| Message ID | 20180706082911.13405-2-aneesh.kumar@linux.ibm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 07/06/18 01:29, Aneesh Kumar K.V wrote: > This patch steal system RAM and use that to emulate pmem device using the > e820 platform driver. > > This adds a new kernel command line 'pmemmap' which takes the format <size[KMG]> > to allocate memory early in the boot. This memory is later registered as > persistent memory range. > > Based on original patch from Oliver OHalloran <oliveroh@au1.ibm.com> > > Not-Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> > --- > drivers/nvdimm/Kconfig | 13 ++++ > drivers/nvdimm/Makefile | 1 + > drivers/nvdimm/memblockpmem.c | 115 ++++++++++++++++++++++++++++++++++ > 3 files changed, 129 insertions(+) > create mode 100644 drivers/nvdimm/memblockpmem.c > > diff --git a/drivers/nvdimm/Kconfig b/drivers/nvdimm/Kconfig > index 50d2a33de441..cbbbcbd4506b 100644 > --- a/drivers/nvdimm/Kconfig > +++ b/drivers/nvdimm/Kconfig > @@ -115,4 +115,17 @@ config OF_PMEM > config PMEM_PLATFORM_DEVICE > bool > > +config MEMBLOCK_PMEM > + bool "pmemmap= parameter support" > + default y > + depends on HAVE_MEMBLOCK > + select PMEM_PLATFORM_DEVICE > + help > + Add support for the pmemmap= kernel command line parameter. This is similar > + to the memmap= parameter available on ACPI platforms, but it uses generic > + kernel facilities (the memblock allocator) to reserve memory rather than adding > + to the e820 table. > + > + Select Y if unsure. > + > endif There's a high barrier for "default y", something like if the platform or device cannot boot without it, it can be "default y". I have doubts that this is OK.
On Fri, Jul 6, 2018 at 1:29 AM, Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> wrote: > This patch steal system RAM and use that to emulate pmem device using the > e820 platform driver. > > This adds a new kernel command line 'pmemmap' which takes the format <size[KMG]> > to allocate memory early in the boot. This memory is later registered as > persistent memory range. > > Based on original patch from Oliver OHalloran <oliveroh@au1.ibm.com> > > Not-Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> > --- > drivers/nvdimm/Kconfig | 13 ++++ > drivers/nvdimm/Makefile | 1 + > drivers/nvdimm/memblockpmem.c | 115 ++++++++++++++++++++++++++++++++++ > 3 files changed, 129 insertions(+) > create mode 100644 drivers/nvdimm/memblockpmem.c > [..] > +/* > + * pmemmap=ss[KMG] > + * > + * This is similar to the memremap=offset[KMG]!size[KMG] paramater > + * for adding a legacy pmem range to the e820 map on x86, but it's > + * platform agnostic. The current memmap=ss!nn option is a non-stop source of bugs and fragility. The fact that this lets the kernel specify the base address helps, but then this is purely just a debug facility because memmap=ss!nn is there to cover platform firmware implementations that fail to mark a given address range as persistent. If this is just for debug, why not use qemu? If this is not for debug what are these systems that don't have proper firmware support?
