5.4-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: e40c1e9da1ec ("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
@@ -277,15 +277,6 @@ 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)
@@ -989,6 +980,17 @@ 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)
