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Bug 2203186 - glibc: Fix cache size detection for hypervisors or older AMD hardware
Summary: glibc: Fix cache size detection for hypervisors or older AMD hardware
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Red Hat Enterprise Linux 9
Classification: Red Hat
Component: glibc
Version: 9.3
Hardware: x86_64
OS: Linux
unspecified
urgent
Target Milestone: rc
: ---
Assignee: Florian Weimer
QA Contact: Sergey Kolosov
URL:
Whiteboard:
Depends On:
Blocks: 2166709 2166710
TreeView+ depends on / blocked
 
Reported: 2023-05-11 13:10 UTC by Carlos O'Donell
Modified: 2023-11-07 10:11 UTC (History)
7 users (show)

Fixed In Version: glibc-2.34-80.el9
Doc Type: No Doc Update
Doc Text:
Clone Of:
Environment:
Last Closed: 2023-11-07 08:37:51 UTC
Type: Bug
Target Upstream Version:
Embargoed:
pm-rhel: mirror+

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Red Hat Issue Tracker RHELPLAN-156960 0 None None None 2023-05-11 13:13:31 UTC
Red Hat Product Errata RHBA-2023:6582 0 None None None 2023-11-07 08:38:14 UTC

Description Carlos O'Donell 2023-05-11 13:10:10 UTC 
The current -67 glibc build uses the upstream cache size detection code which is incorrect under certain hypervisors and older AMD hardware.

We need to do one of two things:
- Revert the current cache size detection code.
- Backport an upstream correction that supports the old cpuid mechanism and the new cpuid mechanism.
Comment 5 Carlos O'Donell 2023-07-14 21:26:05 UTC 
We will be reverting the current AMD cacheline changes until we have a solution that works for old and new CPUs.
Comment 10 Carlos O'Donell 2023-08-14 14:28:26 UTC 
Upstream commit:

commit dcad5c8578130dec7f35fd5b0885304b59f9f543
Author: Sajan Karumanchi <sajan.karumanchi>
Date:   Tue Aug 1 15:20:55 2023 +0000

    x86: Fix for cache computation on AMD legacy cpus.
    
    Some legacy AMD CPUs and hypervisors have the _cpuid_ '0x8000_001D'
    set to Zero, thus resulting in zeroed-out computed cache values.
    This patch reintroduces the old way of cache computation as a
    fail-safe option to handle these exceptions.
    Fixed 'level4_cache_size' value through handle_amd().
    
    Reviewed-by: Premachandra Mallappa <premachandra.mallappa>
    Tested-by: Florian Weimer <fweimer>

Committed to c9s:

commit 3a04eb2e1826da207b64a254af3d17e30a27db11
Author: Florian Weimer <fweimer>
Date:   Fri Aug 11 17:54:52 2023 +0200

    Fix AMD cache size computation for hypervisors, old CPUs (#2166710)
    
    Missing spec file update.
    
    Related: #2166710
Comment 15 errata-xmlrpc 2023-11-07 08:37:51 UTC 
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory (glibc bug fix and enhancement update), and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2023:6582
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