linux-kernel - Re: [PATCH v6 23/34] x86, realmode: Decrypt trampoline area if memory encryption is active

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Message-ID: <dffd4702-9598-40ef-c9ad-ef970df13e32@amd.com>
Date:   Wed, 14 Jun 2017 11:38:57 -0500
From:   Tom Lendacky <thomas.lendacky@....com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     linux-arch@...r.kernel.org, linux-efi@...r.kernel.org,
        kvm@...r.kernel.org, linux-doc@...r.kernel.org, x86@...nel.org,
        kexec@...ts.infradead.org, linux-kernel@...r.kernel.org,
        kasan-dev@...glegroups.com, linux-mm@...ck.org,
        iommu@...ts.linux-foundation.org, Rik van Riel <riel@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Toshimitsu Kani <toshi.kani@....com>,
        Arnd Bergmann <arnd@...db.de>,
        Jonathan Corbet <corbet@....net>,
        Matt Fleming <matt@...eblueprint.co.uk>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Joerg Roedel <joro@...tes.org>,
        Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Larry Woodman <lwoodman@...hat.com>,
        Brijesh Singh <brijesh.singh@....com>,
        Ingo Molnar <mingo@...hat.com>,
        Andy Lutomirski <luto@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Alexander Potapenko <glider@...gle.com>,
        Dave Young <dyoung@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Dmitry Vyukov <dvyukov@...gle.com>
Subject: Re: [PATCH v6 23/34] x86, realmode: Decrypt trampoline area if memory
 encryption is active

On 6/14/2017 11:24 AM, Borislav Petkov wrote:
> On Wed, Jun 07, 2017 at 02:17:09PM -0500, Tom Lendacky wrote:
>> When Secure Memory Encryption is enabled, the trampoline area must not
>> be encrypted. A CPU running in real mode will not be able to decrypt
>> memory that has been encrypted because it will not be able to use addresses
>> with the memory encryption mask.
>>
>> A recent change that added a new system_state value exposed a warning
>> issued by early_ioreamp() when the system_state was not SYSTEM_BOOTING.
>> At the stage where the trampoline area is decrypted, the system_state is
>> now SYSTEM_SCHEDULING. The check was changed to issue a warning if the
>> system_state is greater than or equal to SYSTEM_RUNNING.
> 
> This piece along with the hunk touching system_state absolutely needs to
> be a separate patch as it is unrelated.

Yup, will do.

Thanks,
Tom

>