linux-kernel - [PATCH v4 5/7] drm/i915/gvt: subsitute kvm_read/write_guest with vfio_dma

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Date:   Thu, 12 Mar 2020 23:11:09 -0400
From:   Yan Zhao <yan.y.zhao@...el.com>
To:     intel-gvt-dev@...ts.freedesktop.org, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     alex.williamson@...hat.com, zhenyuw@...ux.intel.com,
        pbonzini@...hat.com, kevin.tian@...el.com, peterx@...hat.com,
        Yan Zhao <yan.y.zhao@...el.com>
Subject: [PATCH v4 5/7] drm/i915/gvt: subsitute kvm_read/write_guest with vfio_dma_rw

As a device model, it is better to read/write guest memory using vfio
interface, so that vfio is able to maintain dirty info of device IOVAs.

Cc: Kevin Tian <kevin.tian@...el.com>
Signed-off-by: Yan Zhao <yan.y.zhao@...el.com>
---
 drivers/gpu/drm/i915/gvt/kvmgt.c | 23 ++---------------------
 1 file changed, 2 insertions(+), 21 deletions(-)

diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c
index 811cee28ae06..cee7376ba39d 100644
--- a/drivers/gpu/drm/i915/gvt/kvmgt.c
+++ b/drivers/gpu/drm/i915/gvt/kvmgt.c
@@ -2050,33 +2050,14 @@ static int kvmgt_rw_gpa(unsigned long handle, unsigned long gpa,
 			void *buf, unsigned long len, bool write)
 {
 	struct kvmgt_guest_info *info;
-	struct kvm *kvm;
-	int idx, ret;
-	bool kthread = current->mm == NULL;
 
 	if (!handle_valid(handle))
 		return -ESRCH;
 
 	info = (struct kvmgt_guest_info *)handle;
-	kvm = info->kvm;
-
-	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) {
-		unuse_mm(kvm->mm);
-		mmput(kvm->mm);
-	}
-
-	return ret;
+	return vfio_dma_rw(kvmgt_vdev(info->vgpu)->vfio_group,
+			   gpa, buf, len, write);
 }
 
 static int kvmgt_read_gpa(unsigned long handle, unsigned long gpa,
-- 
2.17.1