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From: Sean Christopherson <seanjc@google.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
	isaku.yamahata@intel.com, David Matlack <dmatlack@google.com>,
	peterx@redhat.com
Subject: Re: [PATCH 02/16] KVM: x86: clamp host mapping level to max_level in kvm_mmu_max_mapping_level
Date: Fri, 13 Aug 2021 16:28:40 +0000	[thread overview]
Message-ID: <YRaduAFaHZ+w643k@google.com> (raw)
In-Reply-To: <20210807134936.3083984-3-pbonzini@redhat.com>

On Sat, Aug 07, 2021, Paolo Bonzini wrote:
> This patch started as a way to make kvm_mmu_hugepage_adjust a bit simpler,
> in preparation for switching it to struct kvm_page_fault, but it does
> fix a microscopic bug in zapping collapsible PTEs.

I think this also fixes a bug where userspace backs guest memory with a 1gb hugepage
but only assigns a subset of the page to the guest.  1gb pages would be disallowed
by the memslot, but not 2mb.  kvm_mmu_max_mapping_level() would fall through to the
host_pfn_mapping_level() logic, see the 1gb huge, and map the whole thing into the
guest.  I can't imagine any userspace would actually do something like that, but the
failure mode is serious enough that it warrants a Fixes: + Cc: stable@.

  reply	other threads:[~2021-08-13 16:28 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-07 13:49 [PATCH 00/16] KVM: x86: pass arguments on the page fault path via struct kvm_page_fault Paolo Bonzini
2021-08-07 13:49 ` [PATCH 01/16] KVM: MMU: pass unadulterated gpa to direct_page_fault Paolo Bonzini
2021-09-01 22:54   ` Sean Christopherson
2021-08-07 13:49 ` [PATCH 02/16] KVM: x86: clamp host mapping level to max_level in kvm_mmu_max_mapping_level Paolo Bonzini
2021-08-13 16:28   ` Sean Christopherson [this message]
2021-08-07 13:49 ` [PATCH 03/16] KVM: MMU: Introduce struct kvm_page_fault Paolo Bonzini
2021-08-07 13:49 ` [PATCH 04/16] KVM: MMU: change mmu->page_fault() arguments to kvm_page_fault Paolo Bonzini
2021-08-07 13:49 ` [PATCH 05/16] KVM: MMU: change direct_page_fault() " Paolo Bonzini
2021-08-07 13:49 ` [PATCH 06/16] KVM: MMU: change page_fault_handle_page_track() " Paolo Bonzini
2021-09-01 23:04   ` Sean Christopherson
2021-08-07 13:49 ` [PATCH 07/16] KVM: MMU: change try_async_pf() " Paolo Bonzini
2021-09-01 23:05   ` Sean Christopherson
2021-08-07 13:49 ` [PATCH 08/16] KVM: MMU: change handle_abnormal_pfn() " Paolo Bonzini
2021-09-01 23:15   ` Sean Christopherson
2021-08-07 13:49 ` [PATCH 09/16] KVM: MMU: change __direct_map() " Paolo Bonzini
2021-08-07 13:49 ` [PATCH 10/16] KVM: MMU: change FNAME(fetch)() " Paolo Bonzini
2021-08-07 13:49 ` [PATCH 11/16] KVM: MMU: change kvm_tdp_mmu_map() " Paolo Bonzini
2021-08-07 13:49 ` [PATCH 12/16] KVM: MMU: change tdp_mmu_map_handle_target_level() " Paolo Bonzini
2021-08-07 13:49 ` [PATCH 13/16] KVM: MMU: change fast_page_fault() " Paolo Bonzini
2021-08-07 13:49 ` [PATCH 14/16] KVM: MMU: change kvm_mmu_hugepage_adjust() " Paolo Bonzini
2021-08-07 13:49 ` [PATCH 15/16] KVM: MMU: change disallowed_hugepage_adjust() " Paolo Bonzini
2021-08-07 13:49 ` [PATCH 16/16] KVM: MMU: change tracepoints " Paolo Bonzini
2021-09-01 23:28   ` Sean Christopherson
2021-08-12 17:44 ` [PATCH 00/16] KVM: x86: pass arguments on the page fault path via struct kvm_page_fault David Matlack

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