From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-21.5 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,FSL_HELO_FAKE, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DB7E4C433FE for ; Wed, 9 Dec 2020 13:03:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9457323B45 for ; Wed, 9 Dec 2020 13:03:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731964AbgLINCr (ORCPT ); Wed, 9 Dec 2020 08:02:47 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51196 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731953AbgLINCg (ORCPT ); Wed, 9 Dec 2020 08:02:36 -0500 Received: from mail-wm1-x341.google.com (mail-wm1-x341.google.com [IPv6:2a00:1450:4864:20::341]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 16056C061793 for ; Wed, 9 Dec 2020 05:01:50 -0800 (PST) Received: by mail-wm1-x341.google.com with SMTP id e25so1593339wme.0 for ; Wed, 09 Dec 2020 05:01:50 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=JFqrvjW5ggq0+/xnT81gTlAuUmvGAZyqBQrhOvLhybw=; b=irNzgcIs/IhlG7j8FZF1Yv9WPdN0pMZxqPBTBeyPmK0rN9pW3V9W2o+UdnVxXcF7Wy SnL0VE737jZMGGQdewC8LyxdVVX9V8YXIwPAaaWPIQwNgIMsj7pBh8XJ9SMZhGhf6HJU Dzi1RuML9lEOUmJOvWuadpvkhytCcnmmCBD6vSgLJUT7X96tQ5iNOzqkD2qjzuu7TKdl zh/fSWDjkA0YbObX1sKXaOS2fScPAsow6oCpniA+yMs6Kb+Ivx2/Z50wB4g2qOkLfHGU 2tqnUlKn6u8P/kzWqdDPDSnkAgl3ryy79X1lqslCwG5MwNU9ZaaQnm7+lxUQTUi7hGLr aXJw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=JFqrvjW5ggq0+/xnT81gTlAuUmvGAZyqBQrhOvLhybw=; b=mCwTy5mnW1XbYXIX+nQ0axOIl29r+cJcVBRFFq34L82SwDq+iPa7KaI+rrX/ja1O9i +nRnFrZpOHXIaLVKgbR+FPitucd+Q+/QxmY0oiQmbpFBhW7zmAUoeT4kChTD1m3E6PPL 26ad+YN6WKZZ+FHHguBNrmJdbS6gfEJFlooI5k8h3+lSsO0jZlJSXcw16SNyiGHdH6y4 Q5hLVQGXm+i5rHni405oKRYc2iBFBBVySq/mnuYGsNibXJVgZPYL5IJqEEjjqiLN0mqX ugd+f3kjAPJRO6+nv7nnnAAszWlSf1OFKnpbOGGMesUc0WjzEeCfdghMsZ7vp9WuvqaT Lt9A== X-Gm-Message-State: AOAM531PDIAjmtRyKTUNlSVLS9PQ1aD+T9Xe0ZGDj86azsAZ0fLbZadm VXYOBAt1FeIY0XFrRNwiTqPULg== X-Google-Smtp-Source: ABdhPJzbr/oYf7go/KboT2H2FsrRWwB06zZx6/cY2dxrHx2MtzHR88WTcnuzuKEME4w0vvBdeL4NAA== X-Received: by 2002:a1c:287:: with SMTP id 129mr2706564wmc.133.1607518908666; Wed, 09 Dec 2020 05:01:48 -0800 (PST) Received: from google.com ([2a01:4b00:8523:2d03:9d1b:d0eb:db43:6cd2]) by smtp.gmail.com with ESMTPSA id b7sm3474204wrv.47.2020.12.09.05.01.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 09 Dec 2020 05:01:46 -0800 (PST) Date: Wed, 9 Dec 2020 13:01:45 +0000 From: David Brazdil To: Ard Biesheuvel Cc: kvmarm , Linux ARM , Linux Kernel Mailing List , Marc Zyngier , James Morse , Julien Thierry , Suzuki K Poulose , Catalin Marinas , Will Deacon , Mark Rutland , Andrew Scull , Android Kernel Team Subject: Re: [RFC PATCH 5/6] kvm: arm64: Fix constant-pool users in hyp Message-ID: <20201209130145.lh27im2wqjpho5b6@google.com> References: <20201119162543.78001-1-dbrazdil@google.com> <20201119162543.78001-6-dbrazdil@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hey, relized I never replied to this... On Tue, Nov 24, 2020 at 03:08:20PM +0100, Ard Biesheuvel wrote: > On Thu, 19 Nov 2020 at 17:26, David Brazdil wrote: > > > > Hyp code used to use absolute addressing via a constant pool to obtain > > the kernel VA of 3 symbols - panic, __hyp_panic_string and > > __kvm_handle_stub_hvc. This used to work because the kernel would > > relocate the addresses in the constant pool to kernel VA at boot and hyp > > would simply load them from there. > > > > Now that relocations are fixed up to point to hyp VAs, this does not > > work any longer. Rework the helpers to convert hyp VA to kernel VA / PA > > as needed. > > > > Ok, so the reason for the problem is that the literal exists inside > the HYP text, and all literals are fixed up using the HYP mapping, > even if they don't point to something that is mapped at HYP. Would it > make sense to simply disregard literals that point outside of the HYP > VA mapping? That would be possible - I'm about to post a v1 with build-time generation of these relocs and kernel symbols are easily recognizable as they're undefined in that ELF object. But I do worry that that would confuse people a lot. And if somebody referenced a kernel symbol in C (maybe not a use case, but...) they would get different results depending on which addressing mode the compiler picked. > > > Signed-off-by: David Brazdil > > --- > > arch/arm64/include/asm/kvm_mmu.h | 29 +++++++++++++++++++---------- > > arch/arm64/kvm/hyp/nvhe/host.S | 29 +++++++++++++++-------------- > > 2 files changed, 34 insertions(+), 24 deletions(-) > > > > diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h > > index 8cb8974ec9cc..0676ff2105bb 100644 > > --- a/arch/arm64/include/asm/kvm_mmu.h > > +++ b/arch/arm64/include/asm/kvm_mmu.h > > @@ -72,9 +72,14 @@ alternative_cb kvm_update_va_mask > > alternative_cb_end > > .endm > > > > +.macro hyp_pa reg, tmp > > + ldr_l \tmp, hyp_physvirt_offset > > + add \reg, \reg, \tmp > > +.endm > > + > > /* > > - * Convert a kernel image address to a PA > > - * reg: kernel address to be converted in place > > + * Convert a hypervisor VA to a kernel image address > > + * reg: hypervisor address to be converted in place > > * tmp: temporary register > > * > > * The actual code generation takes place in kvm_get_kimage_voffset, and > > @@ -82,18 +87,22 @@ alternative_cb_end > > * perform the register allocation (kvm_get_kimage_voffset uses the > > * specific registers encoded in the instructions). > > */ > > -.macro kimg_pa reg, tmp > > +.macro hyp_kimg reg, tmp > > + /* Convert hyp VA -> PA. */ > > + hyp_pa \reg, \tmp > > + > > + /* Load kimage_voffset. */ > > alternative_cb kvm_get_kimage_voffset > > - movz \tmp, #0 > > - movk \tmp, #0, lsl #16 > > - movk \tmp, #0, lsl #32 > > - movk \tmp, #0, lsl #48 > > + movz \tmp, #0 > > + movk \tmp, #0, lsl #16 > > + movk \tmp, #0, lsl #32 > > + movk \tmp, #0, lsl #48 > > alternative_cb_end > > > > - /* reg = __pa(reg) */ > > - sub \reg, \reg, \tmp > > + /* Convert PA -> kimg VA. */ > > + add \reg, \reg, \tmp > > .endm > > - > > + > > #else > > > > #include > > diff --git a/arch/arm64/kvm/hyp/nvhe/host.S b/arch/arm64/kvm/hyp/nvhe/host.S > > index 596dd5ae8e77..bcb80d525d8c 100644 > > --- a/arch/arm64/kvm/hyp/nvhe/host.S > > +++ b/arch/arm64/kvm/hyp/nvhe/host.S > > @@ -74,27 +74,28 @@ SYM_FUNC_END(__host_enter) > > * void __noreturn __hyp_do_panic(bool restore_host, u64 spsr, u64 elr, u64 par); > > */ > > SYM_FUNC_START(__hyp_do_panic) > > - /* Load the format arguments into x1-7 */ > > - mov x6, x3 > > - get_vcpu_ptr x7, x3 > > - > > - mrs x3, esr_el2 > > - mrs x4, far_el2 > > - mrs x5, hpfar_el2 > > - > > /* Prepare and exit to the host's panic funciton. */ > > mov lr, #(PSR_F_BIT | PSR_I_BIT | PSR_A_BIT | PSR_D_BIT |\ > > PSR_MODE_EL1h) > > msr spsr_el2, lr > > ldr lr, =panic > > + hyp_kimg lr, x6 > > msr elr_el2, lr > > > > - /* > > - * Set the panic format string and enter the host, conditionally > > - * restoring the host context. > > - */ > > + /* Set the panic format string. Use the, now free, LR as scratch. */ > > + ldr lr, =__hyp_panic_string > > + hyp_kimg lr, x6 > > + > > + /* Load the format arguments into x1-7. */ > > + mov x6, x3 > > + get_vcpu_ptr x7, x3 > > + mrs x3, esr_el2 > > + mrs x4, far_el2 > > + mrs x5, hpfar_el2 > > + > > + /* Enter the host, conditionally restoring the host context. */ > > cmp x0, xzr > > - ldr x0, =__hyp_panic_string > > + mov x0, lr > > b.eq __host_enter_without_restoring > > b __host_enter_for_panic > > SYM_FUNC_END(__hyp_do_panic) > > @@ -124,7 +125,7 @@ SYM_FUNC_END(__hyp_do_panic) > > * Preserve x0-x4, which may contain stub parameters. > > */ > > ldr x5, =__kvm_handle_stub_hvc > > - kimg_pa x5, x6 > > + hyp_pa x5, x6 > > br x5 > > .L__vect_end\@: > > .if ((.L__vect_end\@ - .L__vect_start\@) > 0x80) > > -- > > 2.29.2.299.gdc1121823c-goog > >