drm/i915: Sanitycheck PCI BARs

For proper operation of i915 we need usable PCI GTTMMADDR BAR 0
(1 for GEN2). In most cases we also need usable PCI GFXMEM BAR 2.
Let's add functions to check if BARs are set, and that it have
a size greater than 0.
In case GTTMMADDR BAR, let's validate at the beginning of i915
initialization.
For other BARs, let's validate before first use.

Signed-off-by: Piotr Piórkowski <[e-mail]>
Cc: Jani Nikula <[e-mail]>
Cc: Lucas De Marchi <[e-mail]>
Cc: Matt Roper <[e-mail]>
Reviewed-by: Jani Nikula <[e-mail]>
Signed-off-by: Jani Nikula <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/i915/gem/i915_gem_stolen.c

···
 #include "gt/intel_region_lmem.h"
 #include "i915_drv.h"
 #include "i915_gem_stolen.h"
+#include "i915_pci.h"
 #include "i915_reg.h"
 #include "i915_utils.h"
 #include "i915_vgpu.h"
···
 
 	if (WARN_ON_ONCE(instance))
 		return ERR_PTR(-ENODEV);
+
+	if (!i915_pci_resource_valid(pdev, GEN12_LMEM_BAR))
+		return ERR_PTR(-ENXIO);
 
 	/* Use DSM base address instead for stolen memory */
 	dsm_base = intel_uncore_read64(uncore, GEN12_DSMBASE);

drivers/gpu/drm/i915/gt/intel_ggtt.c

···
 #include "intel_gt_regs.h"
 #include "intel_pci_config.h"
 #include "i915_drv.h"
+#include "i915_pci.h"
 #include "i915_scatterlist.h"
 #include "i915_utils.h"
 #include "i915_vgpu.h"
···
 	u16 snb_gmch_ctl;
 
 	if (!HAS_LMEM(i915)) {
+		if (!i915_pci_resource_valid(pdev, GTT_APERTURE_BAR))
+			return -ENXIO;
+
 		ggtt->gmadr = pci_resource(pdev, GTT_APERTURE_BAR);
 		ggtt->mappable_end = resource_size(&ggtt->gmadr);
 	}
···
 	struct pci_dev *pdev = to_pci_dev(i915->drm.dev);
 	unsigned int size;
 	u16 snb_gmch_ctl;
+
+	if (!i915_pci_resource_valid(pdev, GTT_APERTURE_BAR))
+		return -ENXIO;
 
 	ggtt->gmadr = pci_resource(pdev, GTT_APERTURE_BAR);
 	ggtt->mappable_end = resource_size(&ggtt->gmadr);

drivers/gpu/drm/i915/gt/intel_region_lmem.c

···
  */
 
 #include "i915_drv.h"
+#include "i915_pci.h"
 #include "i915_reg.h"
 #include "intel_memory_region.h"
 #include "intel_pci_config.h"
···
 
 	if (!IS_DGFX(i915))
 		return ERR_PTR(-ENODEV);
+
+	if (!i915_pci_resource_valid(pdev, GEN12_LMEM_BAR))
+		return ERR_PTR(-ENXIO);
 
 	if (HAS_FLAT_CCS(i915)) {
 		resource_size_t lmem_range;

drivers/gpu/drm/i915/i915_pci.c

···
 #include "i915_drv.h"
 #include "i915_pci.h"
 #include "i915_reg.h"
+#include "intel_pci_config.h"
 
 #define PLATFORM(x) .platform = (x)
 #define GEN(x) \
···
 	return ret;
 }
 
+bool i915_pci_resource_valid(struct pci_dev *pdev, int bar)
+{
+	if (!pci_resource_flags(pdev, bar))
+		return false;
+
+	if (pci_resource_flags(pdev, bar) & IORESOURCE_UNSET)
+		return false;
+
+	if (!pci_resource_len(pdev, bar))
+		return false;
+
+	return true;
+}
+
+static bool intel_mmio_bar_valid(struct pci_dev *pdev, struct intel_device_info *intel_info)
+{
+	int gttmmaddr_bar = intel_info->graphics.ver == 2 ? GEN2_GTTMMADR_BAR : GTTMMADR_BAR;
+
+	return i915_pci_resource_valid(pdev, gttmmaddr_bar);
+}
+
 static int i915_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 {
 	struct intel_device_info *intel_info =
···
 	 */
 	if (PCI_FUNC(pdev->devfn))
 		return -ENODEV;
+
+	if (!intel_mmio_bar_valid(pdev, intel_info))
+		return -ENXIO;
 
 	/* Detect if we need to wait for other drivers early on */
 	if (intel_modeset_probe_defer(pdev))

drivers/gpu/drm/i915/i915_pci.h

···
 #ifndef __I915_PCI_H__
 #define __I915_PCI_H__
 
+#include <linux/types.h>
+
+struct pci_dev;
+
 int i915_pci_register_driver(void);
 void i915_pci_unregister_driver(void);
+
+bool i915_pci_resource_valid(struct pci_dev *pdev, int bar);
 
 #endif /* __I915_PCI_H__ */