From: Paolo Bonzini <pbonzini@redhat.com>
To: Vadim Rozenfeld <vrozenfe@redhat.com>
Cc: Gleb Natapov <gleb@redhat.com>,
kvm@vger.kernel.org, mtosatti@redhat.com, pl@dlh.net
Subject: Re: [RFC PATCH 1/2] Hyper-H reference counter
Date: Thu, 16 May 2013 16:48:02 +0200 [thread overview]
Message-ID: <5194F1A2.2060402@redhat.com> (raw)
In-Reply-To: <1368714131.18400.11.camel@localhost>
Il 16/05/2013 16:22, Vadim Rozenfeld ha scritto:
>>>>>>>>>>> > >>>>> > > > > + addr = gfn_to_hva(kvm, gfn);
>>>>>>>>>>> > >>>>> > > > > + if (kvm_is_error_hva(addr))
>>>>>>>>>>> > >>>>> > > > > + return 1;
>>>>>>>>>>> > >>>>> > > > > + tsc_ref = 0;
>> >
>> > This should write 0xFFFFFFFF.
> This should write 0
No. You have not writing sensible values to TscScale/TscOffset, hence
the VM should fall back to another time source.
Microsoft docs say "A special value of 0xFFFFFFFF is used to indicate
that this facility is no longer a reliable source of reference time and
the virtual machine must fall back to a different source (for example,
the virtual PM timer)".
So you need to write 0xFFFFFFFF here (though my suggestion would rather
be to remove this part of the patch, and do everything in the next
patch). The next patch should pick 0 if constant TSC is available,
0xFFFFFFFF if it is not.
If the docs are wrong, I stand corrected but then you need a comment
explaining that.
Paolo
next prev parent reply other threads:[~2013-05-16 14:48 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-05-13 11:45 [RFC PATCH 0/2] Hyper-V timers Vadim Rozenfeld
2013-05-13 11:45 ` [RFC PATCH 1/2] Hyper-H reference counter Vadim Rozenfeld
2013-05-13 23:30 ` Eric Northup
2013-05-14 9:46 ` Vadim Rozenfeld
2013-05-16 8:18 ` Gleb Natapov
2013-05-16 8:53 ` Vadim Rozenfeld
2013-05-14 14:14 ` Peter Lieven
2013-05-15 10:24 ` Vadim Rozenfeld
2013-05-16 8:10 ` Gleb Natapov
2013-05-16 8:34 ` Gleb Natapov
2013-05-16 9:13 ` Vadim Rozenfeld
2013-05-16 9:21 ` Gleb Natapov
2013-05-16 9:28 ` Vadim Rozenfeld
2013-05-16 13:37 ` Paolo Bonzini
2013-05-16 14:22 ` Vadim Rozenfeld
2013-05-16 14:48 ` Paolo Bonzini [this message]
2013-05-16 13:44 ` Paolo Bonzini
2013-05-16 14:26 ` Vadim Rozenfeld
2013-05-16 14:45 ` Paolo Bonzini
2013-05-19 6:37 ` Vadim Rozenfeld
2013-05-20 8:05 ` Paolo Bonzini
2013-05-20 8:36 ` Gleb Natapov
2013-05-20 8:42 ` Paolo Bonzini
2013-05-20 8:49 ` Gleb Natapov
2013-05-20 8:56 ` Paolo Bonzini
2013-05-20 9:13 ` Gleb Natapov
2013-05-20 9:25 ` Gleb Natapov
2013-05-20 9:32 ` Paolo Bonzini
2013-05-20 9:41 ` Gleb Natapov
2013-05-20 10:06 ` Peter Lieven
2013-05-20 10:25 ` Vadim Rozenfeld
2013-05-20 10:27 ` Gleb Natapov
2013-05-20 10:44 ` Vadim Rozenfeld
2013-05-20 10:21 ` Vadim Rozenfeld
2013-05-20 9:12 ` Vadim Rozenfeld
2013-05-16 14:40 ` Paolo Bonzini
2013-05-13 11:45 ` [RFC PATCH 2/2] Hyper-V iTSC handler Vadim Rozenfeld
2013-05-16 8:33 ` Gleb Natapov
2013-05-16 8:58 ` Vadim Rozenfeld
2013-05-16 8:02 ` [RFC PATCH 0/2] Hyper-V timers Gleb Natapov
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