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authorArd Biesheuvel <ard.biesheuvel@linaro.org>2018-11-29 12:12:29 -0500
committerIngo Molnar <mingo@kernel.org>2018-11-30 03:37:57 -0500
commit80424b02d42bb22f8ff8839cb93a84ade53b39c0 (patch)
tree3c846aaef4d718a0c7902a91514cbf5ab2a17429
parent5f0b0ecf043a5319e729c11a53bc8294df12dab3 (diff)
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.zyngier@arm.com> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arend van Spriel <arend.vanspriel@broadcom.com> Cc: Bhupesh Sharma <bhsharma@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Eric Snowberg <eric.snowberg@oracle.com> Cc: Hans de Goede <hdegoede@redhat.com> Cc: Joe Perches <joe@perches.com> Cc: Jon Hunter <jonathanh@nvidia.com> Cc: Julien Thierry <julien.thierry@arm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matt Fleming <matt@codeblueprint.co.uk> Cc: Nathan Chancellor <natechancellor@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com> Cc: Sedat Dilek <sedat.dilek@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: YiFei Zhu <zhuyifei1999@gmail.com> Cc: linux-efi@vger.kernel.org Link: http://lkml.kernel.org/r/20181129171230.18699-11-ard.biesheuvel@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
-rw-r--r--drivers/firmware/efi/efi.c21
-rw-r--r--include/linux/efi.h3
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)
997int __ref efi_mem_reserve_persistent(phys_addr_t addr, u64 size) 997int __ref efi_mem_reserve_persistent(phys_addr_t addr, u64 size)
998{ 998{
999 struct linux_efi_memreserve *rsv; 999 struct linux_efi_memreserve *rsv;
1000 int rsvsize = EFI_MEMRESERVE_SIZE(1); 1000 unsigned long prsv;
1001 int rc; 1001 int rc, index;
1002 1002
1003 if (efi_memreserve_root == (void *)ULONG_MAX) 1003 if (efi_memreserve_root == (void *)ULONG_MAX)
1004 return -ENODEV; 1004 return -ENODEV;
@@ -1009,11 +1009,24 @@ int __ref efi_mem_reserve_persistent(phys_addr_t addr, u64 size)
1009 return rc; 1009 return rc;
1010 } 1010 }
1011 1011
1012 rsv = kmalloc(rsvsize, GFP_ATOMIC); 1012 /* first try to find a slot in an existing linked list entry */
1013 for (prsv = efi_memreserve_root->next; prsv; prsv = rsv->next) {
1014 rsv = __va(prsv);
1015 index = atomic_fetch_add_unless(&rsv->count, 1, rsv->size);
1016 if (index < rsv->size) {
1017 rsv->entry[index].base = addr;
1018 rsv->entry[index].size = size;
1019
1020 return 0;
1021 }
1022 }
1023
1024 /* no slot found - allocate a new linked list entry */
1025 rsv = (struct linux_efi_memreserve *)__get_free_page(GFP_ATOMIC);
1013 if (!rsv) 1026 if (!rsv)
1014 return -ENOMEM; 1027 return -ENOMEM;
1015 1028
1016 rsv->size = 1; 1029 rsv->size = EFI_MEMRESERVE_COUNT(PAGE_SIZE);
1017 atomic_set(&rsv->count, 1); 1030 atomic_set(&rsv->count, 1);
1018 rsv->entry[0].base = addr; 1031 rsv->entry[0].base = addr;
1019 rsv->entry[0].size = size; 1032 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 {
1724#define EFI_MEMRESERVE_SIZE(count) (sizeof(struct linux_efi_memreserve) + \ 1724#define EFI_MEMRESERVE_SIZE(count) (sizeof(struct linux_efi_memreserve) + \
1725 (count) * sizeof(((struct linux_efi_memreserve *)0)->entry[0])) 1725 (count) * sizeof(((struct linux_efi_memreserve *)0)->entry[0]))
1726 1726
1727#define EFI_MEMRESERVE_COUNT(size) (((size) - sizeof(struct linux_efi_memreserve)) \
1728 / sizeof(((struct linux_efi_memreserve *)0)->entry[0]))
1729
1727#endif /* _LINUX_EFI_H */ 1730#endif /* _LINUX_EFI_H */