From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg KH Subject: Re: [PATCH 2/2] xen: add acpi_arch_get_root_pointer() for pvh guests Date: Thu, 25 Jan 2018 13:35:15 +0100 Message-ID: <20180125123515.GA30787@kroah.com> References: <20180125100454.23203-1-jgross@suse.com> <20180125100454.23203-3-jgross@suse.com> <20180125103719.GA16777@kroah.com> <033717a8-f53a-3379-1e05-58b3d2bed24b@suse.com> <20180125110051.GA31911@kroah.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail.linuxfoundation.org ([140.211.169.12]:60828 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751916AbeAYMf1 (ORCPT ); Thu, 25 Jan 2018 07:35:27 -0500 Content-Disposition: inline In-Reply-To: Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Juergen Gross Cc: linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org, xen-devel@lists.xenproject.org, lenb@kernel.org, rafael.j.wysocki@intel.com, mingo@redhat.com, boris.ostrovsky@oracle.com, stable@vger.kernel.org On Thu, Jan 25, 2018 at 01:06:26PM +0100, Juergen Gross wrote: > On 25/01/18 12:00, Greg KH wrote: > > On Thu, Jan 25, 2018 at 11:49:35AM +0100, Juergen Gross wrote: > >> On 25/01/18 11:37, Greg KH wrote: > >>> On Thu, Jan 25, 2018 at 11:04:54AM +0100, Juergen Gross wrote: > >>>> Add acpi_arch_get_root_pointer() for Xen PVH guests to communicate > >>>> the address of the RSDP table given to the kernel via Xen start info. > >>>> > >>>> This makes the kernel boot again in PVH mode after on recent Xen the > >>>> RSDP was moved to higher addresses. So up to that change it was pure > >>>> luck that the legacy method to locate the RSDP was working when > >>>> running as PVH mode. > >>>> > >>>> Cc: # 4.11 > >>>> Signed-off-by: Juergen Gross > >>>> --- > >>>> arch/x86/xen/enlighten_pvh.c | 15 ++++++++++++--- > >>>> 1 file changed, 12 insertions(+), 3 deletions(-) > >>>> > >>>> diff --git a/arch/x86/xen/enlighten_pvh.c b/arch/x86/xen/enlighten_pvh.c > >>>> index 436c4f003e17..9a5c3a7fe673 100644 > >>>> --- a/arch/x86/xen/enlighten_pvh.c > >>>> +++ b/arch/x86/xen/enlighten_pvh.c > >>>> @@ -16,15 +16,24 @@ > >>>> /* > >>>> * PVH variables. > >>>> * > >>>> - * xen_pvh and pvh_bootparams need to live in data segment since they > >>>> - * are used after startup_{32|64}, which clear .bss, are invoked. > >>>> + * xen_pvh, pvh_bootparams and pvh_start_info need to live in data segment > >>>> + * since they are used after startup_{32|64}, which clear .bss, are invoked. > >>>> */ > >>>> bool xen_pvh __attribute__((section(".data"))) = 0; > >>>> struct boot_params pvh_bootparams __attribute__((section(".data"))); > >>>> +struct hvm_start_info pvh_start_info __attribute__((section(".data"))); > >>>> > >>>> -struct hvm_start_info pvh_start_info; > >>>> unsigned int pvh_start_info_sz = sizeof(pvh_start_info); > >>>> > >>>> +acpi_physical_address acpi_arch_get_root_pointer(void) > >>>> +{ > >>>> + if (xen_pvh) > >>>> + return pvh_start_info.rsdp_paddr; > >>>> + > >>>> + return 0; > >>>> +} > >>>> +EXPORT_SYMBOL_GPL(acpi_arch_get_root_pointer); > >>> > >>> Why does this have to be an exported symbol? Does this code get built > >>> as a module and will the linker somehow go and rewrite the previous call > >>> places with this one if it gets loaded? > >> > >> With being called by drivers/acpi/... I just wanted to make sure it is > >> working properly even in case the acpi code is built as a module. > > > > I didn't think the core ACPI code can be built as a module, have you > > tried that? > > No, but as the build wouldn't break whenever this is changed I wanted > to make sure the symbol is found. > > If you feel strong about that I can remove the EXPORT_SYMBOL_GPL(). Please don't export symbols that do not need to be exported, that's just a waste. thanks, greg k-h