linux-kernel - Re: [Xen-devel] [PATCH v2 16/16] ARM64: XEN: Initialize Xen specific UEFI runtime services

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Message-ID: <alpine.DEB.2.02.1601191424270.9400@kaball.uk.xensource.com>
Date:	Tue, 19 Jan 2016 14:24:53 +0000
From:	Stefano Stabellini <stefano.stabellini@...citrix.com>
To:	Shannon Zhao <shannon.zhao@...aro.org>
CC:	Stefano Stabellini <stefano.stabellini@...citrix.com>,
	Shannon Zhao <zhaoshenglong@...wei.com>,
	<linux-arm-kernel@...ts.infradead.org>,
	<ard.biesheuvel@...aro.org>, <stefano.stabellini@...rix.com>,
	<david.vrabel@...rix.com>, <mark.rutland@....com>,
	<devicetree@...r.kernel.org>, <linux-efi@...r.kernel.org>,
	<catalin.marinas@....com>, <will.deacon@....com>,
	<linux-kernel@...r.kernel.org>, <xen-devel@...ts.xen.org>,
	<julien.grall@...rix.com>, <peter.huangpeng@...wei.com>
Subject: Re: [Xen-devel] [PATCH v2 16/16] ARM64: XEN: Initialize Xen specific
 UEFI runtime services

On Tue, 19 Jan 2016, Shannon Zhao wrote:
> On 2016/1/19 1:03, Stefano Stabellini wrote:
> > On Fri, 15 Jan 2016, Shannon Zhao wrote:
> > > From: Shannon Zhao <shannon.zhao@...aro.org>
> > > 
> > > When running on Xen hypervisor, runtime services are supported through
> > > hypercall. So call Xen specific function to initialize runtime services.
> > > 
> > > Signed-off-by: Shannon Zhao <shannon.zhao@...aro.org>
> > 
> > Thanks Shannon, much much better!  Just a couple of questions.
> > 
> > 
> > >   arch/arm/xen/enlighten.c |  5 +++++
> > >   arch/arm64/xen/Makefile  |  1 +
> > >   arch/arm64/xen/efi.c     | 36 ++++++++++++++++++++++++++++++++++++
> > >   drivers/xen/Kconfig      |  2 +-
> > >   include/xen/xen-ops.h    |  1 +
> > >   5 files changed, 44 insertions(+), 1 deletion(-)
> > >   create mode 100644 arch/arm64/xen/efi.c
> > > 
> > > diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c
> > > index 485e117..84f27ec 100644
> > > --- a/arch/arm/xen/enlighten.c
> > > +++ b/arch/arm/xen/enlighten.c
> > > @@ -414,6 +414,11 @@ static int __init xen_guest_init(void)
> > >   	if (xen_initial_domain())
> > >   		pvclock_gtod_register_notifier(&xen_pvclock_gtod_notifier);
> > > 
> > > +	if (IS_ENABLED(CONFIG_XEN_EFI)) {
> > > +		if (efi_enabled(EFI_PARAVIRT))
> > > +			xen_efi_runtime_setup();
> > > +	}
> > > +
> > >   	return 0;
> > >   }
> > >   early_initcall(xen_guest_init);
> > > diff --git a/arch/arm64/xen/Makefile b/arch/arm64/xen/Makefile
> > > index 74a8d87..62e6fe2 100644
> > > --- a/arch/arm64/xen/Makefile
> > > +++ b/arch/arm64/xen/Makefile
> > > @@ -1,2 +1,3 @@
> > >   xen-arm-y	+= $(addprefix ../../arm/xen/, enlighten.o grant-table.o p2m.o
> > > mm.o)
> > >   obj-y		:= xen-arm.o hypercall.o
> > > +obj-$(CONFIG_XEN_EFI) += efi.o
> > > diff --git a/arch/arm64/xen/efi.c b/arch/arm64/xen/efi.c
> > > new file mode 100644
> > > index 0000000..33046b0
> > > --- /dev/null
> > > +++ b/arch/arm64/xen/efi.c
> > > @@ -0,0 +1,36 @@
> > > +/*
> > > + * Copyright (c) 2015, Linaro Limited, Shannon Zhao
> > > + *
> > > + * This program is free software; you can redistribute it and/or modify
> > > + * it under the terms of the GNU General Public License as published by
> > > + * the Free Software Foundation; either version 2 of the License, or
> > > + * (at your option) any later version.
> > > + *
> > > + * This program is distributed in the hope that it will be useful,
> > > + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> > > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> > > + * GNU General Public License for more details.
> > > + *
> > > + * You should have received a copy of the GNU General Public License
> > > along
> > > + * with this program.  If not, see <http://www.gnu.org/licenses/>.
> > > + */
> > > +
> > > +#include <linux/efi.h>
> > > +#include <xen/xen-ops.h>
> > > +
> > > +void __init xen_efi_runtime_setup(void)
> > > +{
> > > +	efi.get_time                 = xen_efi_get_time;
> > > +	efi.set_time                 = xen_efi_set_time;
> > > +	efi.get_wakeup_time          = xen_efi_get_wakeup_time;
> > > +	efi.set_wakeup_time          = xen_efi_set_wakeup_time;
> > > +	efi.get_variable             = xen_efi_get_variable;
> > > +	efi.get_next_variable        = xen_efi_get_next_variable;
> > > +	efi.set_variable             = xen_efi_set_variable;
> > > +	efi.query_variable_info      = xen_efi_query_variable_info;
> > > +	efi.update_capsule           = xen_efi_update_capsule;
> > > +	efi.query_capsule_caps       = xen_efi_query_capsule_caps;
> > > +	efi.get_next_high_mono_count = xen_efi_get_next_high_mono_count;
> > > +	efi.reset_system             = NULL;
> > > +}
> > > +EXPORT_SYMBOL_GPL(xen_efi_runtime_setup);
> > 
> > This looks very similar to struct efi efi_xen previously in
> > drivers/xen/efi.c.  Maybe it makes sense to leave struct efi efi_xen in
> > drivers/xen/efi.c, export it in include/xen/xen-ops.h, then here just:
> > 
> >    efi = efi_xen;
> > 
> > Would that improve code readability?
> > 
> Ok.
> > 
> > Correct me if I am wrong, but on ARM64 (differently from x86) it is not
> > necessary to set efi.systab because it is not used, right? If so, it
> > would be best to add a comment here to remember.
> > 
> Not set efi.systab here because it gets the system table through fdt and set
> efi.systab there. See uefi_init() in arch/arm64/kernel.efi.c
> 
> 	efi.systab = early_memremap(efi_system_table,
> 				    sizeof(efi_system_table_t));

