From: linmiaohe <linmiaohe@huawei.com>
To: Vitaly Kuznetsov <vkuznets@redhat.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Sean Christopherson <sean.j.christopherson@intel.com>,
Jim Mattson <jmattson@google.com>
Cc: "kvm list" <kvm@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
"the arch/x86 maintainers" <x86@kernel.org>,
"Radim Krčmář" <rkrcmar@redhat.com>,
"Wanpeng Li" <wanpengli@tencent.com>,
"Joerg Roedel" <joro@8bytes.org>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Ingo Molnar" <mingo@redhat.com>,
"Borislav Petkov" <bp@alien8.de>,
"H . Peter Anvin" <hpa@zytor.com>
Subject: Re: [PATCH] KVM: nVMX: set rflags to specify success in handle_invvpid() default case
Date: Mon, 3 Feb 2020 03:29:19 +0000 [thread overview]
Message-ID: <668e0827d62c489cbf52b7bc5d27ba9b@huawei.com> (raw)
Vitaly Kuznetsov <vkuznets@redhat.com> writes:
> Sean Christopherson <sean.j.christopherson@intel.com> writes:
>> On Thu, Jan 23, 2020 at 10:22:24AM -0800, Jim Mattson wrote:
>>> On Thu, Jan 23, 2020 at 1:54 AM Paolo Bonzini <pbonzini@redhat.com> wrote:
>>> >
>>> > On 23/01/20 10:45, Vitaly Kuznetsov wrote:
>>> > >>> SDM says that "If an
>>> > >>> unsupported INVVPID type is specified, the instruction fails."
>>> > >>> and this is similar to INVEPT and I decided to check what
>>> > >>> handle_invept() does. Well, it does BUG_ON().
>>> > >>>
>>> > >>> Are we doing the right thing in any of these cases?
>>> > >>
>>> > >> Yes, both INVEPT and INVVPID catch this earlier.
>>> > >>
>>> > >> So I'm leaning towards not applying Miaohe's patch.
>>> > >
>>> > > Well, we may at least want to converge on BUG_ON() for both
>>> > > handle_invvpid()/handle_invept(), there's no need for them to differ.
>>> >
>>> > WARN_ON_ONCE + nested_vmx_failValid would probably be better, if we
>>> > really want to change this.
>>> >
>>> > Paolo
>>>
>>> In both cases, something is seriously wrong. The only plausible
>>> explanations are compiler error or hardware failure. It would be nice
>>> to handle *all* such failures with a KVM_INTERNAL_ERROR exit to
>>> userspace. (I'm also thinking of situations like getting a VM-exit
>> for
>>>> INIT.)
>>
>> Ya. Vitaly and I had a similar discussion[*]. The idea we tossed
>> around was to also mark the VM as having encountered a KVM/hardware
>> bug so that the VM is effectively dead. That would also allow
>> gracefully handling bugs that are detected deep in the stack, i.e.
>> can't simply return 0 to get out to userspace.
>
>Yea, I was thinking about introducing a big hammer which would stop the whole VM as soon as possible to make it easier to debug such situations. Something like (not really tested):
>
Yea, please just ignore my origin patch and do what you want. :)
I'm sorry for reply in such a big day. I'am just backing from a really hard festival. :(
next reply other threads:[~2020-02-03 3:29 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-03 3:29 linmiaohe [this message]
2020-02-03 9:48 ` [PATCH] KVM: nVMX: set rflags to specify success in handle_invvpid() default case Vitaly Kuznetsov
-- strict thread matches above, loose matches on Subject: below --
2020-02-04 1:06 linmiaohe
2020-01-23 9:36 linmiaohe
2020-01-23 3:14 linmiaohe
2020-01-23 8:55 ` Vitaly Kuznetsov
2020-01-23 9:23 ` Paolo Bonzini
2020-01-23 9:45 ` Vitaly Kuznetsov
2020-01-23 9:54 ` Paolo Bonzini
2020-01-23 18:22 ` Jim Mattson
2020-01-23 23:01 ` Sean Christopherson
2020-01-24 10:53 ` Vitaly Kuznetsov
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