Re: [PATCH 1/1] x86, e820: Remove direct mapping of reserved space for HT hole around 1TB

[Andreas Herrmann <herrmann.der.user@googlemail.com>]

CC-ing Yinghai Lu <yinghai.lu@oracle.com> as yinghai@kernel.org still
doesn't seem to work.


Andreas

On Tue, Oct 11, 2011 at 05:09:35PM -0500, Jacob Shin wrote:
> The entire HT hole and also the unused address range before that hole
> need to be excluded from direct mapping. Otherwise speculative
> accesses to that reserved region can happen which cause machine
> checks.
> 
> Cc: stable@kernel.org   # > 2.6.32
> Signed-off-by: Jacob Shin <jacob.shin@amd.com>
> ---
>  arch/x86/include/asm/e820.h           |    1 +
>  arch/x86/include/asm/hypertransport.h |    7 +++++
>  arch/x86/include/asm/processor.h      |   16 +++++++++++++
>  arch/x86/kernel/cpu/amd.c             |   40 +++++++++++++++++++++++++++++++++
>  arch/x86/kernel/e820.c                |    6 +++++
>  arch/x86/kernel/setup.c               |    8 +++++-
>  6 files changed, 76 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/include/asm/e820.h b/arch/x86/include/asm/e820.h
> index 908b969..7e4d417 100644
> --- a/arch/x86/include/asm/e820.h
> +++ b/arch/x86/include/asm/e820.h
> @@ -117,6 +117,7 @@ static inline void early_memtest(unsigned long start, unsigned long end)
>  
>  extern unsigned long e820_end_of_ram_pfn(void);
>  extern unsigned long e820_end_of_low_ram_pfn(void);
> +extern unsigned long e820_end_of_ram_under_ht_pfn(void);
>  extern u64 early_reserve_e820(u64 startt, u64 sizet, u64 align);
>  
>  void memblock_x86_fill(void);
> diff --git a/arch/x86/include/asm/hypertransport.h b/arch/x86/include/asm/hypertransport.h
> index 334b1a8..c1d5a08 100644
> --- a/arch/x86/include/asm/hypertransport.h
> +++ b/arch/x86/include/asm/hypertransport.h
> @@ -42,4 +42,11 @@
>  #define HT_IRQ_HIGH_DEST_ID(v)						\
>  	((((v) >> 8) << HT_IRQ_HIGH_DEST_ID_SHIFT) & HT_IRQ_HIGH_DEST_ID_MASK)
>  
> +/*
> + * Memory Region Reserved for HyperTransport
> + */
> +
> +#define HT_RESERVED_MEM_START           0xfd00000000ULL
> +#define HT_RESERVED_MEM_END             0x10000000000ULL
> +
>  #endif /* _ASM_X86_HYPERTRANSPORT_H */
> diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
> index 0d1171c..73ae54f 100644
> --- a/arch/x86/include/asm/processor.h
> +++ b/arch/x86/include/asm/processor.h
> @@ -970,6 +970,22 @@ extern int set_tsc_mode(unsigned int val);
>  
>  extern int amd_get_nb_id(int cpu);
>  
> +#if defined(CONFIG_CPU_SUP_AMD) && defined(CONFIG_X86_64)
> +extern int amd_with_ram_above_ht(void);
> +extern unsigned long amd_init_high_memory_mapping(void);
> +#else
> +static inline int amd_with_ram_above_ht(void)
> +{
> +	return 0;
> +}
> +
> +static inline unsigned long amd_init_high_memory_mapping(void)
> +{
> +	BUG();
> +	return 0;
> +}
> +#endif
> +
>  struct aperfmperf {
>  	u64 aperf, mperf;
>  };
> diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
> index b13ed39..a57b010 100644
> --- a/arch/x86/kernel/cpu/amd.c
> +++ b/arch/x86/kernel/cpu/amd.c
> @@ -7,6 +7,7 @@
