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a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1721922238; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=L0867hIucP5TeDZT7yiZkXdSK7Apv2mhkf3nEKcfjM8=; b=NlL3adqe2KXTBsVsIaQ50vSbtpkbumxxsfSFCy2haeldet3K+LnguVvw8YSwa2qcoCc0KV 31yw1l7DyEEhS0JjWIoccbP2f/LkO7Yq4k7h5pcLr/sFkGYEjlP6UjoQkMNoXuWNAiQgUq CIh2VwVKjkwn3L297Ipvaw5ILDwf868= Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id A92B61007; Thu, 25 Jul 2024 08:44:47 -0700 (PDT) Received: from e133380.arm.com (e133380.arm.com [10.1.197.55]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 312CB3F766; Thu, 25 Jul 2024 08:44:19 -0700 (PDT) Date: Thu, 25 Jul 2024 16:44:13 +0100 From: Dave Martin To: Joey Gouly Cc: linux-arm-kernel@lists.infradead.org, akpm@linux-foundation.org, aneesh.kumar@kernel.org, aneesh.kumar@linux.ibm.com, bp@alien8.de, broonie@kernel.org, catalin.marinas@arm.com, christophe.leroy@csgroup.eu, dave.hansen@linux.intel.com, hpa@zytor.com, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, maz@kernel.org, mingo@redhat.com, mpe@ellerman.id.au, naveen.n.rao@linux.ibm.com, npiggin@gmail.com, oliver.upton@linux.dev, shuah@kernel.org, szabolcs.nagy@arm.com, tglx@linutronix.de, will@kernel.org, x86@kernel.org, kvmarm@lists.linux.dev Subject: Re: [PATCH v4 04/29] arm64: disable trapping of POR_EL0 to EL2 Message-ID: References: <20240503130147.1154804-1-joey.gouly@arm.com> <20240503130147.1154804-5-joey.gouly@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240503130147.1154804-5-joey.gouly@arm.com> X-Stat-Signature: z1oqw5d8s94pmh8ugq3qukmcw44ofjbj X-Rspamd-Queue-Id: 4463C16001D X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1721922263-975253 X-HE-Meta: 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 w6lVwfup uX3KqMMB6JsO4gVHOYekjhUhl0KaD8xCHfSRsvudLYqfqAd7/MCAzG+lxIBouEVGV1HS0Z6/mCZ2U/eDl0cX1fqgW1R2ym5+cKNuI1ANFQxp3pvrjLvrogR0aChKNFyMtnOYrF2ef56hKNcZ5obIprfKWBcORztaD/QlogjwgwBRtSPkKTIh4Btw/3yg6W8VZfCvdryG1gFjyvLaGLWz1bjum4dMburCrwyxKXkiEv5cFALQZGKkj6tMD82QtRHR+tVxOy7w6DtgM/ZqswniU0d2u8oJHWAq/qZbsqs54LSMXpW7lQjr7TqiUQg== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hi, On Fri, May 03, 2024 at 02:01:22PM +0100, Joey Gouly wrote: > Allow EL0 or EL1 to access POR_EL0 without being trapped to EL2. > > Signed-off-by: Joey Gouly > Cc: Catalin Marinas > Cc: Will Deacon > Acked-by: Catalin Marinas > --- > arch/arm64/include/asm/el2_setup.h | 10 +++++++++- > 1 file changed, 9 insertions(+), 1 deletion(-) > > diff --git a/arch/arm64/include/asm/el2_setup.h b/arch/arm64/include/asm/el2_setup.h > index b7afaa026842..df5614be4b70 100644 > --- a/arch/arm64/include/asm/el2_setup.h > +++ b/arch/arm64/include/asm/el2_setup.h > @@ -184,12 +184,20 @@ > .Lset_pie_fgt_\@: > mrs_s x1, SYS_ID_AA64MMFR3_EL1 > ubfx x1, x1, #ID_AA64MMFR3_EL1_S1PIE_SHIFT, #4 > - cbz x1, .Lset_fgt_\@ > + cbz x1, .Lset_poe_fgt_\@ > > /* Disable trapping of PIR_EL1 / PIRE0_EL1 */ > orr x0, x0, #HFGxTR_EL2_nPIR_EL1 > orr x0, x0, #HFGxTR_EL2_nPIRE0_EL1 > > +.Lset_poe_fgt_\@: > + mrs_s x1, SYS_ID_AA64MMFR3_EL1 > + ubfx x1, x1, #ID_AA64MMFR3_EL1_S1POE_SHIFT, #4 > + cbz x1, .Lset_fgt_\@ > + > + /* Disable trapping of POR_EL0 */ > + orr x0, x0, #HFGxTR_EL2_nPOR_EL0 Do I understand correctly that this is just to allow the host to access its own POR_EL0, before (or unless) KVM starts up? KVM always overrides all the EL2 trap controls while running a guest, right? We don't want this bit still set when running in a guest just because KVM doesn't know about POE yet. (Hopefully this follows naturally from the way the KVM code works, but my KVM-fu is a bit rusty.) Also, what about POR_EL1? Do we have to reset that to something sane (and so untrap it here), or it is sufficient if we never turn on POE support in the host, via TCR2_EL1.POE? [...] Cheers ---Dave