On Sat, Jul 7, 2018 at 5:38 AM, Dan Williams <dan.j.williams@intel.com> wrote: > On Fri, Jul 6, 2018 at 1:29 AM, Aneesh Kumar K.V > <aneesh.kumar@linux.ibm.com> wrote: >> This patch steal system RAM and use that to emulate pmem device using the >> e820 platform driver. >> >> This adds a new kernel command line 'pmemmap' which takes the format <size[KMG]> >> to allocate memory early in the boot. This memory is later registered as >> persistent memory range. >> >> Based on original patch from Oliver OHalloran <oliveroh@au1.ibm.com> >> >> Not-Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> >> --- >> drivers/nvdimm/Kconfig | 13 ++++ >> drivers/nvdimm/Makefile | 1 + >> drivers/nvdimm/memblockpmem.c | 115 ++++++++++++++++++++++++++++++++++ >> 3 files changed, 129 insertions(+) >> create mode 100644 drivers/nvdimm/memblockpmem.c >> > [..] >> +/* >> + * pmemmap=ss[KMG] >> + * >> + * This is similar to the memremap=offset[KMG]!size[KMG] paramater >> + * for adding a legacy pmem range to the e820 map on x86, but it's >> + * platform agnostic. > The current memmap=ss!nn option is a non-stop source of bugs and > fragility. The fact that this lets the kernel specify the base address > helps, but then this is purely just a debug facility because > memmap=ss!nn is there to cover platform firmware implementations that > fail to mark a given address range as persistent. > If this is just for debug, why not use qemu? To make a long story short, we have two virtualisation stacks and only one of them is based on qemu. An unfortunately large chunk of our customers (and our internal test systems) run the other one so we need to accommodate them somehow. > If this is not for debug what are these systems that don't have proper firmware > support? I wrote the original version (for RHEL 7.something) for a customer who wanted to do some testing which needed to be run on real hardware for some reason. We couldn't install a FW update on their system so this ended up being the least painful way to get them going. That's not a strong argument for merging this, but the point is that it's sometimes useful to have the capability in the kernel. Oliver
On Fri, Jul 6, 2018 at 6:29 PM, Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> wrote: > This patch steal system RAM and use that to emulate pmem device using the > e820 platform driver. > > This adds a new kernel command line 'pmemmap' which takes the format <size[KMG]> > to allocate memory early in the boot. This memory is later registered as > persistent memory range. > > Based on original patch from Oliver OHalloran <oliveroh@au1.ibm.com> I use this account rather than my internal address for community facing stuff since no one deserves to have IBM email inflicted upon them. Also you left out the apostrophe, you monster! > Not-Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> > --- > drivers/nvdimm/Kconfig | 13 ++++ > drivers/nvdimm/Makefile | 1 + > drivers/nvdimm/memblockpmem.c | 115 ++++++++++++++++++++++++++++++++++ > 3 files changed, 129 insertions(+) > create mode 100644 drivers/nvdimm/memblockpmem.c > > diff --git a/drivers/nvdimm/Kconfig b/drivers/nvdimm/Kconfig > index 50d2a33de441..cbbbcbd4506b 100644 > --- a/drivers/nvdimm/Kconfig > +++ b/drivers/nvdimm/Kconfig > @@ -115,4 +115,17 @@ config OF_PMEM > config PMEM_PLATFORM_DEVICE > bool > > +config MEMBLOCK_PMEM > + bool "pmemmap= parameter support" > + default y > + depends on HAVE_MEMBLOCK > + select PMEM_PLATFORM_DEVICE > + help > + Add support for the pmemmap= kernel command line parameter. This is similar > + to the memmap= parameter available on ACPI platforms, but it uses generic > + kernel facilities (the memblock