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From: Jason Gunthorpe <jgg@nvidia.com>
To: Marc Zyngier <maz@kernel.org>
Cc: ankita@nvidia.com, oliver.upton@linux.dev, joey.gouly@arm.com,
	suzuki.poulose@arm.com, yuzenghui@huawei.com,
	catalin.marinas@arm.com, will@kernel.org, ryan.roberts@arm.com,
	shahuang@redhat.com, lpieralisi@kernel.org, david@redhat.com,
	aniketa@nvidia.com, cjia@nvidia.com, kwankhede@nvidia.com,
	targupta@nvidia.com, vsethi@nvidia.com, acurrid@nvidia.com,
	apopple@nvidia.com, jhubbard@nvidia.com, danw@nvidia.com,
	zhiw@nvidia.com, mochs@nvidia.com, udhoke@nvidia.com,
	dnigam@nvidia.com, alex.williamson@redhat.com,
	sebastianene@google.com, coltonlewis@google.com,
	kevin.tian@intel.com, yi.l.liu@intel.com, ardb@kernel.org,
	akpm@linux-foundation.org, gshan@redhat.com, linux-mm@kvack.org,
	ddutile@redhat.com, tabba@google.com, qperret@google.com,
	seanjc@google.com, kvmarm@lists.linux.dev,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v3 1/1] KVM: arm64: Allow cacheable stage 2 mapping using VMA flags
Date: Tue, 18 Mar 2025 09:57:51 -0300	[thread overview]
Message-ID: <20250318125751.GQ9311@nvidia.com> (raw)
In-Reply-To: <861pv5p0c3.wl-maz@kernel.org>

On Mon, Mar 10, 2025 at 11:54:52AM +0000, Marc Zyngier wrote:

> Which brings me to the next point: FWB is not discoverable from
> userspace. How do you expect a VMM to know what it can or cannot do?

If you add a check at memslot creation time then simply fail the
memslot.

There is nothing the VMM can do except completely fail. There is no
alternative path here where a cachable VMA can be safely made
non-cachable for the guest?

Jason


      parent reply	other threads:[~2025-03-18 12:58 UTC|newest]

Thread overview: 61+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-03-10 10:30 [PATCH v3 0/1] KVM: arm64: Map GPU device memory as cacheable ankita
2025-03-10 10:30 ` [PATCH v3 1/1] KVM: arm64: Allow cacheable stage 2 mapping using VMA flags ankita
2025-03-10 11:54   ` Marc Zyngier
2025-03-11  3:42     ` Ankit Agrawal
2025-03-11 11:18       ` Marc Zyngier
2025-03-11 12:07         ` Ankit Agrawal
2025-03-12  8:21           ` Marc Zyngier
2025-03-17  5:55             ` Ankit Agrawal
2025-03-17  9:27               ` Marc Zyngier
2025-03-17 19:54                 ` Catalin Marinas
2025-03-18  9:39                   ` Marc Zyngier
2025-03-18 12:55                     ` Jason Gunthorpe
2025-03-18 19:27                       ` Catalin Marinas
2025-03-18 19:35                         ` David Hildenbrand
2025-03-18 19:40                           ` Oliver Upton
2025-03-20  3:30                             ` bibo mao
2025-03-20  7:24                               ` bibo mao
2025-03-18 23:17                         ` Jason Gunthorpe
2025-03-19 18:03                           ` Catalin Marinas
2025-03-18 19:30                       ` Oliver Upton
2025-03-18 23:09                         ` Jason Gunthorpe
2025-03-19  7:01                           ` Oliver Upton
2025-03-19 17:04                             ` Jason Gunthorpe
2025-03-19 18:11                               ` Catalin Marinas
2025-03-19 19:22                                 ` Jason Gunthorpe
2025-03-19 21:48                                   ` Catalin Marinas
2025-03-26  8:31                                     ` Ankit Agrawal
2025-03-26 14:53                                       ` Sean Christopherson
2025-03-26 15:42                                         ` Marc Zyngier
2025-03-26 16:10                                           ` Sean Christopherson
2025-03-26 18:02                                             ` Marc Zyngier
2025-03-26 18:24                                               ` Sean Christopherson
2025-03-26 18:51                                                 ` Oliver Upton
2025-03-31 14:44                                                   ` Jason Gunthorpe
2025-03-31 14:56                                                 ` Jason Gunthorpe
2025-04-07 15:20                                                   ` Sean Christopherson
2025-04-07 16:15                                                     ` Jason Gunthorpe
2025-04-07 16:43                                                       ` Sean Christopherson
2025-04-16  8:51                                                         ` Ankit Agrawal
2025-04-21 16:03                                                           ` Ankit Agrawal
2025-04-22  7:49                                                           ` Oliver Upton
2025-04-22 13:54                                                             ` Jason Gunthorpe
2025-04-22 16:50                                                               ` Catalin Marinas
2025-04-22 17:03                                                                 ` Jason Gunthorpe
2025-04-22 21:28                                                                   ` Oliver Upton
2025-04-22 23:35                                                                     ` Jason Gunthorpe
2025-04-23 10:45                                                                       ` Catalin Marinas
2025-04-23 12:02                                                                         ` Jason Gunthorpe
2025-04-23 12:26                                                                           ` Catalin Marinas
2025-04-23 13:03                                                                             ` Jason Gunthorpe
2025-04-29 10:47                                                                               ` Ankit Agrawal
2025-04-29 13:27                                                                                 ` Catalin Marinas
2025-04-29 14:14                                                                                   ` Jason Gunthorpe
2025-04-29 16:03                                                                                     ` Catalin Marinas
2025-04-29 16:44                                                                                       ` Jason Gunthorpe
2025-04-29 18:09                                                                                         ` Catalin Marinas
2025-04-29 18:19                                                                                           ` Jason Gunthorpe
2025-05-07 15:26                                                                                             ` Ankit Agrawal
2025-05-09 12:47                                                                                               ` Catalin Marinas
2025-04-22 14:53                                                             ` Sean Christopherson
2025-03-18 12:57     ` Jason Gunthorpe [this message]

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