KVM: MMU: Don't read pdptrs with mmu spinlock held in mmu_alloc_roots

On svm, kvm_read_pdptr() may require reading guest memory, which can sleep.

Push the spinlock into mmu_alloc_roots(), and only take it after we've read
the pdptr.

Tested-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 51eb6d6abd86..de996380ec26 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -2065,11 +2065,13 @@ static int mmu_alloc_roots(struct kvm_vcpu *vcpu)
                         direct = 1;
                         root_gfn = 0;
                 }
+                spin_lock(&vcpu->kvm->mmu_lock);
                 sp = kvm_mmu_get_page(vcpu, root_gfn, 0,
                                       PT64_ROOT_LEVEL, direct,
                                       ACC_ALL, NULL);
                 root = __pa(sp->spt);
                 ++sp->root_count;
+                spin_unlock(&vcpu->kvm->mmu_lock);
                 vcpu->arch.mmu.root_hpa = root;
                 return 0;
         }
@@ -2093,11 +2095,14 @@ static int mmu_alloc_roots(struct kvm_vcpu *vcpu)
                         direct = 1;
                         root_gfn = i << 30;
                 }
+                spin_lock(&vcpu->kvm->mmu_lock);
                 sp = kvm_mmu_get_page(vcpu, root_gfn, i << 30,
                                       PT32_ROOT_LEVEL, direct,
                                       ACC_ALL, NULL);
                 root = __pa(sp->spt);
                 ++sp->root_count;
+                spin_unlock(&vcpu->kvm->mmu_lock);
+
                 vcpu->arch.mmu.pae_root[i] = root | PT_PRESENT_MASK;
         }
         vcpu->arch.mmu.root_hpa = __pa(vcpu->arch.mmu.pae_root);
@@ -2466,7 +2471,9 @@ int kvm_mmu_load(struct kvm_vcpu *vcpu)
                 goto out;
         spin_lock(&vcpu->kvm->mmu_lock);
         kvm_mmu_free_some_pages(vcpu);
+        spin_unlock(&vcpu->kvm->mmu_lock);
         r = mmu_alloc_roots(vcpu);
+        spin_lock(&vcpu->kvm->mmu_lock);
         mmu_sync_roots(vcpu);
         spin_unlock(&vcpu->kvm->mmu_lock);
         if (r)