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Date: Thu, 2 Apr 2015 12:08:41 -0700
From: Andy Lutomirski <luto@...capital.net>
To: axboe@...com, Boaz Harrosh <boaz@...xistor.com>,
Dan Williams <dan.j.williams@...el.com>,
"H. Peter Anvin" <hpa@...or.com>,
Andy Lutomirski <luto@...capital.net>,
Jens Axboe <axboe@...nel.dk>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Thomas Gleixner <tglx@...utronix.de>,
Borislav Petkov <bp@...en8.de>,
Andrew Morton <akpm@...ux-foundation.org>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Christoph Hellwig <hch@....de>,
Ross Zwisler <ross.zwisler@...ux.intel.com>,
Ingo Molnar <mingo@...nel.org>,
Matthew Wilcox <willy@...ux.intel.com>, keith.busch@...el.com
Cc: "linux-tip-commits@...r.kernel.org"
<linux-tip-commits@...r.kernel.org>
Subject: Re: [tip:x86/pmem] x86/mm: Add support for the non-standard protected
e820 type
On Thu, Apr 2, 2015 at 5:31 AM, tip-bot for Christoph Hellwig
<tipbot@...or.com> wrote:
> Commit-ID: ec776ef6bbe1734c29cd6bd05219cd93b2731bd4
> Gitweb: http://git.kernel.org/tip/ec776ef6bbe1734c29cd6bd05219cd93b2731bd4
> Author: Christoph Hellwig <hch@....de>
> AuthorDate: Wed, 1 Apr 2015 09:12:18 +0200
> Committer: Ingo Molnar <mingo@...nel.org>
> CommitDate: Wed, 1 Apr 2015 17:02:43 +0200
>
> x86/mm: Add support for the non-standard protected e820 type
>
> Various recent BIOSes support NVDIMMs or ADR using a
> non-standard e820 memory type, and Intel supplied reference
> Linux code using this type to various vendors.
>
> Wire this e820 table type up to export platform devices for the
> pmem driver so that we can use it in Linux.
This scares me a bit. Do we know that the upcoming ACPI 6.0
enumeration mechanism *won't* use e820 type 12? If it will, what
stops a non-legacy device from being incorrectly claimed as a legacy
device?
--Andy
>
> Based on earlier work from:
>
> Dave Jiang <dave.jiang@...el.com>
> Dan Williams <dan.j.williams@...el.com>
>
> Includes fixes for NUMA regions from Boaz Harrosh.
>
> Tested-by: Ross Zwisler <ross.zwisler@...ux.intel.com>
> Signed-off-by: Christoph Hellwig <hch@....de>
> Acked-by: Dan Williams <dan.j.williams@...el.com>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: Andy Lutomirski <luto@...capital.net>
> Cc: Boaz Harrosh <boaz@...xistor.com>
> Cc: Borislav Petkov <bp@...en8.de>
> Cc: H. Peter Anvin <hpa@...or.com>
> Cc: Jens Axboe <axboe@...com>
> Cc: Jens Axboe <axboe@...nel.dk>
> Cc: Keith Busch <keith.busch@...el.com>
> Cc: Linus Torvalds <torvalds@...ux-foundation.org>
> Cc: Matthew Wilcox <willy@...ux.intel.com>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: linux-nvdimm@...1.01.org
> Link: http://lkml.kernel.org/r/1427872339-6688-2-git-send-email-hch@lst.de
> [ Minor cleanups. ]
> Signed-off-by: Ingo Molnar <mingo@...nel.org>
> ---
> Documentation/kernel-parameters.txt | 6 +++++
> arch/x86/Kconfig | 10 +++++++
> arch/x86/include/uapi/asm/e820.h | 10 +++++++
> arch/x86/kernel/Makefile | 1 +
> arch/x86/kernel/e820.c | 26 +++++++++++++-----
> arch/x86/kernel/pmem.c | 53 +++++++++++++++++++++++++++++++++++++
> 6 files changed, 100 insertions(+), 6 deletions(-)
>
> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
> index bfcb1a6..c87122d 100644
> --- a/Documentation/kernel-parameters.txt
> +++ b/Documentation/kernel-parameters.txt
> @@ -1965,6 +1965,12 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
> or
> memmap=0x10000$0x18690000
>
> + memmap=nn[KMG]!ss[KMG]
> + [KNL,X86] Mark specific memory as protected.
