Re: [PATCH 2/3] x86/MCE/AMD, EDAC/mce_amd: Enumerate Reserved SMCA bank type

Borislav Petkov
2018-02-08T15:15:29Z

On Thu, Feb 01, 2018 at 12:48:12PM -0600, Yazen Ghannam wrote:
> From: Yazen Ghannam <yazen.ghannam@amd.com>
>
> Currently, bank 4 is reserved on Fam17h, so we chose not to initialize
> bank 4 in the smca_banks array. This means that when we check if a bank
> is initialized, like during boot or resume, we will see that bank 4 is
> not initialized and try to initialize it. This may cause a call trace,
> when resuming from suspend, due to *on_cpu() calls in the init path.

Please be more specific: the rdmsr_*_on_cpu() calls issue an IPI but we're
running with interrupts disabled, which triggers:

WARNING: CPU: 0 PID: 11523 at kernel/smp.c:291 smp_call_function_single+0xdc/0xe0

> Reserved banks will be read-as-zero, so their MCA_IPID register will be
> zero. So, like the smca_banks array, the threshold_banks array will not
> have an entry for a reserved bank since all its MCA_MISC* registers will
> be zero.
>
> Enumerate a "Reserved" bank type that matches on a HWID_MCATYPE of 0,0.
>
> Use the "Reserved" type when checking if a bank is reserved. It's
> possible that other bank numbers may be reserved on future systems.
>
> Don't try to find the block address on reserved banks.
>
> Cc: <stable@vger.kernel.org> # 4.14.x
> Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
> ---
> arch/x86/include/asm/mce.h | 1 +
> arch/x86/kernel/cpu/mcheck/mce_amd.c | 7 +++++++
> drivers/edac/mce_amd.c | 11 +++++++----
> 3 files changed, 15 insertions(+), 4 deletions(-)
>
> diff --git a/arch/x86/include/asm/mce.h b/arch/x86/include/asm/mce.h
> index 96ea4b5ba658..340070415c2c 100644
> --- a/arch/x86/include/asm/mce.h
> +++ b/arch/x86/include/asm/mce.h
> @@ -346,6 +346,7 @@ enum smca_bank_types {
> SMCA_IF, /* Instruction Fetch */
> SMCA_L2_CACHE, /* L2 Cache */
> SMCA_DE, /* Decoder Unit */
> + SMCA_RESERVED, /* Reserved */
> SMCA_EX, /* Execution Unit */
> SMCA_FP, /* Floating Point */
> SMCA_L3_CACHE, /* L3 Cache */
> diff --git a/arch/x86/kernel/cpu/mcheck/mce_amd.c b/arch/x86/kernel/cpu/mcheck/mce_amd.c
> index 4e16afc0794d..bf53b4549a17 100644
> --- a/arch/x86/kernel/cpu/mcheck/mce_amd.c
> +++ b/arch/x86/kernel/cpu/mcheck/mce_amd.c
> @@ -82,6 +82,7 @@ static struct smca_bank_name smca_names[] = {
> [SMCA_IF] = { "insn_fetch", "Instruction Fetch Unit" },
> [SMCA_L2_CACHE] = { "l2_cache", "L2 Cache" },
> [SMCA_DE] = { "decode_unit", "Decode Unit" },
> + [SMCA_RESERVED] = { "reserved", "Reserved" },
> [SMCA_EX] = { "execution_unit", "Execution Unit" },
> [SMCA_FP] = { "floating_point", "Floating Point Unit" },
> [SMCA_L3_CACHE] = { "l3_cache", "L3 Cache" },
> @@ -127,6 +128,9 @@ static enum smca_bank_types smca_get_bank_type(unsigned int bank)
> static struct smca_hwid smca_hwid_mcatypes[] = {
> /* { bank_type, hwid_mcatype, xec_bitmap } */
>
> + /* Reserved type */
> + { SMCA_RESERVED, HWID_MCATYPE(0x00, 0x0), 0x0 },
> +
> /* ZN Core (HWID=0xB0) MCA types */
> { SMCA_LS, HWID_MCATYPE(0xB0, 0x0), 0x1FFFEF },
> { SMCA_IF, HWID_MCATYPE(0xB0, 0x1), 0x3FFF },
> @@ -433,6 +437,9 @@ static u32 get_block_address(unsigned int cpu, u32 current_addr, u32 low, u32 hi
> u32 addr = 0, offset = 0;
>
> if (mce_flags.smca) {

As a last patch in the series: please carve the code in this
if-statement into a smca_get_block_address() helper. And it doesn't need
the stable tag as it is only a cleanup.

Thx.

--
Regards/Gruss,
Boris.

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