
In-Reply-To: <d2b46b84-8930-4304-2946-4d4a16698b24@redhat.com>
On Mon, Nov 22, 2021 at 03:57:17PM +0100, David Hildenbrand wrote:
> On 22.11.21 15:01, Jason Gunthorpe wrote:
> > On Mon, Nov 22, 2021 at 02:35:49PM +0100, David Hildenbrand wrote:
> >> On 22.11.21 14:31, Jason Gunthorpe wrote:
> >>> On Mon, Nov 22, 2021 at 10:26:12AM +0100, David Hildenbrand wrote:
> >>>
> >>>> I do wonder if we want to support sharing such memfds between processes
> >>>> in all cases ... we most certainly don't want to be able to share
> >>>> encrypted memory between VMs (I heard that the kernel has to forbid
> >>>> that). It would make sense in the use case you describe, though.
> >>>
> >>> If there is a F_SEAL_XX that blocks every kind of new access, who
> >>> cares if userspace passes the FD around or not?
> >> I was imagining that you actually would want to do some kind of "change
> >> ownership". But yeah, the intended semantics and all use cases we have
> >> in mind are not fully clear to me yet. If it's really "no new access"
> >> (side note: is "access" the right word?) then sure, we can pass the fd
> >> around.
> >
> > What is "ownership" in a world with kvm and iommu are reading pages
> > out of the same fd?
>
> In the world of encrypted memory / TDX, KVM somewhat "owns" that memory
> IMHO (for example, only it can migrate or swap out these pages; it's
> might be debatable if the TDX module or KVM actually "own" these pages ).
Sounds like it is a swap provider more than an owner?
Jason
WARNING: multiple messages have this Message-ID (diff)
From: Jason Gunthorpe <jgg@ziepe.ca>
To: David Hildenbrand <david@redhat.com>
Cc: Wanpeng Li <wanpengli@tencent.com>,
jun.nakajima@intel.com, kvm@vger.kernel.org,
qemu-devel@nongnu.org, "J . Bruce Fields" <bfields@fieldses.org>,
linux-mm@kvack.org, "H . Peter Anvin" <hpa@zytor.com>,
Chao Peng <chao.p.peng@linux.intel.com>,
ak@linux.intel.com, Jonathan Corbet <corbet@lwn.net>,
Joerg Roedel <joro@8bytes.org>,
x86@kernel.org, Hugh Dickins <hughd@google.com>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
luto@kernel.org, Thomas Gleixner <tglx@linutronix.de>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Jim Mattson <jmattson@google.com>,
dave.hansen@intel.com, Sean Christopherson <seanjc@google.com>,
susie.li@intel.com, Jeff Layton <jlayton@kernel.org>,
linux-kernel@vger.kernel.org, john.ji@intel.com,
Yu Zhang <yu.c.zhang@linux.intel.com>,
linux-fsdevel@vger.kernel.org,
Paolo Bonzini <pbonzini@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Subject: Re: [RFC v2 PATCH 01/13] mm/shmem: Introduce F_SEAL_GUEST
Date: Mon, 22 Nov 2021 11:09:56 -0400 [thread overview]
Message-ID: <20211122150956.GS876299@ziepe.ca> (raw)
In-Reply-To: <d2b46b84-8930-4304-2946-4d4a16698b24@redhat.com>
On Mon, Nov 22, 2021 at 03:57:17PM +0100, David Hildenbrand wrote:
> On 22.11.21 15:01, Jason Gunthorpe wrote:
> > On Mon, Nov 22, 2021 at 02:35:49PM +0100, David Hildenbrand wrote:
> >> On 22.11.21 14:31, Jason Gunthorpe wrote:
> >>> On Mon, Nov 22, 2021 at 10:26:12AM +0100, David Hildenbrand wrote:
> >>>
> >>>> I do wonder if we want to support sharing such memfds between processes
> >>>> in all cases ... we most certainly don't want to be able to share
> >>>> encrypted memory between VMs (I heard that the kernel has to forbid
> >>>> that). It would make sense in the use case you describe, though.
