From: Wei Liu <wei.liu@kernel.org>
To: Dexuan Cui <decui@microsoft.com>
Cc: mhklinux@outlook.com, "K. Y. Srinivasan" <kys@microsoft.com>,
Haiyang Zhang <haiyangz@microsoft.com>,
Wei Liu <wei.liu@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
"maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
<x86@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>,
Daniel Lezcano <daniel.lezcano@linaro.org>,
"open list:Hyper-V/Azure CORE AND DRIVERS"
<linux-hyperv@vger.kernel.org>,
"open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
<linux-kernel@vger.kernel.org>,
stable@vger.kernel.org, Roman Kisel <romank@linux.microsoft.com>
Subject: Re: [PATCH v2] clocksource: hyper-v: Use lapic timer in a TDX VM without paravisor
Date: Mon, 24 Jun 2024 07:06:50 +0000 [thread overview]
Message-ID: <ZnkbCoLqm7wbZGch@liuwe-devbox-debian-v2> (raw)
In-Reply-To: <20240621061614.8339-1-decui@microsoft.com>
On Thu, Jun 20, 2024 at 11:16:14PM -0700, Dexuan Cui wrote:
> In a TDX VM without paravisor, currently the default timer is the Hyper-V
> timer, which depends on the slow VM Reference Counter MSR: the Hyper-V TSC
> page is not enabled in such a VM because the VM uses Invariant TSC as a
> better clocksource and it's challenging to mark the Hyper-V TSC page shared
> in very early boot.
>
> Lower the rating of the Hyper-V timer so the local APIC timer becomes the
> the default timer in such a VM, and print a warning in case Invariant TSC
> is unavailable in such a VM. This change should cause no perceivable
> performance difference.
>
> Cc: stable@vger.kernel.org # 6.6+
> Reviewed-by: Roman Kisel <romank@linux.microsoft.com>
> Signed-off-by: Dexuan Cui <decui@microsoft.com>
Applied to hyperv-fixes. Thanks.
prev parent reply other threads:[~2024-06-24 7:06 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-06-21 6:16 [PATCH v2] clocksource: hyper-v: Use lapic timer in a TDX VM without paravisor Dexuan Cui
2024-06-21 15:18 ` Michael Kelley
2024-06-24 7:06 ` Wei Liu [this message]
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