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KVM: Add general accessors to read and write guest memory
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Signed-off-by: Izik Eidus <izike@qumranet.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
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Izik Eidus authored and Avi Kivity committed Jan 30, 2008
1 parent 290fc38 commit 195aefd
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Showing 3 changed files with 158 additions and 54 deletions.
9 changes: 9 additions & 0 deletions drivers/kvm/kvm.h
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Original file line number Diff line number Diff line change
Expand Up @@ -559,6 +559,15 @@ extern hpa_t bad_page_address;

gfn_t unalias_gfn(struct kvm *kvm, gfn_t gfn);
struct page *gfn_to_page(struct kvm *kvm, gfn_t gfn);
int kvm_read_guest_page(struct kvm *kvm, gfn_t gfn, void *data, int offset,
int len);
int kvm_read_guest(struct kvm *kvm, gpa_t gpa, void *data, unsigned long len);
int kvm_write_guest_page(struct kvm *kvm, gfn_t gfn, const void *data,
int offset, int len);
int kvm_write_guest(struct kvm *kvm, gpa_t gpa, const void *data,
unsigned long len);
int kvm_clear_guest_page(struct kvm *kvm, gfn_t gfn, int offset, int len);
int kvm_clear_guest(struct kvm *kvm, gpa_t gpa, unsigned long len);
struct kvm_memory_slot *gfn_to_memslot(struct kvm *kvm, gfn_t gfn);
void mark_page_dirty(struct kvm *kvm, gfn_t gfn);

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160 changes: 130 additions & 30 deletions drivers/kvm/kvm_main.c
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Original file line number Diff line number Diff line change
Expand Up @@ -400,22 +400,16 @@ static int load_pdptrs(struct kvm_vcpu *vcpu, unsigned long cr3)
gfn_t pdpt_gfn = cr3 >> PAGE_SHIFT;
unsigned offset = ((cr3 & (PAGE_SIZE-1)) >> 5) << 2;
int i;
u64 *pdpt;
int ret;
struct page *page;
u64 pdpte[ARRAY_SIZE(vcpu->pdptrs)];

mutex_lock(&vcpu->kvm->lock);
page = gfn_to_page(vcpu->kvm, pdpt_gfn);
if (!page) {
ret = kvm_read_guest_page(vcpu->kvm, pdpt_gfn, pdpte,
offset * sizeof(u64), sizeof(pdpte));
if (ret < 0) {
ret = 0;
goto out;
}

pdpt = kmap_atomic(page, KM_USER0);
memcpy(pdpte, pdpt+offset, sizeof(pdpte));
kunmap_atomic(pdpt, KM_USER0);

for (i = 0; i < ARRAY_SIZE(pdpte); ++i) {
if ((pdpte[i] & 1) && (pdpte[i] & 0xfffffff0000001e6ull)) {
ret = 0;
Expand Down Expand Up @@ -962,6 +956,127 @@ struct page *gfn_to_page(struct kvm *kvm, gfn_t gfn)
}
EXPORT_SYMBOL_GPL(gfn_to_page);

static int next_segment(unsigned long len, int offset)
{
if (len > PAGE_SIZE - offset)
return PAGE_SIZE - offset;
else
return len;
}

int kvm_read_guest_page(struct kvm *kvm, gfn_t gfn, void *data, int offset,
int len)
{
void *page_virt;
struct page *page;

page = gfn_to_page(kvm, gfn);
if (!page)
return -EFAULT;
page_virt = kmap_atomic(page, KM_USER0);

memcpy(data, page_virt + offset, len);

kunmap_atomic(page_virt, KM_USER0);
return 0;
}
EXPORT_SYMBOL_GPL(kvm_read_guest_page);

int kvm_read_guest(struct kvm *kvm, gpa_t gpa, void *data, unsigned long len)
{
gfn_t gfn = gpa >> PAGE_SHIFT;
int seg;
int offset = offset_in_page(gpa);
int ret;

while ((seg = next_segment(len, offset)) != 0) {
ret = kvm_read_guest_page(kvm, gfn, data, offset, seg);
if (ret < 0)
return ret;
offset = 0;
len -= seg;
data += seg;
++gfn;
}
return 0;
}
EXPORT_SYMBOL_GPL(kvm_read_guest);

int kvm_write_guest_page(struct kvm *kvm, gfn_t gfn, const void *data,
int offset, int len)
{
void *page_virt;
struct page *page;

page = gfn_to_page(kvm, gfn);
if (!page)
return -EFAULT;
page_virt = kmap_atomic(page, KM_USER0);

memcpy(page_virt + offset, data, len);

kunmap_atomic(page_virt, KM_USER0);
mark_page_dirty(kvm, gfn);
return 0;
}
EXPORT_SYMBOL_GPL(kvm_write_guest_page);

int kvm_write_guest(struct kvm *kvm, gpa_t gpa, const void *data,
unsigned long len)
{
gfn_t gfn = gpa >> PAGE_SHIFT;
int seg;
int offset = offset_in_page(gpa);
int ret;

while ((seg = next_segment(len, offset)) != 0) {
ret = kvm_write_guest_page(kvm, gfn, data, offset, seg);
if (ret < 0)
return ret;
offset = 0;
len -= seg;
data += seg;
++gfn;
}
return 0;
}

