KVM: Fix vcpu freeing for guest smp

A vcpu can pin up to four mmu shadow pages, which means the freeing
loop will never terminate.  Fix by first unpinning shadow pages on
all vcpus, then freeing shadow pages.

Signed-off-by: Avi Kivity <avi@qumranet.com>

diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index 3c3231d8dabfdb5a4f8b6ee8323e504fdb5a8ab2..3ff8ee56279cfb436ec07de78a80a985db87ca2e 100644 (file)
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -381,6 +381,16 @@ static void free_pio_guest_pages(struct kvm_vcpu *vcpu)
                }
 }
 
+static void kvm_unload_vcpu_mmu(struct kvm_vcpu *vcpu)
+{
+       if (!vcpu->vmcs)
+               return;
+
+       vcpu_load(vcpu);
+       kvm_mmu_unload(vcpu);
+       vcpu_put(vcpu);
+}
+
 static void kvm_free_vcpu(struct kvm_vcpu *vcpu)
 {
        if (!vcpu->vmcs)
@@ -401,6 +411,11 @@ static void kvm_free_vcpus(struct kvm *kvm)
 {
        unsigned int i;
 
+       /*
+        * Unpin any mmu pages first.
+        */
+       for (i = 0; i < KVM_MAX_VCPUS; ++i)
+               kvm_unload_vcpu_mmu(&kvm->vcpus[i]);
        for (i = 0; i < KVM_MAX_VCPUS; ++i)
                kvm_free_vcpu(&kvm->vcpus[i]);
 }

diff --git a/drivers/kvm/mmu.c b/drivers/kvm/mmu.c
index 5915d7a1c4f7b3e2ae2597de340974a4c9c27905..d4de988d182800452778b40d638d31dead9c71f8 100644 (file)
--- a/drivers/kvm/mmu.c
+++ b/drivers/kvm/mmu.c
@@ -838,11 +838,12 @@ static void mmu_free_roots(struct kvm_vcpu *vcpu)
        int i;
        struct kvm_mmu_page *page;
 
+       if (!VALID_PAGE(vcpu->mmu.root_hpa))
+               return;
 #ifdef CONFIG_X86_64
        if (vcpu->mmu.shadow_root_level == PT64_ROOT_LEVEL) {
                hpa_t root = vcpu->mmu.root_hpa;
 
-               ASSERT(VALID_PAGE(root));
                page = page_header(root);
                --page->root_count;
                vcpu->mmu.root_hpa = INVALID_PAGE;
@@ -853,7 +854,6 @@ static void mmu_free_roots(struct kvm_vcpu *vcpu)
                hpa_t root = vcpu->mmu.pae_root[i];
 
                if (root) {
-                       ASSERT(VALID_PAGE(root));
                        root &= PT64_BASE_ADDR_MASK;
                        page = page_header(root);
                        --page->root_count;