x86/Sandy Bridge: reserve pages when integrated graphics is present

SNB graphics devices have a bug that prevent them from accessing certain
memory ranges, namely anything below 1M and in the pages listed in the
table.  So reserve those at boot if set detect a SNB gfx device on the
CPU to avoid GPU hangs.

Stephane Marchesin had a similar patch to the page allocator awhile
back, but rather than reserving pages up front, it leaked them at
allocation time.

[ hpa: made a number of stylistic changes, marked arrays as static
  const, and made less verbose; use "memblock=debug" for full
  verbosity. ]

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

1 files changed, 78 insertions, 0 deletions

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 23ddd558fbd5..9dcb32545032 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -610,6 +610,81 @@ static __init void reserve_ibft_region(void)
 
 static unsigned reserve_low = CONFIG_X86_RESERVE_LOW << 10;
 
+static bool __init snb_gfx_workaround_needed(void)
+{
+        int i;
+        u16 vendor, devid;
+        static const u16 snb_ids[] = {
+                0x0102,
+                0x0112,
+                0x0122,
+                0x0106,
+                0x0116,
+                0x0126,
+                0x010a,
+        };
+
+        /* Assume no if something weird is going on with PCI */
+        if (!early_pci_allowed())
+                return false;
+
+        vendor = read_pci_config_16(0, 2, 0, PCI_VENDOR_ID);
+        if (vendor != 0x8086)
+                return false;
+
+        devid = read_pci_config_16(0, 2, 0, PCI_DEVICE_ID);
+        for (i = 0; i < ARRAY_SIZE(snb_ids); i++)
+                if (devid == snb_ids[i])
+                        return true;
+
+        return false;
+}
+
+/*
+ * Sandy Bridge graphics has trouble with certain ranges, exclude
+ * them from allocation.
+ */
+static void __init trim_snb_memory(void)
+{
+        static const unsigned long bad_pages[] = {
+                0x20050000,
+                0x20110000,
+                0x20130000,
+                0x20138000,
+                0x40004000,
+        };
+        int i;
+
+        if (!snb_gfx_workaround_needed())
+                return;
+
+        printk(KERN_DEBUG "reserving inaccessible SNB gfx pages\n");
+
+        /*
+         * Reserve all memory below the 1 MB mark that has not
+         * already been reserved.
+         */
+        memblock_reserve(0, 1<<20);
+        
+        for (i = 0; i < ARRAY_SIZE(bad_pages); i++) {
+                if (memblock_reserve(bad_pages[i], PAGE_SIZE))
+                        printk(KERN_WARNING "failed to reserve 0x%08lx\n",
+                               bad_pages[i]);
+        }
+}
+
+/*
+ * Here we put platform-specific memory range workarounds, i.e.
+ * memory known to be corrupt or otherwise in need to be reserved on
+ * specific platforms.
+ *
+ * If this gets used more widely it could use a real dispatch mechanism.
+ */
+static void __init trim_platform_memory_ranges(void)
+{
+        trim_snb_memory();
+}
+
 static void __init trim_bios_range(void)
 {
         /*
@@ -630,6 +705,7 @@ static void __init trim_bios_range(void)
          * take them out.
          */
         e820_remove_range(BIOS_BEGIN, BIOS_END - BIOS_BEGIN, E820_RAM, 1);
+
         sanitize_e820_map(e820.map, ARRAY_SIZE(e820.map), &e820.nr_map);
 }
 
@@ -908,6 +984,8 @@ void __init setup_arch(char **cmdline_p)
 
         setup_real_mode();
 
+        trim_platform_memory_ranges();
+
         init_gbpages();
 
         /* max_pfn_mapped is updated here */