[Intel-gfx] [PATCH] drm/i915: Sanitycheck PCI BARs on probe

[Lucas De Marchi]

On Thu, Jan 20, 2022 at 12:30:49PM +0100, Piorkowski, Piotr wrote:
>From: Piotr Piórkowski <piotr.piorkowski at intel.com>
>
>For proper operation of i915 we need usable PCI BARs:
> - GTTMMADDR BAR 0 (1 for GEN2)
> - GFXMEM BAR 2.
>Lets check before we start the i915 probe that these BARs are set,
>and that they have a size greater than 0.
>
>Signed-off-by: Piotr Piórkowski <piotr.piorkowski at intel.com>
>Cc: Michal Wajdeczko <michal.wajdeczko at intel.com>
>Cc: Jani Nikula <jani.nikula at linux.intel.com>

This sounds reasonable to me... should catch issues in which the BIOS
didn't assign resources properly, PCI subsystem tried to reassign them
and we ended up left withou a BAR.

+Matt Auld who is working on small BAR recovery... slightly related.
Does this look ok?

Acked-by: Lucas De Marchi <lucas.demarchi at intel.com>

thanks
Lucas De Marchi


>---
> drivers/gpu/drm/i915/i915_pci.c         | 33 +++++++++++++++++++++++++
> drivers/gpu/drm/i915/intel_pci_config.h |  5 ++++
> 2 files changed, 38 insertions(+)
>
>diff --git a/drivers/gpu/drm/i915/i915_pci.c b/drivers/gpu/drm/i915/i915_pci.c
>index 8261b6455747..ad60c69d9dd8 100644
>--- a/drivers/gpu/drm/i915/i915_pci.c
>+++ b/drivers/gpu/drm/i915/i915_pci.c
>@@ -29,6 +29,8 @@
> #include "i915_drv.h"
> #include "i915_pci.h"
>
>+#include "intel_pci_config.h"
>+
> #define PLATFORM(x) .platform = (x)
> #define GEN(x) \
> 	.graphics.ver = (x), \
>@@ -1181,6 +1183,34 @@ static bool force_probe(u16 device_id, const char *devices)
> 	return ret;
> }
>
>+static bool __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_bars_valid(struct pci_dev *pdev, struct intel_device_info *intel_info)
>+{
>+	const int gttmmaddr_bar = intel_info->graphics.ver == 2 ? GEN2_GTTMMADR_BAR : GTTMMADR_BAR;
>+	const int gfxmem_bar = GFXMEM_BAR;
>+
>+	if (!__pci_resource_valid(pdev, gttmmaddr_bar))
>+		return false;
>+
>+	if (!__pci_resource_valid(pdev, gfxmem_bar))
>+		return false;
>+
>+	return true;
>+}
>+
> static int i915_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
> {
> 	struct intel_device_info *intel_info =
>@@ -1206,6 +1236,9 @@ static int i915_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
> 	if (PCI_FUNC(pdev->devfn))
> 		return -ENODEV;
>
>+	if (!intel_bars_valid(pdev, intel_info))
>+		return -ENODEV;
>+
> 	/* Detect if we need to wait for other drivers early on */
> 	if (intel_modeset_probe_defer(pdev))
> 		return -EPROBE_DEFER;
>diff --git a/drivers/gpu/drm/i915/intel_pci_config.h b/drivers/gpu/drm/i915/intel_pci_config.h
>index 12cd9d4f23de..c08fd5d48ada 100644
>--- a/drivers/gpu/drm/i915/intel_pci_config.h
>+++ b/drivers/gpu/drm/i915/intel_pci_config.h
>@@ -6,6 +6,11 @@
> #ifndef __INTEL_PCI_CONFIG_H__
> #define __INTEL_PCI_CONFIG_H__
>
>+/* PCI BARs */
>+#define GTTMMADR_BAR				0
>+#define GEN2_GTTMMADR_BAR			1
>+#define GFXMEM_BAR				2
>+
> /* BSM in include/drm/i915_drm.h */
>
> #define MCHBAR_I915				0x44
>-- 
>2.25.1
>