From: Ard Biesheuvel <ard.biesheuvel@linaro.org>
To: Ross Lagerwall <ross.lagerwall@citrix.com>
Cc: linux-efi <linux-efi@vger.kernel.org>,
Darren Hart <dvhart@infradead.org>,
Andy Shevchenko <andy@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
"H. Peter Anvin" <hpa@zytor.com>,
"the arch/x86 maintainers" <x86@kernel.org>,
platform-driver-x86@vger.kernel.org,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Sai Praneeth <sai.praneeth.prakhya@intel.com>
Subject: Re: [PATCH] x86/efi: Don't require non-blocking EFI callbacks
Date: Thu, 26 Sep 2019 17:29:57 +0200 [thread overview]
Message-ID: <CAKv+Gu8ok=v6WaKWW1AmhPgf1-n7p=4h8Tkno9YNW6H8p4fg8w@mail.gmail.com> (raw)
In-Reply-To: <20190926141234.8271-1-ross.lagerwall@citrix.com>
On Thu, 26 Sep 2019 at 16:12, Ross Lagerwall <ross.lagerwall@citrix.com> wrote:
>
> If a backend does not implement non-blocking EFI operations, it implies
> that the normal operations are non-blocking.
Is that documented anywhere?
> Instead of crashing
> dereferencing a NULL pointer, fallback to the normal operations since it
> is safe to do so.
>
I agree that crashing is never the right thing to do, but I wonder
whether we shouldn't just bail instead. If the provided default
operation is non-blocking, the platform can populate the function
pointer with a reference to the default implementation.
> Fixes: 5a58bc1b1edc ("efi/x86: Use non-blocking SetVariable() for efi_delete_dummy_variable()")
> Fixes: ca0e30dcaa53 ("efi: Add nonblocking option to efi_query_variable_store()")
> Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com>
> ---
> arch/x86/platform/efi/quirks.c | 20 ++++++++++++--------
> 1 file changed, 12 insertions(+), 8 deletions(-)
>
> diff --git a/arch/x86/platform/efi/quirks.c b/arch/x86/platform/efi/quirks.c
> index 3b9fd679cea9..4167f5e8f3e8 100644
> --- a/arch/x86/platform/efi/quirks.c
> +++ b/arch/x86/platform/efi/quirks.c
> @@ -106,11 +106,13 @@ early_param("efi_no_storage_paranoia", setup_storage_paranoia);
> */
> void efi_delete_dummy_variable(void)
> {
> - efi.set_variable_nonblocking((efi_char16_t *)efi_dummy_name,
> - &EFI_DUMMY_GUID,
> - EFI_VARIABLE_NON_VOLATILE |
> - EFI_VARIABLE_BOOTSERVICE_ACCESS |
> - EFI_VARIABLE_RUNTIME_ACCESS, 0, NULL);
> + efi_set_variable_t *set_variable = efi.set_variable_nonblocking ?:
> + efi.set_variable;
> +
> + set_variable((efi_char16_t *)efi_dummy_name, &EFI_DUMMY_GUID,
> + EFI_VARIABLE_NON_VOLATILE |
> + EFI_VARIABLE_BOOTSERVICE_ACCESS |
> + EFI_VARIABLE_RUNTIME_ACCESS, 0, NULL);
> }
>
> /*
> @@ -127,10 +129,12 @@ query_variable_store_nonblocking(u32 attributes, unsigned long size)
> {
> efi_status_t status;
> u64 storage_size, remaining_size, max_size;
> + efi_query_variable_info_t *query_variable_info =
> + efi.query_variable_info_nonblocking ?:
> + efi.query_variable_info;
>
> - status = efi.query_variable_info_nonblocking(attributes, &storage_size,
> - &remaining_size,
> - &max_size);
> + status = query_variable_info(attributes, &storage_size,
> + &remaining_size, &max_size);
> if (status != EFI_SUCCESS)
> return status;
>
> --
> 2.21.0
>
next prev parent reply other threads:[~2019-09-26 15:30 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-26 14:12 [PATCH] x86/efi: Don't require non-blocking EFI callbacks Ross Lagerwall
2019-09-26 15:29 ` Ard Biesheuvel [this message]
2019-09-26 15:46 ` Ross Lagerwall
2019-09-26 15:47 ` Ard Biesheuvel
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