From: Sean Christopherson <sean.j.christopherson@intel.com>
To: 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,
Christian Borntraeger <borntraeger@de.ibm.com>,
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 3/3] KVM: x86: Use KVM_BUG/KVM_BUG_ON to handle bugs that are fatal to the VM
Date: Mon, 28 Sep 2020 20:52:57 -0700 [thread overview]
Message-ID: <20200929035257.GH31514@linux.intel.com> (raw)
In-Reply-To: <731dd323-8c66-77ff-cf15-4bbdea34bcf9@redhat.com>
On Fri, Sep 25, 2020 at 11:06:10PM +0200, Paolo Bonzini wrote:
> On 25/09/20 19:12, Sean Christopherson wrote:
> >> Do we actually want to prevent *all* ioctls? E.g. when 'vm bugged'
> >> condition is triggered userspace may want to extract some information to
> >> assist debugging but even things like KVM_GET_[S]REGS will just return
> >> -EIO. I'm not sure it is generally safe to enable *everything* (except
> >> for KVM_RUN which should definitely be forbidden) so maybe your approach
> >> is preferable.
> >
> > The answer to this probably depends on the answer to the first question of
> > when it's appropriate to use KVM_BUG(). E.g. if we limit usage to fatal or
> > dangrous cases, then blocking all ioctls() is probably the right thing do do.
>
> I think usage should be limited to dangerous cases, basically WARN_ON
> level. However I agree with Vitaly that KVM_GET_* should be allowed.
Makes sense.
On the topic of feedback from Vitaly, while dredging through my mailbox I
rediscovered his suggestion of kvm->kvm_internal_bug (or maybe just
kvm->internal_bug) instead of kvm->vm_bugged[*]. Like past me, I like the
"internal" variants better.
[*] https://lkml.kernel.org/r/20190930153358.GD14693@linux.intel.com
> The other question is whether to return -EIO or KVM_EXIT_INTERNAL_ERROR.
> The latter is more likely to be handled already by userspace.
And probably less confusing for unsuspecting users. E.g. -EIO is most
likely to be interpreted as "I screwed up", whereas KVM_EXIT_INTERNAL_ERROR
will correctly be read as "KVM screwed up".
WARNING: multiple messages have this Message-ID (diff)
From: Sean Christopherson <sean.j.christopherson@intel.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Cornelia Huck <cohuck@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Janosch Frank <frankja@linux.ibm.com>,
kvm@vger.kernel.org, Suzuki K Poulose <suzuki.poulose@arm.com>,
Marc Zyngier <maz@kernel.org>, Joerg Roedel <joro@8bytes.org>,
David Hildenbrand <david@redhat.com>,
linux-kernel@vger.kernel.org, kvm-ppc@vger.kernel.org,
linux-mips@vger.kernel.org, Paul Mackerras <paulus@ozlabs.org>,
Christian Borntraeger <borntraeger@de.ibm.com>,
Aleksandar Markovic <aleksandar.qemu.devel@gmail.com>,
James Morse <james.morse@arm.com>,
linux-arm-kernel@lists.infradead.org,
Huacai Chen <chenhc@lemote.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Claudio Imbrenda <imbrenda@linux.ibm.com>,
Julien Thierry <julien.thierry.kdev@gmail.com>,
Jim Mattson <jmattson@google.com>
Subject: Re: [RFC PATCH 3/3] KVM: x86: Use KVM_BUG/KVM_BUG_ON to handle bugs that are fatal to the VM
Date: Mon, 28 Sep 2020 20:52:57 -0700 [thread overview]
Message-ID: <20200929035257.GH31514@linux.intel.com> (raw)
In-Reply-To: <731dd323-8c66-77ff-cf15-4bbdea34bcf9@redhat.com>
On Fri, Sep 25, 2020 at 11:06:10PM +0200, Paolo Bonzini wrote:
> On 25/09/20 19:12, Sean Christopherson wrote:
> >> Do we actually want to prevent *all* ioctls? E.g. when 'vm bugged'
> >> condition is triggered userspace may want to extract some information to
> >> assist debugging but even things like KVM_GET_[S]REGS will just return
> >> -EIO. I'm not sure it is generally safe to enable *everything* (except
> >> for KVM_RUN which should definitely be forbidden) so maybe your approach
> >> is preferable.
> >
> > The answer to this probably depends on the answer to the first question of
> > when it's appropriate to use KVM_BUG(). E.g. if we limit usage to fatal or
> > dangrous cases, then blocking all ioctls() is probably the right thing do do.
>
> I think usage should be limited to dangerous cases, basically WARN_ON
> level. However I agree with Vitaly that KVM_GET_* should be allowed.
Makes sense.
On the topic of feedback from Vitaly, while dredging through my mailbox I
rediscovered his suggestion of kvm->kvm_internal_bug (or maybe just
kvm->internal_bug) instead of kvm->vm_bugged[*]. Like past me, I like the
"internal" variants better.
[*] https://lkml.kernel.org/r/20190930153358.GD14693@linux.intel.com
> The other question is whether to return -EIO or KVM_EXIT_INTERNAL_ERROR.
