drm/hyperv: Fix address space leak when Hyper-V DRM device is removed

When a Hyper-V DRM device is probed, the driver allocates MMIO space for
the vram, and maps it cacheable. If the device removed, or in the error
path for device probing, the MMIO space is released but no unmap is done.
Consequently the kernel address space for the mapping is leaked.

Fix this by adding iounmap() calls in the device removal path, and in the
error path during device probing.

Fixes: f1f63cb ("drm/hyperv: Fix an error handling path in hyperv_vmbus_probe()")
Fixes: a0ab5ab ("drm/hyperv : Removing the restruction of VRAM allocation with PCI bar size")
Signed-off-by: Michael Kelley <mhklinux@outlook.com>
Reviewed-by: Saurabh Sengar <ssengar@linux.microsoft.com>
Tested-by: Saurabh Sengar <ssengar@linux.microsoft.com>
Link: https://lore.kernel.org/r/20250210193441.2414-1-mhklinux@outlook.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Message-ID: <20250210193441.2414-1-mhklinux@outlook.com>

Author: mhklinux

drivers/gpu/drm/hyperv/hyperv_drm_drv.c

@@ -154,6 +154,7 @@ static int hyperv_vmbus_probe(struct hv_device *hdev,
 	return 0;
 
 err_free_mmio:
+	iounmap(hv->vram);
 	vmbus_free_mmio(hv->mem->start, hv->fb_size);
 err_vmbus_close:
 	vmbus_close(hdev->channel);
@@ -172,6 +173,7 @@ static void hyperv_vmbus_remove(struct hv_device *hdev)
 	vmbus_close(hdev->channel);
 	hv_set_drvdata(hdev, NULL);
 
+	iounmap(hv->vram);
 	vmbus_free_mmio(hv->mem->start, hv->fb_size);
 }