From 0a1b60d76b0abcc2a0de4eb96d5dd379cd855f30 Mon Sep 17 00:00:00 2001 From: Zhenyu Wang Date: Fri, 31 Aug 2018 10:58:52 +0800 Subject: drm/i915/gvt: Fix life cycle reference on KVM mm Handle guest mm access life cycle properly with mmget()/mmput(). As noted by Linus, use_mm() depends on valid live page table but KVM's mmgrab() doesn't guarantee that. As vGPU usage depends on guest VM life cycle, need to make sure to use mmget()/mmput() to guarantee VM address access. v3: fix build v2: v1 caused a weird dependence issue which failed for vfio device release, which result invalid mdev vgpu and kvm state without proper release taken. This trys to put right reference around VM address space access instead. Cc: Linus Torvalds Cc: Paolo Bonzini Cc: Zhi Wang Reviewed-by: Zhi Wang Signed-off-by: Zhenyu Wang --- drivers/gpu/drm/i915/gvt/kvmgt.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) (limited to 'drivers') diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c index a45f46d8537f..c7afee37b2b8 100644 --- a/drivers/gpu/drm/i915/gvt/kvmgt.c +++ b/drivers/gpu/drm/i915/gvt/kvmgt.c @@ -32,6 +32,7 @@ #include #include #include +#include #include #include #include @@ -1792,16 +1793,21 @@ static int kvmgt_rw_gpa(unsigned long handle, unsigned long gpa, info = (struct kvmgt_guest_info *)handle; kvm = info->kvm; - if (kthread) + if (kthread) { + if (!mmget_not_zero(kvm->mm)) + return -EFAULT; use_mm(kvm->mm); + } idx = srcu_read_lock(&kvm->srcu); ret = write ? kvm_write_guest(kvm, gpa, buf, len) : kvm_read_guest(kvm, gpa, buf, len); srcu_read_unlock(&kvm->srcu, idx); - if (kthread) + if (kthread) { unuse_mm(kvm->mm); + mmput(kvm->mm); + } return ret; } -- cgit