> + Region of memory to be used, from ss to ss+nn.
> + The memory region may be marked as e820 type 12 (0xc)
> + and is NVDIMM or ADR memory.
> +
> memory_corruption_check=0/1 [X86]
> Some BIOSes seem to corrupt the first 64k of
> memory when doing things like suspend/resume.
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index b7d31ca..9e3bcd6 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -1430,6 +1430,16 @@ config ILLEGAL_POINTER_VALUE
>
> source "mm/Kconfig"
>
> +config X86_PMEM_LEGACY
> + bool "Support non-standard NVDIMMs and ADR protected memory"
> + help
> + Treat memory marked using the non-standard e820 type of 12 as used
> + by the Intel Sandy Bridge-EP reference BIOS as protected memory.
> + The kernel will offer these regions to the 'pmem' driver so
> + they can be used for persistent storage.
> +
> + Say Y if unsure.
> +
> config HIGHPTE
> bool "Allocate 3rd-level pagetables from highmem"
> depends on HIGHMEM
> diff --git a/arch/x86/include/uapi/asm/e820.h b/arch/x86/include/uapi/asm/e820.h
> index d993e33..960a8a9 100644
> --- a/arch/x86/include/uapi/asm/e820.h
> +++ b/arch/x86/include/uapi/asm/e820.h
> @@ -33,6 +33,16 @@
> #define E820_NVS 4
> #define E820_UNUSABLE 5
>
> +/*
> + * This is a non-standardized way to represent ADR or NVDIMM regions that
> + * persist over a reboot. The kernel will ignore their special capabilities
> + * unless the CONFIG_X86_PMEM_LEGACY=y option is set.
> + *
> + * ( Note that older platforms also used 6 for the same type of memory,
> + * but newer versions switched to 12 as 6 was assigned differently. Some
> + * time they will learn... )
> + */
> +#define E820_PRAM 12
>
> /*
> * reserved RAM used by kernel itself
> diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
> index cdb1b70..971f18c 100644
> --- a/arch/x86/kernel/Makefile
> +++ b/arch/x86/kernel/Makefile
> @@ -94,6 +94,7 @@ obj-$(CONFIG_KVM_GUEST) += kvm.o kvmclock.o
> obj-$(CONFIG_PARAVIRT) += paravirt.o paravirt_patch_$(BITS).o
> obj-$(CONFIG_PARAVIRT_SPINLOCKS)+= paravirt-spinlocks.o
> obj-$(CONFIG_PARAVIRT_CLOCK) += pvclock.o
> +obj-$(CONFIG_X86_PMEM_LEGACY) += pmem.o
>
> obj-$(CONFIG_PCSPKR_PLATFORM) += pcspeaker.o
>
> diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
> index 46201de..11cc7d5 100644
> --- a/arch/x86/kernel/e820.c
> +++ b/arch/x86/kernel/e820.c
> @@ -149,6 +149,9 @@ static void __init e820_print_type(u32 type)
> case E820_UNUSABLE:
> printk(KERN_CONT "unusable");
> break;
> + case E820_PRAM:
> + printk(KERN_CONT "persistent (type %u)", type);
> + break;
> default:
> printk(KERN_CONT "type %u", type);
> break;
> @@ -343,7 +346,7 @@ int __init sanitize_e820_map(struct e820entry *biosmap, int max_nr_map,
> * continue building up new bios map based on this
> * information
> */
> - if (current_type != last_type) {
> + if (current_type != last_type || current_type == E820_PRAM) {
> if (last_type != 0) {
> new_bios[new_bios_entry].size =
> change_point[chgidx]->addr - last_addr;
> @@ -688,6 +691,7 @@ void __init e820_mark_nosave_regions(unsigned long limit_pfn)
> register_nosave_region(pfn, PFN_UP(ei->addr));
>
> pfn = PFN_DOWN(ei->addr + ei->size);
> +
> if (ei->type != E820_RAM && ei->type != E820_RESERVED_KERN)
> register_nosave_region(PFN_UP(ei->addr), pfn);
>
> @@ -748,7 +752,7 @@ u64 __init early_reserve_e820(u64 size, u64 align)
> /*
> * Find the highest page frame number we have available
> */
> -static unsigned long __init e820_end_pfn(unsigned long limit_pfn, unsigned type)
> +static unsigned long __init e820_end_pfn(unsigned long limit_pfn)
> {
> int i;
> unsigned long last_pfn = 0;
> @@ -759,7 +763,11 @@ static unsigned long __init e820_end_pfn(unsigned long limit_pfn, unsigned type)
> unsigned long start_pfn;
> unsigned long end_pfn;
>
> - if (ei->type != type)
> + /*
> + * Persistent memory is accounted as ram for purposes of
> + * establishing max_pfn and mem_map.