> >>>
> >>> If there is a F_SEAL_XX that blocks every kind of new access, who
> >>> cares if userspace passes the FD around or not?
> >> I was imagining that you actually would want to do some kind of "change
> >> ownership". But yeah, the intended semantics and all use cases we have
> >> in mind are not fully clear to me yet. If it's really "no new access"
> >> (side note: is "access" the right word?) then sure, we can pass the fd
> >> around.
> >
> > What is "ownership" in a world with kvm and iommu are reading pages
> > out of the same fd?
>
> In the world of encrypted memory / TDX, KVM somewhat "owns" that memory
> IMHO (for example, only it can migrate or swap out these pages; it's
> might be debatable if the TDX module or KVM actually "own" these pages ).
Sounds like it is a swap provider more than an owner?
Jason
next prev parent reply other threads:[~2021-11-22 15:10 UTC|newest]
Thread overview: 99+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-19 13:47 [RFC v2 PATCH 00/13] KVM: mm: fd-based approach for supporting KVM guest private memory Chao Peng
2021-11-19 13:47 ` Chao Peng
2021-11-19 13:47 ` [RFC v2 PATCH 01/13] mm/shmem: Introduce F_SEAL_GUEST Chao Peng
2021-11-19 13:47 ` Chao Peng
2021-11-19 13:51 ` David Hildenbrand
2021-11-19 13:51 ` David Hildenbrand
2021-11-22 13:59 ` Kirill A. Shutemov
2021-11-22 13:59 ` Kirill A. Shutemov
2021-11-19 15:19 ` Jason Gunthorpe
2021-11-19 15:19 ` Jason Gunthorpe
2021-11-19 15:39 ` David Hildenbrand
2021-11-19 15:39 ` David Hildenbrand
2021-11-19 16:00 ` Jason Gunthorpe
2021-11-19 16:00 ` Jason Gunthorpe
2021-11-22 9:26 ` David Hildenbrand
2021-11-22 9:26 ` David Hildenbrand
2021-11-22 13:31 ` Jason Gunthorpe
2021-11-22 13:31 ` Jason Gunthorpe
2021-11-22 13:35 ` David Hildenbrand
2021-11-22 13:35 ` David Hildenbrand
2021-11-22 14:01 ` Jason Gunthorpe
2021-11-22 14:01 ` Jason Gunthorpe
2021-11-22 14:57 ` David Hildenbrand
2021-11-22 14:57 ` David Hildenbrand
2021-11-22 15:09 ` Jason Gunthorpe [this message]
2021-11-22 15:09 ` Jason Gunthorpe
2021-11-22 15:15 ` David Hildenbrand
2021-11-22 15:15 ` David Hildenbrand
2021-11-19 19:18 ` Sean Christopherson
2021-11-19 19:47 ` Jason Gunthorpe
2021-11-19 19:47 ` Jason Gunthorpe
2021-11-19 22:21 ` Sean Christopherson
2021-11-19 23:33 ` Jason Gunthorpe
2021-11-19 23:33 ` Jason Gunthorpe
2021-11-20 1:23 ` Sean Christopherson
2021-11-21 0:05 ` Jason Gunthorpe
2021-11-21 0:05 ` Jason Gunthorpe
2021-11-23 9:06 ` Paolo Bonzini
2021-11-23 9:06 ` Paolo Bonzini
2021-11-23 14:33 ` Chao Peng
2021-11-23 14:33 ` Chao Peng
2021-11-23 15:20 ` David Hildenbrand
2021-11-23 15:20 ` David Hildenbrand
2021-11-23 17:17 ` Jason Gunthorpe
