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From:   Davidlohr Bueso <dave@stgolabs.net>
To:     linux-mm@kvack.org, linux-kernel@vger.kernel.org
Cc:     akpm@linux-foundation.org, willy@infradead.org, mhocko@kernel.org,
        mgorman@techsingularity.net, jglisse@redhat.com,
        ldufour@linux.vnet.ibm.com, dave@stgolabs.net,
        Davidlohr Bueso <dbueso@suse.de>
Subject: [PATCH 09/14] virt: teach the mm about range locking
Date:   Mon, 20 May 2019 21:52:37 -0700
Message-Id: <20190521045242.24378-10-dave@stgolabs.net>
In-Reply-To: <20190521045242.24378-1-dave@stgolabs.net>
References: <20190521045242.24378-1-dave@stgolabs.net>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Conversion is straightforward, mmap_sem is used within the
the same function context most of the time. No change in
semantics.

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
---
 virt/kvm/arm/mmu.c  | 17 ++++++++++-------
 virt/kvm/async_pf.c |  4 ++--
 virt/kvm/kvm_main.c | 11 ++++++-----
 3 files changed, 18 insertions(+), 14 deletions(-)

diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c
index 74b6582eaa3c..85f8b9ccfabe 100644
--- a/virt/kvm/arm/mmu.c
+++ b/virt/kvm/arm/mmu.c
@@ -980,9 +980,10 @@ void stage2_unmap_vm(struct kvm *kvm)
 	struct kvm_memslots *slots;
 	struct kvm_memory_slot *memslot;
 	int idx;
+	DEFINE_RANGE_LOCK_FULL(mmrange);
 
 	idx = srcu_read_lock(&kvm->srcu);
-	down_read(&current->mm->mmap_sem);
+	mm_read_lock(current->mm, &mmrange);
 	spin_lock(&kvm->mmu_lock);
 
 	slots = kvm_memslots(kvm);
@@ -990,7 +991,7 @@ void stage2_unmap_vm(struct kvm *kvm)
 		stage2_unmap_memslot(kvm, memslot);
 
 	spin_unlock(&kvm->mmu_lock);
-	up_read(&current->mm->mmap_sem);
+	mm_read_unlock(current->mm, &mmrange);
 	srcu_read_unlock(&kvm->srcu, idx);
 }
 
@@ -1688,6 +1689,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
 	kvm_pfn_t pfn;
 	pgprot_t mem_type = PAGE_S2;
 	bool logging_active = memslot_is_logging(memslot);
+	DEFINE_RANGE_LOCK_FULL(mmrange);
 	unsigned long vma_pagesize, flags = 0;
 
 	write_fault = kvm_is_write_fault(vcpu);
@@ -1700,11 +1702,11 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
 	}
 
 	/* Let's check if we will get back a huge page backed by hugetlbfs */
-	down_read(&current->mm->mmap_sem);
+	mm_read_lock(current->mm, &mmrange);
 	vma = find_vma_intersection(current->mm, hva, hva + 1);
 	if (unlikely(!vma)) {
 		kvm_err("Failed to find VMA for hva 0x%lx\n", hva);
-		up_read(&current->mm->mmap_sem);
+		mm_read_unlock(current->mm, &mmrange);
 		return -EFAULT;
 	}
 
@@ -1725,7 +1727,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
 	if (vma_pagesize == PMD_SIZE ||
 	    (vma_pagesize == PUD_SIZE && kvm_stage2_has_pmd(kvm)))
 		gfn = (fault_ipa & huge_page_mask(hstate_vma(vma))) >> PAGE_SHIFT;
-	up_read(&current->mm->mmap_sem);
+	mm_read_unlock(current->mm, &mmrange);
 
 	/* We need minimum second+third level pages */
 	ret = mmu_topup_memory_cache(memcache, kvm_mmu_cache_min_pages(kvm),
@@ -2280,6 +2282,7 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
 	hva_t reg_end = hva + mem->memory_size;
 	bool writable = !(mem->flags & KVM_MEM_READONLY);
 	int ret = 0;
+	DEFINE_RANGE_LOCK_FULL(mmrange);
 
 	if (change != KVM_MR_CREATE && change != KVM_MR_MOVE &&
 			change != KVM_MR_FLAGS_ONLY)
@@ -2293,7 +2296,7 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
 	    (kvm_phys_size(kvm) >> PAGE_SHIFT))
 		return -EFAULT;
 
