drm/amdgpu: Restore msix after FLR

After FLR, the msix will be cleared, so need to re-enable it.
Signed-off-by: NPeng Ju Zhou <PengJu.Zhou@amd.com>
Signed-off-by: NEmily.Deng <Emily.Deng@amd.com>
Reviewed-by: NLijo Lazar <lijo.lazar@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

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

@@ -278,6 +278,21 @@ static bool amdgpu_msi_ok(struct amdgpu_device *adev)
 	return true;
 }
 
+static void amdgpu_restore_msix(struct amdgpu_device *adev)
+{
+	u16 ctrl;
+
+	pci_read_config_word(adev->pdev, adev->pdev->msix_cap + PCI_MSIX_FLAGS, &ctrl);
+	if (!(ctrl & PCI_MSIX_FLAGS_ENABLE))
+		return;
+
+	/* VF FLR */
+	ctrl &= ~PCI_MSIX_FLAGS_ENABLE;
+	pci_write_config_word(adev->pdev, adev->pdev->msix_cap + PCI_MSIX_FLAGS, ctrl);
+	ctrl |= PCI_MSIX_FLAGS_ENABLE;
+	pci_write_config_word(adev->pdev, adev->pdev->msix_cap + PCI_MSIX_FLAGS, ctrl);
+}
+
 /**
  * amdgpu_irq_init - initialize interrupt handling
  *
@@ -569,6 +584,9 @@ void amdgpu_irq_gpu_reset_resume_helper(struct amdgpu_device *adev)
 {
 	int i, j, k;
 
+	if (amdgpu_sriov_vf(adev))
+		amdgpu_restore_msix(adev);
+
 	for (i = 0; i < AMDGPU_IRQ_CLIENTID_MAX; ++i) {
 		if (!adev->irq.client[i].sources)
 			continue;