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authorAvi Kivity <avi@qumranet.com>2007-01-06 03:36:45 +0300
committerLinus Torvalds <torvalds@woody.osdl.org>2007-01-06 10:55:25 +0300
commita436036baf331703b4d2c8e8a45f02c597bf6913 (patch)
treeba134b0b42ca42c53e818073af8d51d73771c56b
parent9b7a032567ee1128daeebebfc14d3acedfe28c8c (diff)
downloadlinux-sunxi-a436036baf331703b4d2c8e8a45f02c597bf6913.tar.xz
[PATCH] KVM: MMU: If emulating an instruction fails, try unprotecting the page
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>
-rw-r--r--drivers/kvm/kvm.h1
-rw-r--r--drivers/kvm/kvm_main.c2
-rw-r--r--drivers/kvm/mmu.c58
3 files changed, 61 insertions, 0 deletions
diff --git a/drivers/kvm/kvm.h b/drivers/kvm/kvm.h
index b7068ecd7765..34c43bb4d348 100644
--- a/drivers/kvm/kvm.h
+++ b/drivers/kvm/kvm.h
@@ -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)
{
diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index 047f6f6ed3f6..79032438dd16 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -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;
diff --git a/drivers/kvm/mmu.c b/drivers/kvm/mmu.c
index 6dbd83b86623..1484b7211717 100644
--- a/drivers/kvm/mmu.c
+++ b/drivers/kvm/mmu.c
@@ -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)) {