KVM: Simply gfn_to_page()
Mapping a guest page to a host page is a common operation. Currently,
one has first to find the memory slot where the page belongs (gfn_to_memslot),
then locate the page itself (gfn_to_page()).
This is clumsy, and also won't work well with memory aliases. So simplify
gfn_to_page() not to require memory slot translation first, and instead do it
internally.
Signed-off-by: Avi Kivity <avi@qumranet.com>
diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index 33eade7..a0ec5dd 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -420,12 +420,12 @@
u64 pdpte;
u64 *pdpt;
int ret;
- struct kvm_memory_slot *memslot;
+ struct page *page;
spin_lock(&vcpu->kvm->lock);
- memslot = gfn_to_memslot(vcpu->kvm, pdpt_gfn);
- /* FIXME: !memslot - emulate? 0xff? */
- pdpt = kmap_atomic(gfn_to_page(memslot, pdpt_gfn), KM_USER0);
+ page = gfn_to_page(vcpu->kvm, pdpt_gfn);
+ /* FIXME: !page - emulate? 0xff? */
+ pdpt = kmap_atomic(page, KM_USER0);
ret = 1;
for (i = 0; i < 4; ++i) {
@@ -861,6 +861,17 @@
}
EXPORT_SYMBOL_GPL(gfn_to_memslot);
+struct page *gfn_to_page(struct kvm *kvm, gfn_t gfn)
+{
+ struct kvm_memory_slot *slot;
+
+ slot = gfn_to_memslot(kvm, gfn);
+ if (!slot)
+ return NULL;
+ return slot->phys_mem[gfn - slot->base_gfn];
+}
+EXPORT_SYMBOL_GPL(gfn_to_page);
+
void mark_page_dirty(struct kvm *kvm, gfn_t gfn)
{
int i;
@@ -899,20 +910,20 @@
unsigned offset = addr & (PAGE_SIZE-1);
unsigned tocopy = min(bytes, (unsigned)PAGE_SIZE - offset);
unsigned long pfn;
- struct kvm_memory_slot *memslot;
- void *page;
+ struct page *page;
+ void *page_virt;
if (gpa == UNMAPPED_GVA)
return X86EMUL_PROPAGATE_FAULT;
pfn = gpa >> PAGE_SHIFT;
- memslot = gfn_to_memslot(vcpu->kvm, pfn);
- if (!memslot)
+ page = gfn_to_page(vcpu->kvm, pfn);
+ if (!page)
return X86EMUL_UNHANDLEABLE;
- page = kmap_atomic(gfn_to_page(memslot, pfn), KM_USER0);
+ page_virt = kmap_atomic(page, KM_USER0);
- memcpy(data, page + offset, tocopy);
+ memcpy(data, page_virt + offset, tocopy);
- kunmap_atomic(page, KM_USER0);
+ kunmap_atomic(page_virt, KM_USER0);
bytes -= tocopy;
data += tocopy;
@@ -963,16 +974,14 @@
static int emulator_write_phys(struct kvm_vcpu *vcpu, gpa_t gpa,
unsigned long val, int bytes)
{
- struct kvm_memory_slot *m;
struct page *page;
void *virt;
if (((gpa + bytes - 1) >> PAGE_SHIFT) != (gpa >> PAGE_SHIFT))
return 0;
- m = gfn_to_memslot(vcpu->kvm, gpa >> PAGE_SHIFT);
- if (!m)
+ page = gfn_to_page(vcpu->kvm, gpa >> PAGE_SHIFT);
+ if (!page)
return 0;
- page = gfn_to_page(m, gpa >> PAGE_SHIFT);
kvm_mmu_pre_write(vcpu, gpa, bytes);
mark_page_dirty(vcpu->kvm, gpa >> PAGE_SHIFT);
virt = kmap_atomic(page, KM_USER0);
@@ -2516,15 +2525,11 @@
{
struct kvm *kvm = vma->vm_file->private_data;
unsigned long pgoff;
- struct kvm_memory_slot *slot;
struct page *page;
*type = VM_FAULT_MINOR;
pgoff = ((address - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
- slot = gfn_to_memslot(kvm, pgoff);
- if (!slot)
- return NOPAGE_SIGBUS;
- page = gfn_to_page(slot, pgoff);
+ page = gfn_to_page(kvm, pgoff);
if (!page)
return NOPAGE_SIGBUS;
get_page(page);