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List:       git-commits-head
Subject:    efi: Prevent GICv3 WARN() by mapping the memreserve table before first use
From:       Linux Kernel Mailing List <linux-kernel () vger ! kernel ! org>
Date:       2018-11-30 21:01:29
Message-ID: git-mailbomb-linux-master-976b489120cdab2b1b3a41ffa14661db43d58190 () kernel ! org
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Commit:     976b489120cdab2b1b3a41ffa14661db43d58190
Parent:     2e6e902d185027f8e3cb8b7305238f7e35d6a436
Refname:    refs/heads/master
Web:        https://git.kernel.org/torvalds/c/976b489120cdab2b1b3a41ffa14661db43d58190
Author:     Ard Biesheuvel <ard.biesheuvel@linaro.org>
AuthorDate: Fri Nov 23 22:51:32 2018 +0100
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue Nov 27 13:50:20 2018 +0100

    efi: Prevent GICv3 WARN() by mapping the memreserve table before first use
    
    Mapping the MEMRESERVE EFI configuration table from an early initcall
    is too late: the GICv3 ITS code that creates persistent reservations
    for the boot CPU's LPI tables is invoked from init_IRQ(), which runs
    much earlier than the handling of the initcalls. This results in a
    WARN() splat because the LPI tables cannot be reserved persistently,
    which will result in silent memory corruption after a kexec reboot.
    
    So instead, invoke the initialization performed by the initcall from
    efi_mem_reserve_persistent() itself as well, but keep the initcall so
    that the init is guaranteed to have been called before SMP boot.
    
    Tested-by: Marc Zyngier <marc.zyngier@arm.com>
    Tested-by: Jan Glauber <jglauber@cavium.com>
    Tested-by: John Garry <john.garry@huawei.com>
    Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: linux-efi@vger.kernel.org
    Fixes: 63eb322d89c8 ("efi: Permit calling efi_mem_reserve_persistent() ...")
    Link: http://lkml.kernel.org/r/20181123215132.7951-2-ard.biesheuvel@linaro.org
    Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 drivers/firmware/efi/efi.c | 36 ++++++++++++++++++++++++++----------
 1 file changed, 26 insertions(+), 10 deletions(-)

diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index fad7c62cfc0e..415849bab233 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -969,13 +969,33 @@ bool efi_is_table_address(unsigned long phys_addr)
 static DEFINE_SPINLOCK(efi_mem_reserve_persistent_lock);
 static struct linux_efi_memreserve *efi_memreserve_root __ro_after_init;
 
-int efi_mem_reserve_persistent(phys_addr_t addr, u64 size)
+static int __init efi_memreserve_map_root(void)
+{
+	if (efi.mem_reserve == EFI_INVALID_TABLE_ADDR)
+		return -ENODEV;
+
+	efi_memreserve_root = memremap(efi.mem_reserve,
+				       sizeof(*efi_memreserve_root),
+				       MEMREMAP_WB);
+	if (WARN_ON_ONCE(!efi_memreserve_root))
+		return -ENOMEM;
+	return 0;
+}
+
+int __ref efi_mem_reserve_persistent(phys_addr_t addr, u64 size)
 {
 	struct linux_efi_memreserve *rsv;
+	int rc;
 
-	if (!efi_memreserve_root)
+	if (efi_memreserve_root == (void *)ULONG_MAX)
 		return -ENODEV;
 
+	if (!efi_memreserve_root) {
+		rc = efi_memreserve_map_root();
+		if (rc)
+			return rc;
+	}
+
 	rsv = kmalloc(sizeof(*rsv), GFP_ATOMIC);
 	if (!rsv)
 		return -ENOMEM;
@@ -993,14 +1013,10 @@ int efi_mem_reserve_persistent(phys_addr_t addr, u64 size)
 
 static int __init efi_memreserve_root_init(void)
 {
-	if (efi.mem_reserve == EFI_INVALID_TABLE_ADDR)
-		return -ENODEV;
-
-	efi_memreserve_root = memremap(efi.mem_reserve,
-				       sizeof(*efi_memreserve_root),
-				       MEMREMAP_WB);
-	if (!efi_memreserve_root)
-		return -ENOMEM;
+	if (efi_memreserve_root)
+		return 0;
+	if (efi_memreserve_map_root())
+		efi_memreserve_root = (void *)ULONG_MAX;
 	return 0;
 }
 early_initcall(efi_memreserve_root_init);
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