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[PATCH] KVM: MMU: If emulating an instruction fails, try unprotecting the page

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A page table may have been recycled into a regular page, and so any
instruction can be executed on it.  Unprotect the page and let the cpu do its
thing.

Signed-off-by: Avi Kivity <avi@qumranet.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Avi Kivity 2007-01-05 16:36:45 -08:00 committed by Linus Torvalds
parent 9b7a032567
commit a436036baf
3 changed files with 61 additions and 0 deletions
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1
drivers/kvm/kvm.h
View file

@ -450,6 +450,7 @@ unsigned long segment_base(u16 selector);
void kvm_mmu_pre_write(struct kvm_vcpu *vcpu, gpa_t gpa, int bytes);
void kvm_mmu_post_write(struct kvm_vcpu *vcpu, gpa_t gpa, int bytes);
int kvm_mmu_unprotect_page_virt(struct kvm_vcpu *vcpu, gva_t gva);
static inline struct page *_gfn_to_page(struct kvm *kvm, gfn_t gfn)
{

2
drivers/kvm/kvm_main.c
View file

@ -1063,6 +1063,8 @@ int emulate_instruction(struct kvm_vcpu *vcpu,
}
if (r) {
if (kvm_mmu_unprotect_page_virt(vcpu, cr2))
return EMULATE_DONE;
if (!vcpu->mmio_needed) {
report_emulation_failure(&emulate_ctxt);
return EMULATE_FAIL;

58
drivers/kvm/mmu.c
View file

@ -478,11 +478,62 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
return page;
}
static void kvm_mmu_page_unlink_children(struct kvm_vcpu *vcpu,
struct kvm_mmu_page *page)
{
BUG();
}
static void kvm_mmu_put_page(struct kvm_vcpu *vcpu,
struct kvm_mmu_page *page,
u64 *parent_pte)
{
mmu_page_remove_parent_pte(page, parent_pte);
if (page->role.level > PT_PAGE_TABLE_LEVEL)
kvm_mmu_page_unlink_children(vcpu, page);
hlist_del(&page->hash_link);
list_del(&page->link);
list_add(&page->link, &vcpu->free_pages);
}
static void kvm_mmu_zap_page(struct kvm_vcpu *vcpu,
struct kvm_mmu_page *page)
{
u64 *parent_pte;
while (page->multimapped || page->parent_pte) {
if (!page->multimapped)
parent_pte = page->parent_pte;
else {
struct kvm_pte_chain *chain;
chain = container_of(page->parent_ptes.first,
struct kvm_pte_chain, link);
parent_pte = chain->parent_ptes[0];
}
kvm_mmu_put_page(vcpu, page, parent_pte);
*parent_pte = 0;
}
}
static int kvm_mmu_unprotect_page(struct kvm_vcpu *vcpu, gfn_t gfn)
{
unsigned index;
struct hlist_head *bucket;
struct kvm_mmu_page *page;
struct hlist_node *node, *n;
int r;
pgprintk("%s: looking for gfn %lx\n", __FUNCTION__, gfn);
r = 0;
index = kvm_page_table_hashfn(gfn) % KVM_NUM_MMU_PAGES;
bucket = &vcpu->kvm->mmu_page_hash[index];
hlist_for_each_entry_safe(page, node, n, bucket, hash_link)
if (page->gfn == gfn && !page->role.metaphysical) {
kvm_mmu_zap_page(vcpu, page);
r = 1;
}
return r;
}
static void page_header_update_slot(struct kvm *kvm, void *pte, gpa_t gpa)
@ -1001,6 +1052,13 @@ void kvm_mmu_post_write(struct kvm_vcpu *vcpu, gpa_t gpa, int bytes)
{
}
int kvm_mmu_unprotect_page_virt(struct kvm_vcpu *vcpu, gva_t gva)
{
gpa_t gpa = vcpu->mmu.gva_to_gpa(vcpu, gva);
return kvm_mmu_unprotect_page(vcpu, gpa >> PAGE_SHIFT);
}
static void free_mmu_pages(struct kvm_vcpu *vcpu)
{
while (!list_empty(&vcpu->free_pages)) {