[PATCH 38/41] KVM: Simply gfn_to_page()

Avi Kivity
2007-04-01T14:35:35Z

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-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
---
drivers/kvm/kvm.h | 12 +-----------
drivers/kvm/kvm_main.c | 45 +++++++++++++++++++++++++--------------------
drivers/kvm/mmu.c | 12 ++++--------
drivers/kvm/vmx.c | 6 +++---
4 files changed, 33 insertions(+), 42 deletions(-)

diff --git a/drivers/kvm/kvm.h b/drivers/kvm/kvm.h
index 59357be..d19985a 100644
--- a/drivers/kvm/kvm.h
+++ b/drivers/kvm/kvm.h
@@ -443,11 +443,7 @@ void kvm_emulator_want_group7_invlpg(void);

extern hpa_t bad_page_address;

-static inline struct page *gfn_to_page(struct kvm_memory_slot *slot, gfn_t gfn)
-{
- return slot->phys_mem[gfn - slot->base_gfn];
-}
-
+struct page *gfn_to_page(struct kvm *kvm, gfn_t gfn);
struct kvm_memory_slot *gfn_to_memslot(struct kvm *kvm, gfn_t gfn);
void mark_page_dirty(struct kvm *kvm, gfn_t gfn);

@@ -523,12 +519,6 @@ static inline int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gva_t gva,
return vcpu->mmu.page_fault(vcpu, gva, error_code);
}

-static inline struct page *_gfn_to_page(struct kvm *kvm, gfn_t gfn)
-{
- struct kvm_memory_slot *slot = gfn_to_memslot(kvm, gfn);
- return (slot) ? slot->phys_mem[gfn - slot->base_gfn] : NULL;
-}
-
static inline int is_long_mode(struct kvm_vcpu *vcpu)
{
#ifdef CONFIG_X86_64
diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index 1ef5e9a..aaaf306 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -420,12 +420,12 @@ static int load_pdptrs(struct kvm_vcpu *vcpu, unsigned long cr3)
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 @@ struct kvm_memory_slot *gfn_to_memslot(struct kvm *kvm, gfn_t gfn)
}
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 @@ static int emulator_read_std(unsigned long addr,
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_read_emulated(unsigned long addr,
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);
@@ -2507,15 +2516,11 @@ static struct page *kvm_vm_nopage(struct vm_area_struct *vma,
{
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);
diff --git a/drivers/kvm/mmu.c b/drivers/kvm/mmu.c
index 707f63c..35135ec 100644
--- a/drivers/kvm/mmu.c
+++ b/drivers/kvm/mmu.c
@@ -390,13 +390,11 @@ static void rmap_write_protect(struct kvm_vcpu *vcpu, u64 gfn)
{
struct kvm *kvm = vcpu->kvm;
struct page *page;
- struct kvm_memory_slot *slot;
struct kvm_rmap_desc *desc;
u64 *spte;

- slot = gfn_to_memslot(kvm, gfn);
- BUG_ON(!slot);
- page = gfn_to_page(slot, gfn);
+ page = gfn_to_page(kvm, gfn);
+ BUG_ON(!page);

while (page_private(page)) {
if (!(page_private(page) & 1))
@@ -711,14 +709,12 @@ hpa_t safe_gpa_to_hpa(struct kvm_vcpu *vcpu, gpa_t gpa)

hpa_t gpa_to_hpa(struct kvm_vcpu *vcpu, gpa_t gpa)
{
- struct kvm_memory_slot *slot;
struct page *page;

ASSERT((gpa & HPA_ERR_MASK) == 0);
- slot = gfn_to_memslot(vcpu->kvm, gpa >> PAGE_SHIFT);
- if (!slot)
+ page = gfn_to_page(vcpu->kvm, gpa >> PAGE_SHIFT);
+ if (!page)
return gpa | HPA_ERR_MASK;
- page = gfn_to_page(slot, gpa >> PAGE_SHIFT);
return ((hpa_t)page_to_pfn(page) << PAGE_SHIFT)
| (gpa & (PAGE_SIZE-1));
}
diff --git a/drivers/kvm/vmx.c b/drivers/kvm/vmx.c
index b64b7b7..61a6116 100644
--- a/drivers/kvm/vmx.c
+++ b/drivers/kvm/vmx.c
@@ -926,9 +926,9 @@ static int init_rmode_tss(struct kvm* kvm)
gfn_t fn = rmode_tss_base(kvm) >> PAGE_SHIFT;
char *page;

- p1 = _gfn_to_page(kvm, fn++);
- p2 = _gfn_to_page(kvm, fn++);
- p3 = _gfn_to_page(kvm, fn);
+ p1 = gfn_to_page(kvm, fn++);
+ p2 = gfn_to_page(kvm, fn++);
+ p3 = gfn_to_page(kvm, fn);

if (!p1 || !p2 || !p3) {
kvm_printf(kvm,"%s: gfn_to_page failed\n", __FUNCTION__);