Commit-ID: 80424b02d42bb22f8ff8839cb93a84ade53b39c0 Gitweb: https://git.kernel.org/tip/80424b02d42bb22f8ff8839cb93a84ade53b39c0 Author: Ard Biesheuvel <ard.biesheu...@linaro.org> AuthorDate: Thu, 29 Nov 2018 18:12:29 +0100 Committer: Ingo Molnar <mi...@kernel.org> CommitDate: Fri, 30 Nov 2018 09:37:57 +0100
efi: Reduce the amount of memblock reservations for persistent allocations The current implementation of efi_mem_reserve_persistent() is rather naive, in the sense that for each invocation, it creates a separate linked list entry to describe the reservation. Since the linked list entries themselves need to persist across subsequent kexec reboots, every reservation created this way results in two memblock_reserve() calls at the next boot. On arm64 systems with 100s of CPUs, this may result in a excessive number of memblock reservations, and needless fragmentation. So instead, make use of the newly updated struct linux_efi_memreserve layout to put multiple reservations into a single linked list entry. This should get rid of the numerous tiny memblock reservations, and effectively cut the total number of reservations in half on arm64 systems with many CPUs. [ mingo: build warning fix. ] Tested-by: Marc Zyngier <marc.zyng...@arm.com> Signed-off-by: Ard Biesheuvel <ard.biesheu...@linaro.org> Cc: Andy Lutomirski <l...@kernel.org> Cc: Arend van Spriel <arend.vanspr...@broadcom.com> Cc: Bhupesh Sharma <bhsha...@redhat.com> Cc: Borislav Petkov <b...@alien8.de> Cc: Dave Hansen <dave.han...@intel.com> Cc: Eric Snowberg <eric.snowb...@oracle.com> Cc: Hans de Goede <hdego...@redhat.com> Cc: Joe Perches <j...@perches.com> Cc: Jon Hunter <jonath...@nvidia.com> Cc: Julien Thierry <julien.thie...@arm.com> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Matt Fleming <m...@codeblueprint.co.uk> Cc: Nathan Chancellor <natechancel...@gmail.com> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Sai Praneeth Prakhya <sai.praneeth.prak...@intel.com> Cc: Sedat Dilek <sedat.di...@gmail.com> Cc: Thomas Gleixner <t...@linutronix.de> Cc: YiFei Zhu <zhuyifei1...@gmail.com> Cc: linux-...@vger.kernel.org Link: http://lkml.kernel.org/r/20181129171230.18699-11-ard.biesheu...@linaro.org Signed-off-by: Ingo Molnar <mi...@kernel.org> --- drivers/firmware/efi/efi.c | 21 +++++++++++++++++---- include/linux/efi.h | 3 +++ 2 files changed, 20 insertions(+), 4 deletions(-) diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c index 80b11521627a..4c46ff6f2242 100644 --- a/drivers/firmware/efi/efi.c +++ b/drivers/firmware/efi/efi.c @@ -997,8 +997,8 @@ static int __init efi_memreserve_map_root(void) int __ref efi_mem_reserve_persistent(phys_addr_t addr, u64 size) { struct linux_efi_memreserve *rsv; - int rsvsize = EFI_MEMRESERVE_SIZE(1); - int rc; + unsigned long prsv; + int rc, index; if (efi_memreserve_root == (void *)ULONG_MAX) return -ENODEV; @@ -1009,11 +1009,24 @@ int __ref efi_mem_reserve_persistent(phys_addr_t addr, u64 size) return rc; } - rsv = kmalloc(rsvsize, GFP_ATOMIC); + /* first try to find a slot in an existing linked list entry */ + for (prsv = efi_memreserve_root->next; prsv; prsv = rsv->next) { + rsv = __va(prsv); + index = atomic_fetch_add_unless(&rsv->count, 1, rsv->size); + if (index < rsv->size) { + rsv->entry[index].base = addr; + rsv->entry[index].size = size; + + return 0; + } + } + + /* no slot found - allocate a new linked list entry */ + rsv = (struct linux_efi_memreserve *)__get_free_page(GFP_ATOMIC); if (!rsv) return -ENOMEM; - rsv->size = 1; + rsv->size = EFI_MEMRESERVE_COUNT(PAGE_SIZE); atomic_set(&rsv->count, 1); rsv->entry[0].base = addr; rsv->entry[0].size = size; diff --git a/include/linux/efi.h b/include/linux/efi.h index 4f27640fdcdc..becd5d76a207 100644 --- a/include/linux/efi.h +++ b/include/linux/efi.h @@ -1724,4 +1724,7 @@ struct linux_efi_memreserve { #define EFI_MEMRESERVE_SIZE(count) (sizeof(struct linux_efi_memreserve) + \ (count) * sizeof(((struct linux_efi_memreserve *)0)->entry[0])) +#define EFI_MEMRESERVE_COUNT(size) (((size) - sizeof(struct linux_efi_memreserve)) \ + / sizeof(((struct linux_efi_memreserve *)0)->entry[0])) + #endif /* _LINUX_EFI_H */
