KVM: MMU: Concurrent guest walkers

[sfrench/cifs-2.6.git] / arch / x86 / kvm / paging_tmpl.h

diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index 56b88f7e83eff8a7e5403136aa1d7950a1ddae50..7f83f5557d5ee08118e51f3d43d9bc2116d141ce 100644 (file)
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -368,11 +368,13 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr,
        if (r)
                return r;
 
+       down_read(&current->mm->mmap_sem);
        /*
         * Look up the shadow pte for the faulting address.
         */
        r = FNAME(walk_addr)(&walker, vcpu, addr, write_fault, user_fault,
                             fetch_fault);
+       up_read(&current->mm->mmap_sem);
 
        /*
         * The page is not mapped by the guest.  Let the guest handle it.
@@ -384,6 +386,7 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr,
                return 0;
        }
 
+       mutex_lock(&vcpu->kvm->lock);
        shadow_pte = FNAME(fetch)(vcpu, addr, &walker, user_fault, write_fault,
                                  &write_pt);
        pgprintk("%s: shadow pte %p %llx ptwrite %d\n", __FUNCTION__,
@@ -395,11 +398,14 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr,
        /*
         * mmio: emulate if accessible, otherwise its a guest fault.
         */
-       if (shadow_pte && is_io_pte(*shadow_pte))
+       if (shadow_pte && is_io_pte(*shadow_pte)) {
+               mutex_unlock(&vcpu->kvm->lock);
                return 1;
+       }
 
        ++vcpu->stat.pf_fixed;
        kvm_mmu_audit(vcpu, "post page fault (fixed)");
+       mutex_unlock(&vcpu->kvm->lock);
 
        return write_pt;
 }