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[kvm-devel] [PATCH 07/35] KVM: MMU: ignore zapped root pagetables
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From: Avi K. <av...@qu...> - 2008-04-03 19:32:48
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From: Marcelo Tosatti <mto...@re...>
Mark zapped root pagetables as invalid and ignore such pages during lookup.
This is a problem with the cr3-target feature, where a zapped root table fools
the faulting code into creating a read-only mapping. The result is a lockup
if the instruction can't be emulated.
Signed-off-by: Marcelo Tosatti <mto...@re...>
Cc: Anthony Liguori <ali...@us...>
Signed-off-by: Avi Kivity <av...@qu...>
---
arch/x86/kvm/mmu.c | 12 ++++++++++--
arch/x86/kvm/x86.c | 12 ++++++++++++
include/asm-x86/kvm_host.h | 1 +
include/linux/kvm_host.h | 2 ++
virt/kvm/kvm_main.c | 23 +++++++++++++++++++++++
5 files changed, 48 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index f7541fe..103d008 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -667,7 +667,8 @@ static struct kvm_mmu_page *kvm_mmu_lookup_page(struct kvm *kvm, gfn_t gfn)
index = kvm_page_table_hashfn(gfn);
bucket = &kvm->arch.mmu_page_hash[index];
hlist_for_each_entry(sp, node, bucket, hash_link)
- if (sp->gfn == gfn && !sp->role.metaphysical) {
+ if (sp->gfn == gfn && !sp->role.metaphysical
+ && !sp->role.invalid) {
pgprintk("%s: found role %x\n",
__FUNCTION__, sp->role.word);
return sp;
@@ -792,8 +793,11 @@ static void kvm_mmu_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp)
if (!sp->root_count) {
hlist_del(&sp->hash_link);
kvm_mmu_free_page(kvm, sp);
- } else
+ } else {
list_move(&sp->link, &kvm->arch.active_mmu_pages);
+ sp->role.invalid = 1;
+ kvm_reload_remote_mmus(kvm);
+ }
kvm_mmu_reset_last_pte_updated(kvm);
}
@@ -1073,6 +1077,8 @@ static void mmu_free_roots(struct kvm_vcpu *vcpu)
sp = page_header(root);
--sp->root_count;
+ if (!sp->root_count && sp->role.invalid)
+ kvm_mmu_zap_page(vcpu->kvm, sp);
vcpu->arch.mmu.root_hpa = INVALID_PAGE;
spin_unlock(&vcpu->kvm->mmu_lock);
return;
@@ -1085,6 +1091,8 @@ static void mmu_free_roots(struct kvm_vcpu *vcpu)
root &= PT64_BASE_ADDR_MASK;
sp = page_header(root);
--sp->root_count;
+ if (!sp->root_count && sp->role.invalid)
+ kvm_mmu_zap_page(vcpu->kvm, sp);
}
vcpu->arch.mmu.pae_root[i] = INVALID_PAGE;
}
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 0dd038e..e8e6492 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2658,6 +2658,10 @@ preempted:
kvm_x86_ops->guest_debug_pre(vcpu);
again:
+ if (vcpu->requests)
+ if (test_and_clear_bit(KVM_REQ_MMU_RELOAD, &vcpu->requests))
+ kvm_mmu_unload(vcpu);
+
r = kvm_mmu_reload(vcpu);
if (unlikely(r))
goto out;
@@ -2689,6 +2693,14 @@ again:
goto out;
}
+ if (vcpu->requests)
+ if (test_bit(KVM_REQ_MMU_RELOAD, &vcpu->requests)) {
+ local_irq_enable();
+ preempt_enable();
+ r = 1;
+ goto out;
+ }
+
if (signal_pending(current)) {
local_irq_enable();
preempt_enable();
diff --git a/include/asm-x86/kvm_host.h b/include/asm-x86/kvm_host.h
index 4f5a71a..7535839 100644
--- a/include/asm-x86/kvm_host.h
+++ b/include/asm-x86/kvm_host.h
@@ -140,6 +140,7 @@ union kvm_mmu_page_role {
unsigned pad_for_nice_hex_output : 6;
unsigned metaphysical : 1;
unsigned access : 3;
+ unsigned invalid : 1;
};
};
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index eb88d32..994278f 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -37,6 +37,7 @@
#define KVM_REQ_TLB_FLUSH 0
#define KVM_REQ_MIGRATE_TIMER 1
#define KVM_REQ_REPORT_TPR_ACCESS 2
+#define KVM_REQ_MMU_RELOAD 3
struct kvm_vcpu;
extern struct kmem_cache *kvm_vcpu_cache;
@@ -190,6 +191,7 @@ void kvm_resched(struct kvm_vcpu *vcpu);
void kvm_load_guest_fpu(struct kvm_vcpu *vcpu);
void kvm_put_guest_fpu(struct kvm_vcpu *vcpu);
void kvm_flush_remote_tlbs(struct kvm *kvm);
+void kvm_reload_remote_mmus(struct kvm *kvm);
long kvm_arch_dev_ioctl(struct file *filp,
unsigned int ioctl, unsigned long arg);
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index cf6df51..c41eb57 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -119,6 +119,29 @@ void kvm_flush_remote_tlbs(struct kvm *kvm)
smp_call_function_mask(cpus, ack_flush, NULL, 1);
}
+void kvm_reload_remote_mmus(struct kvm *kvm)
+{
+ int i, cpu;
+ cpumask_t cpus;
+ struct kvm_vcpu *vcpu;
+
+ cpus_clear(cpus);
+ for (i = 0; i < KVM_MAX_VCPUS; ++i) {
+ vcpu = kvm->vcpus[i];
+ if (!vcpu)
+ continue;
+ if (test_and_set_bit(KVM_REQ_MMU_RELOAD, &vcpu->requests))
+ continue;
+ cpu = vcpu->cpu;
+ if (cpu != -1 && cpu != raw_smp_processor_id())
+ cpu_set(cpu, cpus);
+ }
+ if (cpus_empty(cpus))
+ return;
+ smp_call_function_mask(cpus, ack_flush, NULL, 1);
+}
+
+
int kvm_vcpu_init(struct kvm_vcpu *vcpu, struct kvm *kvm, unsigned id)
{
struct page *page;
--
1.5.4.5
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