linux-kernel - [PATCH 2/2] efi: Allow the number of EFI configuration tables entries to be zero

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Message-Id: <20190525112559.7917-3-ard.biesheuvel@linaro.org>
Date:   Sat, 25 May 2019 13:25:59 +0200
From:   Ard Biesheuvel <ard.biesheuvel@...aro.org>
To:     linux-efi@...r.kernel.org, Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>
Cc:     Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        linux-kernel@...r.kernel.org, Gen Zhang <blackgod016574@...il.com>,
        Rob Bradford <robert.bradford@...el.com>
Subject: [PATCH 2/2] efi: Allow the number of EFI configuration tables entries to be zero

From: Rob Bradford <robert.bradford@...el.com>

Only try and access the EFI configuration tables if there there are any
reported. This allows EFI to be continued to used on systems where there
are no configuration table entries.

Signed-off-by: Rob Bradford <robert.bradford@...el.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@...aro.org>
---
 arch/x86/platform/efi/quirks.c | 3 +++
 drivers/firmware/efi/efi.c     | 3 +++
 2 files changed, 6 insertions(+)

diff --git a/arch/x86/platform/efi/quirks.c b/arch/x86/platform/efi/quirks.c
index a25a9fd987a9..e92ab8002dc5 100644
--- a/arch/x86/platform/efi/quirks.c
+++ b/arch/x86/platform/efi/quirks.c
@@ -512,6 +512,9 @@ int __init efi_reuse_config(u64 tables, int nr_tables)
 	void *p, *tablep;
 	struct efi_setup_data *data;
 
+	if (nr_tables == 0)
+		return 0;
+
 	if (!efi_setup)
 		return 0;
 
diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index 55b77c576c42..521a541d02ad 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -636,6 +636,9 @@ int __init efi_config_init(efi_config_table_type_t *arch_tables)
 	void *config_tables;
 	int sz, ret;
 
+	if (efi.systab->nr_tables == 0)
+		return 0;
+
 	if (efi_enabled(EFI_64BIT))
 		sz = sizeof(efi_config_table_64_t);
 	else
-- 
2.20.1