4.19-stable review patch. If anyone has any objections, please let me know.
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From: "Maciej S. Szmigiero" maciej.szmigiero@oracle.com
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@oracle.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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)