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

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Message-ID: <CAMj1kXF2Bi_iyjzUK2zie_pt6Vnm4QwvarHicJoRzUiX7nU0Kw@mail.gmail.com>
Date:   Thu, 9 Feb 2023 00:16:46 +0100
From:   Ard Biesheuvel <ardb@...nel.org>
To:     Darren Hart <darren@...amperecomputing.com>
Cc:     LKML <linux-kernel@...r.kernel.org>, stable@...r.kernel.org,
        linux-efi@...r.kernel.org,
        Alexandru Elisei <alexandru.elisei@...il.com>
Subject: Re: [PATCH] arm64: efi: Force the use of SetVirtualAddressMap() on
 Altra Max machines

Hello Darren,

On Thu, 9 Feb 2023 at 00:14, Darren Hart <darren@...amperecomputing.com> wrote:
>
> 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. Altra Max machines are similarly affected but
> not detected with the strict strcmp test.
>
> Rather than risk greedy matching with strncmp, add a second test for
> Altra Max. Do not refactor to handle multiple tests as these should be
> the only two needed.
>

Famous last words ...

Unfortunately, I just had a report the other day that 'eMAG' and
'Server' (!) are also being used.

https://lore.kernel.org/all/20230131040355.3116-1-justin.he@arm.com/


> 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: Ard Biesheuvel <ardb@...nel.org>
> Signed-off-by: Darren Hart <darren@...amperecomputing.com>
> ---
>  drivers/firmware/efi/libstub/arm64.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/firmware/efi/libstub/arm64.c b/drivers/firmware/efi/libstub/arm64.c
> index ff2d18c42ee7..97f4423059c7 100644
> --- a/drivers/firmware/efi/libstub/arm64.c
> +++ b/drivers/firmware/efi/libstub/arm64.c
> @@ -19,10 +19,10 @@ 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 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, "Altra") && strcmp(type1_family, "Altra Max")))
>                 return false;
>
>         efi_warn("Working around broken SetVirtualAddressMap()\n");
> --
> 2.34.3
>