From: Dave Hansen <dave.hansen@intel.com>
To: David Hildenbrand <david@redhat.com>,
"Roy, Patrick" <roypat@amazon.co.uk>
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Subject: Re: [PATCH v7 06/12] KVM: guest_memfd: add module param for disabling TLB flushing
Date: Thu, 25 Sep 2025 12:59:13 -0700 [thread overview]
Message-ID: <82bff1c4-987f-46cb-833c-bd99eaa46e7a@intel.com> (raw)
In-Reply-To: <c1875a54-0c87-450f-9370-29e7ec4fea3d@redhat.com>
On 9/25/25 12:20, David Hildenbrand wrote:
> On 25.09.25 20:27, Dave Hansen wrote:
>> On 9/24/25 08:22, Roy, Patrick wrote:
>>> Add an option to not perform TLB flushes after direct map manipulations.
>>
>> I'd really prefer this be left out for now. It's a massive can of worms.
>> Let's agree on something that works and has well-defined behavior before
>> we go breaking it on purpose.
>
> May I ask what the big concern here is?
It's not a _big_ concern. I just think we want to start on something
like this as simple, secure, and deterministic as possible.
Let's say that with all the unmaps that load_unaligned_zeropad() faults
start to bite us. It'll take longer to find them if the TLB isn't flushed.
Basically, it'll make the bad things happen sooner rather than later.
next prev parent reply other threads:[~2025-09-25 19:59 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-24 15:10 [PATCH v7 00/12] Direct Map Removal Support for guest_memfd Patrick Roy
2025-09-24 15:10 ` [PATCH v7 01/12] arch: export set_direct_map_valid_noflush to KVM module Patrick Roy
2025-09-24 15:10 ` [PATCH v7 02/12] x86/tlb: export flush_tlb_kernel_range " Patrick Roy
2025-09-24 15:10 ` [PATCH v7 03/12] mm: introduce AS_NO_DIRECT_MAP Patrick Roy
2025-09-24 15:22 ` [PATCH v7 04/12] KVM: guest_memfd: Add stub for kvm_arch_gmem_invalidate Roy, Patrick
2025-09-24 15:22 ` [PATCH v7 05/12] KVM: guest_memfd: Add flag to remove from direct map Roy, Patrick
2025-09-25 11:00 ` David Hildenbrand
2025-09-25 15:52 ` Roy, Patrick
2025-09-25 19:28 ` David Hildenbrand
2025-09-26 14:49 ` Patrick Roy
2025-09-24 15:22 ` [PATCH v7 06/12] KVM: guest_memfd: add module param for disabling TLB flushing Roy, Patrick
2025-09-25 11:02 ` David Hildenbrand
2025-09-25 15:50 ` Roy, Patrick
2025-09-25 19:32 ` David Hildenbrand
2025-09-25 18:27 ` Dave Hansen
2025-09-25 19:20 ` David Hildenbrand
2025-09-25 19:59 ` Dave Hansen [this message]
2025-09-25 20:13 ` David Hildenbrand
2025-09-26 9:46 ` Patrick Roy
2025-09-26 10:53 ` Will Deacon
2025-09-26 20:09 ` David Hildenbrand
2025-09-27 7:38 ` Patrick Roy
2025-09-29 10:20 ` David Hildenbrand
2025-10-11 14:32 ` Patrick Roy
2025-09-24 15:22 ` [PATCH v7 07/12] KVM: selftests: load elf via bounce buffer Roy, Patrick
2025-09-24 15:22 ` [PATCH v7 08/12] KVM: selftests: set KVM_MEM_GUEST_MEMFD in vm_mem_add() if guest_memfd != -1 Roy, Patrick
2025-09-24 15:22 ` [PATCH v7 09/12] KVM: selftests: Add guest_memfd based vm_mem_backing_src_types Roy, Patrick
2025-09-24 15:22 ` [PATCH v7 10/12] KVM: selftests: cover GUEST_MEMFD_FLAG_NO_DIRECT_MAP in existing selftests Roy, Patrick
2025-09-24 15:22 ` [PATCH v7 11/12] KVM: selftests: stuff vm_mem_backing_src_type into vm_shape Roy, Patrick
2025-09-24 15:22 ` [PATCH v7 12/12] KVM: selftests: Test guest execution from direct map removed gmem Roy, Patrick
2025-09-25 10:26 ` [PATCH v7 04/12] KVM: guest_memfd: Add stub for kvm_arch_gmem_invalidate David Hildenbrand
2025-09-25 10:25 ` [PATCH v7 03/12] mm: introduce AS_NO_DIRECT_MAP David Hildenbrand
2025-09-24 15:29 ` [PATCH v7 00/12] Direct Map Removal Support for guest_memfd Roy, Patrick
2025-09-24 15:38 ` David Hildenbrand
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