[Intel-gfx] [RFC PATCH v3 05/19] x86: KVMGT: use kvm_page_track_write_tracking_enable

[Maxim Levitsky]

This allows to enable the write tracking only when KVMGT is
actually used and doesn't carry any penalty otherwise.

Tested by booting a VM with a kvmgt mdev device.

Signed-off-by: Maxim Levitsky <mlevi...@redhat.com>
---
 arch/x86/kvm/Kconfig             | 3 ---
 arch/x86/kvm/mmu/mmu.c           | 2 +-
 drivers/gpu/drm/i915/Kconfig     | 1 -
 drivers/gpu/drm/i915/gvt/kvmgt.c | 5 +++++
 4 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig
index e3cbd77061364..41341905d3734 100644
--- a/arch/x86/kvm/Kconfig
+++ b/arch/x86/kvm/Kconfig
@@ -126,7 +126,4 @@ config KVM_XEN
 
          If in doubt, say "N".
 
-config KVM_EXTERNAL_WRITE_TRACKING
-       bool
-
 endif # VIRTUALIZATION
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index fb744616bf7df..633a3138d68e1 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -5753,7 +5753,7 @@ int kvm_mmu_init_vm(struct kvm *kvm)
        node->track_flush_slot = kvm_mmu_invalidate_zap_pages_in_memslot;
        kvm_page_track_register_notifier(kvm, node);
 
-       if (IS_ENABLED(CONFIG_KVM_EXTERNAL_WRITE_TRACKING) || !tdp_enabled)
+       if (!tdp_enabled)
                mmu_enable_write_tracking(kvm);
 
        return 0;
diff --git a/drivers/gpu/drm/i915/Kconfig b/drivers/gpu/drm/i915/Kconfig
index 98c5450b8eacc..7d8346f4bae11 100644
--- a/drivers/gpu/drm/i915/Kconfig
+++ b/drivers/gpu/drm/i915/Kconfig
@@ -130,7 +130,6 @@ config DRM_I915_GVT_KVMGT
        depends on DRM_I915_GVT
        depends on KVM
        depends on VFIO_MDEV
-       select KVM_EXTERNAL_WRITE_TRACKING
        default n
        help
          Choose this option if you want to enable KVMGT support for
diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c
index 057ec44901045..4c62ab3ef245d 100644
--- a/drivers/gpu/drm/i915/gvt/kvmgt.c
+++ b/drivers/gpu/drm/i915/gvt/kvmgt.c
@@ -1933,6 +1933,7 @@ static int kvmgt_guest_init(struct mdev_device *mdev)
        struct intel_vgpu *vgpu;
        struct kvmgt_vdev *vdev;
        struct kvm *kvm;
+       int ret;
 
        vgpu = mdev_get_drvdata(mdev);
        if (handle_valid(vgpu->handle))
@@ -1948,6 +1949,10 @@ static int kvmgt_guest_init(struct mdev_device *mdev)
        if (__kvmgt_vgpu_exist(vgpu, kvm))
                return -EEXIST;
 
+       ret = kvm_page_track_write_tracking_enable(kvm);
+       if (ret)
+               return ret;
+
        info = vzalloc(sizeof(struct kvmgt_guest_info));
        if (!info)
                return -ENOMEM;
-- 
2.26.3