linux-kernel - Re: [PATCH v3 1/1] KVM: arm64: Allow cacheable stage 2 mapping using VMA flags

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <20250423130323.GE1648741@nvidia.com>
Date: Wed, 23 Apr 2025 10:03:23 -0300
From: Jason Gunthorpe <jgg@...dia.com>
To: Catalin Marinas <catalin.marinas@....com>
Cc: Oliver Upton <oliver.upton@...ux.dev>,
	Ankit Agrawal <ankita@...dia.com>,
	Sean Christopherson <seanjc@...gle.com>,
	Marc Zyngier <maz@...nel.org>,
	"joey.gouly@....com" <joey.gouly@....com>,
	"suzuki.poulose@....com" <suzuki.poulose@....com>,
	"yuzenghui@...wei.com" <yuzenghui@...wei.com>,
	"will@...nel.org" <will@...nel.org>,
	"ryan.roberts@....com" <ryan.roberts@....com>,
	"shahuang@...hat.com" <shahuang@...hat.com>,
	"lpieralisi@...nel.org" <lpieralisi@...nel.org>,
	"david@...hat.com" <david@...hat.com>,
	Aniket Agashe <aniketa@...dia.com>, Neo Jia <cjia@...dia.com>,
	Kirti Wankhede <kwankhede@...dia.com>,
	"Tarun Gupta (SW-GPU)" <targupta@...dia.com>,
	Vikram Sethi <vsethi@...dia.com>, Andy Currid <acurrid@...dia.com>,
	Alistair Popple <apopple@...dia.com>,
	John Hubbard <jhubbard@...dia.com>, Dan Williams <danw@...dia.com>,
	Zhi Wang <zhiw@...dia.com>, Matt Ochs <mochs@...dia.com>,
	Uday Dhoke <udhoke@...dia.com>, Dheeraj Nigam <dnigam@...dia.com>,
	Krishnakant Jaju <kjaju@...dia.com>,
	"alex.williamson@...hat.com" <alex.williamson@...hat.com>,
	"sebastianene@...gle.com" <sebastianene@...gle.com>,
	"coltonlewis@...gle.com" <coltonlewis@...gle.com>,
	"kevin.tian@...el.com" <kevin.tian@...el.com>,
	"yi.l.liu@...el.com" <yi.l.liu@...el.com>,
	"ardb@...nel.org" <ardb@...nel.org>,
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	"gshan@...hat.com" <gshan@...hat.com>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"ddutile@...hat.com" <ddutile@...hat.com>,
	"tabba@...gle.com" <tabba@...gle.com>,
	"qperret@...gle.com" <qperret@...gle.com>,
	"kvmarm@...ts.linux.dev" <kvmarm@...ts.linux.dev>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v3 1/1] KVM: arm64: Allow cacheable stage 2 mapping using
 VMA flags

On Wed, Apr 23, 2025 at 01:26:51PM +0100, Catalin Marinas wrote:

> Ah, good point. So we want a strict cacheable mapping even if there is
> no user/VMM mapping alias. Is it because KVM cannot do cache maintenance
> on the PFNMAP or because the device does not support other memory types?
> Both valid reasons though.

Lack of cache maintenance is the main problem for the vfio-grace device

> In this case KVM still needs to know the properties of the device. Not
> sure how it could best do this without a vma.

Well, the idea I hope to succeed with would annotate this kind of
information inside the page list that would be exchanged through the
FD.

There is an monstrous thread here about this topic:

https://lore.kernel.org/all/20250107142719.179636-1-yilun.xu@linux.intel.com/

I can't find it in the huge thread but I did explain some thoughts on
how it could work

Jason