drm/amdgpu: Checked if the pointer NULL before use it.

For SRIOV on some parts, the host driver does not post VBIOS. So the guest
cannot get bios information. Therefore, adev->virt.fw_reserve.p_pf2vf
and adev->mode_info.atom_context are NULL.
Signed-off-by: Gavin Wan <Gavin.Wan@amd.com>
Reviewed-by: Zhigang Luo <Zhigang.Luo@amd.com>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_device.c

@@ -3855,21 +3855,24 @@ int amdgpu_device_init(struct amdgpu_device *adev,
 	}
 
 	/* enable PCIE atomic ops */
-	if (amdgpu_sriov_vf(adev))
-		adev->have_atomics_support = ((struct amd_sriov_msg_pf2vf_info *)
-			adev->virt.fw_reserve.p_pf2vf)->pcie_atomic_ops_support_flags ==
-			(PCI_EXP_DEVCAP2_ATOMIC_COMP32 | PCI_EXP_DEVCAP2_ATOMIC_COMP64);
+	if (amdgpu_sriov_vf(adev)) {
+		if (adev->virt.fw_reserve.p_pf2vf)
+			adev->have_atomics_support = ((struct amd_sriov_msg_pf2vf_info *)
+						      adev->virt.fw_reserve.p_pf2vf)->pcie_atomic_ops_support_flags ==
+				(PCI_EXP_DEVCAP2_ATOMIC_COMP32 | PCI_EXP_DEVCAP2_ATOMIC_COMP64);
 	/* APUs w/ gfx9 onwards doesn't reply on PCIe atomics, rather it is a
 	 * internal path natively support atomics, set have_atomics_support to true.
 	 */
-	else if ((adev->flags & AMD_IS_APU) &&
-		(adev->ip_versions[GC_HWIP][0] > IP_VERSION(9, 0, 0)))
+	} else if ((adev->flags & AMD_IS_APU) &&
+		   (adev->ip_versions[GC_HWIP][0] > IP_VERSION(9, 0, 0))) {
 		adev->have_atomics_support = true;
-	else
+	} else {
 		adev->have_atomics_support =
 			!pci_enable_atomic_ops_to_root(adev->pdev,
 					  PCI_EXP_DEVCAP2_ATOMIC_COMP32 |
 					  PCI_EXP_DEVCAP2_ATOMIC_COMP64);
+	}
+
 	if (!adev->have_atomics_support)
 		dev_info(adev->dev, "PCIE atomic ops is not supported\n");
 
@@ -3885,7 +3888,8 @@ int amdgpu_device_init(struct amdgpu_device *adev,
 	amdgpu_reset_init(adev);
 
 	/* detect if we are with an SRIOV vbios */
-	amdgpu_device_detect_sriov_bios(adev);
+	if (adev->bios)
+		amdgpu_device_detect_sriov_bios(adev);
 
 	/* check if we need to reset the asic
 	 *  E.g., driver was not cleanly unloaded previously, etc.