allocator) to reserve memory rather than adding > + to the e820 table. > + > + Select Y if unsure. > + > endif > diff --git a/drivers/nvdimm/Makefile b/drivers/nvdimm/Makefile > index 94f7f29146ce..0215ce0182e9 100644 > --- a/drivers/nvdimm/Makefile > +++ b/drivers/nvdimm/Makefile > @@ -5,6 +5,7 @@ obj-$(CONFIG_ND_BTT) += nd_btt.o > obj-$(CONFIG_ND_BLK) += nd_blk.o > obj-$(CONFIG_PMEM_PLATFORM_DEVICE) += nd_e820.o > obj-$(CONFIG_OF_PMEM) += of_pmem.o > +obj-$(CONFIG_MEMBLOCK_PMEM) += memblockpmem.o Does this work when libnvdimm is built as a module? I remember doing something like this and discovering that the early_param() stuff didn't get included in the vmlinux when libnvdimm was built as a module due to how the makefiles worked. It might have been a bug in the RHEL7 tree I was using that has since been fixed upstream. > nd_pmem-y := pmem.o > > diff --git a/drivers/nvdimm/memblockpmem.c b/drivers/nvdimm/memblockpmem.c > new file mode 100644 > index 000000000000..d39772b75fcd > --- /dev/null > +++ b/drivers/nvdimm/memblockpmem.c > @@ -0,0 +1,115 @@ > +// SPDX-License-Identifier: GPL-2.0+ > +/* > + * Copyright (c) 2018 IBM Corporation > + */ > + > +#define pr_fmt(fmt) "memblock pmem: " fmt > + > +#include <linux/libnvdimm.h> > +#include <linux/bootmem.h> > +#include <linux/memblock.h> > +#include <linux/mmzone.h> > +#include <linux/cpu.h> > +#include <linux/platform_device.h> > +#include <linux/init.h> > +#include <linux/ioport.h> > +#include <linux/ctype.h> > +#include <linux/slab.h> > + > +/* > + * Align pmem reservations to the section size so we don't have issues with > + * memory hotplug > + */ > +#ifdef CONFIG_SPARSEMEM > +#define BOOTPMEM_ALIGN (1UL << SECTION_SIZE_BITS) > +#else > +#define BOOTPMEM_ALIGN PFN_DEFAULT_ALIGNMENT > +#endif Is aligning to the section size sufficient? IIRC I had to align it to the memory block size on some systems. Of course, that might have been a RHEL bug that has since been fixed upstream. > + > +static __initdata u64 pmem_size; > +static __initdata phys_addr_t pmem_stolen_memory; > + > +static void alloc_pmem_from_memblock(void) > +{ > + > + pmem_stolen_memory = memblock_alloc_base(pmem_size, > + BOOTPMEM_ALIGN, > + MEMBLOCK_ALLOC_ACCESSIBLE); > + if (!pmem_stolen_memory) { > + pr_err("Failed to allocate memory for PMEM from memblock\n"); > + return; > + } > + > + /* > + * Remove from the memblock reserved range > + */ > + memblock_free(pmem_stolen_memory, pmem_size); > + > + /* > + * Remove from the memblock memory range. > + */ > + memblock_remove(pmem_stolen_memory, pmem_size); > + pr_info("Allocated %ld memory at 0x%lx\n", (unsigned long)pmem_size, > + (unsigned long)pmem_stolen_memory); > + return; > +} > + > +/* > + * pmemmap=ss[KMG] > + * > + * This is similar to the memremap=offset[KMG]!size[KMG] paramater > + * for adding a legacy pmem range to the e820 map on x86, but it's > + * platform agnostic. > + * > + * e.g. pmemmap=16G allocates 16G pmem region I'm not really thrilled with this and I'd rather we kept the <size>@<node id> format and the ability to reserve multiple regions that I had in the old version. I know getting the nid allocations working is a pain in the ass since HAVE_MEMBLOCK_NODE_MAP doesn't specify *when* in the boot process the node map information is actually available, but it's useful functionality and I think the problems are resolvable. It's also possible that the whole memblock approach to this is wrong and we should look at doing something similar to how gigantic pages are allocated at runtime. > + */ > +static int __init parse_pmemmap(char *p) > +{ > + char *old_p = p; > + > + if (!p) > + return -EINVAL; > + > + pmem_size = memparse(p, &p); > + if (p == old_p) > + return -EINVAL; > + > + alloc_pmem_from_memblock(); > + return 0; > +} > +early_param("pmemmap", parse_pmemmap); > + > +static __init int register_e820_pmem(void) > +{ > + struct resource *res, *conflict; > + struct platform_device *pdev; > + > + if (!pmem_stolen_memory) > + return 0; > + > + res = kzalloc(sizeof(*res), GFP_KERNEL); > + if (!res) > + return -1; > + > + memset(res, 0, sizeof(*res)); > + res->start = pmem_stolen_memory; > + res->end = pmem_stolen_memory + pmem_size - 1; > + res->name = "Persistent Memory (legacy)"; > + res->desc = IORES_DESC_PERSISTENT_MEMORY_LEGACY; > + res->flags = IORESOURCE_MEM; > + > + conflict = insert_resource_conflict(&iomem_resource, res); > + if (conflict) { > + pr_err("%pR conflicts, try insert below %pR\n", res, conflict); > + kfree(res); > + return -1; > + } > + /* > + * See drivers/nvdimm/e820.c for the implementation, this is > + * simply here to trigger the module to load on demand. > + */ > + pdev = platform_device_alloc("e820_pmem", -1); > + > + return platform_device_add(pdev); > +} > +device_initcall(register_e820_pmem); > -- > 2.17.1 >
On Sat, Jul 7, 2018 at 12:15 AM, Oliver <oohall@gmail.com> wrote: > On Sat, Jul 7, 2018 at 5:38 AM, Dan Williams <dan.j.williams@intel.com> wrote: >> On Fri, Jul 6, 2018 at 1:29 AM, Aneesh Kumar K.V >> <aneesh.kumar@linux.ibm.com> wrote: >>> This patch steal system RAM and use that to emulate pmem device using the >>> e820 platform driver. >>> >>> This adds a new kernel command line 'pmemmap' which takes the format <size[KMG]> >>> to allocate memory early in the boot. This memory is later registered as >>> persistent memory range. >>> >>> Based on original patch from Oliver OHalloran <oliveroh@au1.ibm.com> >>> >>> Not-Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> >>> --- >>> drivers/nvdimm/Kconfig | 13 ++++ >>> drivers/nvdimm/Makefile | 1 + >>> drivers/nvdimm/memblockpmem.c | 115 ++++++++++++++++++++++++++++++++++ >>> 3 files changed, 129 insertions(+) >>> create mode 100644 drivers/nvdimm/memblockpmem.c >>> >> [..] >>> +/* >>> + * pmemmap=ss[KMG] >>> + * >>> + * This is similar to the memremap=offset[KMG]!size[KMG] paramater >>> + * for adding a legacy pmem range to the e820 map on x86, but it's >>> + * platform agnostic. > >> The current memmap=ss!nn option is a non-stop source of bugs and >> fragility. The fact that this lets the kernel specify the base address >> helps, but then this is purely just a debug facility because >> memmap=ss!nn is there to cover platform firmware implementations that >> fail to mark a given address range as persistent. > >> If this is just for debug, why not use qemu? > > To make a long story short, we have two virtualisation stacks and only one of > them is based on qemu. An unfortunately large chunk of our customers (and > our internal test systems) run the other one so we need to accommodate them > somehow. > >> If this is not for debug what are these systems that don't have proper firmware >> support? > > I wrote the original version (for RHEL 7.something) for a customer who wanted > to do some testing which needed to be run on real hardware for some reason. > We couldn't install a FW update on their system so this ended up being the least > painful way to get them going. That's not a strong argument for > merging this, but > the point is that it's sometimes useful to have the capability in the kernel. Ok, correct me if I'm wrong, but it seems to be purely about debug and emulation? If that's the case would it be acceptable to just add more capabilities to tools/testing/nvdimm/ for what you want to do? That has been our primary vehicle for testing libnvdimm.
