x86/gpu: reserve ICL's graphics stolen memory

ICL changes the registers and addresses to 64 bits.

I also briefly looked at implementing an u64 version of the PCI config
read functions, but I concluded this wouldn't be trivial, so it's not
worth doing it for a single user that can't have any racing problems
while reading the register in two separate operations.

v2:
- Scrub the development (non-public) changelog (Joonas).
- Remove the i915.ko bits so this can be easily backported in order
to properly avoid stolen memory even on machines without i915.ko
(Joonas).
- CC stable for the reasons above.

Issue: VIZ-9250
CC: [e-mail]
Cc: Ingo Molnar <[e-mail]>
Cc: H. Peter Anvin <[e-mail]>
Cc: [e-mail]
Cc: Daniele Ceraolo Spurio <[e-mail]>
Cc: Joonas Lahtinen <[e-mail]>
Signed-off-by: Paulo Zanoni <[e-mail]>
Fixes: 412310019a20 ("drm/i915/icl: Add initial Icelake definitions.")
Reviewed-by: Joonas Lahtinen <[e-mail]>
Acked-by: Ingo Molnar <[e-mail]>
Signed-off-by: Rodrigo Vivi <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

arch/x86/kernel/early-quirks.c

···
 	return bsm & INTEL_BSM_MASK;
 }
 
+static resource_size_t __init gen11_stolen_base(int num, int slot, int func,
+						resource_size_t stolen_size)
+{
+	u64 bsm;
+
+	bsm = read_pci_config(num, slot, func, INTEL_GEN11_BSM_DW0);
+	bsm &= INTEL_BSM_MASK;
+	bsm |= (u64)read_pci_config(num, slot, func, INTEL_GEN11_BSM_DW1) << 32;
+
+	return bsm;
+}
+
 static resource_size_t __init i830_stolen_size(int num, int slot, int func)
 {
 	u16 gmch_ctrl;
···
 	.stolen_size = chv_stolen_size,
 };
 
+static const struct intel_early_ops gen11_early_ops __initconst = {
+	.stolen_base = gen11_stolen_base,
+	.stolen_size = gen9_stolen_size,
+};
+
 static const struct pci_device_id intel_early_ids[] __initconst = {
 	INTEL_I830_IDS(&i830_early_ops),
 	INTEL_I845G_IDS(&i845_early_ops),
···
 	INTEL_CFL_IDS(&gen9_early_ops),
 	INTEL_GLK_IDS(&gen9_early_ops),
 	INTEL_CNL_IDS(&gen9_early_ops),
+	INTEL_ICL_11_IDS(&gen11_early_ops),
 };
 
 struct resource intel_graphics_stolen_res __ro_after_init = DEFINE_RES_MEM(0, 0);

include/drm/i915_drm.h

···
 #define    I845_TSEG_SIZE_512K	(2 << 1)
 #define    I845_TSEG_SIZE_1M	(3 << 1)
 
-#define INTEL_BSM 0x5c
+#define INTEL_BSM		0x5c
+#define INTEL_GEN11_BSM_DW0	0xc0
+#define INTEL_GEN11_BSM_DW1	0xc4
 #define   INTEL_BSM_MASK	(-(1u << 20))
 
 #endif				/* _I915_DRM_H_ */