[PATCH 020/104] KVM: Move gfn_to_page out of kmap/unmap pairs

Avi Kivity
2007-09-17T08:37:46Z

From: Shaohua Li <shaohua.li@intel.com>

gfn_to_page might sleep with swap support. Move it out of the kmap calls.

Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
---
drivers/kvm/kvm.h | 2 +-
drivers/kvm/kvm_main.c | 7 ++--
drivers/kvm/mmu.c | 2 +-
drivers/kvm/paging_tmpl.h | 80 ++++++++++++++++++++++++++------------------
4 files changed, 52 insertions(+), 39 deletions(-)

diff --git a/drivers/kvm/kvm.h b/drivers/kvm/kvm.h
index cec5f05..57504ae 100644
--- a/drivers/kvm/kvm.h
+++ b/drivers/kvm/kvm.h
@@ -599,7 +599,7 @@ int kvm_write_guest(struct kvm_vcpu *vcpu,
unsigned long segment_base(u16 selector);

void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
- const u8 *old, const u8 *new, int bytes);
+ const u8 *new, int bytes);
int kvm_mmu_unprotect_page_virt(struct kvm_vcpu *vcpu, gva_t gva);
void __kvm_mmu_free_some_pages(struct kvm_vcpu *vcpu);
int kvm_mmu_load(struct kvm_vcpu *vcpu);
diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index 093cea3..80ee427 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -1076,7 +1076,6 @@ static int emulator_write_phys(struct kvm_vcpu *vcpu, gpa_t gpa,
{
struct page *page;
void *virt;
- unsigned offset = offset_in_page(gpa);

if (((gpa + bytes - 1) >> PAGE_SHIFT) != (gpa >> PAGE_SHIFT))
return 0;
@@ -1085,7 +1084,7 @@ static int emulator_write_phys(struct kvm_vcpu *vcpu, gpa_t gpa,
return 0;
mark_page_dirty(vcpu->kvm, gpa >> PAGE_SHIFT);
virt = kmap_atomic(page, KM_USER0);
- kvm_mmu_pte_write(vcpu, gpa, virt + offset, val, bytes);
+ kvm_mmu_pte_write(vcpu, gpa, val, bytes);
memcpy(virt + offset_in_page(gpa), val, bytes);
kunmap_atomic(virt, KM_USER0);
return 1;
@@ -1455,7 +1454,7 @@ static int vcpu_register_para(struct kvm_vcpu *vcpu, gpa_t para_state_gpa)

mark_page_dirty(vcpu->kvm, para_state_gpa >> PAGE_SHIFT);
para_state_page = pfn_to_page(para_state_hpa >> PAGE_SHIFT);
- para_state = kmap_atomic(para_state_page, KM_USER0);
+ para_state = kmap(para_state_page);

printk(KERN_DEBUG ".... guest version: %d\n", para_state->guest_version);
printk(KERN_DEBUG ".... size: %d\n", para_state->size);
@@ -1491,7 +1490,7 @@ static int vcpu_register_para(struct kvm_vcpu *vcpu, gpa_t para_state_gpa)

para_state->ret = 0;
err_kunmap_skip:
- kunmap_atomic(para_state, KM_USER0);
+ kunmap(para_state_page);
return 0;
err_gp:
return 1;
diff --git a/drivers/kvm/mmu.c b/drivers/kvm/mmu.c
index 75faef4..5437de2 100644
--- a/drivers/kvm/mmu.c
+++ b/drivers/kvm/mmu.c
@@ -1124,7 +1124,7 @@ static void mmu_pte_write_new_pte(struct kvm_vcpu *vcpu,
}

void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
- const u8 *old, const u8 *new, int bytes)
+ const u8 *new, int bytes)
{
gfn_t gfn = gpa >> PAGE_SHIFT;
struct kvm_mmu_page *page;
diff --git a/drivers/kvm/paging_tmpl.h b/drivers/kvm/paging_tmpl.h
index 01901ec..660243b 100644
--- a/drivers/kvm/paging_tmpl.h
+++ b/drivers/kvm/paging_tmpl.h
@@ -58,7 +58,10 @@ struct guest_walker {
int level;
gfn_t table_gfn[PT_MAX_FULL_LEVELS];
pt_element_t *table;
+ pt_element_t pte;
pt_element_t *ptep;
+ struct page *page;
+ int index;
pt_element_t inherited_ar;
gfn_t gfn;
u32 error_code;
@@ -80,11 +83,14 @@ static int FNAME(walk_addr)(struct guest_walker *walker,
pgprintk("%s: addr %lx\n", __FUNCTION__, addr);
walker->level = vcpu->mmu.root_level;
walker->table = NULL;
+ walker->page = NULL;
+ walker->ptep = NULL;
root = vcpu->cr3;
#if PTTYPE == 64
if (!is_long_mode(vcpu)) {
walker->ptep = &vcpu->pdptrs[(addr >> 30) & 3];
root = *walker->ptep;
+ walker->pte = root;
if (!(root & PT_PRESENT_MASK))
goto not_present;
--walker->level;
@@ -96,7 +102,8 @@ static int FNAME(walk_addr)(struct guest_walker *walker,
walker->level - 1, table_gfn);
slot = gfn_to_memslot(vcpu->kvm, table_gfn);
hpa = safe_gpa_to_hpa(vcpu, root & PT64_BASE_ADDR_MASK);
- walker->table = kmap_atomic(pfn_to_page(hpa >> PAGE_SHIFT), KM_USER0);
+ walker->page = pfn_to_page(hpa >> PAGE_SHIFT);
+ walker->table = kmap_atomic(walker->page, KM_USER0);

