From: Sean Christopherson <seanjc@google.com>
To: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Maxim Levitsky <mlevitsk@redhat.com>,
kvm list <kvm@vger.kernel.org>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
LKML <linux-kernel@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Wanpeng Li <wanpengli@tencent.com>,
Kieran Bingham <kbingham@kernel.org>,
Jessica Yu <jeyu@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
"maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
<x86@kernel.org>, Joerg Roedel <joro@8bytes.org>,
Jim Mattson <jmattson@google.com>, Borislav Petkov <bp@alien8.de>,
Stefano Garzarella <sgarzare@redhat.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Ingo Molnar <mingo@redhat.com>
Subject: Re: [PATCH 2/3] KVM: x86: guest debug: don't inject interrupts while single stepping
Date: Tue, 16 Mar 2021 10:26:34 -0700 [thread overview]
Message-ID: <YFDqSisnoWD5wVdP@google.com> (raw)
In-Reply-To: <31c0bba9-0399-1f15-a59b-a8f035e366e8@siemens.com>
On Tue, Mar 16, 2021, Jan Kiszka wrote:
> On 16.03.21 17:50, Sean Christopherson wrote:
> > Rather than block all events in KVM, what about having QEMU "pause" the timer?
> > E.g. save MSR_TSC_DEADLINE and APIC_TMICT (or inspect the guest to find out
> > which flavor it's using), clear them to zero, then restore both when
> > single-stepping is disabled. I think that will work?
> >
>
> No one can stop the clock, and timers are only one source of interrupts.
> Plus they do not all come from QEMU, some also from KVM or in-kernel
> sources directly.
But are any other sources of interrupts a chronic problem? I 100% agree that
this would not be a robust solution, but neither is blocking events in KVM. At
least with this approach, the blast radius is somewhat contained.
> Would quickly become a mess.
Maybe, but it'd be Qemu's mess ;-)
next prev parent reply other threads:[~2021-03-16 17:28 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-15 22:10 [PATCH 0/3] KVM: my debug patch queue Maxim Levitsky
2021-03-15 22:10 ` [PATCH 1/3] scripts/gdb: rework lx-symbols gdb script Maxim Levitsky
2021-03-16 13:38 ` Jan Kiszka
2021-03-16 14:12 ` Maxim Levitsky
2021-03-15 22:10 ` [PATCH 2/3] KVM: x86: guest debug: don't inject interrupts while single stepping Maxim Levitsky
2021-03-15 23:37 ` Sean Christopherson
2021-03-16 9:16 ` Jan Kiszka
2021-03-16 10:59 ` Maxim Levitsky
2021-03-16 11:27 ` Jan Kiszka
2021-03-16 12:34 ` Maxim Levitsky
2021-03-16 13:46 ` Jan Kiszka
2021-03-16 14:34 ` Maxim Levitsky
2021-03-16 15:31 ` Jan Kiszka
[not found] ` <e2cd978e357155dbab21a523bb8981973bd10da7.camel@redhat.com>
2021-03-16 15:56 ` Jan Kiszka
2021-03-16 16:50 ` Sean Christopherson
2021-03-16 17:01 ` Jan Kiszka
2021-03-16 17:26 ` Sean Christopherson [this message]
2021-03-17 9:20 ` Jan Kiszka
2021-03-16 18:02 ` Maxim Levitsky
2021-03-18 16:02 ` Jan Kiszka
2021-03-18 12:21 ` Jan Kiszka
2021-03-16 10:55 ` Maxim Levitsky
2021-03-15 22:10 ` [PATCH 3/3] KVM: SVM: allow to intercept all exceptions for debug Maxim Levitsky
2021-03-16 8:32 ` Joerg Roedel
2021-03-16 10:51 ` Maxim Levitsky
2021-03-18 9:19 ` Joerg Roedel
2021-03-18 9:24 ` Maxim Levitsky
2021-03-18 15:47 ` Joerg Roedel
2021-03-18 16:35 ` Sean Christopherson
2021-03-18 16:41 ` Maxim Levitsky
2021-03-18 17:22 ` Sean Christopherson
2021-03-16 8:34 ` Borislav Petkov
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