[PATCH v2 4/5] KVM: arm64: Omit tag sync on stage-2 mappings of the zero page

[Catalin Marinas]

On Thu, Jun 04, 2026 at 05:11:56PM +0200, Ard Biesheuvel wrote:
> From: Ard Biesheuvel <ardb at kernel.org>
> 
> Commit
> 
>    f620d66af316 ("arm64: mte: Do not flag the zero page as PG_mte_tagged")
> 
> removed the PG_mte_tagged flag from the zero page, but missed a KVM code
> path that may set this flag on the zero page when it is used in a
> stage-2 CoW mapping of anonymous memory.
> 
> So disregard the zero page explicitly in sanitise_mte_tags().
> 
> Fixes: f620d66af316 ("arm64: mte: Do not flag the zero page as PG_mte_tagged")
> Cc: <stable at vger.kernel.org> # 5.10.x
> Suggested-by: Catalin Marinas <catalin.marinas at arm.com>
> Signed-off-by: Ard Biesheuvel <ardb at kernel.org>

Reviewed-by: Catalin Marinas <catalin.marinas at arm.com>