ASSERT((!is_long_mode(vcpu) && is_pae(vcpu)) ||
(vcpu->cr3 & CR3_NONPAE_RESERVED_BITS) == 0);
@@ -108,6 +115,7 @@ static int FNAME(walk_addr)(struct guest_walker *walker,
hpa_t paddr;

ptep = &walker->table[index];
+ walker->index = index;
ASSERT(((unsigned long)walker->table & PAGE_MASK) ==
((unsigned long)ptep & PAGE_MASK));

@@ -148,16 +156,20 @@ static int FNAME(walk_addr)(struct guest_walker *walker,

walker->inherited_ar &= walker->table[index];
table_gfn = (*ptep & PT_BASE_ADDR_MASK) >> PAGE_SHIFT;
- paddr = safe_gpa_to_hpa(vcpu, *ptep & PT_BASE_ADDR_MASK);
kunmap_atomic(walker->table, KM_USER0);
- walker->table = kmap_atomic(pfn_to_page(paddr >> PAGE_SHIFT),
- KM_USER0);
+ paddr = safe_gpa_to_hpa(vcpu, table_gfn << PAGE_SHIFT);
+ walker->page = pfn_to_page(paddr >> PAGE_SHIFT);
+ walker->table = kmap_atomic(walker->page, KM_USER0);
--walker->level;
walker->table_gfn[walker->level - 1 ] = table_gfn;
pgprintk("%s: table_gfn[%d] %lx\n", __FUNCTION__,
walker->level - 1, table_gfn);
}
- walker->ptep = ptep;
+ walker->pte = *ptep;
+ if (walker->page)
+ walker->ptep = NULL;
+ if (walker->table)
+ kunmap_atomic(walker->table, KM_USER0);
pgprintk("%s: pte %llx\n", __FUNCTION__, (u64)*ptep);
return 1;

@@ -175,13 +187,9 @@ err:
walker->error_code |= PFERR_USER_MASK;
if (fetch_fault)
walker->error_code |= PFERR_FETCH_MASK;
- return 0;
-}
-
-static void FNAME(release_walker)(struct guest_walker *walker)
-{
if (walker->table)
kunmap_atomic(walker->table, KM_USER0);
+ return 0;
}

static void FNAME(mark_pagetable_dirty)(struct kvm *kvm,
@@ -193,7 +201,7 @@ static void FNAME(mark_pagetable_dirty)(struct kvm *kvm,
static void FNAME(set_pte_common)(struct kvm_vcpu *vcpu,
u64 *shadow_pte,
gpa_t gaddr,
- pt_element_t *gpte,
+ pt_element_t gpte,
u64 access_bits,
int user_fault,
int write_fault,
@@ -202,23 +210,34 @@ static void FNAME(set_pte_common)(struct kvm_vcpu *vcpu,
gfn_t gfn)
{
hpa_t paddr;
- int dirty = *gpte & PT_DIRTY_MASK;
+ int dirty = gpte & PT_DIRTY_MASK;
u64 spte = *shadow_pte;
int was_rmapped = is_rmap_pte(spte);

pgprintk("%s: spte %llx gpte %llx access %llx write_fault %d"
" user_fault %d gfn %lx\n",
- __FUNCTION__, spte, (u64)*gpte, access_bits,
+ __FUNCTION__, spte, (u64)gpte, access_bits,
write_fault, user_fault, gfn);

if (write_fault && !dirty) {
- *gpte |= PT_DIRTY_MASK;
+ pt_element_t *guest_ent, *tmp = NULL;
+
+ if (walker->ptep)
+ guest_ent = walker->ptep;
+ else {
+ tmp = kmap_atomic(walker->page, KM_USER0);
+ guest_ent = &tmp[walker->index];
+ }
+
+ *guest_ent |= PT_DIRTY_MASK;
+ if (!walker->ptep)
+ kunmap_atomic(tmp, KM_USER0);
dirty = 1;
FNAME(mark_pagetable_dirty)(vcpu->kvm, walker);
}

spte |= PT_PRESENT_MASK | PT_ACCESSED_MASK | PT_DIRTY_MASK;
- spte |= *gpte & PT64_NX_MASK;
+ spte |= gpte & PT64_NX_MASK;
if (!dirty)
access_bits &= ~PT_WRITABLE_MASK;