> + */
> + if (ei->type != E820_RAM && ei->type != E820_PRAM)
> continue;
>
> start_pfn = ei->addr >> PAGE_SHIFT;
> @@ -784,12 +792,12 @@ static unsigned long __init e820_end_pfn(unsigned long limit_pfn, unsigned type)
> }
> unsigned long __init e820_end_of_ram_pfn(void)
> {
> - return e820_end_pfn(MAX_ARCH_PFN, E820_RAM);
> + return e820_end_pfn(MAX_ARCH_PFN);
> }
>
> unsigned long __init e820_end_of_low_ram_pfn(void)
> {
> - return e820_end_pfn(1UL<<(32 - PAGE_SHIFT), E820_RAM);
> + return e820_end_pfn(1UL << (32-PAGE_SHIFT));
> }
>
> static void early_panic(char *msg)
> @@ -866,6 +874,9 @@ static int __init parse_memmap_one(char *p)
> } else if (*p == '$') {
> start_at = memparse(p+1, &p);
> e820_add_region(start_at, mem_size, E820_RESERVED);
> + } else if (*p == '!') {
> + start_at = memparse(p+1, &p);
> + e820_add_region(start_at, mem_size, E820_PRAM);
> } else
> e820_remove_range(mem_size, ULLONG_MAX - mem_size, E820_RAM, 1);
>
> @@ -907,6 +918,7 @@ static inline const char *e820_type_to_string(int e820_type)
> case E820_ACPI: return "ACPI Tables";
> case E820_NVS: return "ACPI Non-volatile Storage";
> case E820_UNUSABLE: return "Unusable memory";
> + case E820_PRAM: return "Persistent RAM";
> default: return "reserved";
> }
> }
> @@ -940,7 +952,9 @@ void __init e820_reserve_resources(void)
> * pci device BAR resource and insert them later in
> * pcibios_resource_survey()
> */
> - if (e820.map[i].type != E820_RESERVED || res->start < (1ULL<<20)) {
> + if (((e820.map[i].type != E820_RESERVED) &&
> + (e820.map[i].type != E820_PRAM)) ||
> + res->start < (1ULL<<20)) {
> res->flags |= IORESOURCE_BUSY;
> insert_resource(&iomem_resource, res);
> }
> diff --git a/arch/x86/kernel/pmem.c b/arch/x86/kernel/pmem.c
> new file mode 100644
> index 0000000..3420c87
> --- /dev/null
> +++ b/arch/x86/kernel/pmem.c
> @@ -0,0 +1,53 @@
> +/*
> + * Copyright (c) 2015, Christoph Hellwig.
> + */
> +#include <linux/memblock.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +#include <asm/e820.h>
> +#include <asm/page_types.h>
> +#include <asm/setup.h>
> +
> +static __init void register_pmem_device(struct resource *res)
> +{
> + struct platform_device *pdev;
> + int error;
> +
> + pdev = platform_device_alloc("pmem", PLATFORM_DEVID_AUTO);
> + if (!pdev)
> + return;
> +
> + error = platform_device_add_resources(pdev, res, 1);
> + if (error)
> + goto out_put_pdev;
> +
> + error = platform_device_add(pdev);
> + if (error)
> + goto out_put_pdev;
> + return;
> +
> +out_put_pdev:
> + dev_warn(&pdev->dev, "failed to add 'pmem' (persistent memory) device!\n");
> + platform_device_put(pdev);
> +}
> +
> +static __init int register_pmem_devices(void)
> +{
> + int i;
> +
> + for (i = 0; i < e820.nr_map; i++) {
> + struct e820entry *ei = &e820.map[i];
> +
> + if (ei->type == E820_PRAM) {
> + struct resource res = {
> + .flags = IORESOURCE_MEM,
> + .start = ei->addr,
> + .end = ei->addr + ei->size - 1,
> + };
> + register_pmem_device(&res);
> + }
> + }
> +
> + return 0;
> +}
> +device_initcall(register_pmem_devices);
--
Andy Lutomirski
AMA Capital Management, LLC
--
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