Re: [PATCH v15 23/26] sched: early boot clock

From: Dominique Martinet <asmadeus@codewreck.org>
To: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: gnomes@lxorguk.ukuu.org.uk, feng.tang@intel.com,
	kvm@vger.kernel.org, pmladek@suse.com,
	Peter Zijlstra <peterz@infradead.org>,
	heiko.carstens@de.ibm.com, qemu-devel@nongnu.org,
	virtualization@lists.linux-foundation.org,
	Steven Sistare <steven.sistare@oracle.com>,
	hpa@zytor.com, boris.ostrovsky@oracle.com, prarit@redhat.com,
	linux-s390@vger.kernel.org, x86@kernel.org,
	linux@armlinux.org.uk, Daniel Jordan <daniel.m.jordan@oracle.com>,
	mingo@redhat.com, Pavel Tatashin <pavel.tatashin@microsoft.com>,
	john.stultz@linaro.org, Thomas Gleixner <tglx@linutronix.de>,
	Salvatore Bonaccorso <carnil@debian.org>,
	jgross@suse.com, douly.fnst@cn.fujitsu.com, sboyd@codeaurora.org,
	LKML <linux-kernel@vger.kernel.org>,
	schwidefsky@de.ibm.com, pbonzini@redhat.com
Subject: Re: [PATCH v15 23/26] sched: early boot clock
Date: Fri, 4 Jan 2019 00:43:39 +0100	[thread overview]
Message-ID: <20190103234339.GA17457@nautica> (raw)
In-Reply-To: <CA+CK2bC70pnL0Wimb0xt99J4nNfi8W3zuUHgAk-jsPuOP9jpHA@mail.gmail.com>

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Pavel Tatashin wrote on Thu, Jan 03, 2019:
> Could you please send the config file and qemu arguments that were
> used to reproduce this problem.

Running qemu by hand, nothing fancy e.g. this works:

# qemu-system-x86_64 -m 1G -smp 4 -drive file=/root/kvm-wrapper/disks/f2.img,if=virtio -serial mon:stdio --enable-kvm -cpu Haswell -device virtio-rng-pci -nographic

(used a specific cpu just in case but normally runnning with cpu host on
a skylake machine; can probably go older)

qemu is fedora 29 blend as is:
$ qemu-system-x86_64 --version
QEMU emulator version 3.0.0 (qemu-3.0.0-3.fc29)
Copyright (c) 2003-2017 Fabrice Bellard and the QEMU Project developers

compressed .config attached to the mail, this can likely be trimmed down
some as well but that takes more time for me..
I didn't rebuild the kernel so not 100% sure (comes from
/proc/config.gz) but it should work on a 4.20-rc2 kernel as written in
the first few lines; 857baa87b64 I referred to in another mail was
merged in 4.19-rc1 so anything past that is probably OK to reproduce...

Re-checked today with these exact options (fresh VM start; then suspend
laptop for a bit, then reboot VM):
[    0.000000] Hypervisor detected: KVM
[    0.000000] kvm-clock: Using msrs 4b564d01 and 4b564d00
[ 2477.907447] kvm-clock: cpu 0, msr 153a4001, primary cpu clock
[ 2477.907448] clocksource: kvm-clock: mask: 0xffffffffffffffff max_cycles: 0x1cd42e4dffb, max_idle_ns: 881590591483 ns
[ 2477.907450] tsc: Detected 2592.000 MHz processor

As offered previously, happy to help in any way.

Thanks,
-- 
Dominique

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