@@ -273,13 +292,13 @@ unshadowed:
rmap_add(vcpu, shadow_pte);
}

-static void FNAME(set_pte)(struct kvm_vcpu *vcpu, pt_element_t *gpte,
+static void FNAME(set_pte)(struct kvm_vcpu *vcpu, pt_element_t gpte,
u64 *shadow_pte, u64 access_bits,
int user_fault, int write_fault, int *ptwrite,
struct guest_walker *walker, gfn_t gfn)
{
- access_bits &= *gpte;
- FNAME(set_pte_common)(vcpu, shadow_pte, *gpte & PT_BASE_ADDR_MASK,
+ access_bits &= gpte;
+ FNAME(set_pte_common)(vcpu, shadow_pte, gpte & PT_BASE_ADDR_MASK,
gpte, access_bits, user_fault, write_fault,
ptwrite, walker, gfn);
}
@@ -295,22 +314,22 @@ static void FNAME(update_pte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *page,
if (~gpte & (PT_PRESENT_MASK | PT_ACCESSED_MASK))
return;
pgprintk("%s: gpte %llx spte %p\n", __FUNCTION__, (u64)gpte, spte);
- FNAME(set_pte)(vcpu, &gpte, spte, PT_USER_MASK | PT_WRITABLE_MASK, 0,
+ FNAME(set_pte)(vcpu, gpte, spte, PT_USER_MASK | PT_WRITABLE_MASK, 0,
0, NULL, NULL,
(gpte & PT_BASE_ADDR_MASK) >> PAGE_SHIFT);
}

-static void FNAME(set_pde)(struct kvm_vcpu *vcpu, pt_element_t *gpde,
+static void FNAME(set_pde)(struct kvm_vcpu *vcpu, pt_element_t gpde,
u64 *shadow_pte, u64 access_bits,
int user_fault, int write_fault, int *ptwrite,
struct guest_walker *walker, gfn_t gfn)
{
gpa_t gaddr;

- access_bits &= *gpde;
+ access_bits &= gpde;
gaddr = (gpa_t)gfn << PAGE_SHIFT;
if (PTTYPE == 32 && is_cpuid_PSE36())
- gaddr |= (*gpde & PT32_DIR_PSE36_MASK) <<
+ gaddr |= (gpde & PT32_DIR_PSE36_MASK) <<
(32 - PT32_DIR_PSE36_SHIFT);
FNAME(set_pte_common)(vcpu, shadow_pte, gaddr,
gpde, access_bits, user_fault, write_fault,
@@ -328,9 +347,8 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
int level;
u64 *shadow_ent;
u64 *prev_shadow_ent = NULL;
- pt_element_t *guest_ent = walker->ptep;

- if (!is_present_pte(*guest_ent))
+ if (!is_present_pte(walker->pte))
return NULL;

shadow_addr = vcpu->mmu.root_hpa;
@@ -364,12 +382,12 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
if (level - 1 == PT_PAGE_TABLE_LEVEL
&& walker->level == PT_DIRECTORY_LEVEL) {
metaphysical = 1;
- hugepage_access = *guest_ent;
+ hugepage_access = walker->pte;
hugepage_access &= PT_USER_MASK | PT_WRITABLE_MASK;
- if (*guest_ent & PT64_NX_MASK)
+ if (walker->pte & PT64_NX_MASK)
hugepage_access |= (1 << 2);
hugepage_access >>= PT_WRITABLE_SHIFT;
- table_gfn = (*guest_ent & PT_BASE_ADDR_MASK)
+ table_gfn = (walker->pte & PT_BASE_ADDR_MASK)
>> PAGE_SHIFT;
} else {
metaphysical = 0;
@@ -386,12 +404,12 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
}

if (walker->level == PT_DIRECTORY_LEVEL) {
- FNAME(set_pde)(vcpu, guest_ent, shadow_ent,
+ FNAME(set_pde)(vcpu, walker->pte, shadow_ent,
walker->inherited_ar, user_fault, write_fault,
ptwrite, walker, walker->gfn);
} else {
ASSERT(walker->level == PT_PAGE_TABLE_LEVEL);
- FNAME(set_pte)(vcpu, guest_ent, shadow_ent,
+ FNAME(set_pte)(vcpu, walker->pte, shadow_ent,
walker->inherited_ar, user_fault, write_fault,
ptwrite, walker, walker->gfn);
}
@@ -442,7 +460,6 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr,
if (!r) {
pgprintk("%s: guest page fault\n", __FUNCTION__);
inject_page_fault(vcpu, addr, walker.error_code);
- FNAME(release_walker)(&walker);
vcpu->last_pt_write_count = 0; /* reset fork detector */
return 0;
}
@@ -452,8 +469,6 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr,
pgprintk("%s: shadow pte %p %llx ptwrite %d\n", __FUNCTION__,
shadow_pte, *shadow_pte, write_pt);

- FNAME(release_walker)(&walker);
-
if (!write_pt)
vcpu->last_pt_write_count = 0; /* reset fork detector */

@@ -482,7 +497,6 @@ static gpa_t FNAME(gva_to_gpa)(struct kvm_vcpu *vcpu, gva_t vaddr)
gpa |= vaddr & ~PAGE_MASK;
}

- FNAME(release_walker)(&walker);
return gpa;
}

--
1.5.3