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authorArd Biesheuvel <ard.biesheuvel@linaro.org>2018-11-29 18:12:29 +0100
committerIngo Molnar <mingo@kernel.org>2018-11-30 09:37:57 +0100
commit80424b02d42bb22f8ff8839cb93a84ade53b39c0 (patch)
tree3c846aaef4d718a0c7902a91514cbf5ab2a17429 /drivers/firmware/efi
parent5f0b0ecf043a5319e729c11a53bc8294df12dab3 (diff)
downloadlinux-80424b02d42bb22f8ff8839cb93a84ade53b39c0.tar.bz2
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>
Diffstat (limited to 'drivers/firmware/efi')
-rw-r--r--drivers/firmware/efi/efi.c21
1 files changed, 17 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;