linux-kernel - Re: [PATCH] x86/tsc: Use rdtsc_ordered() when RDTSCP or LFENCE

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Message-ID: <8734msg5ce.ffs@tglx>
Date: Sun, 25 Aug 2024 14:22:09 +0200
From: Thomas Gleixner <tglx@...utronix.de>
To: Mario Limonciello <superm1@...nel.org>, Bjorn Helgaas
 <bhelgaas@...gle.com>, Mathias Nyman <mathias.nyman@...el.com>, Mika
 Westerberg <mika.westerberg@...ux.intel.com>
Cc: "open list : PCI SUBSYSTEM" <linux-pci@...r.kernel.org>, open list
 <linux-kernel@...r.kernel.org>, "open list : USB XHCI DRIVER"
 <linux-usb@...r.kernel.org>, Daniel Drake <drake@...lessos.org>, Gary Li
 <Gary.Li@....com>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Ilpo
 Järvinen <ilpo.jarvinen@...ux.intel.com>, Mario
 Limonciello
 <mario.limonciello@....com>
Subject: Re: [PATCH] x86/tsc: Use rdtsc_ordered() when RDTSCP or
 LFENCE_RDTSC are supported

On Thu, Aug 22 2024 at 23:25, Mario Limonciello wrote:

Why is this hidden in a reply to the middle of a PCI patch series?

Sigh.

> From: Mario Limonciello <mario.limonciello@....com>
>
> On AMD processors the TSC has been reported drifting on and off for
> various platforms.  This has been root caused to becaused by out of order
> TSC and HPET counter values.  When the SoC supports RDTSCP or LFENCE_RDTSC
> use ordered tsc reads instead.

This really wants a fixes tag.