2021-11-23 17:17 ` Jason Gunthorpe
2021-11-23 8:54 ` Paolo Bonzini
2021-11-23 8:54 ` Paolo Bonzini
2021-12-03 1:11 ` Andy Lutomirski
2021-12-03 1:11 ` Andy Lutomirski
2021-11-19 13:47 ` [RFC v2 PATCH 02/13] KVM: Add KVM_EXIT_MEMORY_ERROR exit Chao Peng
2021-11-19 13:47 ` Chao Peng
2021-11-19 13:47 ` [RFC v2 PATCH 03/13] KVM: Extend kvm_userspace_memory_region to support fd based memslot Chao Peng
2021-11-19 13:47 ` Chao Peng
2021-11-19 13:47 ` [RFC v2 PATCH 04/13] KVM: Add fd-based memslot data structure and utils Chao Peng
2021-11-19 13:47 ` Chao Peng
2021-11-23 8:41 ` Paolo Bonzini
2021-11-23 8:41 ` Paolo Bonzini
2021-11-23 14:30 ` Chao Peng
2021-11-23 14:30 ` Chao Peng
2021-11-19 13:47 ` [RFC v2 PATCH 05/13] KVM: Implement fd-based memory using new memfd interfaces Chao Peng
2021-11-19 13:47 ` Chao Peng
2021-11-19 13:47 ` [RFC v2 PATCH 06/13] KVM: Register/unregister memfd backed memslot Chao Peng
2021-11-19 13:47 ` Chao Peng
2021-11-25 16:55 ` Steven Price
2021-11-25 16:55 ` Steven Price
2021-11-19 13:47 ` [RFC v2 PATCH 07/13] KVM: Handle page fault for fd based memslot Chao Peng
2021-11-19 13:47 ` Chao Peng
2021-11-20 1:55 ` Yao Yuan
2021-11-20 1:55 ` Yao Yuan
2021-11-22 9:18 ` Chao Peng
2021-11-22 9:18 ` Chao Peng
2021-11-19 13:47 ` [RFC v2 PATCH 08/13] KVM: Rename hva memory invalidation code to cover fd-based offset Chao Peng
2021-11-19 13:47 ` Chao Peng
2021-11-19 13:47 ` [RFC v2 PATCH 09/13] KVM: Introduce kvm_memfd_invalidate_range Chao Peng
2021-11-19 13:47 ` Chao Peng
2021-11-23 8:46 ` Paolo Bonzini
2021-11-23 8:46 ` Paolo Bonzini
2021-11-23 14:24 ` Chao Peng
2021-11-23 14:24 ` Chao Peng
2021-11-19 13:47 ` [RFC v2 PATCH 10/13] KVM: Match inode for invalidation of fd-based slot Chao Peng
2021-11-19 13:47 ` Chao Peng
2021-11-19 13:47 ` [RFC v2 PATCH 11/13] KVM: Add kvm_map_gfn_range Chao Peng
2021-11-19 13:47 ` Chao Peng
2021-11-19 13:47 ` [RFC v2 PATCH 12/13] KVM: Introduce kvm_memfd_fallocate_range Chao Peng
2021-11-19 13:47 ` Chao Peng
2021-11-19 13:47 ` [RFC v2 PATCH 13/13] KVM: Enable memfd based page invalidation/fallocate Chao Peng
2021-11-19 13:47 ` Chao Peng
2021-11-22 14:16 ` Kirill A. Shutemov
2021-11-22 14:16 ` Kirill A. Shutemov
2021-11-23 1:06 ` Chao Peng
2021-11-23 1:06 ` Chao Peng
2021-11-23 9:09 ` Paolo Bonzini
2021-11-23 9:09 ` Paolo Bonzini
2021-11-23 15:00 ` Chao Peng
2021-11-23 15:00 ` Chao Peng
2021-11-23 8:51 ` Paolo Bonzini
2021-11-23 8:51 ` Paolo Bonzini
2021-12-03 1:08 ` [RFC v2 PATCH 00/13] KVM: mm: fd-based approach for supporting KVM guest private memory Andy Lutomirski
2021-12-03 1:08 ` Andy Lutomirski
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