The following commit has been merged into the ras/core branch of tip: Commit-ID: 891e465a1bd8798d5f97c3afb99393f123817fef Gitweb: https://git.kernel.org/tip/891e465a1bd8798d5f97c3afb99393f123817fef Author: Smita Koralahalli <Smita.KoralahalliChannabasappa@xxxxxxx> AuthorDate: Mon, 27 Jun 2022 20:56:46 Committer: Borislav Petkov <bp@xxxxxxx> CommitterDate: Tue, 28 Jun 2022 12:08:10 +02:00 x86/mce: Check whether writes to MCA_STATUS are getting ignored The platform can sometimes - depending on its settings - cause writes to MCA_STATUS MSRs to get ignored, regardless of HWCR[McStatusWrEn]'s value. For further info see PPR for AMD Family 19h, Model 01h, Revision B1 Processors, doc ID 55898 at https://bugzilla.kernel.org/show_bug.cgi?id=206537. Therefore, probe for ignored writes to MCA_STATUS to determine if hardware error injection is at all possible. [ bp: Heavily massage commit message and patch. ] Signed-off-by: Smita Koralahalli <Smita.KoralahalliChannabasappa@xxxxxxx> Signed-off-by: Borislav Petkov <bp@xxxxxxx> Link: https://lore.kernel.org/r/20220214233640.70510-2-Smita.KoralahalliChannabasappa@xxxxxxx --- arch/x86/kernel/cpu/mce/inject.c | 47 +++++++++++++++++++++++++++++- arch/x86/kernel/cpu/mce/internal.h | 2 +- 2 files changed, 48 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/cpu/mce/inject.c b/arch/x86/kernel/cpu/mce/inject.c index 5fbd7ff..12cf2e7 100644 --- a/arch/x86/kernel/cpu/mce/inject.c +++ b/arch/x86/kernel/cpu/mce/inject.c @@ -33,6 +33,8 @@ #include "internal.h" +static bool hw_injection_possible = true; + /* * Collect all the MCi_XXX settings */ @@ -339,6 +341,8 @@ static int __set_inj(const char *buf) for (i = 0; i < N_INJ_TYPES; i++) { if (!strncmp(flags_options[i], buf, strlen(flags_options[i]))) { + if (i > SW_INJ && !hw_injection_possible) + continue; inj_type = i; return 0; } @@ -717,11 +721,54 @@ static void __init debugfs_init(void) &i_mce, dfs_fls[i].fops); } +static void check_hw_inj_possible(void) +{ + int cpu; + u8 bank; + + /* + * This behavior exists only on SMCA systems though its not directly + * related to SMCA. + */ + if (!cpu_feature_enabled(X86_FEATURE_SMCA)) + return; + + cpu = get_cpu(); + + for (bank = 0; bank < MAX_NR_BANKS; ++bank) { + u64 status = MCI_STATUS_VAL, ipid; + + /* Check whether bank is populated */ + rdmsrl(MSR_AMD64_SMCA_MCx_IPID(bank), ipid); + if (!ipid) + continue; + + toggle_hw_mce_inject(cpu, true); + + wrmsrl_safe(mca_msr_reg(bank, MCA_STATUS), status); + rdmsrl_safe(mca_msr_reg(bank, MCA_STATUS), &status); + + if (!status) { + hw_injection_possible = false; + pr_warn("Platform does not allow *hardware* error injection." + "Try using APEI EINJ instead.\n"); + } + + toggle_hw_mce_inject(cpu, false); + + break; + } + + put_cpu(); +} + static int __init inject_init(void) { if (!alloc_cpumask_var(&mce_inject_cpumask, GFP_KERNEL)) return -ENOMEM; + check_hw_inj_possible(); + debugfs_init(); register_nmi_handler(NMI_LOCAL, mce_raise_notify, 0, "mce_notify"); diff --git a/arch/x86/kernel/cpu/mce/internal.h b/arch/x86/kernel/cpu/mce/internal.h index 4ae0e60..7e03f5b 100644 --- a/arch/x86/kernel/cpu/mce/internal.h +++ b/arch/x86/kernel/cpu/mce/internal.h @@ -211,7 +211,7 @@ noinstr u64 mce_rdmsrl(u32 msr); static __always_inline u32 mca_msr_reg(int bank, enum mca_msr reg) { - if (mce_flags.smca) { + if (cpu_feature_enabled(X86_FEATURE_SMCA)) { switch (reg) { case MCA_CTL: return MSR_AMD64_SMCA_MCx_CTL(bank); case MCA_ADDR: return MSR_AMD64_SMCA_MCx_ADDR(bank);
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