From: Cornelia Huck <cohuck@redhat.com>
To: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: linux-s390@vger.kernel.org, Janosch Frank <frankja@linux.ibm.com>,
kvm@vger.kernel.org, Marc Zyngier <marc.zyngier@arm.com>,
James Hogan <jhogan@kernel.org>,
David Hildenbrand <david@redhat.com>,
kvm-ppc@vger.kernel.org, linux-mips@vger.kernel.org,
Paul Mackerras <paulus@ozlabs.org>,
Christian Borntraeger <borntraeger@de.ibm.com>,
Xiao Guangrong <guangrong.xiao@gmail.com>,
Paolo Bonzini <pbonzini@redhat.com>,
kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v2 01/27] KVM: Call kvm_arch_memslots_updated() before updating memslots
Date: Wed, 6 Feb 2019 10:12:11 +0100 [thread overview]
Message-ID: <20190206101211.253cfbd9.cohuck@redhat.com> (raw)
In-Reply-To: <20190205205443.1059-2-sean.j.christopherson@intel.com>
On Tue, 5 Feb 2019 12:54:17 -0800
Sean Christopherson <sean.j.christopherson@intel.com> wrote:
> kvm_arch_memslots_updated() is at this point in time an x86-specific
> hook for handling MMIO generation wraparound. x86 stashes 19 bits of
> the memslots generation number in its MMIO sptes in order to avoid
> full page fault walks for repeat faults on emulated MMIO addresses.
> Because only 19 bits are used, wrapping the MMIO generation number is
> possible, if unlikely. kvm_arch_memslots_updated() alerts x86 that
> the generation has changed so that it can invalidate all MMIO sptes in
> case the effective MMIO generation has wrapped so as to avoid using a
> stale spte, e.g. a (very) old spte that was created with generation==0.
>
> Given that the purpose of kvm_arch_memslots_updated() is to prevent
> consuming stale entries, it needs to be called before the new generation
> is propagated to memslots. Invalidating the MMIO sptes after updating
> memslots means that there is a window where a vCPU could dereference
> the new memslots generation, e.g. 0, and incorrectly reuse an old MMIO
> spte that was created with (pre-wrap) generation==0.
>
> Fixes: e59dbe09f8e6 ("KVM: Introduce kvm_arch_memslots_updated()")
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> ---
> arch/mips/include/asm/kvm_host.h | 2 +-
> arch/powerpc/include/asm/kvm_host.h | 2 +-
> arch/s390/include/asm/kvm_host.h | 2 +-
> arch/x86/include/asm/kvm_host.h | 2 +-
> arch/x86/kvm/mmu.c | 4 ++--
> arch/x86/kvm/x86.c | 4 ++--
> include/linux/kvm_host.h | 2 +-
> virt/kvm/arm/mmu.c | 2 +-
> virt/kvm/kvm_main.c | 7 +++++--
> 9 files changed, 15 insertions(+), 12 deletions(-)
Not an x86 person, but I think that makes sense.
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
next prev parent reply other threads:[~2019-02-06 9:12 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-05 20:54 [PATCH v2 00/27] KVM: x86/mmu: Remove fast invalidate mechanism Sean Christopherson
2019-02-05 20:54 ` [PATCH v2 01/27] KVM: Call kvm_arch_memslots_updated() before updating memslots Sean Christopherson
2019-02-06 9:12 ` Cornelia Huck [this message]
2019-02-12 12:36 ` [PATCH v2 00/27] KVM: x86/mmu: Remove fast invalidate mechanism Paolo Bonzini
[not found] ` <20190205210137.1377-11-sean.j.christopherson@intel.com>
2019-08-13 16:04 ` [PATCH v2 11/27] KVM: x86/mmu: Zap only the relevant pages when removing a memslot Alex Williamson
2019-08-13 17:04 ` Sean Christopherson
2019-08-13 17:57 ` Alex Williamson
2019-08-13 19:33 ` Alex Williamson
2019-08-13 20:19 ` Sean Christopherson
2019-08-13 20:37 ` Paolo Bonzini
2019-08-13 21:14 ` Alex Williamson
2019-08-13 21:15 ` Paolo Bonzini
2019-08-13 22:10 ` Alex Williamson
2019-08-15 14:46 ` Sean Christopherson
2019-08-15 15:23 ` Alex Williamson
2019-08-15 16:00 ` Sean Christopherson
2019-08-15 18:16 ` Alex Williamson
2019-08-15 19:25 ` Sean Christopherson
2019-08-15 20:11 ` Alex Williamson
2019-08-19 16:03 ` Paolo Bonzini
2019-08-20 20:03 ` Sean Christopherson
2019-08-20 20:42 ` Alex Williamson
2019-08-20 21:02 ` Sean Christopherson
2019-08-21 19:08 ` Alex Williamson
2019-08-21 19:35 ` Alex Williamson
2019-08-21 20:30 ` Sean Christopherson
2019-08-23 2:25 ` Sean Christopherson
2019-08-23 22:05 ` Alex Williamson
2019-08-21 20:10 ` Sean Christopherson
2019-08-26 7:36 ` Tian, Kevin
2019-08-26 14:56 ` Sean Christopherson
2020-06-26 17:32 ` Sean Christopherson
2022-10-20 18:31 ` Alexander Graf
2022-10-20 20:37 ` Sean Christopherson
2022-10-20 21:06 ` Alexander Graf
2022-10-21 19:40 ` Sean Christopherson
2022-10-24 6:12 ` Alexander Graf
2022-10-24 15:55 ` Sean Christopherson
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