[PATCH 0/2] KVM: arm64: Reenable MTE on VHE guest exit

[Catalin Marinas]

On Mon, Oct 26, 2026 at 08:23:03AM +0000, Marc Zyngier wrote:
> Upton taking an exception, the CPU sets PSTATE.TCO to ensure that no
> tag fault can be taken while handling the exception. It is SW's job to
> eventually clear it when it is safe to do so.
> 
> It appears that when MTE is enabled and that the kernel is running
> VHE, nothing eventually clears TCO when we come back from the guest,
> so things such as KASAN_HW_TAGS will not work until the next exit to
> userspace.
> 
> This series aims at fixing this. This is not a stable candidate, as
> KASAN is only a debug option.
> 
> Marc Zyngier (2):
>   arm64: Add return value to mte_disable_tco_entry()
>   KVM: arm64: Reenable MTE tag checking on exit from guest when running
>     VHE
> 
>  arch/arm64/include/asm/mte.h    | 10 +++++++---
>  arch/arm64/kvm/hyp/vhe/switch.c |  7 +++++++
>  2 files changed, 14 insertions(+), 3 deletions(-)

For both patches:

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