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Date: Tue, 30 Mar 2010 15:42:16 -0700 From: Greg KH <gregkh@...e.de> To: linux-kernel@...r.kernel.org, stable@...nel.org Cc: stable-review@...nel.org, torvalds@...ux-foundation.org, akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk, Andreas Herrmann <andreas.herrmann3@....com>, "H. Peter Anvin" <hpa@...or.com>, Greg Kroah-Hartman <gregkh@...e.de> Subject: [102/156] x86, amd: Restrict usage of c1e_idle() 2.6.33-stable review patch. If anyone has any objections, please let us know. ------------------ From: Andreas Herrmann <andreas.herrmann3@....com> commit 035a02c1e1de31888e8b6adac0ff667971ac04db upstream. Currently c1e_idle returns true for all CPUs greater than or equal to family 0xf model 0x40. This covers too many CPUs. Meanwhile a respective erratum for the underlying problem was filed (#400). This patch adds the logic to check whether erratum #400 applies to a given CPU. Especially for CPUs where SMI/HW triggered C1e is not supported, c1e_idle() doesn't need to be used. We can check this by looking at the respective OSVW bit for erratum #400. Signed-off-by: Andreas Herrmann <andreas.herrmann3@....com> LKML-Reference: <20100319110922.GA19614@...erich.amd.com> Signed-off-by: H. Peter Anvin <hpa@...or.com> Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de> --- arch/x86/include/asm/msr-index.h | 2 ++ arch/x86/kernel/process.c | 32 ++++++++++++++++++++++++-------- 2 files changed, 26 insertions(+), 8 deletions(-) --- a/arch/x86/include/asm/msr-index.h +++ b/arch/x86/include/asm/msr-index.h @@ -105,6 +105,8 @@ #define MSR_AMD64_PATCH_LEVEL 0x0000008b #define MSR_AMD64_NB_CFG 0xc001001f #define MSR_AMD64_PATCH_LOADER 0xc0010020 +#define MSR_AMD64_OSVW_ID_LENGTH 0xc0010140 +#define MSR_AMD64_OSVW_STATUS 0xc0010141 #define MSR_AMD64_IBSFETCHCTL 0xc0011030 #define MSR_AMD64_IBSFETCHLINAD 0xc0011031 #define MSR_AMD64_IBSFETCHPHYSAD 0xc0011032 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -519,21 +519,37 @@ static int __cpuinit mwait_usable(const } /* - * Check for AMD CPUs, which have potentially C1E support + * Check for AMD CPUs, where APIC timer interrupt does not wake up CPU from C1e. + * For more information see + * - Erratum #400 for NPT family 0xf and family 0x10 CPUs + * - Erratum #365 for family 0x11 (not affected because C1e not in use) */ static int __cpuinit check_c1e_idle(const struct cpuinfo_x86 *c) { + u64 val; if (c->x86_vendor != X86_VENDOR_AMD) - return 0; - - if (c->x86 < 0x0F) - return 0; + goto no_c1e_idle; /* Family 0x0f models < rev F do not have C1E */ - if (c->x86 == 0x0f && c->x86_model < 0x40) - return 0; + if (c->x86 == 0x0F && c->x86_model >= 0x40) + return 1; + + if (c->x86 == 0x10) { + /* + * check OSVW bit for CPUs that are not affected + * by erratum #400 + */ + rdmsrl(MSR_AMD64_OSVW_ID_LENGTH, val); + if (val >= 2) { + rdmsrl(MSR_AMD64_OSVW_STATUS, val); + if (!(val & BIT(1))) + goto no_c1e_idle; + } + return 1; + } - return 1; +no_c1e_idle: + return 0; } static cpumask_var_t c1e_mask; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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