From: Marc Zyngier <maz@kernel.org>
Date: Wed, 24 Feb 2021 09:37:37 +0000
Subject: arm64: Add missing ISB after invalidating TLB in __primary_switch

Git-commit: 9d41053e8dc115c92b8002c3db5f545d7602498b
Patch-mainline: v5.12-rc1
References: git-fixes

Although there has been a bit of back and forth on the subject, it
appears that invalidating TLBs requires an ISB instruction when FEAT_ETS
is not implemented by the CPU.

From the bible:

  | In an implementation that does not implement FEAT_ETS, a TLB
  | maintenance instruction executed by a PE, PEx, can complete at any
  | time after it is issued, but is only guaranteed to be finished for a
  | PE, PEx, after the execution of DSB by the PEx followed by a Context
  | synchronization event

Add the missing ISB in __primary_switch, just in case.

Fixes: 3c5e9f238bc4 ("arm64: head.S: move KASLR processing out of __enable_mmu()")
Suggested-by: Will Deacon <will@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20210224093738.3629662-3-maz@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Mian Yousaf Kaukab <ykaukab@suse.de>
---
 arch/arm64/kernel/head.S |    1 +
 1 file changed, 1 insertion(+)

--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -872,6 +872,7 @@ __primary_switch:
 
 	tlbi	vmalle1				// Remove any stale TLB entries
 	dsb	nsh
+	isb
 
 	msr	sctlr_el1, x19			// re-enable the MMU
 	isb