linux-kernel - [PATCH v11 5/8] KVM: Migrate kvm_vcpu_map() to kvm_follow

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Message-ID: <20240229025759.1187910-6-stevensd@google.com>
Date: Thu, 29 Feb 2024 11:57:56 +0900
From: David Stevens <stevensd@...omium.org>
To: Sean Christopherson <seanjc@...gle.com>,
	Paolo Bonzini <pbonzini@...hat.com>
Cc: Yu Zhang <yu.c.zhang@...ux.intel.com>,
	Isaku Yamahata <isaku.yamahata@...il.com>,
	Zhi Wang <zhi.wang.linux@...il.com>,
	Maxim Levitsky <mlevitsk@...hat.com>,
	kvmarm@...ts.linux.dev,
	linux-kernel@...r.kernel.org,
	kvm@...r.kernel.org,
	David Stevens <stevensd@...omium.org>
Subject: [PATCH v11 5/8] KVM: Migrate kvm_vcpu_map() to kvm_follow_pfn()

From: David Stevens <stevensd@...omium.org>

Migrate kvm_vcpu_map() to kvm_follow_pfn(). Track is_refcounted_page so
that kvm_vcpu_unmap() know whether or not it needs to release the page.

Signed-off-by: David Stevens <stevensd@...omium.org>
---
 include/linux/kvm_host.h |  2 +-
 virt/kvm/kvm_main.c      | 24 ++++++++++++++----------
 2 files changed, 15 insertions(+), 11 deletions(-)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 66516088bb0a..59dc9fbafc08 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -295,6 +295,7 @@ struct kvm_host_map {
 	void *hva;
 	kvm_pfn_t pfn;
 	kvm_pfn_t gfn;
+	bool is_refcounted_page;
 };
 
 /*
@@ -1270,7 +1271,6 @@ void kvm_release_pfn_dirty(kvm_pfn_t pfn);
 void kvm_set_pfn_dirty(kvm_pfn_t pfn);
 void kvm_set_pfn_accessed(kvm_pfn_t pfn);
 
-void kvm_release_pfn(kvm_pfn_t pfn, bool dirty);
 int kvm_read_guest_page(struct kvm *kvm, gfn_t gfn, void *data, int offset,
 			int len);
 int kvm_read_guest(struct kvm *kvm, gpa_t gpa, void *data, unsigned long len);
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 984bcf8511e7..17bf9fd6774e 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -3184,24 +3184,22 @@ struct page *gfn_to_page(struct kvm *kvm, gfn_t gfn)
 }
 EXPORT_SYMBOL_GPL(gfn_to_page);
 
-void kvm_release_pfn(kvm_pfn_t pfn, bool dirty)
-{
-	if (dirty)
-		kvm_release_pfn_dirty(pfn);
-	else
-		kvm_release_pfn_clean(pfn);
-}
-
 int kvm_vcpu_map(struct kvm_vcpu *vcpu, gfn_t gfn, struct kvm_host_map *map)
 {
 	kvm_pfn_t pfn;
 	void *hva = NULL;
 	struct page *page = KVM_UNMAPPED_PAGE;
+	struct kvm_follow_pfn kfp = {
+		.slot = gfn_to_memslot(vcpu->kvm, gfn),
+		.gfn = gfn,
+		.flags = FOLL_GET | FOLL_WRITE,
+		.allow_non_refcounted_struct_page = true,
+	};
 
 	if (!map)
 		return -EINVAL;
 
-	pfn = gfn_to_pfn(vcpu->kvm, gfn);
+	pfn = kvm_follow_pfn(&kfp);
 	if (is_error_noslot_pfn(pfn))
 		return -EINVAL;
 
@@ -3221,6 +3219,7 @@ int kvm_vcpu_map(struct kvm_vcpu *vcpu, gfn_t gfn, struct kvm_host_map *map)
 	map->hva = hva;
 	map->pfn = pfn;
 	map->gfn = gfn;
+	map->is_refcounted_page = !!kfp.refcounted_page;
 
 	return 0;
 }
@@ -3244,7 +3243,12 @@ void kvm_vcpu_unmap(struct kvm_vcpu *vcpu, struct kvm_host_map *map, bool dirty)
 	if (dirty)
 		kvm_vcpu_mark_page_dirty(vcpu, map->gfn);
 
-	kvm_release_pfn(map->pfn, dirty);
+	if (map->is_refcounted_page) {
+		if (dirty)
+			kvm_release_page_dirty(map->page);
+		else
+			kvm_release_page_clean(map->page);
+	}
 
 	map->hva = NULL;
 	map->page = NULL;
-- 
2.44.0.rc1.240.g4c46232300-goog