KVM: MMU: introduce hva_to_pfn_atomic function

Introduce hva_to_pfn_atomic(), it's the fast path and can used in atomic
context, the later patch will use it

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

1 files changed, 19 insertions, 11 deletions

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index da117a6b1e2e..08bd304f8bc7 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -927,11 +927,6 @@ int memslot_id(struct kvm *kvm, gfn_t gfn)
         return memslot - slots->memslots;
 }
 
-static unsigned long gfn_to_hva_memslot(struct kvm_memory_slot *slot, gfn_t gfn)
-{
-        return slot->userspace_addr + (gfn - slot->base_gfn) * PAGE_SIZE;
-}
-
 unsigned long gfn_to_hva(struct kvm *kvm, gfn_t gfn)
 {
         struct kvm_memory_slot *slot;
@@ -943,19 +938,25 @@ unsigned long gfn_to_hva(struct kvm *kvm, gfn_t gfn)
 }
 EXPORT_SYMBOL_GPL(gfn_to_hva);
 
-static pfn_t hva_to_pfn(struct kvm *kvm, unsigned long addr)
+static pfn_t hva_to_pfn(struct kvm *kvm, unsigned long addr, bool atomic)
 {
         struct page *page[1];
         int npages;
         pfn_t pfn;
 
-        might_sleep();
-
-        npages = get_user_pages_fast(addr, 1, 1, page);
+        if (atomic)
+                npages = __get_user_pages_fast(addr, 1, 1, page);
+        else {
+                might_sleep();
+                npages = get_user_pages_fast(addr, 1, 1, page);
+        }
 
         if (unlikely(npages != 1)) {
                 struct vm_area_struct *vma;
 
+                if (atomic)
+                        goto return_fault_page;
+
                 down_read(&current->mm->mmap_sem);
                 if (is_hwpoison_address(addr)) {
                         up_read(&current->mm->mmap_sem);
@@ -968,6 +969,7 @@ static pfn_t hva_to_pfn(struct kvm *kvm, unsigned long addr)
                 if (vma == NULL || addr < vma->vm_start ||
                     !(vma->vm_flags & VM_PFNMAP)) {
                         up_read(&current->mm->mmap_sem);
+return_fault_page:
                         get_page(fault_page);
                         return page_to_pfn(fault_page);
                 }
@@ -981,6 +983,12 @@ static pfn_t hva_to_pfn(struct kvm *kvm, unsigned long addr)
         return pfn;
 }
 
+pfn_t hva_to_pfn_atomic(struct kvm *kvm, unsigned long addr)
+{
+        return hva_to_pfn(kvm, addr, true);
+}
+EXPORT_SYMBOL_GPL(hva_to_pfn_atomic);
+
 pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t gfn)
 {
         unsigned long addr;
@@ -991,7 +999,7 @@ pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t gfn)
                 return page_to_pfn(bad_page);
         }
 
-        return hva_to_pfn(kvm, addr);
+        return hva_to_pfn(kvm, addr, false);
 }
 EXPORT_SYMBOL_GPL(gfn_to_pfn);
 
@@ -999,7 +1007,7 @@ pfn_t gfn_to_pfn_memslot(struct kvm *kvm,
                          struct kvm_memory_slot *slot, gfn_t gfn)
 {
         unsigned long addr = gfn_to_hva_memslot(slot, gfn);
-        return hva_to_pfn(kvm, addr);
+        return hva_to_pfn(kvm, addr, false);
 }
 
 struct page *gfn_to_page(struct kvm *kvm, gfn_t gfn)