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h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=pWr0i6pJSQywxTkp4y67uTu1Uz+4OfYZRorRJvi0pLgHJR8J81nwbJUoeDUDJ01lN gs+poUT8IJdSKiSw4my0FdJrFI4SIer8s1wLwlKM/GNiLPLLlPwuL4naZC7BLSWzF/ 6XZSpSTvGCygqlsuwPJ7YWAPSD/ktcswEvNtsNaE= Date: Thu, 3 Sep 2026 14:44:01 +0530 From: Linu Cherian To: Kevin Brodsky Cc: linux-hardening@vger.kernel.org, Andrew Morton , Andy Lutomirski , Catalin Marinas , Dave Hansen , "David Hildenbrand (Arm)" , Jann Horn , Jeff Xu , Joey Gouly , Kees Cook , Linus Walleij , Marc Zyngier , Mark Brown , Matthew Wilcox , Maxwell Bland , "Mike Rapoport (IBM)" , Peter Zijlstra , Pierre Langlois , =?iso-8859-1?Q?Pierre-Cl=E9ment?= Tosi , Quentin Perret , Rick Edgecombe , Ryan Roberts , Vlastimil Babka , Will Deacon , Yang Shi , Yeoreum Yun , linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, x86@kernel.org, Ira Weiny , Lorenzo Stoakes , Thomas Gleixner Subject: Re: [PATCH RFC v9 09/25] arm64: Enable kpkeys Message-ID: References: <20260818-kpkeys-v9-0-743ad31b2c8f@arm.com> <20260818-kpkeys-v9-9-743ad31b2c8f@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260818-kpkeys-v9-9-743ad31b2c8f@arm.com> X-Rspam-User: X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 569C2C0006 X-Stat-Signature: am9jrg9bj6sx8nphpug5t5c4r8on3ja5 X-HE-Tag: 1788426845-509596 X-HE-Meta: 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 0jgXGdQx /wb6clC+dhjE1vnmfWl1vMK+CXP4NBbRB4qCLeD//iAIKpXJqEb5KHnyLWWYpq3cPdwtrcEUAIKwphmwcjPcmYGWnE4uVxpsAFbiGKRC67TtjKT89mqQa1qGSYifqjwd1LiuIxGZIxWXB4gF812vbXv3J+wdnLrJHpMrqNCyLLz9KSLu/pZr8yY7wEafTxYZBwvXUsigU9CDmIhOMEP1in5ggZlIVy/ntfkoSesNuzrX86vpT4tTlQhEcmMnWYcYq7/rgmPXS9nUABl+F4KJNbY1FqcAqVukGVIPY4bwKhA4k+cepuFeiwlXsowLQaONq76SxTQoJw+YUAfr9NQSjcv/apuzM3bN9FDePy8MsT5M9XgA0uf1bT8N7CzFeiTr3Od/C Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Kevin, On Tue, Aug 18, 2026 at 03:08:51PM +0100, Kevin Brodsky wrote: > This is the final step to enable kpkeys on arm64. We enable > POE at EL1 by setting TCR2_EL1.POE, and initialise POR_EL1 to the > default value, enabling access to the default pkey/POIndex (0). > An ISB is added so that POE restrictions are enforced immediately. > > Having done this, we can now select ARCH_HAS_KPKEYS if ARM64_POE is > enabled. > > Signed-off-by: Kevin Brodsky > --- > arch/arm64/Kconfig | 1 + > arch/arm64/kernel/cpufeature.c | 5 ++++- > 2 files changed, 5 insertions(+), 1 deletion(-) > > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index b3afe0688919..0afa085c66be 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -2202,6 +2202,7 @@ config ARM64_POE > def_bool y > select ARCH_USES_HIGH_VMA_FLAGS > select ARCH_HAS_PKEYS > + select ARCH_HAS_KPKEYS > help > The Permission Overlay Extension is used to implement Memory > Protection Keys. Memory Protection Keys provides a mechanism for > diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c > index 9a22df0c5120..4f2f54007ed6 100644 > --- a/arch/arm64/kernel/cpufeature.c > +++ b/arch/arm64/kernel/cpufeature.c > @@ -76,6 +76,7 @@ > #include > #include > #include > +#include > > #include > #include > @@ -2463,8 +2464,10 @@ static void cpu_enable_mops(const struct arm64_cpu_capabilities *__unused) > #ifdef CONFIG_ARM64_POE > static void cpu_enable_poe(const struct arm64_cpu_capabilities *__unused) > { > - sysreg_clear_set(REG_TCR2_EL1, 0, TCR2_EL1_E0POE); > + write_sysreg_s(POR_EL1_INIT, SYS_POR_EL1); May be we could move this to __cpu_setup. Please see comments on Patch 8. -- Linu Cherian