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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Peter Feiner <pfeiner@google.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Ben Gardon <bgardon@google.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.11 114/152] KVM: x86/mmu: Add comment on __tdp_mmu_set_spte
Date:   Mon,  5 Apr 2021 10:54:23 +0200
Message-Id: <20210405085037.940673331@linuxfoundation.org>
In-Reply-To: <20210405085034.233917714@linuxfoundation.org>
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From: Ben Gardon <bgardon@google.com>

[ Upstream commit fe43fa2f407b9d513f7bcf18142e14e1bf1508d6 ]

__tdp_mmu_set_spte is a very important function in the TDP MMU which
already accepts several arguments and will take more in future commits.
To offset this complexity, add a comment to the function describing each
of the arguemnts.

No functional change intended.

Reviewed-by: Peter Feiner <pfeiner@google.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Ben Gardon <bgardon@google.com>
Message-Id: <20210202185734.1680553-3-bgardon@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/x86/kvm/mmu/tdp_mmu.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 50c088a41dee..6bd86bb4c089 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -397,6 +397,22 @@ static void handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn,
 				      new_spte, level);
 }
 
+/*
+ * __tdp_mmu_set_spte - Set a TDP MMU SPTE and handle the associated bookkeeping
+ * @kvm: kvm instance
+ * @iter: a tdp_iter instance currently on the SPTE that should be set
+ * @new_spte: The value the SPTE should be set to
+ * @record_acc_track: Notify the MM subsystem of changes to the accessed state
+ *		      of the page. Should be set unless handling an MMU
+ *		      notifier for access tracking. Leaving record_acc_track
+ *		      unset in that case prevents page accesses from being
+ *		      double counted.
+ * @record_dirty_log: Record the page as dirty in the dirty bitmap if
+ *		      appropriate for the change being made. Should be set
+ *		      unless performing certain dirty logging operations.
+ *		      Leaving record_dirty_log unset in that case prevents page
+ *		      writes from being double counted.
+ */
 static inline void __tdp_mmu_set_spte(struct kvm *kvm, struct tdp_iter *iter,
 				      u64 new_spte, bool record_acc_track,
 				      bool record_dirty_log)
-- 
2.30.1