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

Maxim Levitsky
2022-04-27T20:04:44Z

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 <mlevitsk@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