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From: tip-bot for Ard Biesheuvel <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: marc.zyngier@arm.com, peterz@infradead.org, bhsharma@redhat.com,
	jonathanh@nvidia.com, arend.vanspriel@broadcom.com,
	julien.thierry@arm.com, natechancellor@gmail.com, bp@alien8.de,
	torvalds@linux-foundation.org, joe@perches.com, mingo@kernel.org,
	ard.biesheuvel@linaro.org, hpa@zytor.com,
	sai.praneeth.prakhya@intel.com, sedat.dilek@gmail.com,
	eric.snowberg@oracle.com, dave.hansen@intel.com,
	hdegoede@redhat.com, linux-kernel@vger.kernel.org,
	matt@codeblueprint.co.uk, luto@kernel.org,
	zhuyifei1999@gmail.com, tglx@linutronix.de
Subject: [tip:efi/core] efi: Reduce the amount of memblock reservations for persistent allocations
Date: Fri, 30 Nov 2018 02:00:57 -0800
Message-ID: <tip-80424b02d42bb22f8ff8839cb93a84ade53b39c0@git.kernel.org> (raw)
In-Reply-To: <20181129171230.18699-11-ard.biesheuvel@linaro.org>

Commit-ID:  80424b02d42bb22f8ff8839cb93a84ade53b39c0
Gitweb:     https://git.kernel.org/tip/80424b02d42bb22f8ff8839cb93a84ade53b39c0
Author:     Ard Biesheuvel <ard.biesheuvel@linaro.org>
AuthorDate: Thu, 29 Nov 2018 18:12:29 +0100
Committer:  Ingo Molnar <mingo@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.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>
---
 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 */

  parent reply index

Thread overview: 50+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-29 17:12 [GIT PULL 00/11] EFI updates Ard Biesheuvel
2018-11-29 17:12 ` [PATCH 01/11] x86/efi: Allocate e820 buffer before calling efi_exit_boot_service Ard Biesheuvel
2018-11-30  7:29   ` Ingo Molnar
2018-11-30  8:26     ` Ard Biesheuvel
2018-11-30  8:36       ` Ingo Molnar
2018-11-30  9:55   ` [tip:efi/core] " tip-bot for Eric Snowberg
2018-11-29 17:12 ` [PATCH 02/11] efi/fdt: Indentation fix Ard Biesheuvel
2018-11-30  7:56   ` [PATCH] efi/fdt: More cleanups Ingo Molnar
2018-11-30  8:31     ` Ard Biesheuvel
2018-11-30  9:48       ` Ingo Molnar
2018-11-30  9:56   ` [tip:efi/core] efi/fdt: Indentation fix tip-bot for Julien Thierry
2018-11-29 17:12 ` [PATCH 03/11] efi/fdt: Simplify get_fdt flow Ard Biesheuvel
2018-11-30  9:57   ` [tip:efi/core] efi/fdt: Simplify the get_fdt() flow tip-bot for Julien Thierry
2018-11-29 17:12 ` [PATCH 04/11] x86/mm/pageattr: Introduce helper function to unmap EFI boot services Ard Biesheuvel
2018-11-30  9:58   ` [tip:efi/core] " tip-bot for Sai Praneeth Prakhya
2018-11-29 17:12 ` [PATCH 05/11] x86/efi: Unmap EFI boot services code/data regions from efi_pgd Ard Biesheuvel
2018-11-30  9:58   ` [tip:efi/core] " tip-bot for Sai Praneeth Prakhya
2018-12-17 18:06     ` Prakhya, Sai Praneeth
2018-12-17 18:10       ` Ard Biesheuvel
2018-12-17 18:42         ` Prakhya, Sai Praneeth
2018-12-17 19:35           ` Ard Biesheuvel
2018-12-17 19:48             ` Prakhya, Sai Praneeth
2018-12-21 17:02               ` Ard Biesheuvel
2018-12-21 17:13                 ` Borislav Petkov
2018-12-21 17:26                   ` Ard Biesheuvel
2018-12-21 19:29                     ` Borislav Petkov
2018-12-22 11:07                       ` Ard Biesheuvel
2019-01-07 15:57                         ` Matt Fleming
2018-12-21 17:52                 ` Prakhya, Sai Praneeth
2018-11-29 17:12 ` [PATCH 06/11] x86/efi: Move efi_<reserve/free>_boot_services() to arch/x86 Ard Biesheuvel
2018-11-30  9:59   ` [tip:efi/core] " tip-bot for Sai Praneeth Prakhya
2018-11-29 17:12 ` [PATCH 07/11] efi/libstub: Disable some warnings for x86{,_64} Ard Biesheuvel
2018-11-30  9:59   ` [tip:efi/core] " tip-bot for Nathan Chancellor
2018-11-29 17:12 ` [PATCH 08/11] firmware: efi: add NULL pointer checks in efivars api functions Ard Biesheuvel
2018-11-30  8:11   ` Ingo Molnar
2018-11-30  8:37     ` Ard Biesheuvel
2018-11-30  9:56   ` [tip:efi/core] firmware/efi: Add NULL pointer checks in efivars API functions tip-bot for Arend van Spriel
2018-11-29 17:12 ` [PATCH 09/11] efi: permit multiple entries in persistent memreserve data structure Ard Biesheuvel
2018-11-30 10:00   ` [tip:efi/core] efi: Permit " tip-bot for Ard Biesheuvel
2018-11-29 17:12 ` [PATCH 10/11] efi: reduce the amount of memblock reservations for persistent allocations Ard Biesheuvel
2018-11-30  8:38   ` Ingo Molnar
2018-11-30  8:39     ` Ard Biesheuvel
2018-11-30 10:00   ` tip-bot for Ard Biesheuvel [this message]
2018-11-29 17:12 ` [PATCH 11/11] efi/x86: earlyprintk - Fix infinite loop on some screen widths Ard Biesheuvel
2018-11-30  8:05   ` Ingo Molnar
2018-11-30  8:32     ` Ard Biesheuvel
2018-11-30  9:55   ` [tip:efi/core] x86/earlyprintk/efi: " tip-bot for YiFei Zhu
2018-11-29 18:27 ` [GIT PULL 00/11] EFI updates Prakhya, Sai Praneeth
2018-11-30 12:01   ` Ard Biesheuvel
2018-11-30 18:01     ` Prakhya, Sai Praneeth

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