linux-kernel - Re: [PATCH V4 0/3] Use mm_struct and switch

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Date:   Mon, 29 Jan 2018 10:51:26 +0000
From:   Ard Biesheuvel <ard.biesheuvel@...aro.org>
To:     Matt Fleming <matt@...eblueprint.co.uk>
Cc:     Sai Praneeth Prakhya <sai.praneeth.prakhya@...el.com>,
        linux-efi@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "Lee, Chun-Yi" <jlee@...e.com>, Borislav Petkov <bp@...en8.de>,
        Tony Luck <tony.luck@...el.com>,
        Andy Lutomirski <luto@...nel.org>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Ricardo Neri <ricardo.neri@...el.com>,
        Ravi Shankar <ravi.v.shankar@...el.com>
Subject: Re: [PATCH V4 0/3] Use mm_struct and switch_mm() instead of manually

On 26 January 2018 at 21:16, Matt Fleming <matt@...eblueprint.co.uk> wrote:
> On Thu, 18 Jan, at 01:01:04PM, Sai Praneeth Prakhya wrote:
>> From: Sai Praneeth <sai.praneeth.prakhya@...el.com>
>>
>> Presently, in x86, to invoke any efi function like
>> efi_set_virtual_address_map() or any efi_runtime_service() the code path
>> typically involves read_cr3() (save previous pgd), write_cr3()
>> (write efi_pgd) and calling efi function. Likewise after returning from
>> efi function the code path typically involves read_cr3() (save efi_pgd),
>> write_cr3() (write previous pgd). We do this couple of times in efi
>> subsystem of Linux kernel, instead we can use helper function
>> efi_switch_mm() to do this. This improves readability and maintainability.
>> Also, instead of maintaining a separate struct "efi_scratch" to store/restore
>> efi_pgd, we can use mm_struct to do this.
>
> FWIW this series looks OK to me.
>
> Reviewed-by: Matt Fleming <matt@...eblueprint.co.uk>

Thanks Matt

I know the x86 guys have been rather busy lately, so I will give them
some more time to respond. If there are no objections raised, I will
queue it for v4.17 in a couple of weeks.