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

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Message-ID: <20250429141437.GC2260709@nvidia.com>
Date: Tue, 29 Apr 2025 11:14:37 -0300
From: Jason Gunthorpe <jgg@...dia.com>
To: Catalin Marinas <catalin.marinas@....com>
Cc: Ankit Agrawal <ankita@...dia.com>,
	Oliver Upton <oliver.upton@...ux.dev>,
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Subject: Re: [PATCH v3 1/1] KVM: arm64: Allow cacheable stage 2 mapping using
 VMA flags

On Tue, Apr 29, 2025 at 02:27:02PM +0100, Catalin Marinas wrote:

> BTW, we should reject exec mappings as well (they probably fail for S1
> VFIO since set_pte_at() will try to do cache maintenance).

To be clear the S2 should leave the mapping as execute allowed
though. Only the VM knows how it will use this memory and VM's do
actually execute out of the cachable PFNMAP VMA today. The VM will set
any execute deny/allow on its S1 table according to how it uses the
memory.

Jason