From: David Hildenbrand <david@redhat.com>
To: "Roy, Patrick" <roypat@amazon.co.uk>,
"seanjc@google.com" <seanjc@google.com>
Cc: "tabba@google.com" <tabba@google.com>,
"ackerleytng@google.com" <ackerleytng@google.com>,
"pbonzini@redhat.com" <pbonzini@redhat.com>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"kvmarm@lists.linux.dev" <kvmarm@lists.linux.dev>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"rppt@kernel.org" <rppt@kernel.org>,
"will@kernel.org" <will@kernel.org>,
"vbabka@suse.cz" <vbabka@suse.cz>,
"Cali, Marco" <xmarcalx@amazon.co.uk>,
"Kalyazin, Nikita" <kalyazin@amazon.co.uk>,
"Thomson, Jack" <jackabt@amazon.co.uk>,
"Manwaring, Derek" <derekmn@amazon.com>
Subject: Re: [PATCH v5 00/12] Direct Map Removal Support for guest_memfd
Date: Thu, 28 Aug 2025 14:50:12 +0200 [thread overview]
Message-ID: <a777f88b-ea12-4aad-88da-2e7011e151b8@redhat.com> (raw)
In-Reply-To: <20250828093902.2719-1-roypat@amazon.co.uk>
On 28.08.25 11:39, Roy, Patrick wrote:
> [ based on kvm/next ]
>
> Unmapping virtual machine guest memory from the host kernel's direct map is a
> successful mitigation against Spectre-style transient execution issues: If the
> kernel page tables do not contain entries pointing to guest memory, then any
> attempted speculative read through the direct map will necessarily be blocked
> by the MMU before any observable microarchitectural side-effects happen. This
> means that Spectre-gadgets and similar cannot be used to target virtual machine
> memory. Roughly 60% of speculative execution issues fall into this category [1,
> Table 1].
>
As discussed, I'll be maintaining a guestmemfd-preview branch where I
just pile patch sets to see how it will all look together.
It's currently based on kvm/next where "stage 1" resides, and has "Add
NUMA mempolicy support for KVM guest-memfdAdd NUMA mempolicy support for
KVM guest-memfd" [1] applied.
There are some minor conflicts with [1] in the "KVM: guest_memfd: Add
flag to remove from direct map" patch, I tried to resolve them, let's
see if I messed up.
https://git.kernel.org/pub/scm/linux/kernel/git/david/linux.git/log/?h=guestmemfd-preview
[1] https://lkml.kernel.org/r/20250827175247.83322-2-shivankg@amd.com
--
Cheers
David / dhildenb
prev parent reply other threads:[~2025-08-28 12:50 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-08-28 9:39 [PATCH v5 00/12] Direct Map Removal Support for guest_memfd Roy, Patrick
2025-08-28 9:39 ` [PATCH v5 01/12] filemap: Pass address_space mapping to ->free_folio() Roy, Patrick
2025-08-28 9:39 ` [PATCH v5 02/12] arch: export set_direct_map_valid_noflush to KVM module Roy, Patrick
2025-08-28 10:07 ` Fuad Tabba
2025-09-01 13:47 ` Roy, Patrick
2025-08-28 9:39 ` [PATCH v5 03/12] mm: introduce AS_NO_DIRECT_MAP Roy, Patrick
2025-08-28 10:21 ` Fuad Tabba
2025-09-01 13:54 ` Roy, Patrick
2025-09-01 14:56 ` Roy, Patrick
2025-09-02 7:59 ` Fuad Tabba
2025-09-02 8:46 ` David Hildenbrand
2025-09-02 8:50 ` Fuad Tabba
2025-09-02 9:18 ` Roy, Patrick
2025-09-02 9:21 ` Fuad Tabba
2025-09-02 9:54 ` David Hildenbrand
2025-08-28 14:26 ` Mike Rapoport
2025-09-01 13:56 ` Roy, Patrick
2025-08-28 21:00 ` David Hildenbrand
2025-09-01 14:03 ` Roy, Patrick
2025-08-31 10:26 ` kernel test robot
2025-09-01 14:05 ` Roy, Patrick
2025-08-28 9:39 ` [PATCH v5 04/12] KVM: guest_memfd: Add flag to remove from direct map Roy, Patrick
2025-08-28 14:54 ` Mike Rapoport
2025-09-01 14:22 ` Roy, Patrick
2025-09-01 14:27 ` Mike Rapoport
2025-08-28 9:39 ` [PATCH v5 05/12] KVM: Documentation: describe GUEST_MEMFD_FLAG_NO_DIRECT_MAP Roy, Patrick
2025-08-28 10:27 ` David Hildenbrand
2025-09-01 14:30 ` Roy, Patrick
2025-09-01 14:43 ` David Hildenbrand
2025-08-28 9:39 ` [PATCH v5 06/12] KVM: selftests: load elf via bounce buffer Roy, Patrick
2025-08-28 9:39 ` [PATCH v5 07/12] KVM: selftests: set KVM_MEM_GUEST_MEMFD in vm_mem_add() if guest_memfd != -1 Roy, Patrick
2025-08-28 9:39 ` [PATCH v5 08/12] KVM: selftests: Add guest_memfd based vm_mem_backing_src_types Roy, Patrick
2025-08-28 9:39 ` [PATCH v5 09/12] KVM: selftests: stuff vm_mem_backing_src_type into vm_shape Roy, Patrick
2025-08-28 9:39 ` [PATCH v5 10/12] KVM: selftests: cover GUEST_MEMFD_FLAG_NO_DIRECT_MAP in mem conversion tests Roy, Patrick
2025-08-28 9:39 ` [PATCH v5 11/12] KVM: selftests: cover GUEST_MEMFD_FLAG_NO_DIRECT_MAP in guest_memfd_test.c Roy, Patrick
2025-08-28 10:26 ` David Hildenbrand
2025-08-28 9:39 ` [PATCH v5 12/12] KVM: selftests: Test guest execution from direct map removed gmem Roy, Patrick
2025-08-28 12:50 ` David Hildenbrand [this message]
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