From: "David Hildenbrand (Arm)" <david@kernel.org>
To: Sean Christopherson <seanjc@google.com>,
Lorenzo Stoakes <ljs@kernel.org>
Cc: Pankaj Gupta <pankaj.gupta@amd.com>,
pbonzini@redhat.com, tglx@kernel.org, mingo@redhat.com,
dave.hansen@linux.intel.com, bp@alien8.de, x86@kernel.org,
thomas.lendacky@amd.com, hpa@zytor.com, yangge1116@126.com,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
stable@vger.kernel.org
Subject: Re: [PATCH] KVM: SEV: drop FOLL_LONGTERM for encrypted region registration
Date: Fri, 10 Jul 2026 18:38:23 +0200 [thread overview]
Message-ID: <ad784f05-b36c-4e91-9f17-4c5b826735d0@kernel.org> (raw)
In-Reply-To: <alEc0I0VysX1p5Nk@google.com>
>>
>> How long ago did I break this though? Why has it taken until now for this to be
>> reported? :) commit 8ac268436e6d ("mm/gup: disallow FOLL_LONGTERM GUP-nonfast
>> writing to file-backed mappings") is from May 2023 :)
>
> The break didn't come from your changes, it came from commit 7e066cb9b71a ("KVM:
> SEV: Use long-term pin when registering encrypted memory regions"). I suggested
> falling back to a non-longterm pin, but David didn't like that idea :-)
Yes, a longterm pin is a longterm pin.
If we don't write to the memory, why do we need a write pin? To make sure that
what we pin was actually unshared?
Well, FOLL_LONGTERM does that nowadays.
... so is maybe dropping the FOLL_WRITE sufficient?
--
Cheers,
David
next prev parent reply other threads:[~2026-07-10 16:38 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-01 14:45 [PATCH] KVM: SEV: drop FOLL_LONGTERM for encrypted region registration Pankaj Gupta
2026-07-01 16:25 ` David Hildenbrand (Arm)
2026-07-01 16:30 ` Sean Christopherson
2026-07-01 16:39 ` David Hildenbrand (Arm)
2026-07-01 16:56 ` Sean Christopherson
2026-07-06 12:03 ` Gupta, Pankaj
2026-07-07 10:04 ` David Hildenbrand (Arm)
2026-07-07 13:45 ` Gupta, Pankaj
2026-07-07 13:59 ` Sean Christopherson
2026-07-07 14:58 ` David Hildenbrand (Arm)
2026-07-08 16:35 ` Gupta, Pankaj
2026-07-09 14:28 ` Lorenzo Stoakes
2026-07-09 15:19 ` Gupta, Pankaj
2026-07-09 15:44 ` Lorenzo Stoakes
2026-07-10 12:57 ` David Hildenbrand (Arm)
2026-07-10 13:05 ` Lorenzo Stoakes
2026-07-10 15:37 ` David Hildenbrand (Arm)
2026-07-10 15:47 ` Sean Christopherson
2026-07-10 16:13 ` Lorenzo Stoakes
2026-07-10 16:24 ` Sean Christopherson
2026-07-10 16:38 ` David Hildenbrand (Arm) [this message]
2026-07-10 16:58 ` Lorenzo Stoakes
2026-07-10 13:06 ` Gupta, Pankaj
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