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KVM: MMU: Fold fix_write_pf() into set_pte_common() 

This prevents some work from being performed twice, and, more importantly,
reduces the number of places where we modify shadow ptes.

Signed-off-by: Avi Kivity <avi@qumranet.com>
This commit is contained in:
Avi Kivity 2007-05-31 15:08:29 +03:00
parent 63b1ad24d2
commit 97a0a01ea9
2 changed files with 68 additions and 111 deletions
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11
drivers/kvm/mmu.c
View File

@ -731,6 +731,17 @@ static int kvm_mmu_unprotect_page(struct kvm_vcpu *vcpu, gfn_t gfn)
return r;
}
static void mmu_unshadow(struct kvm_vcpu *vcpu, gfn_t gfn)
{
struct kvm_mmu_page *page;
while ((page = kvm_mmu_lookup_page(vcpu, gfn)) != NULL) {
pgprintk("%s: zap %lx %x\n",
__FUNCTION__, gfn, page->role.word);
kvm_mmu_zap_page(vcpu, page);
}
}
static void page_header_update_slot(struct kvm *kvm, void *pte, gpa_t gpa)
{
int slot = memslot_id(kvm, gfn_to_memslot(kvm, gpa >> PAGE_SHIFT));

168
drivers/kvm/paging_tmpl.h
View File

@ -197,11 +197,26 @@ static void FNAME(set_pte_common)(struct kvm_vcpu *vcpu,
gpa_t gaddr,
pt_element_t *gpte,
u64 access_bits,
int user_fault,
int write_fault,
int *ptwrite,
struct guest_walker *walker,
gfn_t gfn)
{
hpa_t paddr;
int dirty = *gpte & PT_DIRTY_MASK;
int was_rmapped = is_rmap_pte(*shadow_pte);
pgprintk("%s: spte %llx gpte %llx access %llx write_fault %d"
" user_fault %d gfn %lx\n",
__FUNCTION__, *shadow_pte, (u64)*gpte, access_bits,
write_fault, user_fault, gfn);
if (write_fault && !dirty) {
*gpte |= PT_DIRTY_MASK;
dirty = 1;
FNAME(mark_pagetable_dirty)(vcpu->kvm, walker);
}
*shadow_pte |= access_bits << PT_SHADOW_BITS_OFFSET;
if (!dirty)
@ -209,7 +224,9 @@ static void FNAME(set_pte_common)(struct kvm_vcpu *vcpu,
paddr = gpa_to_hpa(vcpu, gaddr & PT64_BASE_ADDR_MASK);
*shadow_pte |= access_bits;
*shadow_pte |= PT_PRESENT_MASK;
if (access_bits & PT_USER_MASK)
*shadow_pte |= PT_USER_MASK;
if (is_error_hpa(paddr)) {
*shadow_pte |= gaddr;
@ -231,37 +248,50 @@ static void FNAME(set_pte_common)(struct kvm_vcpu *vcpu,
access_bits &= ~PT_WRITABLE_MASK;
}
if (access_bits & PT_WRITABLE_MASK) {
if ((access_bits & PT_WRITABLE_MASK)
|| (write_fault && !is_write_protection(vcpu) && !user_fault)) {
struct kvm_mmu_page *shadow;
*shadow_pte |= PT_WRITABLE_MASK;
if (user_fault) {
mmu_unshadow(vcpu, gfn);
goto unshadowed;
}
shadow = kvm_mmu_lookup_page(vcpu, gfn);
if (shadow) {
pgprintk("%s: found shadow page for %lx, marking ro\n",
__FUNCTION__, gfn);
access_bits &= ~PT_WRITABLE_MASK;
if (is_writeble_pte(*shadow_pte)) {
*shadow_pte &= ~PT_WRITABLE_MASK;
kvm_arch_ops->tlb_flush(vcpu);
*shadow_pte &= ~PT_WRITABLE_MASK;
kvm_arch_ops->tlb_flush(vcpu);
}
if (write_fault)
*ptwrite = 1;
}
}
unshadowed:
if (access_bits & PT_WRITABLE_MASK)
mark_page_dirty(vcpu->kvm, gaddr >> PAGE_SHIFT);
page_header_update_slot(vcpu->kvm, shadow_pte, gaddr);
rmap_add(vcpu, shadow_pte);
if (!was_rmapped)
rmap_add(vcpu, shadow_pte);
}
static void FNAME(set_pte)(struct kvm_vcpu *vcpu, pt_element_t *gpte,
u64 *shadow_pte, u64 access_bits,
int write_fault, gfn_t gfn)
int user_fault, int write_fault, int *ptwrite,
struct guest_walker *walker, gfn_t gfn)
{
ASSERT(*shadow_pte == 0);
access_bits &= *gpte;
*shadow_pte = (*gpte & PT_PTE_COPY_MASK);
*shadow_pte |= (*gpte & PT_PTE_COPY_MASK);
FNAME(set_pte_common)(vcpu, shadow_pte, *gpte & PT_BASE_ADDR_MASK,
gpte, access_bits, write_fault, gfn);
gpte, access_bits, user_fault, write_fault,
ptwrite, walker, gfn);
}
static void FNAME(update_pte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *page,
@ -276,31 +306,34 @@ static void FNAME(update_pte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *page,
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,
0, NULL, NULL,
(gpte & PT_BASE_ADDR_MASK) >> PAGE_SHIFT);
}
static void FNAME(set_pde)(struct kvm_vcpu *vcpu, pt_element_t *gpde,
u64 *shadow_pte, u64 access_bits, int write_fault,
gfn_t gfn)
u64 *shadow_pte, u64 access_bits,
int user_fault, int write_fault, int *ptwrite,
struct guest_walker *walker, gfn_t gfn)
{
gpa_t gaddr;
ASSERT(*shadow_pte == 0);
