| Message ID | 20211019233641.140275-2-Smita.KoralahalliChannabasappa@amd.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | x86/mce: Handle error injection failures in mce-inject module | expand |
On Tue, Oct 19, 2021 at 06:36:37PM -0500, Smita Koralahalli wrote: > 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" error injection check the value of this register before trying > to inject the error. > > Do not impose any limitation 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. > > Signed-off-by: Smita Koralahalli <Smita.KoralahalliChannabasappa@amd.com> > --- > v2: > simulate -> inject. > Corrected according to kernel commenting style. > boot_cpu_has() -> cpu_feature_enabled(). > Error simulation not possible: Bank %llu unpopulated -> > Cannot set IPID - bank %llu unpopulated. > Used user provided IPID value on sw injection without checking > underlying hardware and defined it under inj_ipid_set(). > --- > arch/x86/kernel/cpu/mce/inject.c | 39 +++++++++++++++++++++++++++++--- > 1 file changed, 36 insertions(+), 3 deletions(-) So I gave it a critical look and did some modifications, see below. Looking at those IPID MSRs - they're all read-only, which means for !sw injection, all the module can do is check whether they're 0 - and fail injection in that case - and do the injection otherwise. Ok? --- From: Smita Koralahalli <Smita.KoralahalliChannabasappa@amd.com> Date: Tue, 19 Oct 2021 18:36:37 -0500 Subject: [PATCH] x86/mce/inject: Check if a bank is populated before error injection 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 limitation on a sw-type injection (software-only 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. ] Signed-off-by: Smita Koralahalli <Smita.KoralahalliChannabasappa@amd.com> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20211019233641.140275-2-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 0bfc14041bbb..3333ae7886bd 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 bank %llu - it is unpopulated\n", val); + return -ENODEV; + } + } + +inject: do_inject(); /* Reset injection struct */
On 10/25/21 8:56 AM, Borislav Petkov wrote: > On Tue, Oct 19, 2021 at 06:36:37PM -0500, Smita Koralahalli wrote: >> 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" error injection check the value of this register before trying >> to inject the error. >> >> Do not impose any limitation 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. >> >> Signed-off-by: Smita Koralahalli <Smita.KoralahalliChannabasappa@amd.com> >> --- >> v2: >> simulate -> inject. >> Corrected according to kernel commenting style. >> boot_cpu_has() -> cpu_feature_enabled(). >> Error simulation not possible: Bank %llu unpopulated -> >> Cannot set IPID - bank %llu unpopulated. >> Used user provided IPID value on sw injection without checking >> underlying hardware and defined it under inj_ipid_set(). >> --- >> arch/x86/kernel/cpu/mce/inject.c | 39 +++++++++++++++++++++++++++++--- >> 1 file changed, 36 insertions(+), 3 deletions(-) > So I gave it a critical look and did some modifications, see below. > Looking at those IPID MSRs - they're all read-only, which means for !sw > injection, all the module can do is check whether they're 0 - and fail > injection in that case - and do the injection otherwise. > > Ok? Yes, this looks more clearer. Thank you. > > --- > From: Smita Koralahalli <Smita.KoralahalliChannabasappa@amd.com> > Date: Tue, 19 Oct 2021 18:36:37 -0500 > Subject: [PATCH] x86/mce/inject: Check if a bank is populated before error > injection > > 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 limitation on a sw-type injection (software-only > 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. ] > > Signed-off-by: Smita Koralahalli <Smita.KoralahalliChannabasappa@amd.com> > Signed-off-by: Borislav Petkov <bp@suse.de> > Link: https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flkml.kernel.org%2Fr%2F20211019233641.140275-2-Smita.KoralahalliChannabasappa%40amd.com&data=04%7C01%7CSmita.KoralahalliChannabasappa%40amd.com%7C6da4cbaab660413d27a208d997bf48f1%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637707670099990329%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=Jpecn9lg2XxdqhbLpMIxuSh%2BRA3eafMReXmdLI3SkfM%3D&reserved=0 > --- > 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 0bfc14041bbb..3333ae7886bd 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 bank %llu - it is unpopulated\n", val); > + return -ENODEV; > + } > + } > + > +inject: > do_inject(); > > /* Reset injection struct */
diff --git a/arch/x86/kernel/cpu/mce/inject.c b/arch/x86/kernel/cpu/mce/inject.c index 0bfc14041bbb..601efd104bb4 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) \ @@ -89,13 +88,11 @@ MCE_INJECT_GET(status); MCE_INJECT_GET(misc); MCE_INJECT_GET(addr); MCE_INJECT_GET(synd); -MCE_INJECT_GET(ipid); 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"); -DEFINE_SIMPLE_ATTRIBUTE(ipid_fops, inj_ipid_get, inj_ipid_set, "%llx\n"); static void setup_inj_struct(struct mce *m) { @@ -577,6 +574,25 @@ static int inj_bank_set(void *data, u64 val) } m->bank = val; + + /* + * Read IPID value to determine if a bank is unpopulated on the target + * CPU. + */ + if (cpu_feature_enabled(X86_FEATURE_SMCA)) { + + /* Check for user provided IPID value on a sw injection. */ + if (!m->ipid) { + rdmsrl_on_cpu(m->extcpu, MSR_AMD64_SMCA_MCx_IPID(val), + &m->ipid); + if (!m->ipid) { + pr_err("Cannot set IPID - bank %llu unpopulated\n", + val); + return -ENODEV; + } + } + } + do_inject(); /* Reset injection struct */ @@ -589,6 +605,23 @@ MCE_INJECT_GET(bank); DEFINE_SIMPLE_ATTRIBUTE(bank_fops, inj_bank_get, inj_bank_set, "%llu\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 (val && inj_type == SW_INJ) + m->ipid = val; + } + + return 0; +} + +MCE_INJECT_GET(ipid); + +DEFINE_SIMPLE_ATTRIBUTE(ipid_fops, inj_ipid_get, inj_ipid_set, "%llx\n"); + static const char readme_msg[] = "Description of the files and their usages:\n" "\n"
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" error injection check the value of this register before trying to inject the error. Do not impose any limitation 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. Signed-off-by: Smita Koralahalli <Smita.KoralahalliChannabasappa@amd.com> --- v2: simulate -> inject. Corrected according to kernel commenting style. boot_cpu_has() -> cpu_feature_enabled(). Error simulation not possible: Bank %llu unpopulated -> Cannot set IPID - bank %llu unpopulated. Used user provided IPID value on sw injection without checking underlying hardware and defined it under inj_ipid_set(). --- arch/x86/kernel/cpu/mce/inject.c | 39 +++++++++++++++++++++++++++++--- 1 file changed, 36 insertions(+), 3 deletions(-)