Re: [PATCH 0/3] powerpc/mce: Fix mce handler and add selftest

On 9/17/20 5:59 PM, Michal Suchánek wrote:

Hello,

On Wed, Sep 16, 2020 at 10:52:25PM +0530, Ganesh Goudar wrote:

quoted

This patch series fixes mce handling for pseries, provides debugfs
interface for mce injection and adds selftest to test mce handling
on pseries/powernv machines running in hash mmu mode.
debugfs interface and sleftest are added only for slb multihit
injection, We can add other tests in future if possible.

Ganesh Goudar (3):
   powerpc/mce: remove nmi_enter/exit from real mode handler
   powerpc/mce: Add debugfs interface to inject MCE
   selftest/powerpc: Add slb multihit selftest

Is the below logic sound? It does not agree with what is added here:

void machine_check_exception(struct pt_regs *regs)
{
	int recover = 0;

	/*
	 * BOOK3S_64 does not call this handler as a non-maskable interrupt
	 * (it uses its own early real-mode handler to handle the MCE proper
	 * and then raises irq_work to call this handler when interrupts are
	 * enabled).
	 *
	 * This is silly. The BOOK3S_64 should just call a different function
	 * rather than expecting semantics to magically change. Something
	 * like 'non_nmi_machine_check_exception()', perhaps?
	 */
	const bool nmi = !IS_ENABLED(CONFIG_PPC_BOOK3S_64);

	if (nmi) nmi_enter();

Thanks

Michal

Looks like Nick Piggin has the Justification for it, Ill leave Nick to 
answer this.