From: Zachary Amsden <zach-pghWNbHTmq7QT0dZR+AlfA@public.gmane.org>
To: "Nakajima, Jun" <jun.nakajima-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
Cc: kvm-devel
<kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org>,
Jeremy Fitzhardinge <jeremy-TSDbQ3PG+2Y@public.gmane.org>,
virtualization-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org
Subject: Re: [PATCH 3/3] Eliminate read_cr3 on TLB flush
Date: Wed, 30 May 2007 10:58:33 -0700 [thread overview]
Message-ID: <465DBB49.5030503@vmware.com> (raw)
In-Reply-To: <97D612E30E1F88419025B06CB4CF1BE10259AB81-1a9uaKK1+wJcIJlls4ac1rfspsVTdybXVpNB7YpNyf8@public.gmane.org>
Nakajima, Jun wrote:
> And actually you don't need the write to CR3 to flush TLB because the
> one to CR4 does it. Or does kvm_flush_tlb_kernel assume that CR3 is
> updated at the same time?
>
> Jun
It should not be necessary, but I believe this was added as a workaround
to a PII erratum. I can't find the erratum, however, and the history of
using G bits in Linux is complicated (several bugs introduced and many
intermediate versions of this code). Since this is not performance
critical, I think it is probably best to leave the CR3 reload.
However, being unnecessary on modern processors, I already submitted a
patch to eliminate it on 64-bit (or maybe just told Andi about it, I
can't recall).
Zach
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next prev parent reply other threads:[~2007-05-30 17:58 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-05-30 14:49 [PATCH 0/3] KVM paravirt_ops implementation Anthony Liguori
2007-05-30 14:52 ` [PATCH 1/3] KVM paravirt_ops infrastructure Anthony Liguori
2007-05-30 16:42 ` [kvm-devel] " Nakajima, Jun
[not found] ` <97D612E30E1F88419025B06CB4CF1BE10259AAD7-1a9uaKK1+wJcIJlls4ac1rfspsVTdybXVpNB7YpNyf8@public.gmane.org>
2007-05-30 18:11 ` Anthony Liguori
[not found] ` <465DBE3A.6030908-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
2007-05-30 19:04 ` Nakajima, Jun
[not found] ` <97D612E30E1F88419025B06CB4CF1BE10259AD83-1a9uaKK1+wJcIJlls4ac1rfspsVTdybXVpNB7YpNyf8@public.gmane.org>
2007-05-31 17:31 ` Anthony Liguori
[not found] ` <465F0688.1050702-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
2007-05-31 18:47 ` Nakajima, Jun
2007-05-31 1:02 ` Rusty Russell
2007-05-31 1:15 ` [kvm-devel] " Anthony Liguori
[not found] ` <1180573347.30202.135.camel-bi+AKbBUZKY6gyzm1THtWbp2dZbC/Bob@public.gmane.org>
2007-05-31 7:48 ` Avi Kivity
2007-05-31 9:58 ` Andi Kleen
[not found] ` <200705311158.28632.ak-l3A5Bk7waGM@public.gmane.org>
2007-05-31 10:11 ` Ingo Molnar
[not found] ` <20070531101116.GA10872-X9Un+BFzKDI@public.gmane.org>
2007-05-31 10:40 ` Andi Kleen
[not found] ` <200705311240.19794.ak-l3A5Bk7waGM@public.gmane.org>
2007-05-31 11:12 ` Rusty Russell
2007-05-31 17:28 ` [kvm-devel] " Anthony Liguori
2007-05-31 17:29 ` Anthony Liguori
2007-05-30 14:53 ` [PATCH 2/3][PARAVIRT] Make IO delay a NOP Anthony Liguori
[not found] ` <465D8F03.7000201-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
2007-05-30 14:53 ` [PATCH 3/3] Eliminate read_cr3 on TLB flush Anthony Liguori
[not found] ` <465D8FF5.6040804-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
2007-05-30 15:01 ` Andi Kleen
2007-05-30 15:32 ` Anthony Liguori
2007-05-30 15:38 ` Jeremy Fitzhardinge
2007-05-30 17:11 ` [kvm-devel] " Nakajima, Jun
[not found] ` <465D9A77.90505-TSDbQ3PG+2Y@public.gmane.org>
2007-05-30 17:11 ` Nakajima, Jun
2007-05-30 17:58 ` [kvm-devel] " Zachary Amsden
[not found] ` <97D612E30E1F88419025B06CB4CF1BE10259AB81-1a9uaKK1+wJcIJlls4ac1rfspsVTdybXVpNB7YpNyf8@public.gmane.org>
2007-05-30 17:58 ` Zachary Amsden [this message]
2007-05-30 19:12 ` Nakajima, Jun
[not found] ` <465DBB49.5030503-pghWNbHTmq7QT0dZR+AlfA@public.gmane.org>
2007-05-30 19:12 ` Nakajima, Jun
2007-05-30 19:22 ` [kvm-devel] " Anthony Liguori
2007-05-30 20:40 ` Nakajima, Jun
2007-05-30 21:49 ` Zachary Amsden
[not found] ` <465DCED8.4080506-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
2007-05-30 20:40 ` Nakajima, Jun
[not found] ` <97D612E30E1F88419025B06CB4CF1BE10259AE6D-1a9uaKK1+wJcIJlls4ac1rfspsVTdybXVpNB7YpNyf8@public.gmane.org>
2007-05-30 22:03 ` Anthony Liguori
2007-05-30 22:03 ` [kvm-devel] " Anthony Liguori
2007-05-30 21:49 ` Zachary Amsden
2007-05-31 7:50 ` Avi Kivity
2007-05-31 17:30 ` [kvm-devel] " Anthony Liguori
[not found] ` <465E7E4F.8050208-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-05-31 8:27 ` Zachary Amsden
2007-05-31 17:30 ` Anthony Liguori
2007-05-31 1:12 ` [kvm-devel] " Rusty Russell
2007-05-31 7:50 ` Avi Kivity
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