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Subject: Re: [PATCH v5 02/12] x86/paravirt: switch time pvops functions to use
 static_call()
To:     Boris Ostrovsky <boris.ostrovsky@oracle.com>,
        xen-devel@lists.xenproject.org, x86@kernel.org,
        virtualization@lists.linux-foundation.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        linux-hyperv@vger.kernel.org, kvm@vger.kernel.org
Cc:     Deep Shah <sdeep@vmware.com>,
        "VMware, Inc." <pv-drivers@vmware.com>,
        Russell King <linux@armlinux.org.uk>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        "H. Peter Anvin" <hpa@zytor.com>,
        "K. Y. Srinivasan" <kys@microsoft.com>,
        Haiyang Zhang <haiyangz@microsoft.com>,
        Stephen Hemminger <sthemmin@microsoft.com>,
        Wei Liu <wei.liu@kernel.org>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Sean Christopherson <seanjc@google.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Joerg Roedel <joro@8bytes.org>,
        Stefano Stabellini <sstabellini@kernel.org>
References: <20210308122844.30488-1-jgross@suse.com>
 <20210308122844.30488-3-jgross@suse.com>
 <1346dbb1-c43e-9ac2-10e4-3c10cb2ead78@oracle.com>
From:   =?UTF-8?B?SsO8cmdlbiBHcm/Dnw==?= <jgross@suse.com>
Message-ID: <5cea7551-ce84-c084-ddaf-e84075823bd8@suse.com>
Date:   Tue, 9 Mar 2021 07:14:37 +0100
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From: =?UTF-8?B?SsO8cmdlbiBHcm/Dnw==?= <jgross@suse.com>
To: Boris Ostrovsky <boris.ostrovsky@oracle.com>,
 xen-devel@lists.xenproject.org, x86@kernel.org,
 virtualization@lists.linux-foundation.org,
 linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
 linux-hyperv@vger.kernel.org, kvm@vger.kernel.org
Cc: Deep Shah <sdeep@vmware.com>, "VMware, Inc." <pv-drivers@vmware.com>,
 Russell King <linux@armlinux.org.uk>,
 Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will@kernel.org>,
 Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>,
 Borislav Petkov <bp@alien8.de>, "H. Peter Anvin" <hpa@zytor.com>,
 "K. Y. Srinivasan" <kys@microsoft.com>,
 Haiyang Zhang <haiyangz@microsoft.com>,
 Stephen Hemminger <sthemmin@microsoft.com>, Wei Liu <wei.liu@kernel.org>,
 Paolo Bonzini <pbonzini@redhat.com>, Sean Christopherson
 <seanjc@google.com>, Vitaly Kuznetsov <vkuznets@redhat.com>,
 Wanpeng Li <wanpengli@tencent.com>, Jim Mattson <jmattson@google.com>,
 Joerg Roedel <joro@8bytes.org>, Stefano Stabellini <sstabellini@kernel.org>
Message-ID: <5cea7551-ce84-c084-ddaf-e84075823bd8@suse.com>
Subject: Re: [PATCH v5 02/12] x86/paravirt: switch time pvops functions to use
 static_call()
References: <20210308122844.30488-1-jgross@suse.com>
 <20210308122844.30488-3-jgross@suse.com>
 <1346dbb1-c43e-9ac2-10e4-3c10cb2ead78@oracle.com>
In-Reply-To: <1346dbb1-c43e-9ac2-10e4-3c10cb2ead78@oracle.com>

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On 08.03.21 18:00, Boris Ostrovsky wrote:
>=20
> On 3/8/21 7:28 AM, Juergen Gross wrote:
>> --- a/arch/x86/xen/time.c
>> +++ b/arch/x86/xen/time.c
>> @@ -379,11 +379,6 @@ void xen_timer_resume(void)
>>   	}
>>   }
>>  =20
>> -static const struct pv_time_ops xen_time_ops __initconst =3D {
>> -	.sched_clock =3D xen_sched_clock,
>> -	.steal_clock =3D xen_steal_clock,
>> -};
>> -
>>   static struct pvclock_vsyscall_time_info *xen_clock __read_mostly;
>>   static u64 xen_clock_value_saved;
>>  =20
>> @@ -528,7 +523,8 @@ static void __init xen_time_init(void)
>>   void __init xen_init_time_ops(void)
>>   {
>>   	xen_sched_clock_offset =3D xen_clocksource_read();
>> -	pv_ops.time =3D xen_time_ops;
>> +	static_call_update(pv_steal_clock, xen_steal_clock);
>> +	paravirt_set_sched_clock(xen_sched_clock);
>>  =20
>>   	x86_init.timers.timer_init =3D xen_time_init;
>>   	x86_init.timers.setup_percpu_clockev =3D x86_init_noop;
>> @@ -570,7 +566,8 @@ void __init xen_hvm_init_time_ops(void)
>>   	}
>>  =20
>>   	xen_sched_clock_offset =3D xen_clocksource_read();
>> -	pv_ops.time =3D xen_time_ops;
>> +	static_call_update(pv_steal_clock, xen_steal_clock);
>> +	paravirt_set_sched_clock(xen_sched_clock);
>>   	x86_init.timers.setup_percpu_clockev =3D xen_time_init;
>>   	x86_cpuinit.setup_percpu_clockev =3D xen_hvm_setup_cpu_clockevents;=

>=20
>=20
> There is a bunch of stuff that's common between the two cases so it can=
 be factored out.

Yes.

>=20
>=20
>>  =20
>> diff --git a/drivers/xen/time.c b/drivers/xen/time.c
>> index 108edbcbc040..152dd33bb223 100644
>> --- a/drivers/xen/time.c
>> +++ b/drivers/xen/time.c
>> @@ -7,6 +7,7 @@
>>   #include <linux/math64.h>
>>   #include <linux/gfp.h>
>>   #include <linux/slab.h>
>> +#include <linux/static_call.h>
>>  =20
>>   #include <asm/paravirt.h>
>>   #include <asm/xen/hypervisor.h>
>> @@ -175,7 +176,7 @@ void __init xen_time_setup_guest(void)
>>   	xen_runstate_remote =3D !HYPERVISOR_vm_assist(VMASST_CMD_enable,
>>   					VMASST_TYPE_runstate_update_flag);
>>  =20
>> -	pv_ops.time.steal_clock =3D xen_steal_clock;
>> +	static_call_update(pv_steal_clock, xen_steal_clock);
>>  =20
>=20
>=20
> Do we actually need this? We've already set this up in xen_init_time_op=
s(). (But maybe for ARM).

Correct. Arm needs this.


Juergen

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