Commit 286836a7 authored by Pawan Gupta's avatar Pawan Gupta Committed by Thomas Gleixner
Browse files

x86/cpu: Add a helper function x86_read_arch_cap_msr() 



Add a helper function to read the IA32_ARCH_CAPABILITIES MSR.

Signed-off-by: default avatarPawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Tested-by: default avatarNeelima Krishnan <neelima.krishnan@intel.com>
Reviewed-by: default avatarMark Gross <mgross@linux.intel.com>
Reviewed-by: default avatarTony Luck <tony.luck@intel.com>
Reviewed-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
parent c2955f27

arch/x86/kernel/cpu/common.c

+11 −4
Original line number Diff line number Diff line
@@ -1092,19 +1092,26 @@ static bool __init cpu_matches(unsigned long which) 
	return m && !!(m->driver_data & which);

}



static void __init cpu_set_bug_bits(struct cpuinfo_x86 *c)

u64 x86_read_arch_cap_msr(void)

{

	u64 ia32_cap = 0;



	if (boot_cpu_has(X86_FEATURE_ARCH_CAPABILITIES))

		rdmsrl(MSR_IA32_ARCH_CAPABILITIES, ia32_cap);



	return ia32_cap;

}



static void __init cpu_set_bug_bits(struct cpuinfo_x86 *c)

{

	u64 ia32_cap = x86_read_arch_cap_msr();



	if (cpu_matches(NO_SPECULATION))

		return;



	setup_force_cpu_bug(X86_BUG_SPECTRE_V1);

	setup_force_cpu_bug(X86_BUG_SPECTRE_V2);



	if (cpu_has(c, X86_FEATURE_ARCH_CAPABILITIES))

		rdmsrl(MSR_IA32_ARCH_CAPABILITIES, ia32_cap);



	if (!cpu_matches(NO_SSB) && !(ia32_cap & ARCH_CAP_SSB_NO) &&

	   !cpu_has(c, X86_FEATURE_AMD_SSB_NO))

		setup_force_cpu_bug(X86_BUG_SPEC_STORE_BYPASS);

arch/x86/kernel/cpu/cpu.h

+2 −0
Original line number Diff line number Diff line
@@ -62,4 +62,6 @@ unsigned int aperfmperf_get_khz(int cpu); 


extern void x86_spec_ctrl_setup_ap(void);



extern u64 x86_read_arch_cap_msr(void);



#endif /* ARCH_X86_CPU_H */