From: "Van De Ven, Arjan" <arjan.van.de.ven@intel.com>
To: Paolo Bonzini <pbonzini@redhat.com>,
"valdis.kletnieks@vt.edu" <valdis.kletnieks@vt.edu>
Cc: Jon Masters <jcm@jonmasters.org>,
David Woodhouse <dwmw2@infradead.org>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"x86@kernel.org" <x86@kernel.org>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"torvalds@linux-foundation.org" <torvalds@linux-foundation.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"Hansen, Dave" <dave.hansen@intel.com>,
Ingo Molnar <mingo@kernel.org>
Subject: RE: [PATCH 2/2] x86/speculation: Support "Enhanced IBRS" on future CPUs
Date: Tue, 20 Feb 2018 14:59:05 +0000 [thread overview]
Message-ID: <0575AF4FD06DD142AD198903C74E1CC87A6194AB@ORSMSX103.amr.corp.intel.com> (raw)
In-Reply-To: <2159cdc0-c30d-3bf8-1c25-74bff46a1e91@redhat.com>
> > I meant software wise. You're not going to live migrate from xen to
> > kvm or backwards. or between very radically different versions of the
> > kvm stack.
>
> Forwards migration to a radically newer version certainly happens. So
> when the source hypervisor was too old to tell the VM about IBRS_ALL,
> for example, migration should work properly and the VM should perform
> well on the destination hypervisor.
that makes sense, compatibility in this direction can be done
and is useful as you move a fleet of servers forward
>
> Backwards migration to older hypervisors also happens sometimes, but in
> general it creates more userspace than kernel issues.
>
that direction is obviously harder
next prev parent reply other threads:[~2018-02-20 14:59 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-12 15:27 [PATCH 1/2] x86/speculation: Correct Speculation Control microcode blacklist again David Woodhouse
2018-02-12 15:27 ` [PATCH 2/2] x86/speculation: Support "Enhanced IBRS" on future CPUs David Woodhouse
2018-02-13 7:47 ` Ingo Molnar
2018-02-13 8:12 ` David Woodhouse
2018-02-13 8:02 ` Paolo Bonzini
2018-02-13 8:15 ` David Woodhouse
2018-02-13 9:58 ` Paolo Bonzini
2018-02-13 10:21 ` David Woodhouse
2018-02-13 10:36 ` David Woodhouse
2018-02-13 10:41 ` Paolo Bonzini
2018-02-13 10:53 ` David Woodhouse
2018-02-13 10:55 ` Paolo Bonzini
2018-02-16 9:58 ` David Woodhouse
2018-02-16 10:08 ` Paolo Bonzini
2018-02-16 10:21 ` David Woodhouse
2018-02-16 11:04 ` Paolo Bonzini
2018-02-16 12:10 ` David Woodhouse
2018-02-19 23:37 ` Jon Masters
2018-02-19 23:42 ` Van De Ven, Arjan
2018-02-19 23:53 ` valdis.kletnieks
2018-02-20 0:00 ` Van De Ven, Arjan
2018-02-20 0:13 ` Alan Cox
2018-02-20 0:43 ` Linus Torvalds
2018-02-20 1:03 ` Alan Cox
2018-02-20 1:08 ` Van De Ven, Arjan
2018-02-20 8:52 ` Thomas Gleixner
2018-02-20 11:43 ` Paolo Bonzini
2018-02-20 14:08 ` Van De Ven, Arjan
2018-02-20 14:46 ` Paolo Bonzini
2018-02-20 14:59 ` Van De Ven, Arjan [this message]
2018-02-20 15:09 ` Paolo Bonzini
2018-02-23 18:12 ` Is: RSB Alternative bit in IA32_ARCH_CAPABILITIES Was:Re: " Konrad Rzeszutek Wilk
2018-02-23 18:18 ` Van De Ven, Arjan
2018-02-15 15:21 ` Pavel Machek
2018-02-13 8:57 ` [tip:x86/pti] x86/speculation: Correct Speculation Control microcode blacklist again tip-bot for David Woodhouse
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