linux-kernel - [tip: ras/urgent] x86/MCE/AMD: Do not use rdmsr_safe_on_cpu() in smca

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Date:   Tue, 17 Dec 2019 10:01:09 -0000
From:   "tip-bot2 for Konstantin Khlebnikov" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Konstantin Khlebnikov <khlebnikov@...dex-team.ru>,
        Borislav Petkov <bp@...e.de>,
        Yazen Ghannam <yazen.ghannam@....com>,
        "H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>,
        "linux-edac" <linux-edac@...r.kernel.org>,
        <stable@...r.kernel.org>, Thomas Gleixner <tglx@...utronix.de>,
        Tony Luck <tony.luck@...el.com>, "x86-ml" <x86@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: [tip: ras/urgent] x86/MCE/AMD: Do not use rdmsr_safe_on_cpu() in
 smca_configure()

The following commit has been merged into the ras/urgent branch of tip:

Commit-ID:     246ff09f89e54fdf740a8d496176c86743db3ec7
Gitweb:        https://git.kernel.org/tip/246ff09f89e54fdf740a8d496176c86743db3ec7
Author:        Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
AuthorDate:    Thu, 31 Oct 2019 16:04:48 +03:00
Committer:     Borislav Petkov <bp@...e.de>
CommitterDate: Tue, 17 Dec 2019 09:39:33 +01:00

x86/MCE/AMD: Do not use rdmsr_safe_on_cpu() in smca_configure()

... because interrupts are disabled that early and sending IPIs can
deadlock:

  BUG: sleeping function called from invalid context at kernel/sched/completion.c:99
  in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 0, name: swapper/1
  no locks held by swapper/1/0.
  irq event stamp: 0
  hardirqs last  enabled at (0): [<0000000000000000>] 0x0
  hardirqs last disabled at (0): [<ffffffff8106dda9>] copy_process+0x8b9/0x1ca0
  softirqs last  enabled at (0): [<ffffffff8106dda9>] copy_process+0x8b9/0x1ca0
  softirqs last disabled at (0): [<0000000000000000>] 0x0
  Preemption disabled at:
  [<ffffffff8104703b>] start_secondary+0x3b/0x190
  CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.5.0-rc2+ #1
  Hardware name: GIGABYTE MZ01-CE1-00/MZ01-CE1-00, BIOS F02 08/29/2018
  Call Trace:
   dump_stack
   ___might_sleep.cold.92
   wait_for_completion
   ? generic_exec_single
   rdmsr_safe_on_cpu
   ? wrmsr_on_cpus
   mce_amd_feature_init
   mcheck_cpu_init
   identify_cpu
   identify_secondary_cpu
   smp_store_cpu_info
   start_secondary
   secondary_startup_64

The function smca_configure() is called only on the current CPU anyway,
therefore replace rdmsr_safe_on_cpu() with atomic rdmsr_safe() and avoid
the IPI.

 [ bp: Update commit message. ]

Signed-off-by: Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
Signed-off-by: Borislav Petkov <bp@...e.de>
Reviewed-by: Yazen Ghannam <yazen.ghannam@....com>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: linux-edac <linux-edac@...r.kernel.org>
Cc: <stable@...r.kernel.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Tony Luck <tony.luck@...el.com>
Cc: x86-ml <x86@...nel.org>
Link: https://lkml.kernel.org/r/157252708836.3876.4604398213417262402.stgit@buzz
---
 arch/x86/kernel/cpu/mce/amd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/mce/amd.c b/arch/x86/kernel/cpu/mce/amd.c
index 5167bd2..e41e3b4 100644
--- a/arch/x86/kernel/cpu/mce/amd.c
+++ b/arch/x86/kernel/cpu/mce/amd.c
@@ -269,7 +269,7 @@ static void smca_configure(unsigned int bank, unsigned int cpu)
 	if (smca_banks[bank].hwid)
 		return;

-	if (rdmsr_safe_on_cpu(cpu, MSR_AMD64_SMCA_MCx_IPID(bank), &low, &high)) {
+	if (rdmsr_safe(MSR_AMD64_SMCA_MCx_IPID(bank), &low, &high)) {
 		pr_warn("Failed to read MCA_IPID for bank %d\n", bank);
 		return;
 	}