linux-kernel - Re: [RFC v2 26/32] x86/mm: Move force_dma

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <37da11b3-0313-982d-5a2b-af592db6f9e8@linux.intel.com>
Date:   Mon, 17 May 2021 15:32:01 -0700
From:   "Kuppuswamy, Sathyanarayanan" 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Dave Hansen <dave.hansen@...el.com>
Cc:     Andi Kleen <ak@...ux.intel.com>,
        "Kirill A. Shutemov" <kirill@...temov.name>,
        Peter Zijlstra <peterz@...radead.org>,
        Andy Lutomirski <luto@...nel.org>,
        Dan Williams <dan.j.williams@...el.com>,
        Tony Luck <tony.luck@...el.com>,
        Kirill Shutemov <kirill.shutemov@...ux.intel.com>,
        Kuppuswamy Sathyanarayanan <knsathya@...nel.org>,
        Raj Ashok <ashok.raj@...el.com>, linux-kernel@...r.kernel.org
Subject: Re: [RFC v2 26/32] x86/mm: Move force_dma_unencrypted() to common
 code



On 5/17/21 11:37 AM, Sean Christopherson wrote:
>> Just remember, a "common framework" doesn't mean that it can't be backed
>> by extremely arch-specific mechanisms.
>>
>> For instance, there's a lot of pkey-specific code in mm/mprotect.c.  It
>> still gets optimized away on x86 with all the goodness of X86_FEATUREs.
> Ya, exactly.  Ideally, generic code shouldn't have to differentiate between SEV,
> SEV-ES, SEV-SNP, TDX, etc..., a vanilla "bool is_protected_guest(void)" should
> suffice.  Under the hood, x86's implementation for is_protected_guest() can be
> boot_cpu_has() checks (if we want).

What about the use case of protected_guest_has(flag)? Do you want to call it with
with X86_FEATURE_* flags outside arch/x86 code ?


-- 
Sathyanarayanan Kuppuswamy
Linux Kernel Developer