> The latter is more likely to be handled already by userspace.
And probably less confusing for unsuspecting users. E.g. -EIO is most
likely to be interpreted as "I screwed up", whereas KVM_EXIT_INTERNAL_ERROR
will correctly be read as "KVM screwed up".
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
WARNING: multiple messages have this Message-ID (diff)
From: Sean Christopherson <sean.j.christopherson@intel.com>
To: 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,
Christian Borntraeger <borntraeger@de.ibm.com>,
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 3/3] KVM: x86: Use KVM_BUG/KVM_BUG_ON to handle bugs that are fatal to the VM
Date: Tue, 29 Sep 2020 03:52:57 +0000 [thread overview]
Message-ID: <20200929035257.GH31514@linux.intel.com> (raw)
In-Reply-To: <731dd323-8c66-77ff-cf15-4bbdea34bcf9@redhat.com>
On Fri, Sep 25, 2020 at 11:06:10PM +0200, Paolo Bonzini wrote:
> On 25/09/20 19:12, Sean Christopherson wrote:
> >> Do we actually want to prevent *all* ioctls? E.g. when 'vm bugged'
> >> condition is triggered userspace may want to extract some information to
> >> assist debugging but even things like KVM_GET_[S]REGS will just return
> >> -EIO. I'm not sure it is generally safe to enable *everything* (except
> >> for KVM_RUN which should definitely be forbidden) so maybe your approach
> >> is preferable.
> >
> > The answer to this probably depends on the answer to the first question of
> > when it's appropriate to use KVM_BUG(). E.g. if we limit usage to fatal or
> > dangrous cases, then blocking all ioctls() is probably the right thing do do.
>
> I think usage should be limited to dangerous cases, basically WARN_ON
> level. However I agree with Vitaly that KVM_GET_* should be allowed.
Makes sense.
On the topic of feedback from Vitaly, while dredging through my mailbox I
rediscovered his suggestion of kvm->kvm_internal_bug (or maybe just
kvm->internal_bug) instead of kvm->vm_bugged[*]. Like past me, I like the
"internal" variants better.
[*] https://lkml.kernel.org/r/20190930153358.GD14693@linux.intel.com
> The other question is whether to return -EIO or KVM_EXIT_INTERNAL_ERROR.
> The latter is more likely to be handled already by userspace.
And probably less confusing for unsuspecting users. E.g. -EIO is most
likely to be interpreted as "I screwed up", whereas KVM_EXIT_INTERNAL_ERROR
will correctly be read as "KVM screwed up".
next prev parent reply other threads:[~2020-09-29 3:53 UTC|newest]
Thread overview: 46+ 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 ` Sean Christopherson
2020-09-23 22:45 ` 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 ` Sean Christopherson
2020-09-23 22:45 ` 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 ` Sean Christopherson
2020-09-23 22:45 ` 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
2020-09-23 22:45 ` Sean Christopherson
2020-09-23 22:45 ` Sean Christopherson
2020-09-24 12:34 ` Vitaly Kuznetsov
2020-09-24 12:34 ` Vitaly Kuznetsov
2020-09-24 12:34 ` Vitaly Kuznetsov
2020-09-24 18:11 ` Sean Christopherson
2020-09-25 9:50 ` Vitaly Kuznetsov
2020-09-25 9:50 ` Vitaly Kuznetsov
2020-09-25 9:50 ` Vitaly Kuznetsov
2020-09-25 17:12 ` Sean Christopherson
2020-09-25 17:12 ` Sean Christopherson
2020-09-25 17:12 ` Sean Christopherson
2020-09-25 21:06 ` Paolo Bonzini
2020-09-25 21:06 ` Paolo Bonzini
2020-09-25 21:06 ` Paolo Bonzini
2020-09-29 3:52 ` Sean Christopherson [this message]
2020-09-29 3:52 ` Sean Christopherson
2020-09-29 3:52 ` Sean Christopherson
2020-09-29 9:15 ` Paolo Bonzini
2020-09-29 9:15 ` Paolo Bonzini
2020-09-29 9:15 ` Paolo Bonzini
2020-09-24 6:37 ` [RFC PATCH 0/3] KVM: Introduce "VM bugged" concept Christian Borntraeger
2020-09-24 6:37 ` Christian Borntraeger
2020-09-24 6:37 ` Christian Borntraeger
2020-09-25 16:32 ` Marc Zyngier
2020-09-25 16:32 ` Marc Zyngier
2020-09-25 16:32 ` Marc Zyngier
2020-09-25 17:00 ` Sean Christopherson
2020-09-25 17:00 ` Sean Christopherson
2020-09-25 17:00 ` Sean Christopherson
2020-09-25 21:05 ` Paolo Bonzini
2020-09-25 21:05 ` Paolo Bonzini
2020-09-25 21:05 ` Paolo Bonzini
2020-09-29 9:27 ` Cornelia Huck
2020-09-29 9:27 ` Cornelia Huck
2020-09-29 9:27 ` Cornelia Huck
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