From: Tom Lendacky via iommu <iommu@lists.linux-foundation.org>
To: Borislav Petkov <bp@alien8.de>
Cc: linux-efi@vger.kernel.org, Brijesh Singh <brijesh.singh@amd.com>,
kvm@vger.kernel.org, Peter Zijlstra <peterz@infradead.org>,
Dave Hansen <dave.hansen@linux.intel.com>,
dri-devel@lists.freedesktop.org,
platform-driver-x86@vger.kernel.org,
Will Deacon <will@kernel.org>,
linux-s390@vger.kernel.org, Andi Kleen <ak@linux.intel.com>,
x86@kernel.org, amd-gfx@lists.freedesktop.org,
Christoph Hellwig <hch@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
linux-graphics-maintainer@vmware.com,
Tianyu Lan <Tianyu.Lan@microsoft.com>,
Andy Lutomirski <luto@kernel.org>,
"Kirill A. Shutemov" <kirill@shutemov.name>,
Thomas Gleixner <tglx@linutronix.de>,
kexec@lists.infradead.org, linux-kernel@vger.kernel.org,
iommu@lists.linux-foundation.org, linux-fsdevel@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH v3 5/8] x86/sme: Replace occurrences of sme_active() with cc_platform_has()
Date: Fri, 24 Sep 2021 08:31:46 -0500 [thread overview]
Message-ID: <8ed60226-b3f2-1226-3ce8-afc58acbe1e5@amd.com> (raw)
In-Reply-To: <YU2fsCblZVQpgMvC@zn.tnic>
On 9/24/21 4:51 AM, Borislav Petkov wrote:
> On Fri, Sep 24, 2021 at 12:41:32PM +0300, Kirill A. Shutemov wrote:
>> On Thu, Sep 23, 2021 at 08:21:03PM +0200, Borislav Petkov wrote:
>>> On Thu, Sep 23, 2021 at 12:05:58AM +0300, Kirill A. Shutemov wrote:
>>>> Unless we find other way to guarantee RIP-relative access, we must use
>>>> fixup_pointer() to access any global variables.
>>>
>>> Yah, I've asked compiler folks about any guarantees we have wrt
>>> rip-relative addresses but it doesn't look good. Worst case, we'd have
>>> to do the fixup_pointer() thing.
>>>
>>> In the meantime, Tom and I did some more poking at this and here's a
>>> diff ontop.
>>>
>>> The direction being that we'll stick both the AMD and Intel
>>> *cc_platform_has() call into cc_platform.c for which instrumentation
>>> will be disabled so no issues with that.
>>>
>>> And that will keep all that querying all together in a single file.
>>
>> And still do cc_platform_has() calls in __startup_64() codepath?
>>
>> It's broken.
>>
>> Intel detection in cc_platform_has() relies on boot_cpu_data.x86_vendor
>> which is not initialized until early_cpu_init() in setup_arch(). Given
>> that X86_VENDOR_INTEL is 0 it leads to false-positive.
>
> Yeah, Tom, I had the same question yesterday.
>
> /me looks in his direction.
>
Yup, all the things we talked about.
But we also know that cc_platform_has() gets called a few other times
before boot_cpu_data is initialized - so more false-positives. For
cc_platform_has() to work properly, given the desire to consolidate the
calls, IMO, Intel will have to come up with some early setting that can be
enabled and checked in place of boot_cpu_data or else you live with
false-positives.
Thanks,
Tom
> :-)
>
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next prev parent reply other threads:[~2021-09-24 13:31 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-08 22:58 [PATCH v3 0/8] Implement generic cc_platform_has() helper function Tom Lendacky via iommu
2021-09-08 22:58 ` [PATCH v3 1/8] x86/ioremap: Selectively build arch override encryption functions Tom Lendacky via iommu
2021-09-08 22:58 ` [PATCH v3 2/8] mm: Introduce a function to check for confidential computing features Tom Lendacky via iommu
2021-09-09 7:35 ` Christophe Leroy
2021-09-10 15:02 ` Borislav Petkov
2021-09-08 22:58 ` [PATCH v3 3/8] x86/sev: Add an x86 version of cc_platform_has() Tom Lendacky via iommu
2021-09-11 10:10 ` Borislav Petkov
2021-09-08 22:58 ` [PATCH v3 4/8] powerpc/pseries/svm: Add a powerpc " Tom Lendacky via iommu
2021-09-09 7:40 ` Christophe Leroy
2021-09-14 11:58 ` Borislav Petkov
2021-09-14 14:47 ` Christophe Leroy
2021-09-14 14:56 ` Borislav Petkov
2021-09-15 0:28 ` Michael Ellerman
2021-09-15 10:08 ` Borislav Petkov
2021-09-15 17:18 ` Christophe Leroy
2021-09-15 18:47 ` Borislav Petkov
2021-09-16 7:35 ` Christoph Hellwig
2021-09-16 11:51 ` Michael Ellerman
2021-09-08 22:58 ` [PATCH v3 5/8] x86/sme: Replace occurrences of sme_active() with cc_platform_has() Tom Lendacky via iommu
2021-09-14 18:24 ` Borislav Petkov
2021-09-20 19:23 ` Kirill A. Shutemov
2021-09-21 17:04 ` Tom Lendacky via iommu
2021-09-21 17:47 ` Borislav Petkov
2021-09-21 21:20 ` Kirill A. Shutemov
2021-09-21 21:27 ` Borislav Petkov
2021-09-21 21:34 ` Kirill A. Shutemov
2021-09-21 21:43 ` Tom Lendacky via iommu
2021-09-21 21:58 ` Kirill A. Shutemov
2021-09-22 13:40 ` Tom Lendacky via iommu
2021-09-22 14:30 ` Kirill A. Shutemov
2021-09-22 19:52 ` Borislav Petkov
2021-09-22 21:05 ` Kirill A. Shutemov
2021-09-23 18:21 ` Borislav Petkov
2021-09-24 9:41 ` Kirill A. Shutemov
2021-09-24 9:51 ` Borislav Petkov
2021-09-24 13:31 ` Tom Lendacky via iommu [this message]
2021-09-08 22:58 ` [PATCH v3 6/8] x86/sev: Replace occurrences of sev_active() " Tom Lendacky via iommu
2021-09-08 22:58 ` [PATCH v3 7/8] x86/sev: Replace occurrences of sev_es_active() " Tom Lendacky via iommu
2021-09-08 22:58 ` [PATCH v3 8/8] treewide: Replace the use of mem_encrypt_active() " Tom Lendacky via iommu
2021-09-09 7:25 ` Christophe Leroy
2021-09-09 13:10 ` Tom Lendacky via iommu
2021-09-09 7:32 ` [PATCH v3 0/8] Implement generic cc_platform_has() helper function Christian Borntraeger
2021-09-09 13:01 ` Tom Lendacky via iommu
2021-09-15 16:46 ` Borislav Petkov
2021-09-15 17:26 ` Kuppuswamy, Sathyanarayanan
2021-09-16 15:02 ` Borislav Petkov
2021-09-16 18:38 ` Kuppuswamy, Sathyanarayanan
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