linux-kernel - Re: [tip:x86/urgent] x86/Sandy Bridge: reserve pages when integrated graphics is present

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Message-Id: <75F4BEE6-CB0E-4426-B40B-697451677738@googlemail.com>
Date:	Sun, 13 Jan 2013 21:30:52 +0100
From:	Mathias Krause <minipli@...glemail.com>
To:	hpa@...ux.intel.com
Cc:	linux-kernel@...r.kernel.org, mingo@...nel.org, hpa@...or.com,
	tglx@...utronix.de, linux-tip-commits@...r.kernel.org,
	Stéphane Marchesin <marcheu@...omium.org>,
	Jesse Barnes <jbarnes@...tuousgeek.org>
Subject: Re: [tip:x86/urgent] x86/Sandy Bridge:  reserve pages when integrated graphics is present

Hi Peter,

Am 12.01.2013 um 00:00 schrieb Jesse Barnes <jbarnes@...tuousgeek.org>:

> On Fri, 11 Jan 2013 14:39:04 -0800
> tip-bot for Jesse Barnes <jbarnes@...tuousgeek.org> wrote:
> 
>> Commit-ID:  a9acc5365dbda29f7be2884efb63771dc24bd815
>> Gitweb:     http://git.kernel.org/tip/a9acc5365dbda29f7be2884efb63771dc24bd815
>> Author:     Jesse Barnes <jbarnes@...tuousgeek.org>
>> AuthorDate: Wed, 14 Nov 2012 20:43:31 +0000
>> Committer:  H. Peter Anvin <hpa@...ux.intel.com>
>> CommitDate: Fri, 11 Jan 2013 14:26:38 -0800
>> 
>> 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. ]

That stylistic change introduced the unwanted side effect of leaving the tables in memory after __init cleanup. But that can be fixed, see below :)

>> 
>> Signed-off-by: Jesse Barnes <jbarnes@...tuousgeek.org>
>> Signed-off-by: H. Peter Anvin <hpa@...ux.intel.com>
>> ---
>> arch/x86/kernel/setup.c | 78 +++++++++++++++++++++++++++++++++++++++++++++++++
>> 1 file changed, 78 insertions(+)
>> 
>> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
>> index 23ddd55..9dcb325 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[] = {

__initconst is missing here

>> +		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[] = {

here, too

>> +		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 */
>> 


Regards,
Mathias--
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