From: Christian Borntraeger <borntraeger@de.ibm.com>
To: Sean Christopherson <sean.j.christopherson@intel.com>,
Paolo Bonzini <pbonzini@redhat.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Marc Zyngier <maz@kernel.org>, James Morse <james.morse@arm.com>,
Julien Thierry <julien.thierry.kdev@gmail.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
linux-arm-kernel@lists.infradead.org,
Huacai Chen <chenhc@lemote.com>,
Aleksandar Markovic <aleksandar.qemu.devel@gmail.com>,
linux-mips@vger.kernel.org, Paul Mackerras <paulus@ozlabs.org>,
kvm-ppc@vger.kernel.org, Janosch Frank <frankja@linux.ibm.com>,
David Hildenbrand <david@redhat.com>,
Cornelia Huck <cohuck@redhat.com>,
Claudio Imbrenda <imbrenda@linux.ibm.com>
Subject: Re: [RFC PATCH 0/3] KVM: Introduce "VM bugged" concept
Date: Thu, 24 Sep 2020 08:37:10 +0200 [thread overview]
Message-ID: <ae963411-0373-bb85-b921-d8dde67b7485@de.ibm.com> (raw)
In-Reply-To: <20200923224530.17735-1-sean.j.christopherson@intel.com>
On 24.09.20 00:45, Sean Christopherson wrote:
> This series introduces a concept we've discussed a few times in x86 land.
> The crux of the problem is that x86 has a few cases where KVM could
> theoretically encounter a software or hardware bug deep in a call stack
> without any sane way to propagate the error out to userspace.
>
> Another use case would be for scenarios where letting the VM live will
> do more harm than good, e.g. we've been using KVM_BUG_ON for early TDX
> enabling as botching anything related to secure paging all but guarantees
> there will be a flood of WARNs and error messages because lower level PTE
> operations will fail if an upper level operation failed.
>
> The basic idea is to WARN_ONCE if a bug is encountered, kick all vCPUs out
> to userspace, and mark the VM as bugged so that no ioctls() can be issued
> on the VM or its devices/vCPUs.
>
> RFC as I've done nowhere near enough testing to verify that rejecting the
> ioctls(), evicting running vCPUs, etc... works as intended.
I like the idea. Especially when we add a common "understanding" in QEMU
across all platforms. That would then even allow to propagate an error.
>
> Sean Christopherson (3):
> KVM: Export kvm_make_all_cpus_request() for use in marking VMs as
> bugged
> KVM: Add infrastructure and macro to mark VM as bugged
> KVM: x86: Use KVM_BUG/KVM_BUG_ON to handle bugs that are fatal to the
> VM
>
> arch/x86/kvm/svm/svm.c | 2 +-
> arch/x86/kvm/vmx/vmx.c | 23 ++++++++++++--------
> arch/x86/kvm/x86.c | 4 ++++
> include/linux/kvm_host.h | 45 ++++++++++++++++++++++++++++++++--------
> virt/kvm/kvm_main.c | 11 +++++-----
> 5 files changed, 61 insertions(+), 24 deletions(-)
>
next prev parent reply other threads:[~2020-09-24 6:37 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-23 22:45 [RFC PATCH 0/3] KVM: Introduce "VM bugged" concept Sean Christopherson
2020-09-23 22:45 ` [RFC PATCH 1/3] KVM: Export kvm_make_all_cpus_request() for use in marking VMs as bugged Sean Christopherson
2020-09-23 22:45 ` [RFC PATCH 2/3] KVM: Add infrastructure and macro to mark VM " Sean Christopherson
2020-09-23 22:45 ` [RFC PATCH 3/3] KVM: x86: Use KVM_BUG/KVM_BUG_ON to handle bugs that are fatal to the VM Sean Christopherson
2020-09-24 12:34 ` Vitaly Kuznetsov
[not found] ` <20200924181134.GB9649@linux.intel.com>
2020-09-25 9:50 ` Vitaly Kuznetsov
2020-09-25 17:12 ` Sean Christopherson
2020-09-25 21:06 ` Paolo Bonzini
2020-09-29 3:52 ` Sean Christopherson
2020-09-29 9:15 ` Paolo Bonzini
2020-09-24 6:37 ` Christian Borntraeger [this message]
2020-09-25 16:32 ` [RFC PATCH 0/3] KVM: Introduce "VM bugged" concept Marc Zyngier
2020-09-25 17:00 ` Sean Christopherson
2020-09-25 21:05 ` Paolo Bonzini
2020-09-29 9:27 ` Cornelia Huck
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