On 07/07/2018 01:20 PM, Oliver wrote: > On Fri, Jul 6, 2018 at 6:29 PM, Aneesh Kumar K.V > <aneesh.kumar@linux.ibm.com> wrote: >> This patch steal system RAM and use that to emulate pmem device using the >> e820 platform driver. >> >> This adds a new kernel command line 'pmemmap' which takes the format <size[KMG]> >> to allocate memory early in the boot. This memory is later registered as >> persistent memory range. >> >> Based on original patch from Oliver OHalloran <oliveroh@au1.ibm.com> > > I use this account rather than my internal address for community > facing stuff since > no one deserves to have IBM email inflicted upon them. Also you left out the > apostrophe, you monster! :) Will switch to gmail.com address? > >> Not-Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> >> --- >> drivers/nvdimm/Kconfig | 13 ++++ >> drivers/nvdimm/Makefile | 1 + >> drivers/nvdimm/memblockpmem.c | 115 ++++++++++++++++++++++++++++++++++ >> 3 files changed, 129 insertions(+) >> create mode 100644 drivers/nvdimm/memblockpmem.c >> >> diff --git a/drivers/nvdimm/Kconfig b/drivers/nvdimm/Kconfig >> index 50d2a33de441..cbbbcbd4506b 100644 >> --- a/drivers/nvdimm/Kconfig >> +++ b/drivers/nvdimm/Kconfig >> @@ -115,4 +115,17 @@ config OF_PMEM >> config PMEM_PLATFORM_DEVICE >> bool >> >> +config MEMBLOCK_PMEM >> + bool "pmemmap= parameter support" >> + default y >> + depends on HAVE_MEMBLOCK >> + select PMEM_PLATFORM_DEVICE >> + help >> + Add support for the pmemmap= kernel command line parameter. This is similar >> + to the memmap= parameter available on ACPI platforms, but it uses generic >> + kernel facilities (the memblock allocator) to reserve memory rather than adding >> + to the e820 table. >> + >> + Select Y if unsure. >> + >> endif >> diff --git a/drivers/nvdimm/Makefile b/drivers/nvdimm/Makefile >> index 94f7f29146ce..0215ce0182e9 100644 >> --- a/drivers/nvdimm/Makefile >> +++ b/drivers/nvdimm/Makefile >> @@ -5,6 +5,7 @@ obj-$(CONFIG_ND_BTT) += nd_btt.o >> obj-$(CONFIG_ND_BLK) += nd_blk.o >> obj-$(CONFIG_PMEM_PLATFORM_DEVICE) += nd_e820.o >> obj-$(CONFIG_OF_PMEM) += of_pmem.o >> +obj-$(CONFIG_MEMBLOCK_PMEM) += memblockpmem.o > > Does this work when libnvdimm is built as a module? I remember doing > something like > this and discovering that the early_param() stuff didn't get included > in the vmlinux > when libnvdimm was built as a module due to how the makefiles worked. > It might have > been a bug in the RHEL7 tree I was using that has since been fixed upstream. > I didn't check that. Will do that in next iteration. >> nd_pmem-y := pmem.o >> >> diff --git a/drivers/nvdimm/memblockpmem.c b/drivers/nvdimm/memblockpmem.c >> new file mode 100644 >> index 000000000000..d39772b75fcd >> --- /dev/null >> +++ b/drivers/nvdimm/memblockpmem.c >> @@ -0,0 +1,115 @@ >> +// SPDX-License-Identifier: GPL-2.0+ >> +/* >> + * Copyright (c) 2018 IBM Corporation >> + */ >> + >> +#define pr_fmt(fmt) "memblock pmem: " fmt >> + >> +#include <linux/libnvdimm.h> >> +#include <linux/bootmem.h> >> +#include <linux/memblock.h> >> +#include <linux/mmzone.h> >> +#include <linux/cpu.h> >> +#include <linux/platform_device.h> >> +#include <linux/init.h> >> +#include <linux/ioport.h> >> +#include <linux/ctype.h> >> +#include <linux/slab.h> >> + >> +/* >> + * Align pmem reservations to the section size so we don't have issues with >> + * memory hotplug >> + */ >> +#ifdef CONFIG_SPARSEMEM >> +#define BOOTPMEM_ALIGN (1UL << SECTION_SIZE_BITS) >> +#else >> +#define BOOTPMEM_ALIGN PFN_DEFAULT_ALIGNMENT >> +#endif > > Is aligning to the section size sufficient? IIRC I had to align it to > the memory block > size on some systems. Of course, that might have been a RHEL bug that has > since been fixed upstream. > Ok, I didn't face any issues. But will look more what issues we could face. >> + >> +static __initdata u64 pmem_size; >> +static __initdata phys_addr_t pmem_stolen_memory; >> + >> +static void alloc_pmem_from_memblock(void) >> +{ >> + >> + pmem_stolen_memory = memblock_alloc_base(pmem_size, >> + BOOTPMEM_ALIGN, >> + MEMBLOCK_ALLOC_ACCESSIBLE); >> + if (!pmem_stolen_memory) { >> + pr_err("Failed to allocate memory for PMEM from memblock\n"); >> + return; >> + } >> + >> + /* >> + * Remove from the memblock reserved range >> + */ >> + memblock_free(pmem_stolen_memory, pmem_size); >> + >> + /* >> + * Remove from the memblock memory range. >> + */ >> + memblock_remove(pmem_stolen_memory, pmem_size); >> + pr_info("Allocated %ld memory at 0x%lx\n", (unsigned long)pmem_size, >> + (unsigned long)pmem_stolen_memory); >> + return; >> +} >> + >> +/* >> + * pmemmap=ss[KMG] >> + * >> + * This is similar to the memremap=offset[KMG]!size[KMG] paramater >> + * for adding a legacy pmem range to the e820 map on x86, but it's >> + * platform agnostic. >> + * >> + * e.g. pmemmap=16G allocates 16G pmem region > > I'm not really thrilled with this and I'd rather we kept the <size>@<node id> > format and the ability to reserve multiple regions that I had in the > old version. > > I know getting the nid allocations working is a pain in the ass since > HAVE_MEMBLOCK_NODE_MAP doesn't specify *when* in the boot process > the node map information is actually available, but it's useful > functionality and > I think the problems are resolvable. > The reason I dropped the @nid is because, we do set node details in memblock late (memblock_set_node()). We setup our linear mapped page table before that. That implies, we can't steal memory from memblock and use that for pmem backing if we do the pmem backing allocation after node information is set on memblock. Since we can't use nid, I was not sure there is any value in doing multiple pmem region. > It's also possible that the whole memblock approach to this is wrong and we > should look at doing something similar to how gigantic pages are allocated > at runtime. > >> + */ >> +static int __init parse_pmemmap(char *p) >> +{ >> + char *old_p = p; >> + >> + if (!p) >> + return -EINVAL; >> + >> + pmem_size = memparse(p, &p); >> + if (p == old_p) >> + return -EINVAL; >> + >> + alloc_pmem_from_memblock(); >> + return 0; >> +} >> +early_param("pmemmap", parse_pmemmap); >> + >> +static __init int register_e820_pmem(void) >> +{ >> + struct resource *res, *conflict; >> + struct platform_device *pdev; >> + >> + if (!pmem_stolen_memory) >> + return 0; >> + >> + res = kzalloc(sizeof(*res), GFP_KERNEL); >> + if (!res) >> + return -1; >> + >> + memset(res, 0, sizeof(*res)); >> + res->start = pmem_stolen_memory; >> + res->end = pmem_stolen_memory + pmem_size - 1; >> + res->name = "Persistent Memory (legacy)"; >> + res->desc = IORES_DESC_PERSISTENT_MEMORY_LEGACY; >> + res->flags = IORESOURCE_MEM; >> + >> + conflict = insert_resource_conflict(&iomem_resource, res); >> + if (conflict) { >> + pr_err("%pR conflicts, try insert below %pR\n", res, conflict); >> + kfree(res); >> + return -1; >> + } >> + /* >> + * See drivers/nvdimm/e820.c for the implementation, this is >> + * simply here to trigger the module to load on demand. >> + */ >> + pdev = platform_device_alloc("e820_pmem", -1); >> + >> + return platform_device_add(pdev); >> +} >> +device_initcall(register_e820_pmem); >> -- -aneesh
