From: Ryan Roberts <ryan.roberts@arm.com>
To: Muhammad Usama Anjum <usama.anjum@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Ard Biesheuvel <ardb@kernel.org>,
Ilias Apalodimas <ilias.apalodimas@linaro.org>,
Andrey Ryabinin <ryabinin.a.a@gmail.com>,
Alexander Potapenko <glider@google.com>,
Andrey Konovalov <andreyknvl@gmail.com>,
Dmitry Vyukov <dvyukov@google.com>,
Vincenzo Frascino <vincenzo.frascino@arm.com>,
Andrew Morton <akpm@linux-foundation.org>,
David Hildenbrand <david@kernel.org>,
Lorenzo Stoakes <ljs@kernel.org>,
"Liam R. Howlett" <liam@infradead.org>,
Vlastimil Babka <vbabka@kernel.org>,
Mike Rapoport <rppt@kernel.org>,
Suren Baghdasaryan <surenb@google.com>,
Michal Hocko <mhocko@suse.com>
Cc: linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, linux-efi@vger.kernel.org,
kasan-dev@googlegroups.com, linux-mm@kvack.org
Subject: Re: [PATCH v2 3/6] arm64: use hw_pte_val for HW PTE loads and stores
Date: Thu, 24 Sep 2026 13:23:05 +0100 [thread overview]
Message-ID: <a37eb779-b180-450c-8691-8d31b9717f16@arm.com> (raw)
In-Reply-To: <20260922-pte0_arm-v2-3-a3f1ddff0a8a@arm.com>
On 22/09/2026 18:31, Muhammad Usama Anjum wrote:
> __ptep_get() returns a SW PTE value, while __set_pte_nosync() accepts
> one. When HW PTE storage uses a distinct hw_pte_t, reading or writing
> *ptep as a pte_t no longer satisfies those interfaces.
>
> Use hw_pte_val() to expose the pteval_t stored in either the hw_pte_t
> wrapper or its pte_t alias. __set_pte_nosync() writes pte_val(pte) to
> that storage, while __ptep_get() reads it and reconstructs a pte_t with
> __pte().
>
> This avoids imposing a generic conversion interface between HW and SW
> PTE representations, which may require architecture-specific context
> in the future.
>
> Signed-off-by: Muhammad Usama Anjum <usama.anjum@arm.com>
Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>
> ---
> arch/arm64/include/asm/pgtable.h | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
> index 4768ec59de555..ce6580ab63128 100644
> --- a/arch/arm64/include/asm/pgtable.h
> +++ b/arch/arm64/include/asm/pgtable.h
> @@ -360,7 +360,7 @@ static inline pte_t pte_clear_uffd(pte_t pte)
>
> static inline void __set_pte_nosync(hw_pte_t *ptep, pte_t pte)
> {
> - WRITE_ONCE(*ptep, pte);
> + WRITE_ONCE(hw_pte_val(*ptep), pte_val(pte));
> }
>
> static inline void __set_pte_complete(pte_t pte)
> @@ -381,7 +381,7 @@ static inline void __set_pte(hw_pte_t *ptep, pte_t pte)
>
> static inline pte_t __ptep_get(hw_pte_t *ptep)
> {
> - return READ_ONCE(*ptep);
> + return __pte(READ_ONCE(hw_pte_val(*ptep)));
> }
>
> extern void __sync_icache_dcache(pte_t pteval);
>
next prev parent reply other threads:[~2026-09-24 12:23 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-22 17:31 [PATCH v2 0/6] arm64: distinguish HW PTE pointers from SW PTE value pointers Muhammad Usama Anjum
2026-09-22 17:31 ` [PATCH v2 1/6] arm64: use hw_pte_t for HW PTE pointers Muhammad Usama Anjum
2026-09-24 12:29 ` Ryan Roberts
2026-09-22 17:31 ` [PATCH v2 2/6] arm64: use hw_pte_val for HW PTE atomics Muhammad Usama Anjum
2026-09-24 12:21 ` Ryan Roberts
2026-09-22 17:31 ` [PATCH v2 3/6] arm64: use hw_pte_val for HW PTE loads and stores Muhammad Usama Anjum
2026-09-24 12:23 ` Ryan Roberts [this message]
2026-09-22 17:31 ` [PATCH v2 4/6] arm64: use hw_pte_t for fixmap HW PTEs Muhammad Usama Anjum
2026-09-24 12:23 ` Ryan Roberts
2026-09-22 17:32 ` [PATCH v2 5/6] arm64: use HW PTE accessors in early map_range() Muhammad Usama Anjum
2026-09-22 17:32 ` [PATCH v2 6/6] arm64: enable a distinct type for HW PTEs Muhammad Usama Anjum
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