[PATCH 4.19 019/202] x86/CPU/AMD: Fix disabling XSAVES on AMD family 0x17 due to erratum

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



4.19-stable review patch.  If anyone has any objections, please let me know.

------------------


From: "Maciej S. Szmigiero" <maciej.szmigiero@xxxxxxxxxx>

The stable kernel version backport of the patch disabling XSAVES on AMD
Zen family 0x17 applied this change to the wrong function (init_amd_k6()),
one which isn't called for Zen CPUs.

Move the erratum to the init_amd_zn() function instead.

Add an explicit family 0x17 check to the erratum so nothing will break if
someone naively makes this kernel version call init_amd_zn() also for
family 0x19 in the future (as the current upstream code does).

Fixes: f028a7db9824 ("x86/CPU/AMD: Disable XSAVES on AMD family 0x17")
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 arch/x86/kernel/cpu/amd.c |   20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -271,15 +271,6 @@ static void init_amd_k6(struct cpuinfo_x
 		return;
 	}
 #endif
-	/*
-	 * Work around Erratum 1386.  The XSAVES instruction malfunctions in
-	 * certain circumstances on Zen1/2 uarch, and not all parts have had
-	 * updated microcode at the time of writing (March 2023).
-	 *
-	 * Affected parts all have no supervisor XSAVE states, meaning that
-	 * the XSAVEC instruction (which works fine) is equivalent.
-	 */
-	clear_cpu_cap(c, X86_FEATURE_XSAVES);
 }
 
 static void init_amd_k7(struct cpuinfo_x86 *c)
@@ -979,6 +970,17 @@ static void init_amd_zn(struct cpuinfo_x
 		if (c->x86 == 0x19 && !cpu_has(c, X86_FEATURE_BTC_NO))
 			set_cpu_cap(c, X86_FEATURE_BTC_NO);
 	}
+
+	/*
+	 * Work around Erratum 1386.  The XSAVES instruction malfunctions in
+	 * certain circumstances on Zen1/2 uarch, and not all parts have had
+	 * updated microcode at the time of writing (March 2023).
+	 *
+	 * Affected parts all have no supervisor XSAVE states, meaning that
+	 * the XSAVEC instruction (which works fine) is equivalent.
+	 */
+	if (c->x86 == 0x17)
+		clear_cpu_cap(c, X86_FEATURE_XSAVES);
 }
 
 static bool cpu_has_zenbleed_microcode(void)






[Index of Archives]     [Linux Kernel]     [Kernel Development Newbies]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite Hiking]     [Linux Kernel]     [Linux SCSI]

  Powered by Linux