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@amd.com> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lore.kernel.org/r/20220214233640.70510-2-Smita.KoralahalliChannabasappa@amd.com
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2 changed files with 48 additions and 1 deletions
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@ -33,6 +33,8 @@
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#include "internal.h"
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#include "internal.h"
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static bool hw_injection_possible = true;
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/*
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/*
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* Collect all the MCi_XXX settings
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* Collect all the MCi_XXX settings
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*/
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*/
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@ -339,6 +341,8 @@ static int __set_inj(const char *buf)
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for (i = 0; i < N_INJ_TYPES; i++) {
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for (i = 0; i < N_INJ_TYPES; i++) {
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if (!strncmp(flags_options[i], buf, strlen(flags_options[i]))) {
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if (!strncmp(flags_options[i], buf, strlen(flags_options[i]))) {
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if (i > SW_INJ && !hw_injection_possible)
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continue;
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inj_type = i;
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inj_type = i;
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return 0;
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return 0;
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}
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}
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@ -717,11 +721,54 @@ static void __init debugfs_init(void)
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&i_mce, dfs_fls[i].fops);
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&i_mce, dfs_fls[i].fops);
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}
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}
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static void check_hw_inj_possible(void)
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{
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int cpu;
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u8 bank;
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/*
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* This behavior exists only on SMCA systems though its not directly
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* related to SMCA.
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*/
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if (!cpu_feature_enabled(X86_FEATURE_SMCA))
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return;
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cpu = get_cpu();
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for (bank = 0; bank < MAX_NR_BANKS; ++bank) {
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u64 status = MCI_STATUS_VAL, ipid;
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/* Check whether bank is populated */
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rdmsrl(MSR_AMD64_SMCA_MCx_IPID(bank), ipid);
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if (!ipid)
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continue;
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toggle_hw_mce_inject(cpu, true);
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wrmsrl_safe(mca_msr_reg(bank, MCA_STATUS), status);
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rdmsrl_safe(mca_msr_reg(bank, MCA_STATUS), &status);
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if (!status) {
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hw_injection_possible = false;
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pr_warn("Platform does not allow *hardware* error injection."
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"Try using APEI EINJ instead.\n");
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}
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toggle_hw_mce_inject(cpu, false);
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break;
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}
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put_cpu();
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}
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static int __init inject_init(void)
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static int __init inject_init(void)
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{
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{
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if (!alloc_cpumask_var(&mce_inject_cpumask, GFP_KERNEL))
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if (!alloc_cpumask_var(&mce_inject_cpumask, GFP_KERNEL))
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return -ENOMEM;
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return -ENOMEM;
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check_hw_inj_possible();
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debugfs_init();
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debugfs_init();
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register_nmi_handler(NMI_LOCAL, mce_raise_notify, 0, "mce_notify");
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register_nmi_handler(NMI_LOCAL, mce_raise_notify, 0, "mce_notify");
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@ -211,7 +211,7 @@ noinstr u64 mce_rdmsrl(u32 msr);
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static __always_inline u32 mca_msr_reg(int bank, enum mca_msr reg)
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static __always_inline u32 mca_msr_reg(int bank, enum mca_msr reg)
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{
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{
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if (mce_flags.smca) {
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if (cpu_feature_enabled(X86_FEATURE_SMCA)) {
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switch (reg) {
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switch (reg) {
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case MCA_CTL: return MSR_AMD64_SMCA_MCx_CTL(bank);
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case MCA_CTL: return MSR_AMD64_SMCA_MCx_CTL(bank);
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case MCA_ADDR: return MSR_AMD64_SMCA_MCx_ADDR(bank);
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case MCA_ADDR: return MSR_AMD64_SMCA_MCx_ADDR(bank);
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