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d=arm.com; s=foss; t=1788414993; bh=DY/csfhtR5YKRxNjL+v1oA5BkKG7eZTRM1aibwpAHZw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=jy33b5SC5V6MzaplebERlNq+BFlc9TRUI4ImbVVvxIHngkHgnbxv0tzSSVfsfKXe3 im25pVnAOzQ05+j8tOYvftqbvXK5fe2BOtxDIf0L3t+U05xyFehzWRhUpXS4solPgf W74ItVMEC3SFf0Ed9IfLCQ/BgE1K1Fiix7t9JZPo= Date: Thu, 3 Sep 2026 11:26:29 +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 08/25] arm64: Initialize POR_EL1 register on cpu_resume() Message-ID: References: <20260818-kpkeys-v9-0-743ad31b2c8f@arm.com> <20260818-kpkeys-v9-8-743ad31b2c8f@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260818-kpkeys-v9-8-743ad31b2c8f@arm.com> X-Rspam-User: X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 5834B40002 X-Stat-Signature: hdrxcnhq56npuzyss8dyne1sdsd6eexs X-HE-Tag: 1788414994-117171 X-HE-Meta: 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 x13zuo6M dka4QrfId1txJj52GqgFEOqv7n1tyV3MH0BemNvHQTlV4npebJpb9aOCo8I1rDe3mAIgcxMWL/wDDHUq84OwtFmAFD+XXr922s2nZePdl8LRSIa9C91+ayNWZjRkVt0O5A54ZQTooH09HtvVrZUrX13mhTnJIopTVVjDcXmeuSrC2Mlt5o9r9paufVvJ0dtELrIfpOIi9QcNXGG75MJOQwlnsz6m2APrWXafjKlVoTKegVg54hu2F0Z5uZaBIhwjLxwCuZw9uCjMU/rvmoUEWnpLr9PmdvWfB3NrBvRbKm37dXtybrjtUln/L9e8NJrt61Vb4+jkWmBVQ4MDTjeD1RSr3qOZ6FQQ1BSZYW8/HncdlFz1v10I1fzb2lQh/CgulQUOySfJWBHQw92xB8ymdeUopW7YGSgukdeqDmoBqLrH9mzk= 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 03:08:50PM +0100, Kevin Brodsky wrote: > From: Yeoreum Yun > > The POR_EL1 register is reset to an unknown value after cpu_suspend(). > Since POR_EL1 always holds POR_EL1_INIT when entering cpu_suspend(), > initialize POR_EL1 with POR_EL1_INIT before cpu_do_resume(). > > Signed-off-by: Yeoreum Yun > Signed-off-by: Kevin Brodsky > --- > arch/arm64/kernel/sleep.S | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > diff --git a/arch/arm64/kernel/sleep.S b/arch/arm64/kernel/sleep.S > index f093cdf71be1..e0a6ad85cd24 100644 > --- a/arch/arm64/kernel/sleep.S > +++ b/arch/arm64/kernel/sleep.S > @@ -3,6 +3,7 @@ > #include > #include > #include > +#include > #include > > .text > @@ -134,6 +135,17 @@ SYM_FUNC_START(_cpu_resume) > /* load sp from context */ > ldr x2, [x0, #CPU_CTX_SP] > mov sp, x2 > + > +#ifdef CONFIG_ARM64_POE > +alternative_if_not ARM64_HAS_S1POE > + b .Lskip_por_set > +alternative_else_nop_endif > + mov_q x2, POR_EL1_INIT > + msr_s SYS_POR_EL1, x2 > + /* isb can be skipped since cpu_do_resume() will do it. */ > +.Lskip_por_set: > +#endif /* CONFIG_ARM64_POE */ Would it be better to move this under__cpu_setup ? -- Linu Cherian