linux-kernel - [PATCH 1/3] KVM: x86/mmu: Open code walking TDP MMU roots for mmu

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Date:   Fri, 15 Sep 2023 17:39:14 -0700
From:   Sean Christopherson <seanjc@...gle.com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Pattara Teerapong <pteerapong@...gle.com>,
        David Stevens <stevensd@...gle.com>,
        Yiwei Zhang <zzyiwei@...gle.com>,
        Paul Hsia <paulhsia@...gle.com>
Subject: [PATCH 1/3] KVM: x86/mmu: Open code walking TDP MMU roots for
 mmu_notifier's zap SPTEs

Use the "inner" TDP MMU root walker when zapping SPTEs in response to an
mmu_notifier invalidation instead of invoking kvm_tdp_mmu_zap_leafs().
This will allow reworking for_each_tdp_mmu_root_yield_safe() to do more
work, and to also make it usable in more places, without increasing the
number of params to the point where it adds no value.

The mmu_notifier path is a bit of a special snowflake, e.g. it zaps only a
single address space (because it's per-slot), and can't always yield.

Drop the @can_yield param from tdp_mmu_zap_leafs() as its sole remaining
caller unconditionally passes "true".

Cc: stable@...r.kernel.org
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/mmu/mmu.c     |  2 +-
 arch/x86/kvm/mmu/tdp_mmu.c | 13 +++++++++----
 arch/x86/kvm/mmu/tdp_mmu.h |  4 ++--
 3 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index e1d011c67cc6..59f5e40b8f55 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -6260,7 +6260,7 @@ void kvm_zap_gfn_range(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end)
 	if (tdp_mmu_enabled) {
 		for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++)
 			flush = kvm_tdp_mmu_zap_leafs(kvm, i, gfn_start,
-						      gfn_end, true, flush);
+						      gfn_end, flush);
 	}
 
 	if (flush)
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 6c63f2d1675f..89aaa2463373 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -878,12 +878,12 @@ static bool tdp_mmu_zap_leafs(struct kvm *kvm, struct kvm_mmu_page *root,
  * more SPTEs were zapped since the MMU lock was last acquired.
  */
 bool kvm_tdp_mmu_zap_leafs(struct kvm *kvm, int as_id, gfn_t start, gfn_t end,
-			   bool can_yield, bool flush)
+			   bool flush)
 {
 	struct kvm_mmu_page *root;
 
 	for_each_tdp_mmu_root_yield_safe(kvm, root, as_id)
-		flush = tdp_mmu_zap_leafs(kvm, root, start, end, can_yield, flush);
+		flush = tdp_mmu_zap_leafs(kvm, root, start, end, true, flush);
 
 	return flush;
 }
@@ -1146,8 +1146,13 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
 bool kvm_tdp_mmu_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range,
 				 bool flush)
 {
-	return kvm_tdp_mmu_zap_leafs(kvm, range->slot->as_id, range->start,
-				     range->end, range->may_block, flush);
+	struct kvm_mmu_page *root;
+
+	__for_each_tdp_mmu_root_yield_safe(kvm, root, range->slot->as_id, false, false)
+		flush = tdp_mmu_zap_leafs(kvm, root, range->start, range->end,
+					  range->may_block, flush);
+
+	return flush;
 }
 
 typedef bool (*tdp_handler_t)(struct kvm *kvm, struct tdp_iter *iter,
diff --git a/arch/x86/kvm/mmu/tdp_mmu.h b/arch/x86/kvm/mmu/tdp_mmu.h
index 0a63b1afabd3..eb4fa345d3a4 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.h
+++ b/arch/x86/kvm/mmu/tdp_mmu.h
@@ -20,8 +20,8 @@ __must_check static inline bool kvm_tdp_mmu_get_root(struct kvm_mmu_page *root)
 void kvm_tdp_mmu_put_root(struct kvm *kvm, struct kvm_mmu_page *root,
 			  bool shared);
 
-bool kvm_tdp_mmu_zap_leafs(struct kvm *kvm, int as_id, gfn_t start,
-				 gfn_t end, bool can_yield, bool flush);
+bool kvm_tdp_mmu_zap_leafs(struct kvm *kvm, int as_id, gfn_t start, gfn_t end,
+			   bool flush);
 bool kvm_tdp_mmu_zap_sp(struct kvm *kvm, struct kvm_mmu_page *sp);
 void kvm_tdp_mmu_zap_all(struct kvm *kvm);
 void kvm_tdp_mmu_invalidate_all_roots(struct kvm *kvm);
-- 
2.42.0.459.ge4e396fd5e-goog