From: speck for Pawan Gupta Date: Wed, 9 Oct 2019 16:23:56 -0700 Subject: TAAv6 2 Add a helper function to read IA32_ARCH_CAPABILITIES MSR. If the CPU doesn't support this MSR return 0. Signed-off-by: Pawan Gupta Reviewed-by: Mark Gross Reviewed-by: Tony Luck Tested-by: Neelima Krishnan [bwh: Forward-ported on top of NX: Fix conflict (neighbouring changes) in arch/x86/kernel/cpu/common.c] Signed-off-by: Ben Hutchings --- arch/x86/kernel/cpu/common.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 128808dccd2f..cee109bd7f00 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -1018,13 +1018,20 @@ 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 (cpu_has(c, X86_FEATURE_ARCH_CAPABILITIES)) + 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(); + /* Set ITLB_MULTIHIT bug if cpu is not in the whitelist and not mitigated */ if (!cpu_matches(NO_ITLB_MULTIHIT) && !(ia32_cap & ARCH_CAP_PSCHANGE_MC_NO)) setup_force_cpu_bug(X86_BUG_ITLB_MULTIHIT);