From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932318AbcBANUV (ORCPT ); Mon, 1 Feb 2016 08:20:21 -0500 Received: from mail-wm0-f46.google.com ([74.125.82.46]:38110 "EHLO mail-wm0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932269AbcBANUR (ORCPT ); Mon, 1 Feb 2016 08:20:17 -0500 Date: Mon, 1 Feb 2016 14:20:42 +0100 From: Christoffer Dall To: Marc Zyngier Cc: Catalin Marinas , Will Deacon , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu Subject: Re: [PATCH v2 07/21] arm64: KVM: VHE: Patch out kern_hyp_va Message-ID: <20160201132042.GJ1478@cbox> References: <1453737235-16522-1-git-send-email-marc.zyngier@arm.com> <1453737235-16522-8-git-send-email-marc.zyngier@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1453737235-16522-8-git-send-email-marc.zyngier@arm.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jan 25, 2016 at 03:53:41PM +0000, Marc Zyngier wrote: > The kern_hyp_va macro is pretty meaninless with VHE, as there is > only one mapping - the kernel one. > > In order to keep the code readable and efficient, use runtime > patching to replace the 'and' instruction used to compute the VA > with a 'nop'. > > Signed-off-by: Marc Zyngier > --- > arch/arm64/include/asm/kvm_mmu.h | 11 ++++++++++- > arch/arm64/kvm/hyp/hyp.h | 25 ++++++++++++++++++++++--- > 2 files changed, 32 insertions(+), 4 deletions(-) > > diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h > index d3e6d7b..62f0d14 100644 > --- a/arch/arm64/include/asm/kvm_mmu.h > +++ b/arch/arm64/include/asm/kvm_mmu.h > @@ -23,13 +23,16 @@ > #include > > /* > - * As we only have the TTBR0_EL2 register, we cannot express > + * As ARMv8.0 only has the TTBR0_EL2 register, we cannot express > * "negative" addresses. This makes it impossible to directly share > * mappings with the kernel. > * > * Instead, give the HYP mode its own VA region at a fixed offset from > * the kernel by just masking the top bits (which are all ones for a > * kernel address). > + * > + * ARMv8.1 (using VHE) does have a TTBR1_EL2, and doesn't use these > + * macros (the entire kernel runs at EL2). > */ > #define HYP_PAGE_OFFSET_SHIFT VA_BITS > #define HYP_PAGE_OFFSET_MASK ((UL(1) << HYP_PAGE_OFFSET_SHIFT) - 1) > @@ -56,6 +59,8 @@ > > #ifdef __ASSEMBLY__ > > +#include > +#include > #include > > .macro setup_vtcr tmp1, tmp2 > @@ -84,7 +89,11 @@ > * reg: VA to be converted. > */ > .macro kern_hyp_va reg > +alternative_if_not ARM64_HAS_VIRT_HOST_EXTN > and \reg, \reg, #HYP_PAGE_OFFSET_MASK > +alternative_else > + nop > +alternative_endif > .endm > > #else > diff --git a/arch/arm64/kvm/hyp/hyp.h b/arch/arm64/kvm/hyp/hyp.h > index fb27517..fc502f3 100644 > --- a/arch/arm64/kvm/hyp/hyp.h > +++ b/arch/arm64/kvm/hyp/hyp.h > @@ -25,9 +25,28 @@ > > #define __hyp_text __section(.hyp.text) notrace > > -#define kern_hyp_va(v) (typeof(v))((unsigned long)(v) & HYP_PAGE_OFFSET_MASK) > -#define hyp_kern_va(v) (typeof(v))((unsigned long)(v) - HYP_PAGE_OFFSET \ > - + PAGE_OFFSET) > +static inline unsigned long __kern_hyp_va(unsigned long v) > +{ > + asm volatile(ALTERNATIVE("and %0, %0, %1", > + "nop", > + ARM64_HAS_VIRT_HOST_EXTN) > + : "+r" (v) : "i" (HYP_PAGE_OFFSET_MASK)); > + return v; > +} > + > +#define kern_hyp_va(v) (typeof(v))(__kern_hyp_va((unsigned long)(v))) > + > +static inline unsigned long __hyp_kern_va(unsigned long v) > +{ > + u64 offset = PAGE_OFFSET - HYP_PAGE_OFFSET; > + asm volatile(ALTERNATIVE("add %0, %0, %1", > + "nop", > + ARM64_HAS_VIRT_HOST_EXTN) > + : "+r" (v) : "r" (offset)); > + return v; > +} > + > +#define hyp_kern_va(v) (typeof(v))(__hyp_kern_va((unsigned long)(v))) why do we need this casting of values instead of just defining these inlines and calling them directly with proper typing? -Christoffer > > /** > * hyp_alternate_select - Generates patchable code sequences that are > -- > 2.1.4 >