[PATCH] drm/i915/gvt: clean up vGPU resource r/w length

[Zhenyu Wang]

We can do max of 64bit for vGPU resource e.g MMIO r/w access, but
original KVMGT code just always force to do max of 32bit access.
This cleans up for old duplicated code block and allows for 64bit
access in one call. Also remove unnecessary resource length check
for both MMIO and config space access.

Cc: Xiong Zhang <xiong.y.zhang at intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw at linux.intel.com>
---
 drivers/gpu/drm/i915/gvt/cfg_space.c |  6 ---
 drivers/gpu/drm/i915/gvt/handlers.c  |  3 --
 drivers/gpu/drm/i915/gvt/kvmgt.c     | 86 +++++++++---------------------------
 3 files changed, 22 insertions(+), 73 deletions(-)

diff --git a/drivers/gpu/drm/i915/gvt/cfg_space.c b/drivers/gpu/drm/i915/gvt/cfg_space.c
index 40af17ec6312..7cf90db5ec00 100644
--- a/drivers/gpu/drm/i915/gvt/cfg_space.c
+++ b/drivers/gpu/drm/i915/gvt/cfg_space.c
@@ -98,9 +98,6 @@ static void vgpu_pci_cfg_mem_write(struct intel_vgpu *vgpu, unsigned int off,
 int intel_vgpu_emulate_cfg_read(struct intel_vgpu *vgpu, unsigned int offset,
 	void *p_data, unsigned int bytes)
 {
-	if (WARN_ON(bytes > 4))
-		return -EINVAL;
-
 	if (WARN_ON(offset + bytes > INTEL_GVT_MAX_CFG_SPACE_SZ))
 		return -EINVAL;
 
@@ -285,9 +282,6 @@ int intel_vgpu_emulate_cfg_write(struct intel_vgpu *vgpu, unsigned int offset,
 {
 	int ret;
 
-	if (WARN_ON(bytes > 4))
-		return -EINVAL;
-
 	if (WARN_ON(offset + bytes > INTEL_GVT_MAX_CFG_SPACE_SZ))
 		return -EINVAL;
 
diff --git a/drivers/gpu/drm/i915/gvt/handlers.c b/drivers/gpu/drm/i915/gvt/handlers.c
index d85264d48585..b8efda3374fa 100644
--- a/drivers/gpu/drm/i915/gvt/handlers.c
+++ b/drivers/gpu/drm/i915/gvt/handlers.c
@@ -3034,9 +3034,6 @@ int intel_vgpu_mmio_reg_rw(struct intel_vgpu *vgpu, unsigned int offset,
 	gvt_mmio_func func;
 	int ret;
 
-	if (WARN_ON(bytes > 4))
-		return -EINVAL;
-
 	/*
 	 * Handle special MMIO blocks.
 	 */
diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c
index fd0c85f9ef3c..9e8e3562bdef 100644
--- a/drivers/gpu/drm/i915/gvt/kvmgt.c
+++ b/drivers/gpu/drm/i915/gvt/kvmgt.c
@@ -692,47 +692,26 @@ static ssize_t intel_vgpu_read(struct mdev_device *mdev, char __user *buf,
 {
 	unsigned int done = 0;
 	int ret;
+	char tmp[8];
 
 	while (count) {
 		size_t filled;
 
-		if (count >= 4 && !(*ppos % 4)) {
-			u32 val;
-
-			ret = intel_vgpu_rw(mdev, (char *)&val, sizeof(val),
-					ppos, false);
-			if (ret <= 0)
-				goto read_err;
-
-			if (copy_to_user(buf, &val, sizeof(val)))
-				goto read_err;
-
+		if (count >= 8 && !(*ppos % 8)) {
+			filled = 8;
+		} else if (count >= 4 && !(*ppos % 4)) {
 			filled = 4;
 		} else if (count >= 2 && !(*ppos % 2)) {
-			u16 val;
-
-			ret = intel_vgpu_rw(mdev, (char *)&val, sizeof(val),
-					ppos, false);
-			if (ret <= 0)
-				goto read_err;
-
-			if (copy_to_user(buf, &val, sizeof(val)))
-				goto read_err;
-
 			filled = 2;
-		} else {
-			u8 val;
-
-			ret = intel_vgpu_rw(mdev, &val, sizeof(val), ppos,
-					false);
-			if (ret <= 0)
-				goto read_err;
+		} else
+			filled = 1;
 
-			if (copy_to_user(buf, &val, sizeof(val)))
-				goto read_err;
+		ret = intel_vgpu_rw(mdev, tmp, filled, ppos, false);
+		if (ret <= 0)
+			goto read_err;
 
-			filled = 1;
-		}
+		if (copy_to_user(buf, tmp, filled))
+			goto read_err;
 
 		count -= filled;
 		done += filled;
@@ -752,47 +731,26 @@ static ssize_t intel_vgpu_write(struct mdev_device *mdev,
 {
 	unsigned int done = 0;
 	int ret;
+	char val[8];
 
 	while (count) {
 		size_t filled;
 
-		if (count >= 4 && !(*ppos % 4)) {
-			u32 val;
-
-			if (copy_from_user(&val, buf, sizeof(val)))
-				goto write_err;
-
-			ret = intel_vgpu_rw(mdev, (char *)&val, sizeof(val),
-					ppos, true);
-			if (ret <= 0)
-				goto write_err;
-
+		if (count >= 8 && !(*ppos % 8)) {
+			filled = 8;
+		} else if (count >= 4 && !(*ppos % 4)) {
 			filled = 4;
 		} else if (count >= 2 && !(*ppos % 2)) {
-			u16 val;
-
-			if (copy_from_user(&val, buf, sizeof(val)))
-				goto write_err;
-
-			ret = intel_vgpu_rw(mdev, (char *)&val,
-					sizeof(val), ppos, true);
-			if (ret <= 0)
-				goto write_err;
-
 			filled = 2;
-		} else {
-			u8 val;
-
-			if (copy_from_user(&val, buf, sizeof(val)))
-				goto write_err;
+		} else
+			filled = 1;
 
-			ret = intel_vgpu_rw(mdev, &val, sizeof(val),
-					ppos, true);
-			if (ret <= 0)
-				goto write_err;
+		if (copy_from_user(val, buf, filled))
+			goto write_err;
 
-			filled = 1;
-		}
+		ret = intel_vgpu_rw(mdev, val, filled, ppos, true);
+		if (ret <= 0)
+			goto write_err;
 
 		count -= filled;
 		done += filled;
-- 
2.13.2