linux-kernel - [PATCH v9 4/6] KVM: Migrate kvm_vcpu_map to __kvm_follow

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Message-ID: <20230911021637.1941096-5-stevensd@google.com>
Date:   Mon, 11 Sep 2023 11:16:34 +0900
From:   David Stevens <stevensd@...omium.org>
To:     Sean Christopherson <seanjc@...gle.com>
Cc:     Yu Zhang <yu.c.zhang@...ux.intel.com>,
        Isaku Yamahata <isaku.yamahata@...il.com>,
        Zhi Wang <zhi.wang.linux@...il.com>, kvmarm@...ts.linux.dev,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        David Stevens <stevensd@...omium.org>
Subject: [PATCH v9 4/6] 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 2ed08ae1a9be..b95c79b7833b 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -294,6 +294,7 @@ struct kvm_host_map {
 	void *hva;
 	kvm_pfn_t pfn;
 	kvm_pfn_t gfn;
+	bool is_refcounted_page;
 };
 
 /*
@@ -1228,7 +1229,6 @@ 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 235c5cb3fdac..913de4e86d9d 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2886,24 +2886,22 @@ 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 foll = {
+		.slot = gfn_to_memslot(vcpu->kvm, gfn),
+		.gfn = gfn,
+		.flags = FOLL_WRITE,
+		.allow_non_refcounted_struct_page = true,
+	};
 
 	if (!map)
 		return -EINVAL;
 
-	pfn = gfn_to_pfn(vcpu->kvm, gfn);
+	pfn = __kvm_follow_pfn(&foll);
 	if (is_error_noslot_pfn(pfn))
 		return -EINVAL;
 
@@ -2923,6 +2921,7 @@ 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 = foll.is_refcounted_page;
 
 	return 0;
 }
@@ -2946,7 +2945,12 @@ 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;
-- 
2.42.0.283.g2d96d420d3-goog