This is a note to let you know that I've just added the patch titled
x86/perf: Avoid warning for Arch LBR without XSAVE
to the 5.16-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-perf-avoid-warning-for-arch-lbr-without-xsave.patch
and it can be found in the queue-5.16 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 7eecdd3291c389a346d234ccdc62ade6a511935b
Author: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Date: Wed Dec 15 12:40:29 2021 -0800
x86/perf: Avoid warning for Arch LBR without XSAVE
[ Upstream commit 8c16dc047b5dd8f7b3bf4584fa75733ea0dde7dc ]
Some hypervisors support Arch LBR, but without the LBR XSAVE support.
The current Arch LBR init code prints a warning when the xsave size (0) is
unexpected. Avoid printing the warning for the "no LBR XSAVE" case.
Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/20211215204029.150686-1-ak@xxxxxxxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/x86/events/intel/lbr.c b/arch/x86/events/intel/lbr.c
index 8043213b75a52..fa947c4fbd1f8 100644
--- a/arch/x86/events/intel/lbr.c
+++ b/arch/x86/events/intel/lbr.c
@@ -1726,6 +1726,9 @@ static bool is_arch_lbr_xsave_available(void)
* Check the LBR state with the corresponding software structure.
* Disable LBR XSAVES support if the size doesn't match.
*/
+ if (xfeature_size(XFEATURE_LBR) == 0)
+ return false;
+
if (WARN_ON(xfeature_size(XFEATURE_LBR) != get_lbr_state_size()))
return false;
