From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: David Hildenbrand <david@redhat.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>,
Andy Lutomirski <luto@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Sean Christopherson <seanjc@google.com>,
Jim Mattson <jmattson@google.com>,
David Rientjes <rientjes@google.com>,
"Edgecombe, Rick P" <rick.p.edgecombe@intel.com>,
"Kleen, Andi" <andi.kleen@intel.com>,
"Yamahata, Isaku" <isaku.yamahata@intel.com>,
x86@kernel.org, kvm@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Oscar Salvador <osalvador@suse.de>,
Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Subject: Re: [RFCv1 7/7] KVM: unmap guest memory using poisoned pages
Date: Fri, 9 Apr 2021 17:12:11 +0300 [thread overview]
Message-ID: <20210409141211.wfbyzflj7ygtx7ex@box.shutemov.name> (raw)
In-Reply-To: <5ef83789-ffa5-debd-9ea2-50d831262237@redhat.com>
On Fri, Apr 09, 2021 at 03:50:42PM +0200, David Hildenbrand wrote:
> > > 3. Allow selected users to still grab the pages (esp. KVM to fault them into
> > > the page tables).
> >
> > As long as fault leads to non-present PTEs we are fine. Usespace still may
> > want to mlock() some of guest memory. There's no reason to prevent this.
>
> I'm curious, even get_user_pages() will lead to a present PTE as is, no? So
> that will need modifications I assume. (although I think it fundamentally
> differs to the way get_user_pages() works - trigger a fault first, then
> lookup the PTE in the page tables).
For now, the patch has two step poisoning: first fault in, on the add to
shadow PTE -- poison. By the time VM has chance to use the page it's
poisoned and unmapped from the host userspace.
--
Kirill A. Shutemov
next prev parent reply other threads:[~2021-04-09 14:12 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-02 15:26 [RFCv1 0/7] TDX and guest memory unmapping Kirill A. Shutemov
2021-04-02 15:26 ` [RFCv1 1/7] x86/mm: Move force_dma_unencrypted() to common code Kirill A. Shutemov
2021-04-02 15:26 ` [RFCv1 2/7] x86/kvm: Introduce KVM memory protection feature Kirill A. Shutemov
2021-04-08 9:52 ` Borislav Petkov
2021-04-09 13:36 ` Kirill A. Shutemov
2021-04-09 14:37 ` Borislav Petkov
2021-04-02 15:26 ` [RFCv1 3/7] x86/kvm: Make DMA pages shared Kirill A. Shutemov
2021-04-02 15:26 ` [RFCv1 4/7] x86/kvm: Use bounce buffers for KVM memory protection Kirill A. Shutemov
2021-04-02 15:26 ` [RFCv1 5/7] x86/kvmclock: Share hvclock memory with the host Kirill A. Shutemov
2021-04-02 15:26 ` [RFCv1 6/7] x86/realmode: Share trampoline area if KVM memory protection enabled Kirill A. Shutemov
2021-04-02 15:26 ` [RFCv1 7/7] KVM: unmap guest memory using poisoned pages Kirill A. Shutemov
2021-04-06 7:44 ` David Hildenbrand
2021-04-06 10:50 ` Kirill A. Shutemov
2021-04-06 14:33 ` Dave Hansen
2021-04-06 14:57 ` David Hildenbrand
2021-04-07 13:16 ` Kirill A. Shutemov
2021-04-07 13:31 ` Christophe de Dinechin
2021-04-07 14:09 ` Andi Kleen
2021-04-07 14:09 ` David Hildenbrand
2021-04-07 14:36 ` Kirill A. Shutemov
2021-04-06 17:52 ` Tom Lendacky
2021-04-07 14:55 ` David Hildenbrand
2021-04-07 15:10 ` Andi Kleen
2021-04-09 13:33 ` Kirill A. Shutemov
2021-04-09 13:50 ` David Hildenbrand
2021-04-09 14:12 ` Kirill A. Shutemov [this message]
2021-04-09 14:18 ` David Hildenbrand
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