linux-kernel - Re: [REGRESSION] x86/efi: Make efi_enter/leave_mm() use the use_/unuse_temporary

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Message-ID: <20250429182904.GL4198@noisy.programming.kicks-ass.net>
Date: Tue, 29 Apr 2025 20:29:04 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: Jani Nikula <jani.nikula@...ux.intel.com>
Cc: "Borah, Chaitanya Kumar" <chaitanya.kumar.borah@...el.com>,
	"luto@...nel.org" <luto@...nel.org>,
	"intel-gfx@...ts.freedesktop.org" <intel-gfx@...ts.freedesktop.org>,
	"intel-xe@...ts.freedesktop.org" <intel-xe@...ts.freedesktop.org>,
	"Kurmi, Suresh Kumar" <suresh.kumar.kurmi@...el.com>,
	"Saarinen, Jani" <jani.saarinen@...el.com>,
	"De Marchi, Lucas" <lucas.demarchi@...el.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...nel.org>
Subject: Re: [REGRESSION] x86/efi: Make efi_enter/leave_mm() use the
 use_/unuse_temporary_mm() machinery (linux-next)

On Tue, Apr 29, 2025 at 12:01:22PM +0300, Jani Nikula wrote:
> On Thu, 24 Apr 2025, "Borah, Chaitanya Kumar" <chaitanya.kumar.borah@...el.com> wrote:
> > +Andy, Ingo
> >
> > Friendly reminder.
> > Issue is still seen on latest linux-next runs.
> >
> > https://intel-gfx-ci.01.org/tree/linux-next/next-20250424/bat-rpls-4/boot0.txt
> >
> > Regards
> >
> > Chaitanya
> 
> Andy, Ingo -
> 
> Commit e7021e2fe0b4 ("x86/efi: Make efi_enter/leave_mm() use the
> use_/unuse_temporary_mm() machinery") on linux-next regresses as
> reported by Chaitanya
> 
> Please look into it.

Does your kernel include the below?

---
commit aef1d0209ddf127a8069aca5fa3a062be4136b76
Author: Peter Zijlstra <peterz@...radead.org>
Date:   Fri Apr 18 11:50:34 2025 +0200

    x86/mm: Fix {,un}use_temporary_mm() IRQ state
    
    As the function switch_mm_irqs_off() implies, it ought to be called with
    IRQs *off*. Commit 58f8ffa91766 ("x86/mm: Allow temporary MMs when IRQs
    are on") caused this to not be the case for EFI.
    
    Ensure IRQs are off where it matters.
    
    Fixes: 58f8ffa91766 ("x86/mm: Allow temporary MMs when IRQs are on")
    Reported-by: Borislav Petkov (AMD) <bp@...en8.de>
    Tested-by: Borislav Petkov (AMD) <bp@...en8.de>
    Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
    Signed-off-by: Ingo Molnar <mingo@...nel.org>
    Cc: H. Peter Anvin <hpa@...or.com>
    Cc: Andrew Morton <akpm@...ux-foundation.org>
    Cc: Andy Lutomirski <luto@...nel.org>
    Cc: Linus Torvalds <torvalds@...ux-foundation.org>
    Cc: Rik van Riel <riel@...riel.com>
    Link: https://lore.kernel.org/r/20250418095034.GR38216@noisy.programming.kicks-ass.net

diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 79c124f6f3f2..39761c7765bd 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -986,6 +986,7 @@ struct mm_struct *use_temporary_mm(struct mm_struct *temp_mm)
 	struct mm_struct *prev_mm;
 
 	lockdep_assert_preemption_disabled();
+	guard(irqsave)();
 
 	/*
 	 * Make sure not to be in TLB lazy mode, as otherwise we'll end up
@@ -1018,6 +1019,7 @@ struct mm_struct *use_temporary_mm(struct mm_struct *temp_mm)
 void unuse_temporary_mm(struct mm_struct *prev_mm)
 {
 	lockdep_assert_preemption_disabled();
+	guard(irqsave)();
 
 	/* Clear the cpumask, to indicate no TLB flushing is needed anywhere */
 	cpumask_clear_cpu(smp_processor_id(), mm_cpumask(this_cpu_read(cpu_tlbstate.loaded_mm)));