>  #include <asm/apic.h>
>  #include <asm/cpu.h>
>  #include <asm/pci-direct.h>
> +#include <asm/hypertransport.h>
>  
>  #ifdef CONFIG_X86_64
>  # include <asm/numa_64.h>
> @@ -755,3 +756,42 @@ bool cpu_has_amd_erratum(const int *erratum)
>  }
>  
>  EXPORT_SYMBOL_GPL(cpu_has_amd_erratum);
> +
> +#if defined(CONFIG_CPU_SUP_AMD) && defined(CONFIG_X86_64)
> +int __cpuinit amd_with_ram_above_ht(void)
> +{
> +	if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD &&
> +	    max_pfn << PAGE_SHIFT >= HT_RESERVED_MEM_START)
> +		return 1;
> +
> +	return 0;
> +}
> +
> +/*
> + * On AMD systems, memory region 0xfd_0000_0000 ~ 0xff_ffff_ffff is reserved by
> + * HyperTransport and cannot be used by the processor. On systems with more than
> + * 1TB of RAM, BIOS may take memory immediately below the HT region and "hoist"
> + * it up above the HT region, leaving a hole.
> + */
> +unsigned long __cpuinit amd_init_high_memory_mapping(void)
> +{
> +	unsigned long ret;
> +
> +	/* remove HT region from the e820 map, if it's declared as usable */
> +	e820_remove_range(HT_RESERVED_MEM_START,
> +			  HT_RESERVED_MEM_END - HT_RESERVED_MEM_START,
> +			  E820_RAM, 1);
> +	sanitize_e820_map(e820.map, ARRAY_SIZE(e820.map), &e820.nr_map);
> +
> +	/* direct mapping of high memory under HT */
> +	ret = init_memory_mapping(1UL << 32,
> +		e820_end_of_ram_under_ht_pfn() << PAGE_SHIFT);
> +
> +	/* skip HT region, direct mapping of high memory above HT */
> +	if (max_pfn << PAGE_SHIFT >= HT_RESERVED_MEM_END)
> +		ret = init_memory_mapping(HT_RESERVED_MEM_END,
> +					  max_pfn << PAGE_SHIFT);
> +
> +	return ret;
> +}
> +#endif
> diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
> index 3e2ef84..c0ba036 100644
> --- a/arch/x86/kernel/e820.c
> +++ b/arch/x86/kernel/e820.c
> @@ -22,6 +22,7 @@
>  #include <asm/e820.h>
>  #include <asm/proto.h>
>  #include <asm/setup.h>
> +#include <asm/hypertransport.h>
>  
>  /*
>   * The e820 map is the map that gets modified e.g. with command line parameters
> @@ -826,6 +827,11 @@ unsigned long __init e820_end_of_low_ram_pfn(void)
>  	return e820_end_pfn(1UL<<(32 - PAGE_SHIFT), E820_RAM);
>  }
>  
> +unsigned long __init e820_end_of_ram_under_ht_pfn(void)
> +{
> +	return e820_end_pfn(HT_RESERVED_MEM_START >> PAGE_SHIFT, E820_RAM);
> +}
> +
>  static void early_panic(char *msg)
>  {
>  	early_printk(msg);
> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> index afaf384..84d0968 100644
> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -937,8 +937,12 @@ void __init setup_arch(char **cmdline_p)
>  
>  #ifdef CONFIG_X86_64
>  	if (max_pfn > max_low_pfn) {
> -		max_pfn_mapped = init_memory_mapping(1UL<<32,
> -						     max_pfn<<PAGE_SHIFT);
> +		if (amd_with_ram_above_ht())
> +			max_pfn_mapped = amd_init_high_memory_mapping();
> +		else
> +			max_pfn_mapped = init_memory_mapping(1UL << 32,
> +				max_pfn << PAGE_SHIFT);
> +
>  		/* can we preseve max_low_pfn ?*/
>  		max_low_pfn = max_pfn;
>  	}
> -- 
> 1.7.1
> 
> 
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