linux-kernel - RE: [PATCH v2 09/13] clocksource: hyper-v: Adjust hv_read_tsc_page_tsc() to avoid special casing U64

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <BYAPR21MB16881F78BE5B6D9E9846A438D77CA@BYAPR21MB1688.namprd21.prod.outlook.com>
Date:   Fri, 19 May 2023 18:38:37 +0000
From:   "Michael Kelley (LINUX)" <mikelley@...rosoft.com>
To:     Peter Zijlstra <peterz@...radead.org>,
        "bigeasy@...utronix.de" <bigeasy@...utronix.de>
CC:     Mark Rutland <Mark.Rutland@....com>,
        "maz@...nel.org" <maz@...nel.org>,
        "catalin.marinas@....com" <catalin.marinas@....com>,
        "will@...nel.org" <will@...nel.org>,
        "chenhuacai@...nel.org" <chenhuacai@...nel.org>,
        "kernel@...0n.name" <kernel@...0n.name>,
        "hca@...ux.ibm.com" <hca@...ux.ibm.com>,
        "gor@...ux.ibm.com" <gor@...ux.ibm.com>,
        "agordeev@...ux.ibm.com" <agordeev@...ux.ibm.com>,
        "borntraeger@...ux.ibm.com" <borntraeger@...ux.ibm.com>,
        "svens@...ux.ibm.com" <svens@...ux.ibm.com>,
        "pbonzini@...hat.com" <pbonzini@...hat.com>,
        "wanpengli@...cent.com" <wanpengli@...cent.com>,
        "vkuznets@...hat.com" <vkuznets@...hat.com>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "bp@...en8.de" <bp@...en8.de>,
        "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
        "x86@...nel.org" <x86@...nel.org>, "hpa@...or.com" <hpa@...or.com>,
        "jgross@...e.com" <jgross@...e.com>,
        "boris.ostrovsky@...cle.com" <boris.ostrovsky@...cle.com>,
        "daniel.lezcano@...aro.org" <daniel.lezcano@...aro.org>,
        KY Srinivasan <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        "wei.liu@...nel.org" <wei.liu@...nel.org>,
        Dexuan Cui <decui@...rosoft.com>,
        "rafael@...nel.org" <rafael@...nel.org>,
        "longman@...hat.com" <longman@...hat.com>,
        "boqun.feng@...il.com" <boqun.feng@...il.com>,
        "pmladek@...e.com" <pmladek@...e.com>,
        "senozhatsky@...omium.org" <senozhatsky@...omium.org>,
        "rostedt@...dmis.org" <rostedt@...dmis.org>,
        "john.ogness@...utronix.de" <john.ogness@...utronix.de>,
        "juri.lelli@...hat.com" <juri.lelli@...hat.com>,
        "vincent.guittot@...aro.org" <vincent.guittot@...aro.org>,
        "dietmar.eggemann@....com" <dietmar.eggemann@....com>,
        "bsegall@...gle.com" <bsegall@...gle.com>,
        "mgorman@...e.de" <mgorman@...e.de>,
        "bristot@...hat.com" <bristot@...hat.com>,
        "vschneid@...hat.com" <vschneid@...hat.com>,
        "jstultz@...gle.com" <jstultz@...gle.com>,
        "sboyd@...nel.org" <sboyd@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "loongarch@...ts.linux.dev" <loongarch@...ts.linux.dev>,
        "linux-s390@...r.kernel.org" <linux-s390@...r.kernel.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>
Subject: RE: [PATCH v2 09/13] clocksource: hyper-v: Adjust
 hv_read_tsc_page_tsc() to avoid special casing U64_MAX

From: Peter Zijlstra <peterz@...radead.org> Sent: Friday, May 19, 2023 3:21 AM
> 
> Currently hv_read_tsc_page_tsc() (ab)uses the (valid) time value of
> U64_MAX as an error return. This breaks the clean wrap-around of the
> clock.
> 
> Modify the function signature to return a boolean state and provide
> another u64 pointer to store the actual time on success. This obviates
> the need to steal one time value and restores the full counter width.
> 
> Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
> ---
>  arch/x86/include/asm/vdso/gettimeofday.h |   10 ++++++----
>  arch/x86/kvm/x86.c                       |    7 +++----
>  drivers/clocksource/hyperv_timer.c       |   16 +++++++++++-----
>  include/clocksource/hyperv_timer.h       |   24 +++++++++---------------
>  4 files changed, 29 insertions(+), 28 deletions(-)
> 

Reviewed-by: Michael Kelley <mikelley@...rosoft.com>