drm/i915/gvt: Fix aperture read/write emulation when enable x-no-mmap=on

When add 'x-no-mmap=on' for vfio-pci option, aperture access in guest
is emulated. But the vgpu_aperture_rw() function take wrong offset when
do memcpy, since vgpu->gm.aperture_va is not the base of entire aperture.
This mistake cause GPU command in guest get lost and so the seqno is not
updated in engine HWSP.

This patch fix this, and it also move the emulation code to kvmgt.
Because only vfio need to emulate it. Put aperture rw to MMIO emulation
path breaks assumptions in xengt.

v2: Remove PAGE_ALIGN for size (zhenyu)

Fixes: f090a00df9ec ("drm/i915/gvt: Add emulation for BAR2 (aperture) with normal file RW approach")
Signed-off-by: Changbin Du <changbin.du@intel.com>
Signed-off-by: Zhi Wang <zhi.a.wang@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

1 files changed, 34 insertions, 2 deletions

diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c
index eb92572056c3..801a3375c7b4 100644
--- a/drivers/gpu/drm/i915/gvt/kvmgt.c
+++ b/drivers/gpu/drm/i915/gvt/kvmgt.c
@@ -651,6 +651,39 @@ static int intel_vgpu_bar_rw(struct intel_vgpu *vgpu, int bar, uint64_t off,
 	return ret;
 }
 
+static inline bool intel_vgpu_in_aperture(struct intel_vgpu *vgpu, uint64_t off)
+{
+	return off >= vgpu_aperture_offset(vgpu) &&
+	       off < vgpu_aperture_offset(vgpu) + vgpu_aperture_sz(vgpu);
+}
+
+static int intel_vgpu_aperture_rw(struct intel_vgpu *vgpu, uint64_t off,
+		void *buf, unsigned long count, bool is_write)
+{
+	void *aperture_va;
+
+	if (!intel_vgpu_in_aperture(vgpu, off) ||
+	    !intel_vgpu_in_aperture(vgpu, off + count)) {
+		gvt_vgpu_err("Invalid aperture offset %llu\n", off);
+		return -EINVAL;
+	}
+
+	aperture_va = io_mapping_map_wc(&vgpu->gvt->dev_priv->ggtt.iomap,
+					ALIGN_DOWN(off, PAGE_SIZE),
+					count + offset_in_page(off));
+	if (!aperture_va)
+		return -EIO;
+
+	if (is_write)
+		memcpy(aperture_va + offset_in_page(off), buf, count);
+	else
+		memcpy(buf, aperture_va + offset_in_page(off), count);
+
+	io_mapping_unmap(aperture_va);
+
+	return 0;
+}
+
 static ssize_t intel_vgpu_rw(struct mdev_device *mdev, char *buf,
 			size_t count, loff_t *ppos, bool is_write)
 {
@@ -679,8 +712,7 @@ static ssize_t intel_vgpu_rw(struct mdev_device *mdev, char *buf,
 					buf, count, is_write);
 		break;
 	case VFIO_PCI_BAR2_REGION_INDEX:
-		ret = intel_vgpu_bar_rw(vgpu, PCI_BASE_ADDRESS_2, pos,
-					buf, count, is_write);
+		ret = intel_vgpu_aperture_rw(vgpu, pos, buf, count, is_write);
 		break;
 	case VFIO_PCI_BAR1_REGION_INDEX:
 	case VFIO_PCI_BAR3_REGION_INDEX: