AMD 3200 Revision History - Page 58

Guest, Performance, Counters, Inaccurate

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Revision Guide for AMD Family 15h Models 00h-0Fh Processors 48063 Rev. 3.18 October 2012 672 SVM Guest Performance Counters May Be Inaccurate Due to SMI Description Performance Event Counters[5:0] (MSRC001_020[B,9,7,5,3,1]) incorrectly count events in SystemManagement Mode (SMM) after a Secure Virtual Machine (SVM) guest receives a System-Management Interrupt (SMI) that is not intercepted by the host. This occurs when guest event counting is enabled by setting Performance Event Select[5:0][HostGuestOnly] = 01b (MSRC001_020[A,8,6,4,2,0][41:40]) and EFER[SVME] = 1b (MSRC000_0080[12]). Potential Effect on System Performance monitoring software overcounts events for an SVM guest when non-intercepted SMIs occur. Suggested Workaround Contact your AMD representative for information on a BIOS update. When the workaround is enabled, the processor swaps the HostGuestOnly bits (i.e. bits 41 and 40 of MSRC001_020[A,8,6,4,2,0] are exchanged) before entering SMM from SVM guest mode and again on the corresponding RSM. Fix Planned Yes 58 Product Errata

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672
SVM
Guest
Performance
Counters
May
Be
Inaccurate
Due
to
SMI
Description
Performance
Event
Counters
[5:0] (
MSRC
001_020[
B
,9,7,5,3,1]
incorrectly
count
events
in
System-
Management
Mode
(
SMM
after
a
Secure
Virtual
Machine
(
SVM
guest
receives
a
System-Management
Interrupt
(
SMI
that
is
not
intercepted
by
the
host
.
This
occurs
when
guest
event
counting
is
enabled
by
setting
Performance
Event
Select
[5:0][
HostGuestOnly
] = 01
b
(
MSRC
001_020[
A
,8,6,4,2,0][41:40]
and
EFER
[
SVME
]
= 1
b
(
MSRC
000_0080[12] .
Potential
Effect
on
System
Performance
monitoring
software
overcounts
events
for
an
SVM
guest
when
non-intercepted
SMIs
occur
.
Suggested
Workaround
Contact
your
AMD
representative
for
information
on
a
BIOS
update
.
When
the
workaround
is
enabled
,
the
processor
swaps
the
HostGuestOnly
bits
(
i
.
e
.
bits
41
and
40
of
MSRC
001_020[
A
,8,6,4,2,0]
are
exchanged
before
entering
SMM
from
SVM
guest
mode
and
again
on
the
corresponding
RSM
.
Fix
Planned
Yes
Revision
Guide
for
AMD
Family
15
h
Models
00
h-
0
Fh
Processors
48063
Rev
. 3.18
October
2012
58
Product
Errata