• Dan Williams's avatar
    device-dax: add dis-contiguous resource support · 60e93dc0
    Dan Williams authored
    Break the requirement that device-dax instances are physically contiguous.
    With this constraint removed it allows fragmented available capacity to
    be fully allocated.
    
    This capability is useful to mitigate the "noisy neighbor" problem with
    memory-side-cache management for virtual machines, or any other scenario
    where a platform address boundary also designates a performance boundary.
    For example a direct mapped memory side cache might rotate cache colors at
    1GB boundaries.  With dis-contiguous allocations a device-dax instance
    could be configured to contain only 1 cache color.
    
    It also satisfies Joao's use case (see link) for partitioning memory for
    exclusive guest access.  It allows for a future potential mode where the
    host kernel need not allocate 'struct page' capacity up-front.
    Reported-by: default avatarJoao Martins <joao.m.martins@oracle.com>
    Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Cc: Andy Lutomirski <luto@kernel.org>
    Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
    Cc: Ard Biesheuvel <ardb@kernel.org>
    Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
    Cc: Ben Skeggs <bskeggs@redhat.com>
    Cc: Bjorn Helgaas <bhelgaas@google.com>
    Cc: Borislav Petkov <bp@alien8.de>
    Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
    Cc: Brice Goglin <Brice.Goglin@inria.fr>
    Cc: Catalin Marinas <catalin.marinas@arm.com>
    Cc: Daniel Vetter <daniel@ffwll.ch>
    Cc: Dave Hansen <dave.hansen@linux.intel.com>
    Cc: Dave Jiang <dave.jiang@intel.com>
    Cc: David Airlie <airlied@linux.ie>
    Cc: David Hildenbrand <david@redhat.com>
    Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    Cc: "H. Peter Anvin" <hpa@zytor.com>
    Cc: Hulk Robot <hulkci@huawei.com>
    Cc: Ingo Molnar <mingo@redhat.com>
    Cc: Ira Weiny <ira.weiny@intel.com>
    Cc: Jason Gunthorpe <jgg@mellanox.com>
    Cc: Jason Yan <yanaijie@huawei.com>
    Cc: Jeff Moyer <jmoyer@redhat.com>
    Cc: "Jérôme Glisse" <jglisse@redhat.com>
    Cc: Jia He <justin.he@arm.com>
    Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
    Cc: Juergen Gross <jgross@suse.com>
    Cc: kernel test robot <lkp@intel.com>
    Cc: Michael Ellerman <mpe@ellerman.id.au>
    Cc: Mike Rapoport <rppt@linux.ibm.com>
    Cc: Paul Mackerras <paulus@ozlabs.org>
    Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
    Cc: Randy Dunlap <rdunlap@infradead.org>
    Cc: Stefano Stabellini <sstabellini@kernel.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Tom Lendacky <thomas.lendacky@amd.com>
    Cc: Vishal Verma <vishal.l.verma@intel.com>
    Cc: Vivek Goyal <vgoyal@redhat.com>
    Cc: Wei Yang <richard.weiyang@linux.alibaba.com>
    Cc: Will Deacon <will@kernel.org>
    Link: https://lore.kernel.org/lkml/20200110190313.17144-1-joao.m.martins@oracle.com/
    Link: https://lkml.kernel.org/r/159643104304.4062302.16561669534797528660.stgit@dwillia2-desk3.amr.corp.intel.com
    Link: https://lkml.kernel.org/r/160106116875.30709.11456649969327399771.stgit@dwillia2-desk3.amr.corp.intel.comSigned-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    60e93dc0
bus.c 27.1 KB