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From: Aurelien Jarno <>
Cc: Aurelien Jarno <>
Subject: [PATCH] elf: Fix tst-cpu-features-cpuinfo for KVM guests on some AMD systems [BZ #28704]
Date: Fri, 17 Dec 2021 20:36:09 +0100	[thread overview]
Message-ID: <> (raw)

On KVM guests running on some AMD systems, the IBRS feature is reported
as a synthetic feature using the Intel feature, while the cpuinfo entry
keeps the same. Handle that by first checking the presence of the Intel
feature on AMD systems.

Fixes bug 28704.

(cherry picked from commit 94058f6cde8b887178885954740ac6c866d25eab)
 NEWS                                   | 1 +
 sysdeps/x86/tst-cpu-features-cpuinfo.c | 9 ++++++++-
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/NEWS b/NEWS
index 6864af471c..1214ec4727 100644
--- a/NEWS
+++ b/NEWS
@@ -24,6 +24,7 @@ The following bugs are resolved with this release:
   [28532] powerpc64[le]: CFI for assembly templated syscalls is incorrect
   [28678] nptl/tst-create1 hangs sporadically
   [28700] "dns [!UNAVAIL=return] files" NSS default for hosts is not useful
+  [28704] elf/tst-cpu-features-cpuinfo fails for KVM guests on some AMD systems
 Version 2.34
diff --git a/sysdeps/x86/tst-cpu-features-cpuinfo.c b/sysdeps/x86/tst-cpu-features-cpuinfo.c
index 2d4927f5e5..830aaca2ec 100644
--- a/sysdeps/x86/tst-cpu-features-cpuinfo.c
+++ b/sysdeps/x86/tst-cpu-features-cpuinfo.c
@@ -169,7 +169,14 @@ do_test (int argc, char **argv)
   else if (cpu_features->basic.kind == arch_kind_amd)
       fails += CHECK_PROC (ibpb, AMD_IBPB);
-      fails += CHECK_PROC (ibrs, AMD_IBRS);
+      /* The IBRS feature on AMD processors is reported using the Intel feature
+       * on KVM guests (synthetic bit).  In both cases the cpuinfo entry is the
+       * same.  */
+        fails += CHECK_PROC (ibrs, IBRS_IBPB);
+      else
+        fails += CHECK_PROC (ibrs, AMD_IBRS);
       fails += CHECK_PROC (stibp, AMD_STIBP);
   fails += CHECK_PROC (ibt, IBT);

                 reply	other threads:[~2021-12-17 19:36 UTC|newest]

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