drm/i915/gvt: Add emulation for BAR2 (aperture) with normal file RW approach

For vfio-pci, if the region support MMAP then it should support both
mmap and normal file access. The user-space is free to choose which is
being used. For qemu, we just need add 'x-no-mmap=on' for vfio-pci
option.

Currently GVTg only support MMAP for BAR2. So GVTg will not work when
user turn on x-no-mmap option.

This patch added file style access for BAR2, aka the GPU aperture. We
map the entire aperture partition of active vGPU to kernel space when
guest driver try to enable PCI Memory Space. Then we redirect the file
RW operation from kvmgt to this mapped area.

Link: https://bugzilla.redhat.com/show_bug.cgi?id=1458032
Signed-off-by: Changbin Du <changbin.du@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>

1 files changed, 45 insertions, 2 deletions

diff --git a/drivers/gpu/drm/i915/gvt/mmio.c b/drivers/gpu/drm/i915/gvt/mmio.c
index 980ec8906b1e..1e1310f50289 100644
--- a/drivers/gpu/drm/i915/gvt/mmio.c
+++ b/drivers/gpu/drm/i915/gvt/mmio.c
@@ -45,8 +45,7 @@
  */
 int intel_vgpu_gpa_to_mmio_offset(struct intel_vgpu *vgpu, u64 gpa)
 {
-	u64 gttmmio_gpa = *(u64 *)(vgpu_cfg_space(vgpu) + PCI_BASE_ADDRESS_0) &
-			  ~GENMASK(3, 0);
+	u64 gttmmio_gpa = intel_vgpu_get_bar_gpa(vgpu, PCI_BASE_ADDRESS_0);
 	return gpa - gttmmio_gpa;
 }
 
@@ -57,6 +56,38 @@ int intel_vgpu_gpa_to_mmio_offset(struct intel_vgpu *vgpu, u64 gpa)
 	(reg >= gvt->device_info.gtt_start_offset \
 	 && reg < gvt->device_info.gtt_start_offset + gvt_ggtt_sz(gvt))
 
+static bool vgpu_gpa_is_aperture(struct intel_vgpu *vgpu, uint64_t gpa)
+{
+	u64 aperture_gpa = intel_vgpu_get_bar_gpa(vgpu, PCI_BASE_ADDRESS_2);
+	u64 aperture_sz = vgpu_aperture_sz(vgpu);
+
+	return gpa >= aperture_gpa && gpa < aperture_gpa + aperture_sz;
+}
+
+static int vgpu_aperture_rw(struct intel_vgpu *vgpu, uint64_t gpa,
+			    void *pdata, unsigned int size, bool is_read)
+{
+	u64 aperture_gpa = intel_vgpu_get_bar_gpa(vgpu, PCI_BASE_ADDRESS_2);
+	u64 offset = gpa - aperture_gpa;
+
+	if (!vgpu_gpa_is_aperture(vgpu, gpa + size - 1)) {
+		gvt_vgpu_err("Aperture rw out of range, offset %llx, size %d\n",
+			     offset, size);
+		return -EINVAL;
+	}
+
+	if (!vgpu->gm.aperture_va) {
+		gvt_vgpu_err("BAR is not enabled\n");
+		return -ENXIO;
+	}
+
+	if (is_read)
+		memcpy(pdata, vgpu->gm.aperture_va + offset, size);
+	else
+		memcpy(vgpu->gm.aperture_va + offset, pdata, size);
+	return 0;
+}
+
 static void failsafe_emulate_mmio_rw(struct intel_vgpu *vgpu, uint64_t pa,
 		void *p_data, unsigned int bytes, bool read)
 {
@@ -133,6 +164,12 @@ int intel_vgpu_emulate_mmio_read(struct intel_vgpu *vgpu, uint64_t pa,
 	}
 	mutex_lock(&gvt->lock);
 
+	if (vgpu_gpa_is_aperture(vgpu, pa)) {
+		ret = vgpu_aperture_rw(vgpu, pa, p_data, bytes, true);
+		mutex_unlock(&gvt->lock);
+		return ret;
+	}
+
 	if (atomic_read(&vgpu->gtt.n_write_protected_guest_page)) {
 		struct intel_vgpu_guest_page *gp;
 
@@ -224,6 +261,12 @@ int intel_vgpu_emulate_mmio_write(struct intel_vgpu *vgpu, uint64_t pa,
 
 	mutex_lock(&gvt->lock);
 
+	if (vgpu_gpa_is_aperture(vgpu, pa)) {
+		ret = vgpu_aperture_rw(vgpu, pa, p_data, bytes, false);
+		mutex_unlock(&gvt->lock);
+		return ret;
+	}
+
 	if (atomic_read(&vgpu->gtt.n_write_protected_guest_page)) {
 		struct intel_vgpu_guest_page *gp;