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=-13.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 5327DC433ED for ; Mon, 17 May 2021 11:44:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 352B961242 for ; Mon, 17 May 2021 11:44:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229681AbhEQLqM (ORCPT ); Mon, 17 May 2021 07:46:12 -0400 Received: from foss.arm.com ([217.140.110.172]:49076 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229445AbhEQLqM (ORCPT ); Mon, 17 May 2021 07:46:12 -0400 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 9DD3B1042; Mon, 17 May 2021 04:44:55 -0700 (PDT) Received: from C02TD0UTHF1T.local (unknown [10.57.3.85]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 845F73F73D; Mon, 17 May 2021 04:44:52 -0700 (PDT) Date: Mon, 17 May 2021 12:44:49 +0100 From: Mark Rutland To: Michael Kelley Cc: "will@kernel.org" , "catalin.marinas@arm.com" , "lorenzo.pieralisi@arm.com" , "sudeep.holla@arm.com" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "linux-hyperv@vger.kernel.org" , "linux-efi@vger.kernel.org" , "arnd@arndb.de" , "wei.liu@kernel.org" , "ardb@kernel.org" , "daniel.lezcano@linaro.org" , KY Srinivasan Subject: Re: [PATCH v10 2/7] arm64: hyperv: Add Hyper-V hypercall and register access utilities Message-ID: <20210517114449.GB62656@C02TD0UTHF1T.local> References: <1620841067-46606-1-git-send-email-mikelley@microsoft.com> <1620841067-46606-3-git-send-email-mikelley@microsoft.com> <20210514125243.GC30645@C02TD0UTHF1T.local> 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-hyperv@vger.kernel.org On Fri, May 14, 2021 at 03:14:41PM +0000, Michael Kelley wrote: > From: Mark Rutland Sent: Friday, May 14, 2021 5:53 AM > > > > On Wed, May 12, 2021 at 10:37:42AM -0700, Michael Kelley wrote: > > > hyperv-tlfs.h defines Hyper-V interfaces from the Hyper-V Top Level > > > Functional Spec (TLFS), and #includes the architecture-independent > > > part of hyperv-tlfs.h in include/asm-generic. The published TLFS > > > is distinctly oriented to x86/x64, so the ARM64-specific > > > hyperv-tlfs.h includes information for ARM64 that is not yet formally > > > published. The TLFS is available here: > > > > > > docs.microsoft.com/en-us/virtualization/hyper-v-on-windows/reference/tlfs > > > > > > mshyperv.h defines Linux-specific structures and routines for > > > interacting with Hyper-V on ARM64, and #includes the architecture- > > > independent part of mshyperv.h in include/asm-generic. > > > > > > Use these definitions to provide utility functions to make > > > Hyper-V hypercalls and to get and set Hyper-V provided > > > registers associated with a virtual processor. > > > > > > Signed-off-by: Michael Kelley > > > Reviewed-by: Sunil Muthuswamy > > > --- > > > MAINTAINERS | 3 + > > > arch/arm64/Kbuild | 1 + > > > arch/arm64/hyperv/Makefile | 2 + > > > arch/arm64/hyperv/hv_core.c | 130 +++++++++++++++++++++++++++++++++++ > > > arch/arm64/include/asm/hyperv-tlfs.h | 69 +++++++++++++++++++ > > > arch/arm64/include/asm/mshyperv.h | 54 +++++++++++++++ > > > 6 files changed, 259 insertions(+) > > > create mode 100644 arch/arm64/hyperv/Makefile > > > create mode 100644 arch/arm64/hyperv/hv_core.c > > > create mode 100644 arch/arm64/include/asm/hyperv-tlfs.h > > > create mode 100644 arch/arm64/include/asm/mshyperv.h > > > > > +/* > > > + * hv_do_hypercall- Invoke the specified hypercall > > > + */ > > > +u64 hv_do_hypercall(u64 control, void *input, void *output) > > > +{ > > > + struct arm_smccc_res res; > > > + u64 input_address; > > > + u64 output_address; > > > + > > > + input_address = input ? virt_to_phys(input) : 0; > > > + output_address = output ? virt_to_phys(output) : 0; > > > > I may have asked this before, but are `input` and `output` always linear > > map pointers, or can they ever be vmalloc pointers? > > > > Otherwise, this looks fine to me. > > The caller must ensure that hypercall arguments are aligned to > 4 Kbytes, and no larger than 4 Kbytes, since that's the page size > used by Hyper-V regardless of the guest page size. A per-CPU > 4 Kbyte memory area (hyperv_pcpu_input_arg) meeting these > requirements is pre-allocated that callers can use for this purpose. What I was trying to find out was how that was allocated, as vmalloc()'d pointers aren't legitimate to pass to virt_to_phys(). >From scanning ahead to patch 5, I see that memory comes from kmalloc(), and so it is legitimate to use virt_to_phys(). I see; and from patch 5 I see that memory come from kmalloc(), and will therefore be part of the linear map, and so virt_to_phys() is legitimate. What I was asking here was how that memory was allocated. So long as those are the only buffers used, this looks fine to me. Thanks, Mark.