[PATCH v2 5/10] KVM: MMU: introduce gfn_to_pfn_atomic() function

Xiao Guangrong
2010-06-25T12:06:28Z

Introduce gfn_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>
---
arch/x86/mm/gup.c | 2 ++
include/linux/kvm_host.h | 1 +
virt/kvm/kvm_main.c | 32 +++++++++++++++++++++++++-------
3 files changed, 28 insertions(+), 7 deletions(-)

diff --git a/arch/x86/mm/gup.c b/arch/x86/mm/gup.c
index 738e659..0c9034b 100644
--- a/arch/x86/mm/gup.c
+++ b/arch/x86/mm/gup.c
@@ -6,6 +6,7 @@
*/
#include <linux/sched.h>
#include <linux/mm.h>
+#include <linux/module.h>
#include <linux/vmstat.h>
#include <linux/highmem.h>

@@ -274,6 +275,7 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,

return nr;
}
+EXPORT_SYMBOL_GPL(__get_user_pages_fast);

/**
* get_user_pages_fast() - pin user pages in memory
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 9289d1a..515fefd 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -295,6 +295,7 @@ 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 gfn_to_pfn_atomic(struct kvm *kvm, gfn_t gfn);
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);
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 885d3f5..60bb3d5 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -924,19 +924,25 @@ 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_bad_page;
+
down_read(&current->mm->mmap_sem);
if (is_hwpoison_address(addr)) {
up_read(&current->mm->mmap_sem);
@@ -949,6 +955,7 @@ 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_bad_page:
get_page(bad_page);
return page_to_pfn(bad_page);
}
@@ -962,7 +969,7 @@ static pfn_t hva_to_pfn(struct kvm *kvm, unsigned long addr)
return pfn;
}

-pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t gfn)
+pfn_t __gfn_to_pfn(struct kvm *kvm, gfn_t gfn, bool atomic)
{
unsigned long addr;

@@ -972,7 +979,18 @@ 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, atomic);
+}
+
+pfn_t gfn_to_pfn_atomic(struct kvm *kvm, gfn_t gfn)
+{
+ return __gfn_to_pfn(kvm, gfn, true);
+}
+EXPORT_SYMBOL_GPL(gfn_to_pfn_atomic);
+
+pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t gfn)
+{
+ return __gfn_to_pfn(kvm, gfn, false);
}
EXPORT_SYMBOL_GPL(gfn_to_pfn);

@@ -980,7 +998,7 @@ 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)
--
1.6.1.2