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

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Message-ID: <FFF73D592F13FD46B8700F0A279B802F2E3F763C@ORSMSX114.amr.corp.intel.com>
Date:   Tue, 19 Dec 2017 06:23:51 +0000
From:   "Prakhya, Sai Praneeth" <sai.praneeth.prakhya@...el.com>
To:     Bhupesh Sharma <bhsharma@...hat.com>
CC:     "linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Lee, Chun-Yi" <jlee@...e.com>, Borislav Petkov <bp@...en8.de>,
        "Luck, Tony" <tony.luck@...el.com>,
        Andy Lutomirski <luto@...nel.org>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        "Neri, Ricardo" <ricardo.neri@...el.com>,
        "Matt Fleming" <matt@...eblueprint.co.uk>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        "Shankar, Ravi V" <ravi.v.shankar@...el.com>
Subject: RE: [PATCH 0/3] Use mm_struct and switch_mm() instead of manually

> > Changes in V3:
> > 1. When CPUMASK_OFFSTACK is enabled, switch_mm_irqs_off() sets cpumask
> > by calling cpumask_set_cpu(). This panics kernel as efi_mm is not
> > initialized, therefore initialize efi_mm in efi_alloc_page_tables().
> 
> Thanks for the v3.
> 
> I confirmed that the issue I saw with the v2 when I enabled 'efi=debug' on the
> sgi-uv 300 machine (i.e the NULL pointer access while accessing
> mm_cpumask(next), in the function call
> 'switch_mm_irqs_off') is fixed in the v3.
> 
> Also as I noted during the v2 review, introducing the 'efi_switch_mm() ' helper
> instead of manually twiddling with %cr3 seems more cleaner (having personally
> debugged this leg several times on the underlying x86 EFI machines).
> 
> So in addition to me testing this on the sgi-uv300 and Dell Optiplex EFI enabled
> machine, please feel free to add:
> 
> Reviewed-by: Bhupesh Sharma <bhsharma@...hat.com>
> 

Hi  Bhupesh,

Thanks for the review and re-iterating the usefulness of this patch set.

Regards,
Sai