linux-kernel - [PATCH 07/26] mm: asi: Switch to unrestricted address space before a context switch

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Message-ID: <20240712-asi-rfc-24-v1-7-144b319a40d8@google.com>
Date: Fri, 12 Jul 2024 17:00:25 +0000
From: Brendan Jackman <jackmanb@...gle.com>
To: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, 
	Dave Hansen <dave.hansen@...ux.intel.com>, "H. Peter Anvin" <hpa@...or.com>, 
	Andy Lutomirski <luto@...nel.org>, Peter Zijlstra <peterz@...radead.org>, 
	Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>, 
	Alexandre Chartre <alexandre.chartre@...cle.com>, Liran Alon <liran.alon@...cle.com>, 
	Jan Setje-Eilers <jan.setjeeilers@...cle.com>, Catalin Marinas <catalin.marinas@....com>, 
	Will Deacon <will@...nel.org>, Mark Rutland <mark.rutland@....com>, 
	Andrew Morton <akpm@...ux-foundation.org>, Mel Gorman <mgorman@...e.de>, 
	Lorenzo Stoakes <lstoakes@...il.com>, David Hildenbrand <david@...hat.com>, Vlastimil Babka <vbabka@...e.cz>, 
	Michal Hocko <mhocko@...nel.org>, Khalid Aziz <khalid.aziz@...cle.com>, 
	Juri Lelli <juri.lelli@...hat.com>, Vincent Guittot <vincent.guittot@...aro.org>, 
	Dietmar Eggemann <dietmar.eggemann@....com>, Steven Rostedt <rostedt@...dmis.org>, 
	Valentin Schneider <vschneid@...hat.com>, Paul Turner <pjt@...gle.com>, Reiji Watanabe <reijiw@...gle.com>, 
	Junaid Shahid <junaids@...gle.com>, Ofir Weisse <oweisse@...gle.com>, 
	Yosry Ahmed <yosryahmed@...gle.com>, Patrick Bellasi <derkling@...gle.com>, 
	KP Singh <kpsingh@...gle.com>, Alexandra Sandulescu <aesa@...gle.com>, 
	Matteo Rizzo <matteorizzo@...gle.com>, Jann Horn <jannh@...gle.com>
Cc: x86@...nel.org, linux-kernel@...r.kernel.org, linux-mm@...ck.org, 
	kvm@...r.kernel.org, Brendan Jackman <jackmanb@...gle.com>
Subject: [PATCH 07/26] mm: asi: Switch to unrestricted address space before a
 context switch

From: Junaid Shahid <junaids@...gle.com>

To keep things simpler for the time being, we disallow context switches
within the restricted address space. In the future, we would be able to
relax this limitation for the case of context switches to different
threads within the same process (or to the idle thread and back).

Signed-off-by: Junaid Shahid <junaids@...gle.com>
Signed-off-by: Brendan Jackman <jackmanb@...gle.com>
---
 kernel/sched/core.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 7019a40457a6..e65ac22e5a28 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -77,6 +77,7 @@
 #include <asm/irq_regs.h>
 #include <asm/switch_to.h>
 #include <asm/tlb.h>
+#include <asm/asi.h>
 
 #define CREATE_TRACE_POINTS
 #include <linux/sched/rseq_api.h>
@@ -5353,6 +5354,8 @@ static __always_inline struct rq *
 context_switch(struct rq *rq, struct task_struct *prev,
 	       struct task_struct *next, struct rq_flags *rf)
 {
+	asi_exit();
+
 	prepare_task_switch(rq, prev, next);
 
 	/*

-- 
2.45.2.993.g49e7a77208-goog