From 5f0b0ecf043a5319e729c11a53bc8294df12dab3 Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Thu, 29 Nov 2018 18:12:28 +0100 Subject: efi: Permit multiple entries in persistent memreserve data structure In preparation of updating efi_mem_reserve_persistent() to cause less fragmentation when dealing with many persistent reservations, update the struct definition and the code that handles it currently so it can describe an arbitrary number of reservations using a single linked list entry. The actual optimization will be implemented in a subsequent patch. Tested-by: Marc Zyngier Signed-off-by: Ard Biesheuvel Cc: Andy Lutomirski Cc: Arend van Spriel Cc: Bhupesh Sharma Cc: Borislav Petkov Cc: Dave Hansen Cc: Eric Snowberg Cc: Hans de Goede Cc: Joe Perches Cc: Jon Hunter Cc: Julien Thierry Cc: Linus Torvalds Cc: Matt Fleming Cc: Nathan Chancellor Cc: Peter Zijlstra Cc: Sai Praneeth Prakhya Cc: Sedat Dilek Cc: Thomas Gleixner Cc: YiFei Zhu Cc: linux-efi@vger.kernel.org Link: http://lkml.kernel.org/r/20181129171230.18699-10-ard.biesheuvel@linaro.org Signed-off-by: Ingo Molnar --- drivers/firmware/efi/efi.c | 39 +++++++++++++++++++++++++++------------ 1 file changed, 27 insertions(+), 12 deletions(-) (limited to 'drivers/firmware/efi/efi.c') diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c index 415849bab233..80b11521627a 100644 --- a/drivers/firmware/efi/efi.c +++ b/drivers/firmware/efi/efi.c @@ -602,21 +602,33 @@ int __init efi_apply_persistent_mem_reservations(void) while (prsv) { struct linux_efi_memreserve *rsv; - - /* reserve the entry itself */ - memblock_reserve(prsv, sizeof(*rsv)); - - rsv = early_memremap(prsv, sizeof(*rsv)); - if (rsv == NULL) { + u8 *p; + int i; + + /* + * Just map a full page: that is what we will get + * anyway, and it permits us to map the entire entry + * before knowing its size. + */ + p = early_memremap(ALIGN_DOWN(prsv, PAGE_SIZE), + PAGE_SIZE); + if (p == NULL) { pr_err("Could not map UEFI memreserve entry!\n"); return -ENOMEM; } - if (rsv->size) - memblock_reserve(rsv->base, rsv->size); + rsv = (void *)(p + prsv % PAGE_SIZE); + + /* reserve the entry itself */ + memblock_reserve(prsv, EFI_MEMRESERVE_SIZE(rsv->size)); + + for (i = 0; i < atomic_read(&rsv->count); i++) { + memblock_reserve(rsv->entry[i].base, + rsv->entry[i].size); + } prsv = rsv->next; - early_memunmap(rsv, sizeof(*rsv)); + early_memunmap(p, PAGE_SIZE); } } @@ -985,6 +997,7 @@ 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; if (efi_memreserve_root == (void *)ULONG_MAX) @@ -996,12 +1009,14 @@ int __ref efi_mem_reserve_persistent(phys_addr_t addr, u64 size) return rc; } - rsv = kmalloc(sizeof(*rsv), GFP_ATOMIC); + rsv = kmalloc(rsvsize, GFP_ATOMIC); if (!rsv) return -ENOMEM; - rsv->base = addr; - rsv->size = size; + rsv->size = 1; + atomic_set(&rsv->count, 1); + rsv->entry[0].base = addr; + rsv->entry[0].size = size; spin_lock(&efi_mem_reserve_persistent_lock); rsv->next = efi_memreserve_root->next; -- cgit From 80424b02d42bb22f8ff8839cb93a84ade53b39c0 Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Thu, 29 Nov 2018 18:12:29 +0100 Subject: 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 Signed-off-by: Ard Biesheuvel Cc: Andy Lutomirski Cc: Arend van Spriel Cc: Bhupesh Sharma Cc: Borislav Petkov Cc: Dave Hansen Cc: Eric Snowberg Cc: Hans de Goede Cc: Joe Perches Cc: Jon Hunter Cc: Julien Thierry Cc: Linus Torvalds Cc: Matt Fleming Cc: Nathan Chancellor Cc: Peter Zijlstra Cc: Sai Praneeth Prakhya Cc: Sedat Dilek Cc: Thomas Gleixner Cc: YiFei Zhu Cc: linux-efi@vger.kernel.org Link: http://lkml.kernel.org/r/20181129171230.18699-11-ard.biesheuvel@linaro.org Signed-off-by: Ingo Molnar --- drivers/firmware/efi/efi.c | 21 +++++++++++++++++---- 1 file changed, 17 insertions(+), 4 deletions(-) (limited to 'drivers/firmware/efi/efi.c') 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; -- cgit