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

From: Shannon Zhao <zhaoshenglong@huawei.com>
To: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: <linux-arm-kernel@lists.infradead.org>,
	<ard.biesheuvel@linaro.org>, <stefano.stabellini@citrix.com>,
	<david.vrabel@citrix.com>, <mark.rutland@arm.com>,
	<devicetree@vger.kernel.org>, <linux-efi@vger.kernel.org>,
	<catalin.marinas@arm.com>, <will.deacon@arm.com>,
	<linux-kernel@vger.kernel.org>, <xen-devel@lists.xen.org>,
	<julien.grall@citrix.com>, <shannon.zhao@linaro.org>,
	<peter.huangpeng@huawei.com>
Subject: Re: [Xen-devel] [PATCH v2 16/16] ARM64: XEN: Initialize Xen specific UEFI runtime services
Date: Fri, 22 Jan 2016 11:58:13 +0800	[thread overview]
Message-ID: <56A1A8D5.1020500@huawei.com> (raw)
In-Reply-To: <alpine.DEB.2.02.1601181634070.9400@kaball.uk.xensource.com>

On 2016/1/19 1:03, Stefano Stabellini wrote:
> On Fri, 15 Jan 2016, Shannon Zhao wrote:
>> > From: Shannon Zhao <shannon.zhao@linaro.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@linaro.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?

Rethink about this. It's a little different on ARM since we call
xen_efi_runtime_setup after parsing the FDT and setting some members of
efi already, e.g. efi.systab, efi.acpi20. So it necessary to have a
different way to initialize the struct efi.

Thanks,
-- 
Shannon