x86/msr: Make source of unrecognised MSR writes unambiguous

In many cases, task_struct.comm isn't enough to distinguish the
offender, since for interpreted languages it's likely just going to be
"python3" or whatever. Add the pid to make it unambiguous.

 [ bp: Make the printk string a single line for easier grepping. ]
Signed-off-by: Chris Down <chris@chrisdown.name>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/6f6fbd0ee6c99bc5e47910db700a6642159db01b.1598011595.git.chris@chrisdown.name

arch/x86/kernel/msr.c

@@ -102,8 +102,8 @@ static int filter_write(u32 reg)
 	if (reg == MSR_IA32_ENERGY_PERF_BIAS)
 		return 0;
 
-	pr_err("Write to unrecognized MSR 0x%x by %s\n"
-	       "Please report to x86@kernel.org\n", reg, current->comm);
+	pr_err("Write to unrecognized MSR 0x%x by %s (pid: %d). Please report to x86@kernel.org.\n",
+	       reg, current->comm, current->pid);
 
 	return 0;
 }