From: oss@buserror•net (Scott Wood)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH v4 3/4] arm64: arch_timer: Work around QorIQ Erratum A-008585
Date: Thu, 08 Sep 2016 20:08:56 -0500 [thread overview]
Message-ID: <1473383336.30217.96.camel@buserror.net> (raw)
In-Reply-To: <20160826134004.7e86e798@arm.com>
On Fri, 2016-08-26 at 13:40 +0100, Marc Zyngier wrote:
> On Thu, 7 Jul 2016 02:46:11 -0500
> Scott Wood <oss@buserror•net> wrote:
>
> (+Mark)
>
> >
> > ?static __always_inline
> > ?u32 arch_timer_reg_read_cp15(int access, enum arch_timer_reg reg)
> > ?{
> > @@ -66,19 +102,19 @@ u32 arch_timer_reg_read_cp15(int access, enum
> > arch_timer_reg reg)
> > ? if (access == ARCH_TIMER_PHYS_ACCESS) {
> > ? switch (reg) {
> > ? case ARCH_TIMER_REG_CTRL:
> > - asm volatile("mrs %0,??cntp_ctl_el0" : "=r"
> > (val));
> > + asm volatile("mrs %0, cntp_ctl_el0" : "=r"
> > (val));
> Spurious change?
>
> >
> > ? break;
> > ? case ARCH_TIMER_REG_TVAL:
> > - asm volatile("mrs %0, cntp_tval_el0" : "=r"
> > (val));
> > + val = _arch_timer_get_ptval();
> > ? break;
> > ? }
> > ? } else if (access == ARCH_TIMER_VIRT_ACCESS) {
> > ? switch (reg) {
> > ? case ARCH_TIMER_REG_CTRL:
> > - asm volatile("mrs %0,??cntv_ctl_el0" : "=r"
> > (val));
> > + asm volatile("mrs %0, cntv_ctl_el0" : "=r"
> > (val));
> Here too?
No, it's not spurious.
I answered this in?http://lists.infradead.org/pipermail/linux-arm-kernel/2016-
June/438310.html
The extra spacing seemed to be an attempt to get things to line up between the
CTRL and TVAL asm statements.??When the TVAL case was converted to a function
call, there was nothing for the above to line up with, so I moved it back to
normal spacing.
> I'm still worried that this series doesn't address Xen or KVM guests
> that need to be made aware of the broken timers.
>
> At the very least, I'd like a kernel command line option that'd let the
> user reliably run its VMs. You can do something along the lines of
> 46fd5c6b, and have a command line argument like
> "clocksource.arm_arch_timer.fsl-a008585=1", which would enable the
> workaround.
OK, I'll respin with a command line argument to use for now. ?Mike Caraman has
said he plans to do a better solution for KVM -- Mike, have you had a chance
to look at this?
-Scott
next prev parent reply other threads:[~2016-09-09 1:08 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-07 7:46 [PATCH v4 1/4] arm64: arch_timer: Add device tree binding for A-008585 erratum Scott Wood
2016-07-07 7:46 ` [PATCH v4 2/4] arm64: dts: Add timer erratum property for LS2080A and LS1043A Scott Wood
2016-07-07 7:46 ` [PATCH v4 3/4] arm64: arch_timer: Work around QorIQ Erratum A-008585 Scott Wood
2016-08-26 12:40 ` Marc Zyngier
2016-09-09 1:08 ` Scott Wood [this message]
2016-09-09 6:53 ` Marc Zyngier
2016-09-09 5:20 ` Ding Tianhong
2016-09-09 7:06 ` Marc Zyngier
2016-07-07 7:46 ` [PATCH v4 4/4] arm/arm64: arch_timer: Use archdata to indicate vdso suitability Scott Wood
2016-07-07 15:18 ` Will Deacon
2016-08-25 11:04 ` [PATCH v4 1/4] arm64: arch_timer: Add device tree binding for A-008585 erratum Matthias Brugger
2016-09-08 11:46 ` Ding Tianhong
2016-09-08 12:07 ` Marc Zyngier
2016-09-08 12:31 ` Ding Tianhong
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