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Subject[ 109/128] x86/Sandy Bridge: reserve pages when integrated graphics is present
3.2-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jesse Barnes <jbarnes@virtuousgeek.org>

commit a9acc5365dbda29f7be2884efb63771dc24bd815 upstream.

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>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
arch/x86/kernel/setup.c | 78 +++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 78 insertions(+)

--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -631,6 +631,81 @@ static __init void reserve_ibft_region(v

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)
{
/*
@@ -651,6 +726,7 @@ 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);
}

@@ -930,6 +1006,8 @@ void __init setup_arch(char **cmdline_p)

setup_trampolines();

+ trim_platform_memory_ranges();
+
init_gbpages();

/* max_pfn_mapped is updated here */



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