[PATCH v7 2/5] KVM: MMU: introduce hva_to_pfn_atomic function

[Xiao Guangrong]

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 <xiaoguangr...@cn.fujitsu.com>
---
 include/linux/kvm_host.h |    7 +++++++
 virt/kvm/kvm_main.c      |   30 +++++++++++++++++++-----------
 2 files changed, 26 insertions(+), 11 deletions(-)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index c13cc48..307d0e2 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -296,6 +296,7 @@ void kvm_release_page_dirty(struct page *page);
 void kvm_set_page_dirty(struct page *page);
 void kvm_set_page_accessed(struct page *page);
 
+pfn_t hva_to_pfn_atomic(struct kvm *kvm, unsigned long addr);
 pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t gfn);
 pfn_t gfn_to_pfn_memslot(struct kvm *kvm,
                         struct kvm_memory_slot *slot, gfn_t gfn);
@@ -518,6 +519,12 @@ static inline void kvm_guest_exit(void)
        current->flags &= ~PF_VCPU;
 }
 
+static inline unsigned long gfn_to_hva_memslot(struct kvm_memory_slot *slot,
+                                              gfn_t gfn)
+{
+       return slot->userspace_addr + (gfn - slot->base_gfn) * PAGE_SIZE;
+}
+
 static inline gpa_t gfn_to_gpa(gfn_t gfn)
 {
        return (gpa_t)gfn << PAGE_SHIFT;
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index b78b794..2dc0c18 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)
-- 
1.7.0.4

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