Received-SPF: pass (google.com: domain of linux-crypto-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Wed, 16 Nov 2022 19:33:27 +0100
From:   Borislav Petkov <bp@alien8.de>
To:     "Kalra, Ashish" <ashish.kalra@amd.com>
Cc:     Vlastimil Babka <vbabka@suse.cz>, x86@kernel.org,
        linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
        linux-coco@lists.linux.dev, linux-mm@kvack.org,
        linux-crypto@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com,
        jroedel@suse.de, thomas.lendacky@amd.com, hpa@zytor.com,
        ardb@kernel.org, pbonzini@redhat.com, seanjc@google.com,
        vkuznets@redhat.com, jmattson@google.com, luto@kernel.org,
        dave.hansen@linux.intel.com, slp@redhat.com, pgonda@google.com,
        peterz@infradead.org, srinivas.pandruvada@linux.intel.com,
        rientjes@google.com, dovmurik@linux.ibm.com, tobin@ibm.com,
        michael.roth@amd.com, kirill@shutemov.name, ak@linux.intel.com,
        tony.luck@intel.com, marcorr@google.com,
        sathyanarayanan.kuppuswamy@linux.intel.com, alpergun@google.com,
        dgilbert@redhat.com, jarkko@kernel.org,
        "Kaplan, David" <David.Kaplan@amd.com>,
        Naoya Horiguchi <naoya.horiguchi@nec.com>,
        Miaohe Lin <linmiaohe@huawei.com>,
        Oscar Salvador <osalvador@suse.de>
Subject: Re: [PATCH Part2 v6 14/49] crypto: ccp: Handle the legacy TMR
 allocation when SNP is enabled
Message-ID: <Y3Us9wSX9DrWqCyq@zn.tnic>
References: <dc89b2f4-1053-91ac-aeac-bb3b25f9ebc7@amd.com>
 <Y2JS7kn8Q9P4rXso@zn.tnic>
 <c2ce6317-aa51-2a2b-2d75-ad1fd269f3fa@amd.com>
 <7882353e-2b13-d35a-b462-cef35ee56f51@suse.cz>
 <5b27a05e-09ad-9139-67b1-77b90731419f@amd.com>
 <9d9f1afe-c981-4df9-f012-89c4cb783cc3@amd.com>
 <973c6f79-38ad-aa30-bfec-c2a1c7db5d70@suse.cz>
 <8692e736-7518-d6d2-ae83-720e42e7a059@amd.com>
 <41b8c83e-2a1a-1dda-945e-99329ca8e7e9@suse.cz>
 <711e6027-1b4f-4aed-47a6-305396d05893@amd.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
In-Reply-To: <711e6027-1b4f-4aed-47a6-305396d05893@amd.com>
Precedence: bulk

On Wed, Nov 16, 2022 at 12:01:11PM -0600, Kalra, Ashish wrote:
> Ok, so i will work on implementing this leaked pages list and put it on a
> sev/snp associated structure.

See __sgx_sanitize_pages() and the poison list there, for an example.

> Also to add here, we will actually get a not-present #PF instead of the RMP
> violation #PF on writing to these leaked pages, as these pages would have
> been removed from the kernel direct map.

So if you do the list and still have the kernel raise a RMP fault for
those pages, traversing that list in the RMP handler to check whether
the page is there on it, should be a lot faster operation than doing the
#PF thing and removing them from the direct map.

And sorry for misleading you about UPM - we were thinking wrong
yesterday.

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette