From e48d008bd13eaa9068ff59c65275d17516179f7b Mon Sep 17 00:00:00 2001 From: Smita Koralahalli Date: Thu, 4 Nov 2021 16:58:41 -0500 Subject: [PATCH] x86/mce/inject: Check if a bank is populated before injecting The MCA_IPID register uniquely identifies a bank's type on Scalable MCA (SMCA) systems. When an MCA bank is not populated, the MCA_IPID register will read as zero and writes to it will be ignored. On a hw-type error injection (injection which writes the actual MCA registers in an attempt to cause a real MCE) check the value of this register before trying to inject the error. Do not impose any limitations on a sw injection and allow the user to test out all the decoding paths without relying on the available hardware, as its purpose is to just test the code. [ bp: Heavily massage. ] Link: https://lkml.kernel.org/r/20211019233641.140275-2-Smita.KoralahalliChannabasappa@amd.com Signed-off-by: Smita Koralahalli Signed-off-by: Borislav Petkov Link: https://lore.kernel.org/r/20211104215846.254012-2-Smita.KoralahalliChannabasappa@amd.com --- arch/x86/kernel/cpu/mce/inject.c | 42 +++++++++++++++++++++++++++++++- 1 file changed, 41 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/cpu/mce/inject.c b/arch/x86/kernel/cpu/mce/inject.c index 0bfc14041bbb4..725e8e4331a92 100644 --- a/arch/x86/kernel/cpu/mce/inject.c +++ b/arch/x86/kernel/cpu/mce/inject.c @@ -74,7 +74,6 @@ MCE_INJECT_SET(status); MCE_INJECT_SET(misc); MCE_INJECT_SET(addr); MCE_INJECT_SET(synd); -MCE_INJECT_SET(ipid); #define MCE_INJECT_GET(reg) \ static int inj_##reg##_get(void *data, u64 *val) \ @@ -95,6 +94,20 @@ DEFINE_SIMPLE_ATTRIBUTE(status_fops, inj_status_get, inj_status_set, "%llx\n"); DEFINE_SIMPLE_ATTRIBUTE(misc_fops, inj_misc_get, inj_misc_set, "%llx\n"); DEFINE_SIMPLE_ATTRIBUTE(addr_fops, inj_addr_get, inj_addr_set, "%llx\n"); DEFINE_SIMPLE_ATTRIBUTE(synd_fops, inj_synd_get, inj_synd_set, "%llx\n"); + +/* Use the user provided IPID value on a sw injection. */ +static int inj_ipid_set(void *data, u64 val) +{ + struct mce *m = (struct mce *)data; + + if (cpu_feature_enabled(X86_FEATURE_SMCA)) { + if (inj_type == SW_INJ) + m->ipid = val; + } + + return 0; +} + DEFINE_SIMPLE_ATTRIBUTE(ipid_fops, inj_ipid_get, inj_ipid_set, "%llx\n"); static void setup_inj_struct(struct mce *m) @@ -577,6 +590,33 @@ static int inj_bank_set(void *data, u64 val) } m->bank = val; + + /* + * sw-only injection allows to write arbitrary values into the MCA + * registers because it tests only the decoding paths. + */ + if (inj_type == SW_INJ) + goto inject; + + /* + * Read IPID value to determine if a bank is populated on the target + * CPU. + */ + if (cpu_feature_enabled(X86_FEATURE_SMCA)) { + u64 ipid; + + if (rdmsrl_on_cpu(m->extcpu, MSR_AMD64_SMCA_MCx_IPID(val), &ipid)) { + pr_err("Error reading IPID on CPU%d\n", m->extcpu); + return -EINVAL; + } + + if (!ipid) { + pr_err("Cannot inject into unpopulated bank %llu\n", val); + return -ENODEV; + } + } + +inject: do_inject(); /* Reset injection struct */ -- 2.30.2