int kvm_clear_guest_page(struct kvm *kvm, gfn_t gfn, int offset, int len)
{
void *page_virt;
struct page *page;

page = gfn_to_page(kvm, gfn);
if (!page)
return -EFAULT;
page_virt = kmap_atomic(page, KM_USER0);

memset(page_virt + offset, 0, len);

kunmap_atomic(page_virt, KM_USER0);
return 0;
}
EXPORT_SYMBOL_GPL(kvm_clear_guest_page);

int kvm_clear_guest(struct kvm *kvm, gpa_t gpa, unsigned long len)
{
gfn_t gfn = gpa >> PAGE_SHIFT;
int seg;
int offset = offset_in_page(gpa);
int ret;

while ((seg = next_segment(len, offset)) != 0) {
ret = kvm_clear_guest_page(kvm, gfn, offset, seg);
if (ret < 0)
return ret;
offset = 0;
len -= seg;
++gfn;
}
return 0;
}
EXPORT_SYMBOL_GPL(kvm_clear_guest);

/* WARNING: Does not work on aliased pages. */
void mark_page_dirty(struct kvm *kvm, gfn_t gfn)
{
Expand All @@ -988,21 +1103,13 @@ int emulator_read_std(unsigned long addr,
gpa_t gpa = vcpu->mmu.gva_to_gpa(vcpu, addr);
unsigned offset = addr & (PAGE_SIZE-1);
unsigned tocopy = min(bytes, (unsigned)PAGE_SIZE - offset);
unsigned long pfn;
struct page *page;
void *page_virt;
int ret;

if (gpa == UNMAPPED_GVA)
return X86EMUL_PROPAGATE_FAULT;
pfn = gpa >> PAGE_SHIFT;
page = gfn_to_page(vcpu->kvm, pfn);
if (!page)
ret = kvm_read_guest(vcpu->kvm, gpa, data, tocopy);
if (ret < 0)
return X86EMUL_UNHANDLEABLE;
page_virt = kmap_atomic(page, KM_USER0);

memcpy(data, page_virt + offset, tocopy);

kunmap_atomic(page_virt, KM_USER0);

bytes -= tocopy;
data += tocopy;
Expand Down Expand Up @@ -1095,19 +1202,12 @@ static int emulator_read_emulated(unsigned long addr,
static int emulator_write_phys(struct kvm_vcpu *vcpu, gpa_t gpa,
const void *val, int bytes)
{
struct page *page;
void *virt;
int ret;

if (((gpa + bytes - 1) >> PAGE_SHIFT) != (gpa >> PAGE_SHIFT))
return 0;
page = gfn_to_page(vcpu->kvm, gpa >> PAGE_SHIFT);
if (!page)
ret = kvm_write_guest(vcpu->kvm, gpa, val, bytes);
if (ret < 0)
return 0;
mark_page_dirty(vcpu->kvm, gpa >> PAGE_SHIFT);
virt = kmap_atomic(page, KM_USER0);
kvm_mmu_pte_write(vcpu, gpa, val, bytes);
memcpy(virt + offset_in_page(gpa), val, bytes);
kunmap_atomic(virt, KM_USER0);
return 1;
}

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43 changes: 19 additions & 24 deletions drivers/kvm/vmx.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1387,33 +1387,28 @@ static void vmx_set_gdt(struct kvm_vcpu *vcpu, struct descriptor_table *dt)

static int init_rmode_tss(struct kvm* kvm)
{
struct page *p1, *p2, *p3;
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);
u16 data = 0;
int r;

if (!p1 || !p2 || !p3) {
kvm_printf(kvm,"%s: gfn_to_page failed\n", __FUNCTION__);
r = kvm_clear_guest_page(kvm, fn, 0, PAGE_SIZE);
if (r < 0)
return 0;
data = TSS_BASE_SIZE + TSS_REDIRECTION_SIZE;
r = kvm_write_guest_page(kvm, fn++, &data, 0x66, sizeof(u16));
if (r < 0)
return 0;
r = kvm_clear_guest_page(kvm, fn++, 0, PAGE_SIZE);
if (r < 0)
return 0;
r = kvm_clear_guest_page(kvm, fn, 0, PAGE_SIZE);
if (r < 0)
return 0;
data = ~0;
r = kvm_write_guest_page(kvm, fn, &data, RMODE_TSS_SIZE - 2 * PAGE_SIZE - 1,
sizeof(u8));
if (r < 0)
return 0;
}

page = kmap_atomic(p1, KM_USER0);
clear_page(page);
*(u16*)(page + 0x66) = TSS_BASE_SIZE + TSS_REDIRECTION_SIZE;
kunmap_atomic(page, KM_USER0);

page = kmap_atomic(p2, KM_USER0);
clear_page(page);
kunmap_atomic(page, KM_USER0);

page = kmap_atomic(p3, KM_USER0);
clear_page(page);
*(page + RMODE_TSS_SIZE - 2 * PAGE_SIZE - 1) = ~0;
kunmap_atomic(page, KM_USER0);

return 1;
}

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