linux-kernel - [PATCH v2] arm64: efi: Force the use of SetVirtualAddressMap() on eMAG and Altra Max machines

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Message-Id: <2ab9645789707f31fd37c49435e476d4b5c38a0a.1675901828.git.darren@os.amperecomputing.com>
Date:   Wed,  8 Feb 2023 16:28:21 -0800
From:   Darren Hart <darren@...amperecomputing.com>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     stable@...r.kernel.org, linux-efi@...r.kernel.org,
        Alexandru Elisei <alexandru.elisei@...il.com>,
        Justin He <Justin.He@....com>,
        Huacai Chen <chenhuacai@...nel.org>,
        "Jason A. Donenfeld" <Jason@...c4.com>,
        Ard Biesheuvel <ardb@...nel.org>
Subject: [PATCH v2] arm64: efi: Force the use of SetVirtualAddressMap() on eMAG and Altra Max machines

Commit 550b33cfd445 ("arm64: efi: Force the use of SetVirtualAddressMap()
on Altra machines") identifies the Altra family via the family field in
the type#1 SMBIOS record. eMAG and Altra Max machines are similarly
affected but not detected with the strict strcmp test.

The type1_family smbios string is not an entirely reliable means of
identifying systems with this issue as OEMs can, and do, use their own
strings for these fields. However, until we have a better solution,
capture the bulk of these systems by adding strcmp matching for "eMAG"
and "Altra Max".

Fixes: 550b33cfd445 ("arm64: efi: Force the use of SetVirtualAddressMap() on Altra machines")
Cc: <stable@...r.kernel.org> # 6.1.x
Cc: <linux-efi@...r.kernel.org>
Cc: Alexandru Elisei <alexandru.elisei@...il.com>
Cc: Justin He <Justin.He@....com>
Cc: Huacai Chen <chenhuacai@...nel.org>
Cc: "Jason A. Donenfeld" <Jason@...c4.com>
Cc: Ard Biesheuvel <ardb@...nel.org>
Signed-off-by: Darren Hart <darren@...amperecomputing.com>
---
V1 -> V2: include eMAG

 drivers/firmware/efi/libstub/arm64.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/firmware/efi/libstub/arm64.c b/drivers/firmware/efi/libstub/arm64.c
index ff2d18c42ee7..4501652e11ab 100644
--- a/drivers/firmware/efi/libstub/arm64.c
+++ b/drivers/firmware/efi/libstub/arm64.c
@@ -19,10 +19,13 @@ static bool system_needs_vamap(void)
 	const u8 *type1_family = efi_get_smbios_string(1, family);
 
 	/*
-	 * Ampere Altra machines crash in SetTime() if SetVirtualAddressMap()
-	 * has not been called prior.
+	 * Ampere eMAG, Altra, and Altra Max machines crash in SetTime() if
+	 * SetVirtualAddressMap() has not been called prior.
 	 */
-	if (!type1_family || strcmp(type1_family, "Altra"))
+	if (!type1_family || (
+	    strcmp(type1_family, "eMAG") &&
+	    strcmp(type1_family, "Altra") &&
+	    strcmp(type1_family, "Altra Max")))
 		return false;
 
 	efi_warn("Working around broken SetVirtualAddressMap()\n");
-- 
2.34.3