I see now. Then it might be still good to add a comment about that.


> > > diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
> > > index 73708ac..27d216a 100644
> > > --- a/drivers/xen/Kconfig
> > > +++ b/drivers/xen/Kconfig
> > > @@ -268,7 +268,7 @@ config XEN_HAVE_PVMMU
> > > 
> > >   config XEN_EFI
> > >   	def_bool y
> > > -	depends on X86_64 && EFI
> > > +	depends on (ARM64 || X86_64) && EFI
> > > 
> > >   config XEN_AUTO_XLATE
> > >   	def_bool y
> > > diff --git a/include/xen/xen-ops.h b/include/xen/xen-ops.h
> > > index c83a338..36ff8e4 100644
> > > --- a/include/xen/xen-ops.h
> > > +++ b/include/xen/xen-ops.h
> > > @@ -107,6 +107,7 @@ efi_status_t
> > > xen_efi_update_capsule(efi_capsule_header_t **capsules,
> > >   efi_status_t xen_efi_query_capsule_caps(efi_capsule_header_t **capsules,
> > >   					unsigned long count, u64 *max_size,
> > >   					int *reset_type);
> > > +void xen_efi_runtime_setup(void);
> > 
> > xen_efi_runtime_setup is not defined on x86, but this header is not arch
> > specific.
> > 
> 
> -- 
> Shannon
>