From: Vitaly Kuznetsov <vkuznets@redhat.com>
To: Wei Liu <wei.liu@kernel.org>,
Linux on Hyper-V List <linux-hyperv@vger.kernel.org>
Cc: Wei Liu <wei.liu@kernel.org>,
Stephen Hemminger <sthemmin@microsoft.com>,
Haiyang Zhang <haiyangz@microsoft.com>,
Daniel Lezcano <daniel.lezcano@linaro.org>,
virtualization@lists.linux-foundation.org,
Linux Kernel List <linux-kernel@vger.kernel.org>,
Nuno Das Neves <nudasnev@microsoft.com>,
Sunil Muthuswamy <sunilmut@microsoft.com>,
Michael Kelley <mikelley@microsoft.com>,
Vineeth Pillai <viremana@linux.microsoft.com>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH RFC v1 05/18] clocksource/hyperv: use MSR-based access if running as root
Date: Tue, 15 Sep 2020 12:10:04 +0200 [thread overview]
Message-ID: <874knzl5ab.fsf@vitty.brq.redhat.com> (raw)
In-Reply-To: <20200914112802.80611-6-wei.liu@kernel.org>
Wei Liu <wei.liu@kernel.org> writes:
> Signed-off-by: Wei Liu <wei.liu@kernel.org>
> ---
> drivers/clocksource/hyperv_timer.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/drivers/clocksource/hyperv_timer.c b/drivers/clocksource/hyperv_timer.c
> index 09aa44cb8a91..fe96082ce85e 100644
> --- a/drivers/clocksource/hyperv_timer.c
> +++ b/drivers/clocksource/hyperv_timer.c
> @@ -426,6 +426,9 @@ static bool __init hv_init_tsc_clocksource(void)
> if (!(ms_hyperv.features & HV_MSR_REFERENCE_TSC_AVAILABLE))
> return false;
>
> + if (hv_root_partition)
> + return false;
> +
Out of pure curiosity,
TSC page clocksource seems to be available to the root partition (as
HV_MSR_REFERENCE_TSC_AVAILABLE is set), why don't we use it? (I
understand that with TSC scaling support in modern CPUs even migration
is a no-issue and we can use raw TSC but this all seems to be
independent from root/non-root partition question).
> hv_read_reference_counter = read_hv_clock_tsc;
> phys_addr = virt_to_phys(hv_get_tsc_page());
--
Vitaly
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next parent reply other threads:[~2020-09-15 10:10 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20200914112802.80611-1-wei.liu@kernel.org>
[not found] ` <20200914112802.80611-6-wei.liu@kernel.org>
2020-09-15 10:10 ` Vitaly Kuznetsov [this message]
[not found] ` <20200914112802.80611-7-wei.liu@kernel.org>
2020-09-15 10:16 ` [PATCH RFC v1 06/18] x86/hyperv: allocate output arg pages if required Vitaly Kuznetsov
[not found] ` <20200915124318.z6tisek5y4d7e254@liuwe-devbox-debian-v2>
[not found] ` <20200916154200.7nf74vjmqu3f6sfq@liuwe-devbox-debian-v2>
2020-09-16 16:10 ` Vitaly Kuznetsov
[not found] ` <20200914112802.80611-8-wei.liu@kernel.org>
2020-09-15 10:27 ` [PATCH RFC v1 07/18] x86/hyperv: extract partition ID from Microsoft Hypervisor if necessary Vitaly Kuznetsov
[not found] ` <20200914112802.80611-9-wei.liu@kernel.org>
2020-09-15 10:32 ` [PATCH RFC v1 08/18] x86/hyperv: handling hypercall page setup for root Vitaly Kuznetsov
[not found] ` <20200915103710.cqmdvzh5lys4wsqo@liuwe-devbox-debian-v2>
2020-09-15 11:02 ` Vitaly Kuznetsov
[not found] ` <20200915111657.boa4cneqjqtmcaaq@liuwe-devbox-debian-v2>
2020-09-15 11:23 ` Vitaly Kuznetsov
2020-09-16 21:34 ` [EXTERNAL] " Sunil Muthuswamy via Virtualization
2020-09-17 11:06 ` Vitaly Kuznetsov
[not found] ` <20200914115928.83184-1-wei.liu@kernel.org>
2020-09-15 11:00 ` [PATCH RFC v1 09/18] x86/hyperv: provide a bunch of helper functions Vitaly Kuznetsov
[not found] ` <20200914115928.83184-2-wei.liu@kernel.org>
2020-09-15 11:14 ` [PATCH RFC v1 10/18] x86/hyperv: implement and use hv_smp_prepare_cpus Vitaly Kuznetsov
[not found] ` <20200914115928.83184-5-wei.liu@kernel.org>
2020-09-15 11:16 ` [PATCH RFC v1 13/18] asm-generic/hyperv: introduce hv_device_id and auxiliary structures Vitaly Kuznetsov
[not found] ` <20200914112802.80611-5-wei.liu@kernel.org>
2020-09-18 9:12 ` [PATCH RFC v1 04/18] iommu/hyperv: don't setup IRQ remapping when running as root Joerg Roedel
[not found] ` <20200914115928.83184-4-wei.liu@kernel.org>
2020-10-01 14:33 ` [PATCH RFC v1 12/18] asm-generic/hyperv: update hv_interrupt_entry Rob Herring
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