Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756315AbbGPRs2 (ORCPT ); Thu, 16 Jul 2015 13:48:28 -0400 Received: from foss.arm.com ([217.140.101.70]:45239 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755883AbbGPRs1 (ORCPT ); Thu, 16 Jul 2015 13:48:27 -0400 Date: Thu, 16 Jul 2015 18:48:23 +0100 From: Will Deacon To: Marc Zyngier Cc: Catalin Marinas , Christoffer Dall , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "kvm@vger.kernel.org" , "kvmarm@lists.cs.columbia.edu" Subject: Re: [PATCH 10/13] arm64: Add support for running Linux in EL2 mode Message-ID: <20150716174823.GP26390@arm.com> References: <1436372356-30410-1-git-send-email-marc.zyngier@arm.com> <1436372356-30410-11-git-send-email-marc.zyngier@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1436372356-30410-11-git-send-email-marc.zyngier@arm.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2330 Lines: 73 On Wed, Jul 08, 2015 at 05:19:13PM +0100, Marc Zyngier wrote: > With the ARMv8.1 VHE, the architecture is able to (almost) transparently > run the kernel at EL2, despite being written for EL1. > > This patch takes care of the "almost" part, mostly preventing the kernel > from dropping from EL2 to EL1, and setting up the HYP configuration. > > Signed-off-by: Marc Zyngier > --- > arch/arm64/kernel/head.S | 23 ++++++++++++++++++++++- > 1 file changed, 22 insertions(+), 1 deletion(-) > > diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S > index c0ff3ce..a179747 100644 > --- a/arch/arm64/kernel/head.S > +++ b/arch/arm64/kernel/head.S > @@ -29,6 +29,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -481,8 +482,16 @@ CPU_LE( bic x0, x0, #(3 << 24) ) // Clear the EE and E0E bits for EL1 > isb > ret > > + /* Check for VHE being present */ > +2: mrs x2, id_aa64mmfr1_el1 > + ubfx x2, x2, #8, #4 > + > /* Hyp configuration. */ > -2: mov x0, #(1 << 31) // 64-bit EL1 > + mov x0, #HCR_RW // 64-bit EL1 > + cbz x2, set_hcr > + orr x0, x0, #HCR_TGE // Enable Host Extensions > + orr x0, x0, #HCR_E2H > +set_hcr: > msr hcr_el2, x0 > > /* Generic timers. */ > @@ -522,6 +531,9 @@ CPU_LE( movk x0, #0x30d0, lsl #16 ) // Clear EE and E0E on LE systems > > /* Coprocessor traps. */ > mov x0, #0x33ff These bits are RES0 with VHE enabled, afaict. > + cbz x2, set_cptr > + orr x0, x0, #(3 << 20) // Don't trap FP > +set_cptr: > msr cptr_el2, x0 // Disable copro. traps to EL2 > > #ifdef CONFIG_COMPAT > @@ -531,6 +543,15 @@ CPU_LE( movk x0, #0x30d0, lsl #16 ) // Clear EE and E0E on LE systems > /* Stage-2 translation */ > msr vttbr_el2, xzr > > + cbz x2, install_el2_stub > + > + setup_vtcr x4, x5 > + > + mov w20, #BOOT_CPU_MODE_EL2 // This CPU booted in EL2 You do this in install_el2_stub as well -- can you move it above the cbz? Will -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/