Re: [PATCH v7 11/45] arm64: RME: RTT tear down

Gavin Shan
2025-03-03T06:26:01Z

On 2/14/25 2:13 AM, Steven Price wrote:
> The RMM owns the stage 2 page tables for a realm, and KVM must request
> that the RMM creates/destroys entries as necessary. The physical pages
> to store the page tables are delegated to the realm as required, and can
> be undelegated when no longer used.
>
> Creating new RTTs is the easy part, tearing down is a little more
> tricky. The result of realm_rtt_destroy() can be used to effectively
> walk the tree and destroy the entries (undelegating pages that were
> given to the realm).
>
> Signed-off-by: Steven Price <steven.price@arm.com>
> Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
> ---
> Changes since v6:
> * Move rme_rtt_level_mapsize() and supporting defines from kvm_rme.h
> into rme.c as they are only used in that file.
> Changes since v5:
> * Rename some RME_xxx defines to do with page sizes as RMM_xxx - they are
> a property of the RMM specification not the RME architecture.
> Changes since v2:
> * Moved {alloc,free}_delegated_page() and ensure_spare_page() to a
> later patch when they are actually used.
> * Some simplifications now rmi_xxx() functions allow NULL as an output
> parameter.
> * Improved comments and code layout.
> ---
> arch/arm64/include/asm/kvm_rme.h | 7 ++
> arch/arm64/kvm/mmu.c | 6 +-
> arch/arm64/kvm/rme.c | 128 +++++++++++++++++++++++++++++++
> 3 files changed, 138 insertions(+), 3 deletions(-)

Reviewed-by: Gavin Shan <gshan@redhat.com>