[PATCH 11/33] KVM: MMU: Let the walker extract the target page gfn from the pte

Avi Kivity
2007-01-04T16:00:06Z

This fixes a problem where set_pte_common() looked for shadowed pages based
on the page directory gfn (a huge page) instead of the actual gfn being
mapped.

Signed-off-by: Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>

Index: linux-2.6/drivers/kvm/mmu.c
===================================================================
--- linux-2.6.orig/drivers/kvm/mmu.c
+++ linux-2.6/drivers/kvm/mmu.c
@@ -752,7 +752,8 @@ static inline void set_pte_common(struct
u64 *shadow_pte,
gpa_t gaddr,
int dirty,
- u64 access_bits)
+ u64 access_bits,
+ gfn_t gfn)
{
hpa_t paddr;

@@ -779,10 +780,10 @@ static inline void set_pte_common(struct
if (access_bits & PT_WRITABLE_MASK) {
struct kvm_mmu_page *shadow;

- shadow = kvm_mmu_lookup_page(vcpu, gaddr >> PAGE_SHIFT);
+ shadow = kvm_mmu_lookup_page(vcpu, gfn);
if (shadow) {
pgprintk("%s: found shadow page for %lx, marking ro\n",
- __FUNCTION__, (gfn_t)(gaddr >> PAGE_SHIFT));
+ __FUNCTION__, gfn);
access_bits &= ~PT_WRITABLE_MASK;
*shadow_pte &= ~PT_WRITABLE_MASK;
}
Index: linux-2.6/drivers/kvm/paging_tmpl.h
===================================================================
--- linux-2.6.orig/drivers/kvm/paging_tmpl.h
+++ linux-2.6/drivers/kvm/paging_tmpl.h
@@ -62,6 +62,7 @@ struct guest_walker {
pt_element_t *table;
pt_element_t *ptep;
pt_element_t inherited_ar;
+ gfn_t gfn;
};

/*
@@ -113,12 +114,23 @@ static void FNAME(walk_addr)(struct gues
if (is_present_pte(*ptep) && !(*ptep & PT_ACCESSED_MASK))
*ptep |= PT_ACCESSED_MASK;

- if (!is_present_pte(*ptep) ||
- walker->level == PT_PAGE_TABLE_LEVEL ||
- (walker->level == PT_DIRECTORY_LEVEL &&
- (*ptep & PT_PAGE_SIZE_MASK) &&
- (PTTYPE == 64 || is_pse(vcpu))))
+ if (!is_present_pte(*ptep))
+ break;
+
+ if (walker->level == PT_PAGE_TABLE_LEVEL) {
+ walker->gfn = (*ptep & PT_BASE_ADDR_MASK)
+ >> PAGE_SHIFT;
+ break;
+ }
+
+ if (walker->level == PT_DIRECTORY_LEVEL
+ && (*ptep & PT_PAGE_SIZE_MASK)
+ && (PTTYPE == 64 || is_pse(vcpu))) {
+ walker->gfn = (*ptep & PT_DIR_BASE_ADDR_MASK)
+ >> PAGE_SHIFT;
+ walker->gfn += PT_INDEX(addr, PT_PAGE_TABLE_LEVEL);
break;
+ }

if (walker->level != 3 || is_long_mode(vcpu))
walker->inherited_ar &= walker->table[index];
@@ -143,30 +155,29 @@ static void FNAME(release_walker)(struct
}

static void FNAME(set_pte)(struct kvm_vcpu *vcpu, u64 guest_pte,
- u64 *shadow_pte, u64 access_bits)
+ u64 *shadow_pte, u64 access_bits, gfn_t gfn)
{
ASSERT(*shadow_pte == 0);
access_bits &= guest_pte;
*shadow_pte = (guest_pte & PT_PTE_COPY_MASK);
set_pte_common(vcpu, shadow_pte, guest_pte & PT_BASE_ADDR_MASK,
- guest_pte & PT_DIRTY_MASK, access_bits);
+ guest_pte & PT_DIRTY_MASK, access_bits, gfn);
}

static void FNAME(set_pde)(struct kvm_vcpu *vcpu, u64 guest_pde,
- u64 *shadow_pte, u64 access_bits,
- int index)
+ u64 *shadow_pte, u64 access_bits, gfn_t gfn)
{
gpa_t gaddr;

ASSERT(*shadow_pte == 0);
access_bits &= guest_pde;
- gaddr = (guest_pde & PT_DIR_BASE_ADDR_MASK) + PAGE_SIZE * index;
+ gaddr = (gpa_t)gfn << PAGE_SHIFT;
if (PTTYPE == 32 && is_cpuid_PSE36())
gaddr |= (guest_pde & PT32_DIR_PSE36_MASK) <<
(32 - PT32_DIR_PSE36_SHIFT);
*shadow_pte = guest_pde & PT_PTE_COPY_MASK;
set_pte_common(vcpu, shadow_pte, gaddr,
- guest_pde & PT_DIRTY_MASK, access_bits);
+ guest_pde & PT_DIRTY_MASK, access_bits, gfn);
}

/*
@@ -214,10 +225,12 @@ static u64 *FNAME(fetch)(struct kvm_vcpu
*prev_shadow_ent |= PT_SHADOW_PS_MARK;
FNAME(set_pde)(vcpu, *guest_ent, shadow_ent,
walker->inherited_ar,
- PT_INDEX(addr, PT_PAGE_TABLE_LEVEL));
+ walker->gfn);
} else {
ASSERT(walker->level == PT_PAGE_TABLE_LEVEL);
- FNAME(set_pte)(vcpu, *guest_ent, shadow_ent, walker->inherited_ar);
+ FNAME(set_pte)(vcpu, *guest_ent, shadow_ent,
+ walker->inherited_ar,
+ walker->gfn);
}
return shadow_ent;
}
@@ -291,7 +304,7 @@ static int FNAME(fix_write_pf)(struct kv
return 0;
}

- gfn = (*guest_ent & PT64_BASE_ADDR_MASK) >> PAGE_SHIFT;
+ gfn = walker->gfn;
if (kvm_mmu_lookup_page(vcpu, gfn)) {
pgprintk("%s: found shadow page for %lx, marking ro\n",
__FUNCTION__, gfn);