From: "Manwaring, Derek" <derekmn@amazon.com>
To: David Hildenbrand <david@redhat.com>,
Elliot Berman <quic_eberman@quicinc.com>,
Andrew Morton <akpm@linux-foundation.org>,
"Paolo Bonzini" <pbonzini@redhat.com>,
Sean Christopherson <seanjc@google.com>,
"Fuad Tabba" <tabba@google.com>,
Patrick Roy <roypat@amazon.co.uk>, <qperret@google.com>,
Ackerley Tng <ackerleytng@google.com>
Cc: <linux-coco@lists.linux.dev>, <linux-arm-msm@vger.kernel.org>,
<linux-kernel@vger.kernel.org>, <linux-mm@kvack.org>,
<kvm@vger.kernel.org>, Alexander Graf <graf@amazon.de>,
Moritz Lipp <mlipp@amazon.at>,
"Claudio Canella" <canellac@amazon.at>
Subject: Re: [PATCH RFC 3/4] mm: guest_memfd: Add option to remove guest private memory from direct map
Date: Thu, 15 Aug 2024 12:08:05 -0700 [thread overview]
Message-ID: <3ea89d7f-fc29-4c80-a123-94673e526ca5@amazon.com> (raw)
In-Reply-To: <396fb134-f43e-4263-99a8-cfcef82bfd99@amazon.com>
On 2024-08-07 17:16-0700 Derek Manwaring wrote:
> All that said, we're also dependent on hardware not being subject to
> L1TF-style issues for the currently proposed non-CoCo method to be
> effective. We're simply clearing the Present bit while the physmap PTE
> still points to the guest physical page.
I was wrong here. The set_direct_map_invalid_noflush implementation
moves through __change_page_attr and pfn_pte, eventually arriving at
flip_protnone_guard where the PFN is inverted & thus no longer valid for
pages marked not present. So we do benefit from that prior work's extra
protection against L1TF.
Thank you for finding this, Patrick.
Derek
next prev parent reply other threads:[~2024-08-15 19:08 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-08-05 18:34 [PATCH RFC 0/4] mm: Introduce guest_memfd library Elliot Berman
2024-08-05 18:34 ` [PATCH RFC 1/4] mm: Introduce guest_memfd Elliot Berman
2024-08-06 13:48 ` David Hildenbrand
2024-08-08 18:39 ` Ackerley Tng
2024-08-05 18:34 ` [PATCH RFC 2/4] kvm: Convert to use mm/guest_memfd Elliot Berman
2024-08-05 18:34 ` [PATCH RFC 3/4] mm: guest_memfd: Add option to remove guest private memory from direct map Elliot Berman
2024-08-06 14:08 ` David Hildenbrand
[not found] ` <396fb134-f43e-4263-99a8-cfcef82bfd99@amazon.com>
2024-08-15 19:08 ` Manwaring, Derek [this message]
2024-08-06 15:39 ` Patrick Roy
[not found] ` <20240806104702482-0700.eberman@hu-eberman-lv.qualcomm.com>
[not found] ` <a43ae745-9907-425f-b09d-a49405d6bc2d@amazon.co.uk>
[not found] ` <90886a03-ad62-4e98-bc05-63875faa9ccc@amazon.co.uk>
[not found] ` <20240807113514068-0700.eberman@hu-eberman-lv.qualcomm.com>
[not found] ` <7166d51c-7757-44f2-a6f8-36da3e86bf90@amazon.co.uk>
2024-08-08 22:16 ` Elliot Berman
2024-08-09 15:02 ` Patrick Roy
2024-08-19 10:09 ` Mike Rapoport
2024-08-20 16:56 ` Elliot Berman
2024-08-21 14:26 ` Mike Rapoport
2024-08-05 18:34 ` [PATCH RFC 4/4] mm: guest_memfd: Add ability for mmap'ing pages Elliot Berman
2024-08-06 13:51 ` David Hildenbrand
[not found] ` <20240806093625007-0700.eberman@hu-eberman-lv.qualcomm.com>
[not found] ` <a7c5bfc0-1648-4ae1-ba08-e706596e014b@redhat.com>
2024-08-08 21:41 ` Elliot Berman
2024-08-08 21:55 ` David Hildenbrand
2024-08-08 22:26 ` Elliot Berman
2024-08-09 7:16 ` David Hildenbrand
2024-08-15 7:24 ` Fuad Tabba
2024-08-16 9:48 ` David Hildenbrand
2024-08-16 11:19 ` Fuad Tabba
2024-08-16 17:45 ` Ackerley Tng
2024-08-16 18:08 ` David Hildenbrand
2024-08-16 21:52 ` Ackerley Tng
2024-08-16 22:03 ` David Hildenbrand
2024-08-16 23:52 ` Elliot Berman
2024-08-06 15:48 ` Patrick Roy
2024-08-08 18:51 ` Ackerley Tng
2024-08-08 21:42 ` Elliot Berman
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