From: "Andy Lutomirski" <luto@kernel.org>
To: "Sean Christopherson" <seanjc@google.com>
Cc: "Chao Peng" <chao.p.peng@linux.intel.com>,
"kvm list" <kvm@vger.kernel.org>,
"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
"Linux API" <linux-api@vger.kernel.org>,
linux-doc@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>,
"the arch/x86 maintainers" <x86@kernel.org>,
"H. Peter Anvin" <hpa@zytor.com>,
"Hugh Dickins" <hughd@google.com>,
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"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>,
"Nakajima, Jun" <jun.nakajima@intel.com>,
"Dave Hansen" <dave.hansen@intel.com>,
"Andi Kleen" <ak@linux.intel.com>,
"David Hildenbrand" <david@redhat.com>,
aarcange@redhat.com, ddutile@redhat.com, dhildenb@redhat.com,
"Quentin Perret" <qperret@google.com>,
"Michael Roth" <michael.roth@amd.com>,
"Michal Hocko" <mhocko@suse.com>
Subject: Re: [PATCH v6 4/8] KVM: Extend the memslot to support fd-based private memory
Date: Sat, 21 May 2022 21:03:01 -0700 [thread overview]
Message-ID: <f0f9c66d-ae94-4eb1-b7e5-6a0a9f0d4798@www.fastmail.com> (raw)
In-Reply-To: <YofeZps9YXgtP3f1@google.com>
On Fri, May 20, 2022, at 11:31 AM, Sean Christopherson wrote:
> But a dedicated KVM ioctl() to add/remove shared ranges would be easy
> to implement
> and wouldn't necessarily even need to interact with the memslots. It
> could be a
> consumer of memslots, e.g. if we wanted to disallow registering regions
> without an
> associated memslot, but I think we'd want to avoid even that because
> things will
> get messy during memslot updates, e.g. if dirty logging is toggled or a
> shared
> memory region is temporarily removed then we wouldn't want to destroy
> the tracking.
>
> I don't think we'd want to use a bitmap, e.g. for a well-behaved guest, XArray
> should be far more efficient.
>
> One benefit to explicitly tracking this in KVM is that it might be
> useful for
> software-only protected VMs, e.g. KVM could mark a region in the XArray
> as "pending"
> based on guest hypercalls to share/unshare memory, and then complete
> the transaction
> when userspace invokes the ioctl() to complete the share/unshare.
That makes sense.
If KVM goes this route, perhaps there the allowed states for a GPA should include private, shared, and also private-and-shared. Then anyone who wanted to use the same masked GPA for shared and private on TDX could do so if they wanted to.
next prev parent reply other threads:[~2022-05-22 4:03 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-19 15:37 [PATCH v6 0/8] KVM: mm: fd-based approach for supporting KVM guest private memory Chao Peng
2022-05-19 15:37 ` [PATCH v6 1/8] mm: Introduce memfile_notifier Chao Peng
2022-05-19 15:37 ` [PATCH v6 2/8] mm/shmem: Support memfile_notifier Chao Peng
2022-05-19 15:37 ` [PATCH v6 3/8] mm/memfd: Introduce MFD_INACCESSIBLE flag Chao Peng
2022-05-31 19:15 ` Vishal Annapurve
2022-06-01 10:17 ` Chao Peng
2022-06-01 12:11 ` Gupta, Pankaj
2022-06-02 10:07 ` Chao Peng
2022-06-14 20:23 ` Sean Christopherson
2022-06-15 8:53 ` Chao Peng
2022-05-19 15:37 ` [PATCH v6 4/8] KVM: Extend the memslot to support fd-based private memory Chao Peng
2022-05-20 17:57 ` Andy Lutomirski
2022-05-20 18:31 ` Sean Christopherson
2022-05-22 4:03 ` Andy Lutomirski [this message]
2022-05-23 13:21 ` Chao Peng
2022-05-23 15:22 ` Sean Christopherson
2022-05-30 13:26 ` Chao Peng
2022-06-10 16:14 ` Sean Christopherson
2022-06-14 6:45 ` Chao Peng
2022-06-23 22:59 ` Michael Roth
2022-06-24 8:54 ` Chao Peng
2022-06-24 13:01 ` Michael Roth
2022-06-17 20:52 ` Sean Christopherson
2022-06-17 21:27 ` Sean Christopherson
2022-06-20 14:09 ` Chao Peng
2022-06-20 14:08 ` Chao Peng
2022-05-19 15:37 ` [PATCH v6 5/8] KVM: Add KVM_EXIT_MEMORY_FAULT exit Chao Peng
2022-05-19 15:37 ` [PATCH v6 6/8] KVM: Handle page fault for private memory Chao Peng
2022-06-17 21:30 ` Sean Christopherson
2022-06-20 14:16 ` Chao Peng
2022-08-19 0:40 ` Kirill A. Shutemov
2022-08-25 23:43 ` Sean Christopherson
2022-06-24 3:58 ` Nikunj A. Dadhania
2022-06-24 9:02 ` Chao Peng
2022-06-30 19:14 ` Vishal Annapurve
2022-06-30 22:21 ` Michael Roth
2022-07-01 1:21 ` Xiaoyao Li
2022-07-07 20:08 ` Sean Christopherson
2022-07-08 3:29 ` Xiaoyao Li
2022-07-20 23:08 ` Vishal Annapurve
2022-07-21 9:45 ` Chao Peng
2022-05-19 15:37 ` [PATCH v6 7/8] KVM: Enable and expose KVM_MEM_PRIVATE Chao Peng
2022-06-23 22:07 ` Michael Roth
2022-06-24 8:43 ` Chao Peng
2022-05-19 15:37 ` [PATCH v6 8/8] memfd_create.2: Describe MFD_INACCESSIBLE flag Chao Peng
2022-06-06 20:09 ` [PATCH v6 0/8] KVM: mm: fd-based approach for supporting KVM guest private memory Vishal Annapurve
2022-06-07 6:57 ` Chao Peng
2022-06-08 0:55 ` Marc Orr
2022-06-08 2:18 ` Chao Peng
2022-06-08 19:37 ` Vishal Annapurve
2022-06-09 20:29 ` Sean Christopherson
2022-06-14 7:28 ` Chao Peng
2022-06-14 17:37 ` Andy Lutomirski
2022-06-14 19:08 ` Sean Christopherson
2022-06-14 20:59 ` Andy Lutomirski
2022-06-15 9:17 ` Chao Peng
2022-06-15 14:29 ` Sean Christopherson
2022-06-10 0:11 ` Marc Orr
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