From:   Chao Peng <chao.p.peng@linux.intel.com>
To:     kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
        qemu-devel@nongnu.org
Cc:     Paolo Bonzini <pbonzini@redhat.com>,
        Jonathan Corbet <corbet@lwn.net>,
        Sean Christopherson <seanjc@google.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Joerg Roedel <joro@8bytes.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        x86@kernel.org, "H . Peter Anvin" <hpa@zytor.com>,
        Hugh Dickins <hughd@google.com>,
        Jeff Layton <jlayton@kernel.org>,
        "J . Bruce Fields" <bfields@fieldses.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Yu Zhang <yu.c.zhang@linux.intel.com>,
        Chao Peng <chao.p.peng@linux.intel.com>,
        "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
        luto@kernel.org, john.ji@intel.com, susie.li@intel.com,
        jun.nakajima@intel.com, dave.hansen@intel.com, ak@linux.intel.com,
        david@redhat.com
Subject: [RFC v2 PATCH 09/13] KVM: Introduce kvm_memfd_invalidate_range
Date:   Fri, 19 Nov 2021 21:47:35 +0800
Message-Id: <20211119134739.20218-10-chao.p.peng@linux.intel.com>
In-Reply-To: <20211119134739.20218-1-chao.p.peng@linux.intel.com>
References: <20211119134739.20218-1-chao.p.peng@linux.intel.com>
Precedence: bulk

Invalidate on fd-based memslot can reuse the code from existing MMU
notifier.

Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com>
Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com>
---
 include/linux/kvm_host.h |  3 +++
 virt/kvm/kvm_main.c      | 35 +++++++++++++++++++++++++++++++++++
 2 files changed, 38 insertions(+)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 925c4d9f0a31..f0fd32f6eab3 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1883,4 +1883,7 @@ static inline void kvm_handle_signal_exit(struct kvm_vcpu *vcpu)
 /* Max number of entries allowed for each kvm dirty ring */
 #define  KVM_DIRTY_RING_MAX_ENTRIES  65536
 
+int kvm_memfd_invalidate_range(struct kvm *kvm, struct inode *inode,
+			       unsigned long start, unsigned long end);
+
 #endif
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index d9a6890dd18a..090afbadb03f 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -811,6 +811,35 @@ static int kvm_init_mmu_notifier(struct kvm *kvm)
 	return mmu_notifier_register(&kvm->mmu_notifier, current->mm);
 }
 
+int kvm_memfd_invalidate_range(struct kvm *kvm, struct inode *inode,
+			       unsigned long start, unsigned long end)
+{
+	int ret;
+	const struct kvm_useraddr_range useraddr_range = {
+		.start		= start,
+		.end		= end,
+		.pte		= __pte(0),
+		.handler	= kvm_unmap_gfn_range,
+		.on_lock	= (void *)kvm_null_fn,
+		.flush_on_ret	= true,
+		.may_block	= false,
+	};
+
+
+	/* Prevent memslot modification */
+	spin_lock(&kvm->mn_invalidate_lock);
+	kvm->mn_active_invalidate_count++;
+	spin_unlock(&kvm->mn_invalidate_lock);
+
+	ret = __kvm_handle_useraddr_range(kvm, &useraddr_range);
+
+	spin_lock(&kvm->mn_invalidate_lock);
+	kvm->mn_active_invalidate_count--;
+	spin_unlock(&kvm->mn_invalidate_lock);
+
+	return ret;
+}
+
 #else  /* !(CONFIG_MMU_NOTIFIER && KVM_ARCH_WANT_MMU_NOTIFIER) */
 
 static int kvm_init_mmu_notifier(struct kvm *kvm)
@@ -818,6 +847,12 @@ static int kvm_init_mmu_notifier(struct kvm *kvm)
 	return 0;
 }
 
+int kvm_memfd_invalidate_range(struct kvm *kvm, struct inode *inode,
+			       unsigned long start, unsigned long end)
+{
+	return 0;
+}
+
 #endif /* CONFIG_MMU_NOTIFIER && KVM_ARCH_WANT_MMU_NOTIFIER */
 
 #ifdef CONFIG_HAVE_KVM_PM_NOTIFIER
-- 
2.17.1