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From:   Fenghua Yu <fenghua.yu@intel.com>
To:     "Thomas Gleixner" <tglx@linutronix.de>,
        "Dave Hansen" <dave.hansen@linux.intel.com>,
        "Ingo Molnar" <mingo@redhat.com>, "Borislav Petkov" <bp@alien8.de>,
        "Peter Zijlstra" <peterz@infradead.org>,
        "Andy Lutomirski" <luto@kernel.org>,
        "Tony Luck" <tony.luck@intel.com>,
        "Lu Baolu" <baolu.lu@linux.intel.com>,
        "Joerg Roedel" <joro@8bytes.org>,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        "Jacob Pan" <jacob.jun.pan@linux.intel.com>,
        "Ashok Raj" <ashok.raj@intel.com>,
        "Ravi V Shankar" <ravi.v.shankar@intel.com>
Cc:     iommu@lists.linux-foundation.org, "x86" <x86@kernel.org>,
        "linux-kernel" <linux-kernel@vger.kernel.org>,
        Fenghua Yu <fenghua.yu@intel.com>
Subject: [PATCH v3 07/11] sched: Define and initialize a flag to identify valid PASID in the task
Date:   Fri, 28 Jan 2022 12:29:01 -0800
Message-Id: <20220128202905.2274672-8-fenghua.yu@intel.com>
In-Reply-To: <20220128202905.2274672-1-fenghua.yu@intel.com>
References: <20220128202905.2274672-1-fenghua.yu@intel.com>
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From: Peter Zijlstra <peterz@infradead.org>

Add a new single bit field to the task structure to track whether this task
has initialized the IA32_PASID MSR to the mm's PASID.

Initialize the field to zero when creating a new task with fork/clone.

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Co-developed-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
---
v2:
- Change condition to more accurate CONFIG_IOMMU_SVA (Jacob)

 include/linux/sched.h | 3 +++
 kernel/fork.c         | 4 ++++
 2 files changed, 7 insertions(+)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index f5b2be39a78c..812e40c5bde5 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -938,6 +938,9 @@ struct task_struct {
 	/* Recursion prevention for eventfd_signal() */
 	unsigned			in_eventfd_signal:1;
 #endif
+#ifdef CONFIG_IOMMU_SVA
+	unsigned			pasid_activated:1;
+#endif
 
 	unsigned long			atomic_flags; /* Flags requiring atomic access. */
 
diff --git a/kernel/fork.c b/kernel/fork.c
index c03c6682464c..51fd1df994b7 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -968,6 +968,10 @@ static struct task_struct *dup_task_struct(struct task_struct *orig, int node)
 	tsk->use_memdelay = 0;
 #endif
 
+#ifdef CONFIG_IOMMU_SVA
+	tsk->pasid_activated = 0;
+#endif
+
 #ifdef CONFIG_MEMCG
 	tsk->active_memcg = NULL;
 #endif
-- 
2.35.0