access_bits &= *gpde;
gaddr = (gpa_t)gfn << PAGE_SHIFT;
if (PTTYPE == 32 && is_cpuid_PSE36())
gaddr |= (*gpde & PT32_DIR_PSE36_MASK) <<
(32 - PT32_DIR_PSE36_SHIFT);
*shadow_pte = *gpde & PT_PTE_COPY_MASK;
*shadow_pte |= *gpde & PT_PTE_COPY_MASK;
FNAME(set_pte_common)(vcpu, shadow_pte, gaddr,
gpde, access_bits, write_fault, gfn);
gpde, access_bits, user_fault, write_fault,
ptwrite, walker, gfn);
}
/*
* Fetch a shadow pte for a specific level in the paging hierarchy.
*/
static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
struct guest_walker *walker, int write_fault)
struct guest_walker *walker,
int user_fault, int write_fault, int *ptwrite)
{
hpa_t shadow_addr;
int level;
@ -330,7 +363,7 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
shadow_ent = ((u64 *)__va(shadow_addr)) + index;
if (is_present_pte(*shadow_ent) || is_io_pte(*shadow_ent)) {
if (level == PT_PAGE_TABLE_LEVEL)
return shadow_ent;
break;
shadow_addr = *shadow_ent & PT64_BASE_ADDR_MASK;
prev_shadow_ent = shadow_ent;
continue;
@ -365,94 +398,17 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
if (prev_shadow_ent)
*prev_shadow_ent |= PT_SHADOW_PS_MARK;
FNAME(set_pde)(vcpu, guest_ent, shadow_ent,
walker->inherited_ar, write_fault, walker->gfn);
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,
walker->inherited_ar,
write_fault, walker->gfn);
walker->inherited_ar, user_fault, write_fault,
ptwrite, walker, walker->gfn);
}
return shadow_ent;
}
/*
* The guest faulted for write. We need to
*
* - check write permissions
* - update the guest pte dirty bit
* - update our own dirty page tracking structures
*/
static int FNAME(fix_write_pf)(struct kvm_vcpu *vcpu,
u64 *shadow_ent,
struct guest_walker *walker,
gva_t addr,
int user,
int *write_pt)
{
pt_element_t *guest_ent;
int writable_shadow;
gfn_t gfn;
struct kvm_mmu_page *page;
if (is_writeble_pte(*shadow_ent))
return !user || (*shadow_ent & PT_USER_MASK);
writable_shadow = *shadow_ent & PT_SHADOW_WRITABLE_MASK;
if (user) {
/*
* User mode access. Fail if it's a kernel page or a read-only
* page.
*/
if (!(*shadow_ent & PT_SHADOW_USER_MASK) || !writable_shadow)
return 0;
ASSERT(*shadow_ent & PT_USER_MASK);
} else
/*
* Kernel mode access. Fail if it's a read-only page and
* supervisor write protection is enabled.
*/
if (!writable_shadow) {
if (is_write_protection(vcpu))
return 0;
*shadow_ent &= ~PT_USER_MASK;
}
guest_ent = walker->ptep;
if (!is_present_pte(*guest_ent)) {
*shadow_ent = 0;
return 0;
}
gfn = walker->gfn;
if (user) {
/*
* Usermode page faults won't be for page table updates.
*/
while ((page = kvm_mmu_lookup_page(vcpu, gfn)) != NULL) {
pgprintk("%s: zap %lx %x\n",
__FUNCTION__, gfn, page->role.word);
kvm_mmu_zap_page(vcpu, page);
}
} else if (kvm_mmu_lookup_page(vcpu, gfn)) {
pgprintk("%s: found shadow page for %lx, marking ro\n",
__FUNCTION__, gfn);
mark_page_dirty(vcpu->kvm, gfn);
FNAME(mark_pagetable_dirty)(vcpu->kvm, walker);
*guest_ent |= PT_DIRTY_MASK;
*write_pt = 1;
return 0;
}
mark_page_dirty(vcpu->kvm, gfn);
*shadow_ent |= PT_WRITABLE_MASK;
FNAME(mark_pagetable_dirty)(vcpu->kvm, walker);
*guest_ent |= PT_DIRTY_MASK;
rmap_add(vcpu, shadow_ent);
return 1;
}
/*
* Page fault handler. There are several causes for a page fault:
* - there is no shadow pte for the guest pte
@ -475,7 +431,6 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr,
int fetch_fault = error_code & PFERR_FETCH_MASK;
struct guest_walker walker;
u64 *shadow_pte;
int fixed;
int write_pt = 0;
int r;
@ -503,19 +458,10 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr,
return 0;
}
shadow_pte = FNAME(fetch)(vcpu, addr, &walker, write_fault);
pgprintk("%s: shadow pte %p %llx\n", __FUNCTION__,
shadow_pte, *shadow_pte);
/*
* Update the shadow pte.
*/
if (write_fault)
fixed = FNAME(fix_write_pf)(vcpu, shadow_pte, &walker, addr,
user_fault, &write_pt);
pgprintk("%s: updated shadow pte %p %llx\n", __FUNCTION__,
shadow_pte, *shadow_pte);
shadow_pte = FNAME(fetch)(vcpu, addr, &walker, user_fault, write_fault,
&write_pt);
pgprintk("%s: shadow pte %p %llx ptwrite %d\n", __FUNCTION__,
shadow_pte, *shadow_pte, write_pt);
FNAME(release_walker)(&walker);