On 07/07/2018 11:06 PM, Dan Williams wrote: > On Sat, Jul 7, 2018 at 12:15 AM, Oliver <oohall@gmail.com> wrote: >> On Sat, Jul 7, 2018 at 5:38 AM, Dan Williams <dan.j.williams@intel.com> wrote: >>> On Fri, Jul 6, 2018 at 1:29 AM, Aneesh Kumar K.V >>> <aneesh.kumar@linux.ibm.com> wrote: >>>> This patch steal system RAM and use that to emulate pmem device using the >>>> e820 platform driver. >>>> >>>> This adds a new kernel command line 'pmemmap' which takes the format <size[KMG]> >>>> to allocate memory early in the boot. This memory is later registered as >>>> persistent memory range. >>>> >>>> Based on original patch from Oliver OHalloran <oliveroh@au1.ibm.com> >>>> >>>> Not-Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> >>>> --- >>>> drivers/nvdimm/Kconfig | 13 ++++ >>>> drivers/nvdimm/Makefile | 1 + >>>> drivers/nvdimm/memblockpmem.c | 115 ++++++++++++++++++++++++++++++++++ >>>> 3 files changed, 129 insertions(+) >>>> create mode 100644 drivers/nvdimm/memblockpmem.c >>>> >>> [..] >>>> +/* >>>> + * pmemmap=ss[KMG] >>>> + * >>>> + * This is similar to the memremap=offset[KMG]!size[KMG] paramater >>>> + * for adding a legacy pmem range to the e820 map on x86, but it's >>>> + * platform agnostic. >> >>> The current memmap=ss!nn option is a non-stop source of bugs and >>> fragility. The fact that this lets the kernel specify the base address >>> helps, but then this is purely just a debug facility because >>> memmap=ss!nn is there to cover platform firmware implementations that >>> fail to mark a given address range as persistent. >> >>> If this is just for debug, why not use qemu? >> >> To make a long story short, we have two virtualisation stacks and only one of >> them is based on qemu. An unfortunately large chunk of our customers (and >> our internal test systems) run the other one so we need to accommodate them >> somehow. >> >>> If this is not for debug what are these systems that don't have proper firmware >>> support? >> >> I wrote the original version (for RHEL 7.something) for a customer who wanted >> to do some testing which needed to be run on real hardware for some reason. >> We couldn't install a FW update on their system so this ended up being the least >> painful way to get them going. That's not a strong argument for >> merging this, but >> the point is that it's sometimes useful to have the capability in the kernel. > > Ok, correct me if I'm wrong, but it seems to be purely about debug and > emulation? If that's the case would it be acceptable to just add more > capabilities to tools/testing/nvdimm/ for what you want to do? That > has been our primary vehicle for testing libnvdimm. > What we need is the ability to run with fsdax on hypervisor other than KVM. -aneesh
On Sun, Jul 8, 2018 at 10:17 PM, Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> wrote: > On 07/07/2018 11:06 PM, Dan Williams wrote: [..] > What we need is the ability to run with fsdax on hypervisor other than KVM. That sounds like a production use case? How can it be actual persistent memory if the kernel is picking the physical address backing the range?
