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Message-ID: <50057A01.9010401@linux.vnet.ibm.com>
Date: Tue, 17 Jul 2012 22:43:13 +0800
From: Xiao Guangrong <xiaoguangrong@...ux.vnet.ibm.com>
To: Xiao Guangrong <xiaoguangrong@...ux.vnet.ibm.com>
CC: Avi Kivity <avi@...hat.com>, Marcelo Tosatti <mtosatti@...hat.com>,
LKML <linux-kernel@...r.kernel.org>, KVM <kvm@...r.kernel.org>
Subject: [PATCH 05/10] KVM: reorganize hva_to_pfn
We do too many things in hva_to_pfn, this patch reorganize the code,
let it be better readable
Signed-off-by: Xiao Guangrong <xiaoguangrong@...ux.vnet.ibm.com>
---
virt/kvm/kvm_main.c | 161 +++++++++++++++++++++++++++++++--------------------
1 files changed, 99 insertions(+), 62 deletions(-)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index a89c7b8..54fb47b 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1096,84 +1096,121 @@ static inline int check_user_page_hwpoison(unsigned long addr)
return rc == -EHWPOISON;
}
-static pfn_t hva_to_pfn(unsigned long addr, bool atomic, bool *async,
- bool write_fault, bool *writable)
+/*
+ * The atomic path to get the writable pfn which will be stored in @pfn,
+ * true indicates success, otherwise false is returned.
+ */
+static bool hva_to_pfn_fast(unsigned long addr, bool atomic, bool *async,
+ bool write_fault, bool *writable, pfn_t *pfn)
{
struct page *page[1];
- int npages = 0;
- pfn_t pfn;
+ int npages;
- /* we can do it either atomically or asynchronously, not both */
- BUG_ON(atomic && async);
+ if (!(async || atomic))
+ return false;
- BUG_ON(!write_fault && !writable);
+ npages = __get_user_pages_fast(addr, 1, 1, page);
+ if (npages == 1) {
+ *pfn = page_to_pfn(page[0]);
+
+ if (writable)
+ *writable = true;
+ return true;
+ }
+
+ return false;
+}
+
+/*
+ * The slow path to get the pfn of the specified host virtual address,
+ * 1 indicates success, -errno is returned if error is detected.
+ */
+static int hva_to_pfn_slow(unsigned long addr, bool *async, bool write_fault,
+ bool *writable, pfn_t *pfn)
+{
+ struct page *page[1];
+ int npages = 0;
+
+ might_sleep();
if (writable)
- *writable = true;
+ *writable = write_fault;
- if (atomic || async)
- npages = __get_user_pages_fast(addr, 1, 1, page);
+ if (async) {
+ down_read(¤t->mm->mmap_sem);
+ npages = get_user_page_nowait(current, current->mm,
+ addr, write_fault, page);
+ up_read(¤t->mm->mmap_sem);
+ } else
+ npages = get_user_pages_fast(addr, 1, write_fault,
+ page);
- if (unlikely(npages != 1) && !atomic) {
- might_sleep();
+ if (npages != 1)
+ return npages;
- if (writable)
- *writable = write_fault;
-
- if (async) {
- down_read(¤t->mm->mmap_sem);
- npages = get_user_page_nowait(current, current->mm,
- addr, write_fault, page);
- up_read(¤t->mm->mmap_sem);
- } else
- npages = get_user_pages_fast(addr, 1, write_fault,
- page);
-
- /* map read fault as writable if possible */
- if (unlikely(!write_fault) && npages == 1) {
- struct page *wpage[1];
-
- npages = __get_user_pages_fast(addr, 1, 1, wpage);
- if (npages == 1) {
- *writable = true;
- put_page(page[0]);
- page[0] = wpage[0];
- }
- npages = 1;
+ /* map read fault as writable if possible */
+ if (unlikely(!write_fault)) {
+ struct page *wpage[1];
+
+ npages = __get_user_pages_fast(addr, 1, 1, wpage);
+ if (npages == 1) {
+ *writable = true;
+ put_page(page[0]);
+ page[0] = wpage[0];
}
+
+ npages = 1;
}
+ *pfn = page_to_pfn(page[0]);
+ return npages;
+}
- if (unlikely(npages != 1)) {
- struct vm_area_struct *vma;
+static pfn_t hva_to_pfn(unsigned long addr, bool atomic, bool *async,
+ bool write_fault, bool *writable)
+{
+ struct vm_area_struct *vma;
+ pfn_t pfn = 0;
+ int npages;
- if (atomic)
- return get_fault_pfn();
+ /* we can do it either atomically or asynchronously, not both */
+ BUG_ON(atomic && async);
- down_read(¤t->mm->mmap_sem);
- if (npages == -EHWPOISON ||
- (!async && check_user_page_hwpoison(addr))) {
- up_read(¤t->mm->mmap_sem);
- get_page(hwpoison_page);
- return page_to_pfn(hwpoison_page);
- }
+ BUG_ON(!write_fault && !writable);
- vma = find_vma_intersection(current->mm, addr, addr+1);
-
- if (vma == NULL)
- pfn = get_fault_pfn();
- else if ((vma->vm_flags & VM_PFNMAP)) {
- pfn = ((addr - vma->vm_start) >> PAGE_SHIFT) +
- vma->vm_pgoff;
- BUG_ON(!kvm_is_mmio_pfn(pfn));
- } else {
- if (async && (vma->vm_flags & VM_WRITE))
- *async = true;
- pfn = get_fault_pfn();
- }
- up_read(¤t->mm->mmap_sem);
- } else
- pfn = page_to_pfn(page[0]);
+ if (hva_to_pfn_fast(addr, atomic, async, write_fault, writable, &pfn))
+ return pfn;
+ if (atomic)
+ return get_fault_pfn();
+
+ npages = hva_to_pfn_slow(addr, async, write_fault, writable, &pfn);
+ if (npages == 1)
+ return pfn;
+
+ down_read(¤t->mm->mmap_sem);
+ if (npages == -EHWPOISON ||
+ (!async && check_user_page_hwpoison(addr))) {
+ get_page(hwpoison_page);
+ pfn = page_to_pfn(hwpoison_page);
+ goto exit;
+ }
+
+ vma = find_vma_intersection(current->mm, addr, addr + 1);
+
+ if (vma == NULL)
+ pfn = get_fault_pfn();
+ else if ((vma->vm_flags & VM_PFNMAP)) {
+ pfn = ((addr - vma->vm_start) >> PAGE_SHIFT) +
+ vma->vm_pgoff;
+ BUG_ON(!kvm_is_mmio_pfn(pfn));
+ } else {
+ if (async && (vma->vm_flags & VM_WRITE))
+ *async = true;
+ pfn = get_fault_pfn();
+ }
+
+exit:
+ up_read(¤t->mm->mmap_sem);
return pfn;
}
--
1.7.7.6
--
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