From: Paolo Bonzini <pbonzini@redhat.com>
To: Brijesh Singh <brijesh.singh@amd.com>,
Sean Christopherson <sean.j.christopherson@intel.com>
Cc: Borislav Petkov <bp@suse.de>, "x86@kernel.org" <x86@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"Lendacky, Thomas" <Thomas.Lendacky@amd.com>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: SEV guest regression in 4.18
Date: Fri, 24 Aug 2018 17:50:14 +0200 [thread overview]
Message-ID: <25d2cf1f-11ee-ecba-73a9-15a9553a3d96@redhat.com> (raw)
In-Reply-To: <c565ae1c-c2f0-8a43-b1f5-404c2efe7c56@amd.com>
On 24/08/2018 17:41, Brijesh Singh wrote:
>>>
>>> Wouldn't that result in exposing/leaking whatever code/data happened
>>> to reside on the same 2M page (or corrupting it if the entire page
>>> isn't decrypted)? Or are you suggesting that we'd also leave the
>>> encrypted mapping intact?
>>
>> Yes, exactly the latter, because...
>
>
> Hardware does not enforce coherency between the encrypted and
> unencrypted mapping for the same physical page. So, creating a
> two mapping of same physical address will lead a possible data
> corruption.
>
> Note, SME creates two mapping of the same physical address to perform
> in-place encryption of kernel and initrd images; this is a special case
> and APM documents steps on how to do this.
Ah, so that's what I was thinking about. But a single cache line would
never be used both encrypted and unencrypted, would it?
Paolo
next prev parent reply other threads:[~2018-08-24 15:50 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-20 22:11 Brijesh Singh
2018-08-21 8:39 ` Borislav Petkov
2018-08-21 14:37 ` Brijesh Singh
2018-08-21 15:19 ` Borislav Petkov
2018-08-21 16:07 ` Brijesh Singh
2018-08-22 8:14 ` Borislav Petkov
2018-08-22 15:00 ` Sean Christopherson
2018-08-22 20:11 ` Brijesh Singh
2018-08-23 11:26 ` Paolo Bonzini
2018-08-23 15:29 ` Sean Christopherson
2018-08-23 16:16 ` Paolo Bonzini
2018-08-24 15:41 ` Brijesh Singh
2018-08-24 15:50 ` Paolo Bonzini [this message]
2018-08-24 18:47 ` Brijesh Singh
2018-08-25 4:47 ` Borislav Petkov
2018-08-24 16:24 ` Sean Christopherson
2018-08-24 18:48 ` Brijesh Singh
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