From: Paul Durrant <xadimgnik@gmail.com>
To: Sean Christopherson <seanjc@google.com>,
Paolo Bonzini <pbonzini@redhat.com>,
David Woodhouse <dwmw2@infradead.org>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
syzbot+352e553a86e0d75f5120@syzkaller.appspotmail.com,
Paul Durrant <pdurrant@amazon.com>,
David Woodhouse <dwmw@amazon.co.uk>,
Vitaly Kuznetsov <vkuznets@redhat.com>
Subject: Re: [PATCH 01/10] KVM: x86: Don't take kvm->lock when iterating over vCPUs in suspend notifier
Date: Tue, 21 Jan 2025 16:01:33 +0000 [thread overview]
Message-ID: <5cc5a8ef-b405-44f8-b799-ec9db39ac695@xen.org> (raw)
In-Reply-To: <20250118005552.2626804-2-seanjc@google.com>
On 18/01/2025 00:55, Sean Christopherson wrote:
> When queueing vCPU PVCLOCK updates in response to SUSPEND or HIBERNATE,
> don't take kvm->lock as doing so can trigger a largely theoretical
> deadlock, it is perfectly safe to iterate over the xarray of vCPUs without
> holding kvm->lock, and kvm->lock doesn't protect kvm_set_guest_paused() in
> any way (pv_time.active and pvclock_set_guest_stopped_request are
> protected by vcpu->mutex, not kvm->lock).
>
> Reported-by: syzbot+352e553a86e0d75f5120@syzkaller.appspotmail.com
> Closes: https://lore.kernel.org/all/677c0f36.050a0220.3b3668.0014.GAE@google.com
> Fixes: 7d62874f69d7 ("kvm: x86: implement KVM PM-notifier")
> Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Paul Durrant <paul@xen.org>
next prev parent reply other threads:[~2025-01-21 16:01 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-01-18 0:55 [PATCH 00/10] KVM: x86: pvclock fixes and cleanups Sean Christopherson
2025-01-18 0:55 ` [PATCH 01/10] KVM: x86: Don't take kvm->lock when iterating over vCPUs in suspend notifier Sean Christopherson
2025-01-21 16:01 ` Paul Durrant [this message]
2025-01-18 0:55 ` [PATCH 02/10] KVM: x86: Eliminate "handling" of impossible errors during SUSPEND Sean Christopherson
2025-01-21 16:03 ` Paul Durrant
2025-01-18 0:55 ` [PATCH 03/10] KVM: x86: Drop local pvclock_flags variable in kvm_guest_time_update() Sean Christopherson
2025-01-21 16:05 ` Paul Durrant
2025-01-18 0:55 ` [PATCH 04/10] KVM: x86: Set PVCLOCK_GUEST_STOPPED only for kvmclock, not for Xen PV clock Sean Christopherson
2025-01-21 16:42 ` Paul Durrant
2025-01-21 17:09 ` Sean Christopherson
2025-01-21 17:15 ` Paul Durrant
2025-01-21 18:32 ` Sean Christopherson
2025-01-18 0:55 ` [PATCH 05/10] KVM: x86: Don't bleed PVCLOCK_GUEST_STOPPED across PV clocks Sean Christopherson
2025-01-21 16:54 ` Paul Durrant
2025-01-21 17:11 ` Sean Christopherson
2025-01-18 0:55 ` [PATCH 06/10] KVM: x86/xen: Use guest's copy of pvclock when starting timer Sean Christopherson
2025-01-21 16:58 ` Paul Durrant
2025-01-21 18:45 ` Sean Christopherson
2025-01-18 0:55 ` [PATCH 07/10] KVM: x86: Pass reference pvclock as a param to kvm_setup_guest_pvclock() Sean Christopherson
2025-01-21 17:00 ` Paul Durrant
2025-01-18 0:55 ` [PATCH 08/10] KVM: x86: Remove per-vCPU "cache" of its reference pvclock Sean Christopherson
2025-01-21 17:03 ` Paul Durrant
2025-01-18 0:55 ` [PATCH 09/10] KVM: x86: Setup Hyper-V TSC page before Xen PV clocks (during clock update) Sean Christopherson
2025-01-20 14:49 ` Vitaly Kuznetsov
2025-01-21 15:44 ` Sean Christopherson
2025-01-21 15:59 ` Paul Durrant
2025-01-21 17:16 ` David Woodhouse
2025-01-21 17:30 ` Paul Durrant
2025-01-18 0:55 ` [PATCH 10/10] KVM: x86: Override TSC_STABLE flag for Xen PV clocks in kvm_guest_time_update() Sean Christopherson
2025-01-21 17:05 ` Paul Durrant
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