diff --git a/drivers/nvdimm/Kconfig b/drivers/nvdimm/Kconfig index 50d2a33de441..cbbbcbd4506b 100644 --- a/drivers/nvdimm/Kconfig +++ b/drivers/nvdimm/Kconfig @@ -115,4 +115,17 @@ config OF_PMEM config PMEM_PLATFORM_DEVICE bool +config MEMBLOCK_PMEM + bool "pmemmap= parameter support" + default y + depends on HAVE_MEMBLOCK + select PMEM_PLATFORM_DEVICE + help + Add support for the pmemmap= kernel command line parameter. This is similar + to the memmap= parameter available on ACPI platforms, but it uses generic + kernel facilities (the memblock allocator) to reserve memory rather than adding + to the e820 table. + + Select Y if unsure. + endif diff --git a/drivers/nvdimm/Makefile b/drivers/nvdimm/Makefile index 94f7f29146ce..0215ce0182e9 100644 --- a/drivers/nvdimm/Makefile +++ b/drivers/nvdimm/Makefile @@ -5,6 +5,7 @@ obj-$(CONFIG_ND_BTT) += nd_btt.o obj-$(CONFIG_ND_BLK) += nd_blk.o obj-$(CONFIG_PMEM_PLATFORM_DEVICE) += nd_e820.o obj-$(CONFIG_OF_PMEM) += of_pmem.o +obj-$(CONFIG_MEMBLOCK_PMEM) += memblockpmem.o nd_pmem-y := pmem.o diff --git a/drivers/nvdimm/memblockpmem.c b/drivers/nvdimm/memblockpmem.c new file mode 100644 index 000000000000..d39772b75fcd --- /dev/null +++ b/drivers/nvdimm/memblockpmem.c @@ -0,0 +1,115 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * Copyright (c) 2018 IBM Corporation + */ + +#define pr_fmt(fmt) "memblock pmem: " fmt + +#include <linux/libnvdimm.h> +#include <linux/bootmem.h> +#include <linux/memblock.h> +#include <linux/mmzone.h> +#include <linux/cpu.h> +#include <linux/platform_device.h> +#include <linux/init.h> +#include <linux/ioport.h> +#include <linux/ctype.h> +#include <linux/slab.h> + +/* + * Align pmem reservations to the section size so we don't have issues with + * memory hotplug + */ +#ifdef CONFIG_SPARSEMEM +#define BOOTPMEM_ALIGN (1UL << SECTION_SIZE_BITS) +#else +#define BOOTPMEM_ALIGN PFN_DEFAULT_ALIGNMENT +#endif + +static __initdata u64 pmem_size; +static __initdata phys_addr_t pmem_stolen_memory; + +static void alloc_pmem_from_memblock(void) +{ + + pmem_stolen_memory = memblock_alloc_base(pmem_size, + BOOTPMEM_ALIGN, + MEMBLOCK_ALLOC_ACCESSIBLE); + if (!pmem_stolen_memory) { + pr_err("Failed to allocate memory for PMEM from memblock\n"); + return; + } + + /* + * Remove from the memblock reserved range + */ + memblock_free(pmem_stolen_memory, pmem_size); + + /* + * Remove from the memblock memory range. + */ + memblock_remove(pmem_stolen_memory, pmem_size); + pr_info("Allocated %ld memory at 0x%lx\n", (unsigned long)pmem_size, + (unsigned long)pmem_stolen_memory); + return; +} + +/* + * pmemmap=ss[KMG] + * + * This is similar to the memremap=offset[KMG]!size[KMG] paramater + * for adding a legacy pmem range to the e820 map on x86, but it's + * platform agnostic. + * + * e.g. pmemmap=16G allocates 16G pmem region + */ +static int __init parse_pmemmap(char *p) +{ + char *old_p = p; + + if (!p) + return -EINVAL; + + pmem_size = memparse(p, &p); + if (p == old_p) + return -EINVAL; + + alloc_pmem_from_memblock(); + return 0; +} +early_param("pmemmap", parse_pmemmap); + +static __init int register_e820_pmem(void) +{ + struct resource *res, *conflict; + struct platform_device *pdev; + + if (!pmem_stolen_memory) + return 0; + + res = kzalloc(sizeof(*res), GFP_KERNEL); + if (!res) + return -1; + + memset(res, 0, sizeof(*res)); + res->start = pmem_stolen_memory; + res->end = pmem_stolen_memory + pmem_size - 1; + res->name = "Persistent Memory (legacy)"; + res->desc = IORES_DESC_PERSISTENT_MEMORY_LEGACY; + res->flags = IORESOURCE_MEM; + + conflict = insert_resource_conflict(&iomem_resource, res); + if (conflict) { + pr_err("%pR conflicts, try insert below %pR\n", res, conflict); + kfree(res); + return -1; + } + /* + * See drivers/nvdimm/e820.c for the implementation, this is + * simply here to trigger the module to load on demand. + */ + pdev = platform_device_alloc("e820_pmem", -1); + + return platform_device_add(pdev); +} +device_initcall(register_e820_pmem);