| From foo@baz Mon May 21 22:23:33 CEST 2018 |
| From: Borislav Petkov <bp@suse.de> |
| Date: Thu, 7 Sep 2017 19:08:21 +0200 |
| Subject: x86/cpu/AMD: Fix erratum 1076 (CPB bit) |
| |
| From: Borislav Petkov <bp@suse.de> |
| |
| commit f7f3dc00f61261cdc9ccd8b886f21bc4dffd6fd9 upstream |
| |
| CPUID Fn8000_0007_EDX[CPB] is wrongly 0 on models up to B1. But they do |
| support CPB (AMD's Core Performance Boosting cpufreq CPU feature), so fix that. |
| |
| Signed-off-by: Borislav Petkov <bp@suse.de> |
| Cc: Linus Torvalds <torvalds@linux-foundation.org> |
| Cc: Peter Zijlstra <peterz@infradead.org> |
| Cc: Sherry Hurwitz <sherry.hurwitz@amd.com> |
| Cc: Thomas Gleixner <tglx@linutronix.de> |
| Link: http://lkml.kernel.org/r/20170907170821.16021-1-bp@alien8.de |
| Signed-off-by: Ingo Molnar <mingo@kernel.org> |
| Signed-off-by: David Woodhouse <dwmw@amazon.co.uk> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| arch/x86/kernel/cpu/amd.c | 11 +++++++++++ |
| 1 file changed, 11 insertions(+) |
| |
| --- a/arch/x86/kernel/cpu/amd.c |
| +++ b/arch/x86/kernel/cpu/amd.c |
| @@ -749,6 +749,16 @@ static void init_amd_bd(struct cpuinfo_x |
| } |
| } |
| |
| +static void init_amd_zn(struct cpuinfo_x86 *c) |
| +{ |
| + /* |
| + * Fix erratum 1076: CPB feature bit not being set in CPUID. It affects |
| + * all up to and including B1. |
| + */ |
| + if (c->x86_model <= 1 && c->x86_stepping <= 1) |
| + set_cpu_cap(c, X86_FEATURE_CPB); |
| +} |
| + |
| static void init_amd(struct cpuinfo_x86 *c) |
| { |
| u32 dummy; |
| @@ -779,6 +789,7 @@ static void init_amd(struct cpuinfo_x86 |
| case 0x10: init_amd_gh(c); break; |
| case 0x12: init_amd_ln(c); break; |
| case 0x15: init_amd_bd(c); break; |
| + case 0x17: init_amd_zn(c); break; |
| } |
| |
| /* Enable workaround for FXSAVE leak */ |