-	down_read(&current->mm->mmap_sem);
+	mm_read_lock(current->mm, &mmrange);
 	/*
 	 * A memory region could potentially cover multiple VMAs, and any holes
 	 * between them, so iterate over all of them to find out if we can map
@@ -2361,7 +2364,7 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
 		stage2_flush_memslot(kvm, memslot);
 	spin_unlock(&kvm->mmu_lock);
 out:
-	up_read(&current->mm->mmap_sem);
+	mm_read_unlock(current->mm, &mmrange);
 	return ret;
 }
 
diff --git a/virt/kvm/async_pf.c b/virt/kvm/async_pf.c
index e93cd8515134..03d9f9bc5270 100644
--- a/virt/kvm/async_pf.c
+++ b/virt/kvm/async_pf.c
@@ -87,11 +87,11 @@ static void async_pf_execute(struct work_struct *work)
 	 * mm and might be done in another context, so we must
 	 * access remotely.
 	 */
-	down_read(&mm->mmap_sem);
+	mm_read_lock(mm, &mmrange);
 	get_user_pages_remote(NULL, mm, addr, 1, FOLL_WRITE, NULL, NULL,
 			      &locked, &mmrange);
 	if (locked)
-		up_read(&mm->mmap_sem);
+		mm_read_unlock(mm, &mmrange);
 
 	kvm_async_page_present_sync(vcpu, apf);
 
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index e1484150a3dd..421652e66a03 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1331,6 +1331,7 @@ EXPORT_SYMBOL_GPL(kvm_is_visible_gfn);
 unsigned long kvm_host_page_size(struct kvm *kvm, gfn_t gfn)
 {
 	struct vm_area_struct *vma;
+	DEFINE_RANGE_LOCK_FULL(mmrange);
 	unsigned long addr, size;
 
 	size = PAGE_SIZE;
@@ -1339,7 +1340,7 @@ unsigned long kvm_host_page_size(struct kvm *kvm, gfn_t gfn)
 	if (kvm_is_error_hva(addr))
 		return PAGE_SIZE;
 
-	down_read(&current->mm->mmap_sem);
+	mm_read_lock(current->mm, &mmrange);
 	vma = find_vma(current->mm, addr);
 	if (!vma)
 		goto out;
@@ -1347,7 +1348,7 @@ unsigned long kvm_host_page_size(struct kvm *kvm, gfn_t gfn)
 	size = vma_kernel_pagesize(vma);
 
 out:
-	up_read(&current->mm->mmap_sem);
+	mm_read_unlock(current->mm, &mmrange);
 
 	return size;
 }
@@ -1588,8 +1589,8 @@ static kvm_pfn_t hva_to_pfn(unsigned long addr, bool atomic, bool *async,
 {
 	struct vm_area_struct *vma;
 	kvm_pfn_t pfn = 0;
-	int npages, r;
 	DEFINE_RANGE_LOCK_FULL(mmrange);
+	int npages, r;
 
 	/* we can do it either atomically or asynchronously, not both */
 	BUG_ON(atomic && async);
@@ -1604,7 +1605,7 @@ static kvm_pfn_t hva_to_pfn(unsigned long addr, bool atomic, bool *async,
 	if (npages == 1)
 		return pfn;
 
-	down_read(&current->mm->mmap_sem);
+	mm_read_lock(current->mm, &mmrange);
 	if (npages == -EHWPOISON ||
 	      (!async && check_user_page_hwpoison(addr))) {
 		pfn = KVM_PFN_ERR_HWPOISON;
@@ -1629,7 +1630,7 @@ static kvm_pfn_t hva_to_pfn(unsigned long addr, bool atomic, bool *async,
 		pfn = KVM_PFN_ERR_FAULT;
 	}
 exit:
-	up_read(&current->mm->mmap_sem);
+	mm_read_unlock(current->mm, &mmrange);
 	return pfn;
 }
 
-- 
2.16.4