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[66.111.4.228]) by smtp.gmail.com with ESMTPSA id t198sm354933qke.6.2019.12.17.21.47.36 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 17 Dec 2019 21:47:37 -0800 (PST) Received: from compute6.internal (compute6.nyi.internal [10.202.2.46]) by mailauth.nyi.internal (Postfix) with ESMTP id 751CC22223; Wed, 18 Dec 2019 00:47:35 -0500 (EST) Received: from mailfrontend1 ([10.202.2.162]) by compute6.internal (MEProxy); Wed, 18 Dec 2019 00:47:35 -0500 X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedufedrvddtkedgkeelucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmne cujfgurhepfffhvffukfhfgggtuggjfgesthdtredttdervdenucfhrhhomhepuehoqhhu nhcuhfgvnhhguceosghoqhhunhdrfhgvnhhgsehgmhgrihhlrdgtohhmqeenucfkphephe dvrdduheehrdduuddurdejudenucfrrghrrghmpehmrghilhhfrhhomhepsghoqhhunhdo mhgvshhmthhprghuthhhphgvrhhsohhnrghlihhthidqieelvdeghedtieegqddujeejke ehheehvddqsghoqhhunhdrfhgvnhhgpeepghhmrghilhdrtghomhesfhhigihmvgdrnhgr mhgvnecuvehluhhsthgvrhfuihiivgeptd X-ME-Proxy: Received: from localhost (unknown [52.155.111.71]) by mail.messagingengine.com (Postfix) with ESMTPA id 06F2B8005A; Wed, 18 Dec 2019 00:47:33 -0500 (EST) Date: Wed, 18 Dec 2019 13:47:32 +0800 From: Boqun Feng To: Vitaly Kuznetsov Cc: Michael Kelley , Vincenzo Frascino , Catalin Marinas , Will Deacon , Thomas Gleixner , "K. Y. Srinivasan" , Haiyang Zhang , Stephen Hemminger , Sasha Levin , xen-devel@lists.xenproject.org, Stefano Stabellini , linux-hyperv@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [RFC 6/6] arm64: hyperv: Enable vDSO Message-ID: <20191218054732.GK97412@debian-boqun.qqnc3lrjykvubdpftowmye0fmh.lx.internal.cloudapp.net> References: <20191216001922.23008-1-boqun.feng@gmail.com> <20191216001922.23008-7-boqun.feng@gmail.com> <87y2vb82lz.fsf@vitty.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87y2vb82lz.fsf@vitty.brq.redhat.com> User-Agent: Mutt/1.12.2 (2019-09-21) Sender: linux-hyperv-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-hyperv@vger.kernel.org On Tue, Dec 17, 2019 at 03:10:16PM +0100, Vitaly Kuznetsov wrote: > Boqun Feng writes: > > > Similar to x86, add a new vclock_mode VCLOCK_HVCLOCK, and reuse the > > hv_read_tsc_page() for userspace to read tsc page clocksource. > > > > Signed-off-by: Boqun Feng (Microsoft) > > --- > > arch/arm64/include/asm/clocksource.h | 3 ++- > > arch/arm64/include/asm/mshyperv.h | 2 +- > > arch/arm64/include/asm/vdso/gettimeofday.h | 19 +++++++++++++++++++ > > 3 files changed, 22 insertions(+), 2 deletions(-) > > > > diff --git a/arch/arm64/include/asm/clocksource.h b/arch/arm64/include/asm/clocksource.h > > index fbe80057468c..c6acd45fe748 100644 > > --- a/arch/arm64/include/asm/clocksource.h > > +++ b/arch/arm64/include/asm/clocksource.h > > @@ -4,7 +4,8 @@ > > > > #define VCLOCK_NONE 0 /* No vDSO clock available. */ > > #define VCLOCK_CNTVCT 1 /* vDSO should use cntvcnt */ > > -#define VCLOCK_MAX 1 > > +#define VCLOCK_HVCLOCK 2 /* vDSO should use vread_hvclock() */ > > +#define VCLOCK_MAX 2 > > > > struct arch_clocksource_data { > > int vclock_mode; > > diff --git a/arch/arm64/include/asm/mshyperv.h b/arch/arm64/include/asm/mshyperv.h > > index 0afb00e3501d..7c85dd816dca 100644 > > --- a/arch/arm64/include/asm/mshyperv.h > > +++ b/arch/arm64/include/asm/mshyperv.h > > @@ -90,7 +90,7 @@ extern void hv_get_vpreg_128(u32 reg, struct hv_get_vp_register_output *result); > > #define hv_set_reference_tsc(val) \ > > hv_set_vpreg(HV_REGISTER_REFERENCE_TSC, val) > > #define hv_set_clocksource_vdso(val) \ > > - ((val).archdata.vclock_mode = VCLOCK_NONE) > > + ((val).archdata.vclock_mode = VCLOCK_HVCLOCK) > > > > #if IS_ENABLED(CONFIG_HYPERV) > > #define hv_enable_stimer0_percpu_irq(irq) enable_percpu_irq(irq, 0) > > diff --git a/arch/arm64/include/asm/vdso/gettimeofday.h b/arch/arm64/include/asm/vdso/gettimeofday.h > > index e6e3fe0488c7..7e689b903f4d 100644 > > --- a/arch/arm64/include/asm/vdso/gettimeofday.h > > +++ b/arch/arm64/include/asm/vdso/gettimeofday.h > > @@ -67,6 +67,20 @@ int clock_getres_fallback(clockid_t _clkid, struct __kernel_timespec *_ts) > > return ret; > > } > > > > +#ifdef CONFIG_HYPERV_TIMER > > +/* This will override the default hv_get_raw_timer() */ > > +#define hv_get_raw_timer() __arch_counter_get_cntvct() > > +#include > > + > > +extern struct ms_hyperv_tsc_page > > +_hvclock_page __attribute__((visibility("hidden"))); > > + > > +static u64 vread_hvclock(void) > > +{ > > + return hv_read_tsc_page(&_hvclock_page); > > +} > > +#endif > > The function is almost the same on x86 (&_hvclock_page -> > &hvclock_page), would it maybe make sense to move this to arch neutral > clocksource/hyperv_timer.h? > I'm not sure whether the underscore matters in the vDSO data symbol, so I follow the architectural name convention. If the leading underscore doesn't have special purpose I'm happy to move this to arch neutral header file. > > + > > static __always_inline u64 __arch_get_hw_counter(s32 clock_mode) > > { > > u64 res; > > @@ -78,6 +92,11 @@ static __always_inline u64 __arch_get_hw_counter(s32 clock_mode) > > if (clock_mode == VCLOCK_NONE) > > return __VDSO_USE_SYSCALL; > > > > +#ifdef CONFIG_HYPERV_TIMER > > + if (likely(clock_mode == VCLOCK_HVCLOCK)) > > + return vread_hvclock(); > > I'm not sure likely() is justified here: it'll make ALL builds which > enable CONFIG_HYPERV_TIMER (e.g. distro kernels) to prefer > VCLOCK_HVCLOCK, even if the kernel is not running on Hyper-V. > Make sense. Thanks for pointing this out! I will change it in the next version. Regards, Boqun > > +#endif > > + > > /* > > * This isb() is required to prevent that the counter value > > * is speculated. > > -- > Vitaly >