[PATCH] KVM: arm64: nested: Fix VA sign extension in VNCR/TLBI paths

[Greg KH]

On Mon, Sep 01, 2025 at 11:15:51PM +0900, Gyujeong Jin wrote:
> From: gyutrange <wlsrbwjd643 at naver.com>
> 
> VNCR/TLBI VA reconstruction currently uses bit 48 as the sign bit,
> but for 48-bit virtual addresses the correct sign bit is bit 47.
> Using 48 can mis-canonicalize addresses in the negative half and may
> cause missed invalidations.
> 
> Although VNCR_EL2 encodes other architectural fields (RESS, BADDR;
> see Arm ARM D24.2.206), sign_extend64() interprets its second argument
> as the index of the sign bit. Passing 48 prevents propagation of the
> canonical sign bit for 48-bit VAs.
> 
> Impact:
> - Incorrect canonicalization of VAs with bit47=1
> - Potential stale VNCR pseudo-TLB entries after TLBI or MMU notifier
> - Possible incorrect translation/permissions or DoS when combined
>   with other issues
> 
> Fixes: 667304740537 ("KVM: arm64: Mask out non-VA bits from TLBI VA* on VNCR invalidation")
> Cc: stable at vger.kernel.org
> Reported-by: DongHa Lee <gap-dev at example.com>
> Reported-by: Gyujeong Jin <wlsrbwjd7232 at gmail.com>
> Reported-by: Daehyeon Ko <4ncient at example.com>
> Reported-by: Geonha Lee <leegn4a at example.com>
> Reported-by: Hyungyu Oh <dqpc_lover at example.com>
> Reported-by: Jaewon Yang <r4mbb1 at example.com>

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